Volume with Abstracts

Geologic Problem Solving with Microfossils An International Conference in Memory of Garry D. Jones

Rice University Houston, Texas USA March 6-11, 2005

Abstracts Volume with Program A publication of NAMS (North American Micropaleontology Section) - a special interest section of SEPM (Society for Sedimentary Geology)

Editors Ron F. Waszczak Thomas D. Demchuk

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Geologic Problem Solving with Microfossils Conference Organizing Committee

General Chair Thomas D. Demchuk ConocoPhillips

Technical Program Chair Ron F. Waszczak ConocoPhillips

Program Committee Co-Chairs Brian J. O’Neill Shell International Exploration and Production Inc.

Shirley E. van Heck Shell International Exploration and Production Inc.

Martin B. Farley University of North Carolina at Pembroke

Conference Advisory Committee Roger J. Witmer UNOCAL 76

Nancy L. Engelhardt-Moore Devon Energy Corporation

Robert S. Nail Nail Geosciences

James H. Gamber BP America

Jason Lundquist BP America

Peter P. McLaughlin, Jr. Delaware Geological Survey, University of Delaware

Miriam E. Katz Rutgers University

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NAMS (North American Micropaleontology Section) SEPM President Peter P. McLaughlin, Jr. Delaware Geological Survey, University of Delaware

Secretary Robert S. Nail Nail Geosciences

Treasurer Martin B. Farley University of North Carolina at Pembroke

President Elect James H. Gamber BP America

Past President Miriam E. Katz Rutgers University

Newsletter Editor Jason Lundquist BP America

SEPM (Society for Sedimentary Geology) Headquarters Staff Executive Director Howard Harper Business Manager Theresa Scott Publications Coordinator Kris A. Farnsworth Events and Conference Manager Judy Tarpley Membership Services Michele Woods

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A TRIBUTE TO GARRY DAVIS JONES November 24, 1952 —May 6, 2004 On May 6, 2004, the world of applied paleontology dimmed with the premature death of Garry D. Jones at the age of 51. Garry was a dynamo in oil industry biostratigraphy moving it forward even during the difficult economic times of the 1990s.

Garry received a Bachelor’s degree from Catawba College in North Carolina in 1974. He went on to study benthic foraminiferal ecology with Charlie Ross receiving a Masters of Science degree from Western Washington University in 1977.

Garry then returned to the East Coast, completing a Ph.D. under Fred Swain at the University of Delaware.

Garry’s dissertation “Foraminiferal Paleontology and Geology of Lower Claibornian Rocks, Inner Coastal Plain, North Carolina” formed the basis of North Carolina Geological Survey Bulletin 8 published in 1983.

In 1981 Garry joined UNOCAL as a research biostratigrapher in Brea, California. At UNOCAL he was an active participant in the Woods Hole Oceanographic Institute’s Integrated Cenozoic Biostratigraphy program and also the University of South Carolina’s Gulf of Mexico Foraminiferal Morphometrics and Isotope project. It was at Brea that Garry worked on North Sea data and published on a paleoecological model of late Paleocene agglutinated foraminifera using the paleo-slope transect approach. Using microfossils to solve geologic problems would be a continuing theme in Garry’s work. He wrote and coauthored many UNOCAL technical memoranda over the course of his career.

In 1992 Garry moved to Lafayette, Louisiana, and plunged into Gulf Coast biostratigraphy with both feet. Garry built a strong network of experienced workers to quickly come up to speed on the massive knowledge base of the Gulf Coast Cenozoic. He employed the expertise of Felix Gradstein and the RASC program to glean which were the most reliable bioevents in this challenging section. Garry was also a moving force behind the effort to compile a Rosetta stone for the confusing array of formal and informal synonymies used in industry. The 1999 Picou et al. publication “Gulf of Mexico Basin biostratigraphic index microfossils, A geoscientist’s guide, Foraminifers and nannofossils, Oligocene through Pleistocene, Parts I and II: Foraminifers” would probably not have come to pass without Garry’s persistent urging.

In 1996 Garry’s good friend and colleague Anthony Gary left UNOCAL to found the Technical Alliance for Computational Stratigraphy (TACS) and industry consortium to complete the development of the Integrated Paleontologic System (IPS). Garry became a champion for this tool, publishing several papers and abstracts on this topic (Jones et al. 1996; Jones, 1997; Jones et al, 2002; Jones et al, 2003, Olson et al., 2003). In 2000, Garry moved to Sugar Land, Texas, and handled all of UNOCAL’s deepwater exploration biostratigraphy.

Garry was also an excellent teacher. Beginning in 1999 he (with colleagues from Shell, Chevron and Texaco) taught short courses for industry geoscientists and university students on the application of biostratigraphy to the oil industry. The course was offered 10 times (including Oslo and London offerings in 2002) and received very good reviews. In 2000 Garry became an adjunct professor at Rice University, teaching a semester long Applied Biostratigraphy course that year, and again in 2002.

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Garry was a very active member of the North American Micropaleontology Section of SEPM, serving as President 2001-2002. At the time of his death Garry was moving full steam ahead on all fronts: Though deeply involved with UNOCAL drilling wells, he was the organizing force behind the upcoming NAMS hosted conference “Geologic Problem Solving with Microfossils” (cosponsored by the Cushman Foundation) to be held March 6-11, 2005, at Rice University, Houston, Texas. He was also less than a month away from teaching the biostratigraphy short course at the University of Massachuetts at Amherst and was preparing to teach his Rice class in the fall of 2004.

Garry displayed the same enthusiasm in his private life that he did in his profession. He was an avid golfer from early childhood through adulthood. He was a devoted husband and father to his family and a wonderful friend to many of us. A fund has been established to help cover education costs for his two young daughters, Callie and Maggie: The Garry Jones Children’s Educational Fund, P.O. Box 17985, Sugar Land, TX 77496 (non tax-deductible). You may also choose to donate to the Garry Jones Memorial Fund for NAMS Student Research, by mailing a check payable to SEPM Foundation (write fund name on check) to: Martin Farley, NAMS Treasurer, University of North Carolina at Pembroke, Geology/Geography Dept., BA206, Pembroke, NC 28372 (taxdeductible).

Jones, G.D. 1983. Foraminiferal biostratigraphy and depositional history of the middle Eocene rocks of the Coastal Plain of North Carolina. Special Publication 8. North Carolina Geological Survey: Raleigh.

Jones, G.D., 1997. Interpreting sequence stratigraphic architecture from biostratigraphic signatures: Case studies from the northern Gulf of Mexico, GCAGS Transactions, v. 47, p. 654.

Jones, G.D., A. Gary, and V. Waters, 1996. Applying the integrated paleontological system: Interpreting sequence stratigraphic architecture from microfossil signatures, Oligocene to Pleistocene section, Gulf of Mexico, In J.E. Repetski, ed., Sixth North American Paleontological Convention Abstracts of Papers, Paleontological Society Special Pub. No. 3, p. 202.

Jones, G.D., A.C. Gary, B. Kohl, R.H. Fillon, H.H. Roberts, B.J. O’Neill and R.J. Witmer, 2003. Biostratigraphic techniques for locating the position of ancient shelf margins: Examples from the Neogene of the Northern Gulf of Mexico, In H.H. Roberts, N.C. Rosen, R.H. Fillon and J.B. Anderson (eds.), Shelf Margin Deltas and Linked Down Slope Petroleum Systems: Global Significance and Future Exploration Potential, 23rd Annual GCSSEPM Foundation Bob F. Perkins Research Conference, p.767-784.

Olson, H.C., A.C. Gary and G.D. Jones, 2003. Similarity curves as indicators of stratigraphic discontinuities, In H.C. Olson and R.M. Leckie (eds.), Micropaleontologic proxies for sea-level change and stratigraphic continuities, SEPM (Society for Sedimentary Geology), Sp. Pub. 75, p. 89-96.

Brian J. O’Neill, Shell International Exploration and Production Inc. P.O. Box 51510 New Orleans, LA 70151-1510 (Reprinted with permission of author and Journal of Foraminiferal Research.

Modified slightly from the original announcement in the J.F.R., v. 34, no. 4, pp. 327-328

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GEOLOGIC PROBLEM SOLVING WITH MICROFOSSILS PROGRAM AND SCHEDULE Sunday, 6-March 3:00-7:00 pm CONFERENCE CHECK-IN: WARWICK HOTEL – LOBBY 7:00-9:00 pm ICE-BREAKER: WARWICK HOTEL – TERRACE LOUNGE

~ ORAL PROGRAM ~ Monday, 7-March 7:15 am 8:00 am

Coffee, RICE CAMPUS – HAMMAN HALL Oral Sessions, Welcome EUSTACY AND TECTONICS

8:05 am Invited keynote: John B. Anderson Antarctic Ice Sheet Evolution and the Cenozoic Eustatic Record……………………...p. 1 8:25 am David K. Watkins; Ryan Weber Reworking of Eocene Nannofossils in CIROS-1 and the Initiation of Antarctic Coastal Glaciation……………………………………………………………………..…...……p. 2 8:45 am A. Husinec; B. Sokac Shallow Marine Benthic Biota as Proxy for Sea-Level and Sedimentary History, Carbonates of Bahama-Type Mesozoic Platform, Southern Croatia………………...…p. 3 9:05 am C. N. Denison Modification of Palynomorph Assemblages by Ravinement Processes in a Mesotidal Barred Coastal Environment……………………………………………………………p. 4 9:25 am Sandra Crespo de Cabrera Early - Middle Miocene Transgressive - Regressive Cycle in Eastern Venezuela Basin: Foraminiferal Response to Relative Sea-Level Changes…………………………….…p. 5 9:45 am

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10:05 am Jaime Rueda-Gaxiola Palynomorphs: A Tool for Solving the Geologic Problem of the Gulf of Mexico and its Mexican Petroleum Sub-Basins Origin…………………………………………….......p. 6 10:25 am Walter W. Wornardt Jr. Microfossil Abundance and Diversity Histograms: The Key to Interpreting Maximum Flooding Surface Condensed Sections, Source Rocks and Seals………………………p. 7 10:45 am Richard H. Fluegeman Early Oligocene Benthic Foraminiferal Paleoecology and Sequence Stratigraphy in the Eastern Gulf Coastal Plain……………………………………………………………...p. 8 11:05 am R. Catanzariti; A. Cerrina Feroni; N. Levi; G. Ottria The Northern Apennines (Italy): A Perfect Mountain Belt for Solving Geological Problems with Microfossils…………………………………………………………….p. 9 11:25 am J. F. Longoria; Rogelio Monreal Carrera The Use of Planktonic Microfossils to Resolve Tectonic and Paleogeographic Uncertainties in the Lower Cretaceous of Sonora, Mexico…………………………...p. 10 11:45 am – 1:15 pm Lunch, LEY CENTER, GRAND HALL – Poster Exhibit Area Oral Sessions (continued), HAMMAN HALL RESERVOIRS AND DRILLING 1:15 pm Invited Keynote, Michael D. Simmons The Role of Biostratigraphy in Subsurface Sequence Stratigraphic Models…………p. 11 1:35 pm Lea Holstein; David J. Jutson A Biozonation for Controlled Top Reservoir Approach: Avoiding Mud Loss and Stuck Drill Pipe in the Danish Chalk Fields…………………………………………………p. 12 1:55 pm P. P. McLaughlin; R. N. Benson Application of Micropaleontology to Water Resource Problems: Aquifer Stratigraphy in the Coastal Plain of Delaware (Middle Atlantic Region, United States)…………......p. 13 2:15 pm Gregory P. Wahlman; Douglas R. Tasker Wolfcampian (Lower Permian) Carbonate Microfacies and Fusulinid Biostratigraphy along Eastern Central Basin Platform, West Texas………………….………………..p. 14 2:35 pm Alex Cullum; Iain Prince Biostratigraphy while Drilling (BWD): How Well Site Biostratigraphy is Helping Statoil to Drill Better Wells and Save Money in the Norwegian Offshore Sector…...………p. 15 ____________________________________ Geologic Problem Solving with Microfossils

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2:55 pm

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3:15 pm Paul R. Marshall; Elisabeth A. Nairn Developments in Biosteering Techniques and their Application to Solving ReservoirScale, Subsurface Geological/Geophysical Problems………………………….……..p. 16 3:35 pm M. Rogerson; H. Tijbosch; T. J. Kouwenhoven; G. J. van der Zwaan; B. J. O'Neill; C. J. van der Zwan; G. Postma; K. Kleverlaan Recognition of Sub-Facies within a Miocene Canyon and Fan System by Use of Benthic Foraminiferal Assemblages……………………………………………..…………….p. 17 3:55 pm Craig Harvey; Nicholas Holmes New Microfacies Methods and Applications in Mudrock Characterization and Reservoir Modelling from the Early Paleocene of Mid Norway……………………….………..p. 18 4:15 pm Iain Prince, Arnfinn Kjøsavik Barriers, Baffles and Biostratigraphy: The Integration of Production and Geological Data to Maximize Recovery from Glitne, the Smallest Stand-Alone Field in Norway…….p. 19 4:35 pm Richard H. Fillon Micropaleontology and Lithology of Deep-Water Sediments: Application of Multiple Overlapping Foraminiferal Litho-Biofacies Theory to Cuttings-Based Analysis of Reservoir Properties…………………………………………………………………...p. 20 5:00 pm -7:00 pm

POSTER EXHIBITION AND MINI ICE-BREAKER LEY CENTER, GRAND HALL – Poster Exhibit Area

Tuesday, 8-March 7:15 am 8:00 am

Coffee, RICE CAMPUS – HAMMAN HALL Oral Sessions, Welcome TOOLS AND TECHNIQUES

8:05 am Invited keynote: Ernest A. Mancini Establishment of a Chronostratigraphic Framework for Stratal Correlation, Sedimentary Basin Geohistory Reconstruction, and Petroleum Exploration, Northern Gulf of Mexico…………………………………………………………………………..….....p. 21 8:25 am Barrie Dale; Amy L. Dale; Iain Prince; Craig Harvey Statistical Modeling of Ecological Signals (SMES): New Applications for Biostratigraphy and Environmental Geology…………………………………………p. 22 ____________________________________ Geologic Problem Solving with Microfossils

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8:45 am Glenn Johnson; Anthony Gary; Douglas Ekart A New Approach for the Analysis of Assemblages within Biostratigraphical Data….p. 23 9:05 am Guillem Mateu-Vicens; Pamela Hallock; Marco Brandano Amphistegina, Red Algae and Paleobathymetry: The Lower Tortonian Distally Steepened Ramp of Menorca, Balearic Islands (Spain)……………...……………….p. 24 9:25 am Andrew R. Bowman; Garry D. Jones; Roger J. Witmer; Anthony Gary Application of a Statistically-Derived, Integrated Biozonation to a Deepwater Miocene Gulf of Mexico Field………………………………………………………………….p. 25 9:45 am

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10:05 am F. M. Gradstein; O. Hammer; E. Anthonissen; G. D. Jones Increasing Resolution in Exploration Biostratigraphy with Crossplots of RASC and CONOP Sequences……………………………………………………………………p. 26 10:25 am Anthony Gary; Glenn Johnson; Douglas Ekart A Fuzzy Inference System for Modeling Biostratigraphical Concepts……………….p. 27 10:45 am Richard A. Denne Assemblage-Based Biozonations: A Key Tool in the Detection of Reworked Fossils…………………………………………………………………………………p. 28 11:05 am Eric Monteil; Andrew Kelman New Insight into the Palynology of the Cretaceous Otway Basin, South Australia, Based on the Application of Quantitative Biostratigraphic Methodologies………………….p. 29 11:25 am William N. Krebs, Thomas D. Demchuk Graphic Correlation and Sequence Stratigraphy of Two Sirt Basin (Libya) Wells…..p. 30 11:45 am – 1:15 pm Lunch, LEY CENTER, GRAND HALL - Poster Exhibit Area Oral Sessions (continued), HAMMAN HALL PALEO OCEANOGRAPHY 1:15 pm Invited keynote: Henk Brinkhuis; Matthew Huber; AppySluijs; Jeroen Warnaar; Catherine E. Stickley; Jonathan P. Bujak; James C. Zachos From Greenhouse to Icehouse: Evidence for Late Early Eocene Concomitant Cooling of Southern Ocean Surface Waters and Global Deep Waters from Dinoflagellate Endemism…………………………………………………………………………..…p. 31 ____________________________________ Geologic Problem Solving with Microfossils

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1:35 am Lizette Leon-Rodriguez Planktonic Foraminifera Record of the Mid Albian Sea-Level Rise, Upper Magdalena Valley, Colombia……………………………………………………………………...p. 32 1:55 pm Fabian Duque-Botero; Florentin Maurrasse Cyanobacterial Productivity, Variations in the Organic Matter and Facies of the Indidura Formation (Cenomanian-Turonian), NE Mexico…………………………….……….p. 33 2:15 pm Emily Browning; David K. Watkins Calcareous Nannofossil Evidence of Significantly Elevated Primary Productivity during Aptian/Albian Ocean Anoxic Event 1b……………………………………………….p. 34 2:35 pm Amanda Ruth Dillon; David K. Watkins Evolutionary Trends in Axopodorhabdus biramiculatus……………………………...p. 35 2:55 pm

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3:15 pm Martin R. Langer Tracking Geologic Changes from Global Biogeographic Patterns: The Resolution Power of Larger Foraminifera…………………………………………...…………………...p. 36 3:35 pm Ellen De Man; Stefaan Van Simaeys The Rupelian/Chattian Boundary in the Southern North Sea Basin: New Insights in the Glacio-Eustatic Driven Unconformity………………………………………………...p. 37 3:55 pm Stijn De Schepper; Martin J. Head Plio-Pleistocene Dinoflagellate Cysts from DSDP Hole 610A, Eastern North Atlantic, and Biostratigraphic Application to Shallow Marine Environments………………….p. 38 4:15 pm Henk Brinkhuis Arctic Drilling: IODP 302 …………………………………………………………...p. 39 7:00 pm -10:30 pm PLENARY DINNER, WITH TRIBUTE TO GARRY D. JONES Followed by Guest Speaker, NASA Astronaut Mike Fincke HOUSTON MUSEUM OF NATURAL SCIENCE

Wednesday, 9-March 7:15 am 8:00 am

Coffee, RICE CAMPUS – HAMMAN HALL Oral Sessions, Welcome

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BIO CHRONOLOGIC CORRELATION 8:05 am Invited keynote: James G. Ogg Geologic Time Scale 2004…………………………………………………………….p. 40 8:25 am C.A. Jaramillo; M. Rueda; F. Parra; G. Rodriguez Biostratigraphy Breaking Paradigms: The Absence of the Mirador Formation in the Eastern Llanos of Colombia……………………………………………………...…...p. 41 8:45 am Peter A. Hochuli; Ulrich Heimhofer; Stefan Burla; Helmi Weissert A Fresh Look at the Potomac Group across the Atlantic: Correlation of Angiosperm Pollen Records between the Eastern USA and Portugal…………………………...…p. 42 9:05 am Matthew D. Lutz; David M. Harwood Warm Surface Water Events: Integrating New Pliocene Siliceous Microfossil Paleobiogeographic Data with Other Southern Ocean Proxies…………….…………p. 43 ECOLOGIC ANALOGS 9:25 am Alice S. Chang; R. Timothy Patterson; Andreas Prokoph; Helen M. Roe Solar Influence on Climate and Diatoms in the Northeast Pacific……………………p. 44 9:45 am

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10:05 am R. Timothy Patterson; Andrew P. Dalby; Helen M. Roe Salt Marsh Foraminifera as Sea-Level Indicators in New Brunswick and British Columbia: A Quantitative Approach to Assessing Regional Variability in Taphonomic Biasing and Preferred Faunal Habitat…………………………………………………p. 45 10:25 am Brooke Olson; Marek Leckie; Adre Droxler; Gerald Dickens Late Quaternary Foraminiferal Assemblage Changes in Relation to Sea-Level and Sequence Stratigraphic Principles on the Mixed Siliciclastic - Carbonate Belize Margin…………………………………………………………………………………p. 46 10:45 am Katrine Husum; Elisabeth Alve Benthic Foraminiferal Responses to Eutrophication and Hypoxia/Anoxia in Norwegian Silled Fjord Basins: Development and Assessment of Quantitative Faunal Indice…p. 47 11:05 am L. A. Febo; J. H. Wrenn; W. N. Krebs A Holocene - ?Late Pleistocene Lacustrine Record of Diatom and Chrysophyte Cyst Distributions for Catahoula Lake, Louisiana: Paleoenvironmental Significance…….p. 48 11:25 am – 2:00 pm Free Time, Individual Preference ____________________________________ Geologic Problem Solving with Microfossils

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2:00 pm – 4:00 pm

ROUND TABLE – GEOLOGIC TIME SCALE Discussion Facilitator: Felix Gradstein HAMMAN HALL

~ POSTER PROGRAM ~ Monday, 7-March and Tuesday, 8-March 11:45 am - 1:15 pm Monday, 7-March 5:00 pm - 7:00 pm LEY CENTER, GRAND HALL BIO SEQUENCE STRATIGRAPHY Marta Carrillo; Diana Cabrera; Arelis Farias Biostratigraphic Characterization of the Carito Field, Northern Monagas, Venezuela……………………………………………………………………………..p. 49 D. M. Burns Using Fusulines to Determine Periodicity of Sequence Stratigraphy Cycles…………p. 50 R. Catanzariti; A. Cerrina Feroni; N. Levi; G. Ottria The Foredeep Basin Evolution in the Northern Apennines (Italy)……………………p. 51 R. Catanzariti; A. Cerrina Feroni; N. Levi; G. Ottria The Reconstruction of Complex Structural Stackings at Upper Crustal Levels through Nannofossil Biostratigraphy: Two Examples from the Northern Apennines (Italy)....p. 52 Walter W. Wornardt Jr. Ages of Maximum Flooding Surfaces, Sequences Boundaries in the Cenozoic and Mesozoic……………………………………………………………………………....p. 53 Walter W. Wornardt Jr. High-Resolution Biostratigraphy in Reservoir Sequence Analysis: A Risk Reduction Technology for the 2000’s……………………………………………………….……p. 54 Thomas D. Davies; Keith A. Knabe; Chengjie Liu; Yow-Yuh Chen; Ting C. Huang: John Snedden "Globalization" of Sequence Stratigraphy through Biostratigraphy………………….p. 55 ____________________________________ Geologic Problem Solving with Microfossils

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RESERVOIRS AND DRILLING James H. Gamber; Jeffrey A. Stein Reservoir-Scale Biostratigraphic Resolution in Near-Salt and Sub-Salt GoM Fields..p. 56 Dennis Alberto Sánchez Zambrano High-Resolution Biostratigraphy and Depositional Environment of the Miocene to Pleistocene Sequences in the Plataforma Deltana and Eastern Venezuelan Basin…...p. 57 TOOLS AND TECHNIQUES Felix M. Gradstein; James G. Ogg A Geologic Time Scale 2004: Why, How and Where Next!………………………...p. 58 Emil Platon; Paul Sikora StrataPlot – A New Graphic Correlation Tool………………………………………..p. 59 Emil Platon; Anthony Gary An Artificial Intelligence Machine for Paleoenvironmental Interpretation of Micropaleontological Data from Well Samples……………………………………....p. 60 Peter R. Thompson Computational Biochronology………………………………………………………...p. 61 Paul Watson; Elisabeth Nairn Stratigraphy to Seismic (StS): A Technique to Provide Digital Biostratigraphic Information for the Seismic Interpreter and its Impact on Geological Problem Solving………………………………………………………………………………...p. 62 Alicia Kahn; Hui Liu; Marie-Pierre Aubry; Colomban de Vargas Morphologic and Genetic Variations among Indian Ocean Calcareous Nannoplankton………………………………………………………………………...p. 63 Hermann Duque-Caro Microstratigraphic Changes: A Methodology to Identify Stratigraphic Packages and Geologic Events…………………………………………………………………….....p. 64 Chioma U. Udeze; John V. Firth; Thomas D. Olszewski Sample Preparation for Quantitative Analyses of Calcareous Nannofossils for Paleoceanographic Studies…………………………………………………………....p. 65 Pi Suhr Willumsen; Barrie Dale; Iain Prince Palynological Processing of Tropical Late Oligocene - Miocene Deep-Sea Fan Deposits: Angolan Basin, West-Central Africa……………………………………………….....p. 66 ____________________________________ Geologic Problem Solving with Microfossils

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Armando Antonio Scarparo Cunha; Amauri L. Bastos; Marcos H. P. Mauricio; Sidnei Paciornik Telemicroscopy System for Calcareous Nannofossil Analyses……………………....p. 67 PALEO OCEANOGRAPHY Rosemary Cody; David Harwood Paleoecology of Southern Ocean Diatoms and Pliocene Climate Variation: HighResolution Quantitative Biostratigraphy of ODP Legs 119 and 120………………....p. 68 Valquíria Porfírio Barbosa; Oscar Strohschoen Jr. Oligocene-Miocene Paleoceanographic Events of Campos Basin, Brazil: Evidence from Deep-sea Benthic Foraminifera…………………………………………………….....p. 69 Katrine Husum, Elisabeth Alve Paleoecological Interpretation of Benthic Foraminiferal Assemblages from Clastic Paleogene Environments Using Modern Analogues: Possibilities and Limitations.....p. 70 D. Michoux, S. Piriou Dinoflagellate Cysts in Neogene Palynological Assemblages from the Deep Offshore of the Gulf of Guinea: More than Meets the Eye…………………………………………………....p. 71 BIO CHRONOLOGIC CORRELATION Eric de Kaenel A Revision of the Reticulofenestrid Taxonomy and Biostratigraphy ………………...p. 72 Diana Cabrera; Alfonzo Solangel; Javier Helenes Oligocene-Miocene Dinoflagellate Cysts and Continental Palynomorphs in the Furrial Field-Eastern Venezuela……………………………………………………………....p. 73 Jacqueline Jouval Benthic Foraminifera from Early Carbonate Sediments of Chimana-El Cantil Formations: Biostratigraphic Use for Oil and Gas Exploration in North-Eastern Venezuela……...p. 74 Rafael Ramirez; Olga M. V. Rodriguez; Dennis Alberto Sánchez Zambrano Biostratigraphy Impact in the Geology Study during Exploration Drilling, Northwest Monagas Oilfields, Eastern Venezuelan Basin………………………………………..p. 75 M. Rueda; C.A. Jaramillo A Palynological Zonation for the Cretaceous-Tertiary of Colombia…………...…….p. 76 Yanina Narvaez Nannostratigraphy of Eocene Strata in the Talara Basin, Peru…………………...…..p. 77 ____________________________________ Geologic Problem Solving with Microfossils

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Merlynd K. Nestell, Galina P. Nestell, Michael J. Sweatt Middle Permian (Capitanian) Microfossils from the "Rader Slide", Guadalupe Mountains, West Texas…………………………………………………………….....p. 78 Héctor R. Ruiz; Julieta G. Martínez; Víctor O. Martínez; Rodolfo T. Guerra; Alberto T. Segura Biostratigraphy: Recent Studies of a Pliocene/Pleistocene Section from the Tampico Misantla Basin, Southeastern Gulf of Mexico………………………………………...p. 79 Stephan A. Root Miocene Nannofossil Bioevent Summary with High Resolution Emphasis on GoM Events…………………………………………………………………………………p. 80 Amule H. Olusola; M. A. Sowunmi The Age of Offshore Niger Delta Sediments Inferred from Palynological Evidence...p. 81 Pi Suhr Willumsen; Barrie Dale; Iain Prince Late Oligocene - Miocene Dinoflagellate Cysts from Deep-Sea Fan Deposits from Mid Latitudes: Angola, West-Central Africa……………………………………………....p. 82 Victor Nda; Juliette Tea; Raphaël Yao; Adèle Atteba Biostratigraphic Characterisation of Ivorian Late Albian Sequences………………....p. 83 J. G. S. Goodall; C. Hannaford; G. Scotford; M. D’Cruz High-Resolution Palynostratigraphy of a Sand Rich Turbidite System, the Angel Formation, Carnarvon Basin, Australia…………………………………………….....p. 84 G. W. Hughes Micropalaeontology and Palaeoenvironments of Saudi Arabian Upper Permian Carbonates and Reservoirs…………………………………………………………....p. 85 G. W. Hughes Micropalaeontology and Palaeoenvironments of Selected Saudi Arabian Middle Jurassic Carbonates and Reservoirs…………………………………………………………....p. 86 A. Dhubeeb; G. W. Hughes Micropalaentology and Palaeoenvironment of Late Jurassic Carbonate Formations and Reservoirs in Saudi Arabia…………………………………………………………....p. 87 Gonzalo Jiménez-Moreno; Martin J. Head; Mathias Harzhauser Early and Middle Miocene Dinoflagellate Cyst Stratigraphy of the Pannonian and Vienna Basins, Central Europe…………………………………………………………….….p. 88

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ENVIRONMENTAL ANALYSIS Eduardo Leorri; Alejandro Cearreta; M. Jesús Irabien Environmental Regeneration of the Bilbao Estuary (N. Spain): Microfaunal and Geochemical Evidence……………………………………...………………………...p. 89 Eduardo Leorri; Ronald E. Martin; Peter P. McLaughlin Micropaleontological Proxies of the Recent Environmental Transformation in the St. Jones Estuary (Delaware, USA)……………………………………………………....p. 90 Pamela Buzas-Stephens; Martin A. Buzas Foraminiferal Population Change as a Result of Increased Inflow into Nueces Bay, Texas…………………………………………………………………………………..p. 91 Richard Hoefling; Christian Weiss; Heinz Juergen Tobschall Benthic Foraminifera Tests as Proxy Indicators of Sediment Pollution in the Macro-Tidal Red River Mouths (North Vietnam)…………………………………………………..p. 92 Susanne Moskalski; Ronald Martin; Peter McLaughlin Palynologic Determination of Changes in Historical-Era Sedimentation and Vegetation in Marshes Flanking the St. Jones River, Delaware, USA……………………………....p. 93 Francine M.G. McCarthy; Steve M. Blasco; John H. McAndrews; Sarah H. Tiffin; C. F. Michael Lewis Reconstructing the Postglacial History of Georgian Bay, North American Great Lakes, Using Fossil Pollen and Protists……………………………………………………....p. 94 Olivia C. Buchan; Ronald D. Lewis Assemblages of Recent Large Benthic Foraminifera and Taphofacies Combined with Grain Characteristics as Indicators of Environmental Variables in Sea-Grass Beds, San Salvador, Bahamas………………………………………………………...………….p. 95 Beatriz B. Eichler; Patrícia P. B. Eichler; André R. Rodrigues; Evelyn R. M. Pereira; Patricia B. P. Kfouri Foraminiferal Assemblages from Brazilian Environments………………………..….p. 96 Patrícia Pinheiro Beck Eichler; Barun K. Sen Gupta; Beatriz Beck Eichler; Edmo J. Campos Foraminiferal Diversity Trends in the Sediments of the Brazilian Continental Shelf between 27ºS and 30ºS…………………………………………………………….….p. 97 J. H. Wrenn; L. A. Febo; R. A. Tedford; V. M. Bryant, Jr.; W. N. Krebs; R. M. Camors Initial Results of an Integrated Micropaleontologic and Sedimentologic Study of Catahoula Lake, Louisiana…………………………………………………………....p. 98 ____________________________________ Geologic Problem Solving with Microfossils

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Rebecca A. Tedford; John H. Wrenn; Robin M. Camors Diagnostic Phytoliths from Mixed Hardwood Forest Plants and Soils, Catahoula Lake, Louisiana……………………………………………………………………………....p. 99

~ FIELD TRIP ~ UPPER CRETACEOUS STRATIGRAPHY OF CENTRAL TEXAS 10-11 March Leaders: Jason Lundquist and Jeffery Stein Reservation Required

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GEOLOGIC PROBLEM SOLVING WITH MICROFOSSILS ABSTRACTS VOLUME

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Antarctic Ice Sheet Evolution and the Cenozoic Eustatic Record John B. Anderson There are two widely used proxies for global ice volume changes and associated eustasy, the oxygen isotope record and the Haq et al. (1987) eustatic curve. At best, the two proxies show broad similarity, but they provide a vague long-term record for Cenozoic cryosphere evolution. The isotopic curve impels slow build-up of ice beginning in the late Eocene time, although there are major differences of opinion about early ice sheet evolution by people who generated the composite isotope curves. The eustatic curve implies significant ice volume changes since at least Paleocene time, with a permanent ice sheet having evolved by the late Oligocene. The volumes of ice implied by eustatic curves calls for fluctuations of 100 to 200 meters during the Oligocene and Miocene.

This calls for unrealistic volumes of ice on Antarctica at this time. So, both proxies for ice sheet evolution have their problems. Our understanding of Antarctica’s glacial history has now progressed to the point that assessment of the proxy records with the geological record of ice volumes changes is now possible.

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Reworking of Eocene Nannofossils in CIROS-1 and the Initiation of Antarctic Coastal Glaciation David K. Watkins; Ryan Weber Proxy evidence for the initiation of glaciation in Antarctica indicates significant iceberg calving (ice-rafted debris) and global temperature decline (e.g., δ18O records from deep sea cores) near the Eocene/Oligocene boundary. The record of the CIROS-1 hole, drilled in the McMurdo area of the Ross Sea, has been interpreted to indicate significant glacial activity proximal to Antarctica in the late Eocene. In addition, this implies that the Ross Sea Graben opened as early as the early late Eocene. This age is based on paleomagnetic extrapolation utilizing the first occurrence of the calcareous nannofossil Isthmolithus recurvus. This extrapolation yielded an early late Eocene (Chron 12r) age for the base of CIROS-1. There are several lines of geological and paleontological evidence that cast doubt on the validity of this early late Eocene age determination. Nannofossils are extremely rare in abundance and sporadic in occurrence throughout CIROS-1, with most assemblages associated with sandstone or silty sandstone while finer-grained lithologies are generally barren of calcareous microfossils. Re-examination of the nannofossil succession indicates the presence of a stratigraphic inversion in the sequence, with the middle Eocene Discoaster saipanenis occurring stratigraphically above Reticulofenestra oamaruensis (restricted to the late Eocene). The stratigraphic inversion and the preferential association of (extremely rare) nannofossils with coarse-grained lithologies strongly suggest that these fossils are reworked. A similar reworked association of similar age has been well documented from nearby Cape Roberts drilling. This reworking may have been the result of initial tectonic movement associated with the opening of the Ross Sea Graben and/or the initial movement of glacial ice from the interior ice fields down to the coast.

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Shallow Marine Benthic Biota as Proxy for Sea-Level and Sedimentary History, Carbonates of Bahama-Type Mesozoic Platform, Southern Croatia A. Husinec; B. Sokac The Mesozoic, Barremian-Aptian deposits of southern Croatia comprise a succession of shallow tropical-water, inner platform deposits that formed on a Bahama-type isolated platform in the Dinarides. This succession is dominated by benthic foraminifera and calcareous algae, and is exposed in a nearly continuous outcrop section on the island of Mljet, southern Croatia. It has been studied in terms of biostratigraphy, paleoecology and sedimentary facies. The analysis of the microfossil association has provided a detailed biostratigraphic zonation based on the stratigraphic distribution of either benthic foraminifera or calcareous algae. The present study, calibrated against the standard regional biostratigraphic zonation for the Eastern Adriatic Lower Cretaceous, documents that several species of benthic foraminifera and calcareous algae have exceptional agediagnostic value for the Early Cretaceous biostratigraphy. These Barremian calcareous algae species Salpingoporella melitae and S. muehlbergii, and Early Aptian benthic foraminifera Palorbitolina lenticularis and Voloshinoides murgensis are abundant, have a widespread distribution and a restricted stratigraphic range. They evolved rapidly and became extinct suddenly. The carbonate platform, because of its isolated position within the Late Mesozoic Tethyan Ocean, was free of terrigenous influences. The region was also tectonically quiet during most of the Early Cretaceous. Consequently, benthic distribution within oligotrophic habitats of the study area was primarily controlled by sealevel oscillations, variations in oceanic circulation rate and nutrient availability in surface waters. This study shows that Early Cretaceous diversification of benthic foraminifera in the area investigated, follows the regional relative sea-level curve for that period and the major foraminiferal turnovers coincide with sea-level rise and fall. During relative sealevel rises associated with reduced oceanic circulation and the expansion of nutrient-poor, shallow tropical waters, organisms were able to diversify into various euphotic habitats within the shallow subtidal platform interior. Regressive episodes resulted in reduction of oligotrophic habitats and decreased species richness.

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Modification of Palynomorph Assemblages by Ravinement Processes in a Mesotidal Barred Coastal Environment C. N. Denison The billion barrel Numbi field, offshore Cabinda (an enclave of Angola, West Africa) was discovered in 1982, with first production in 1987. Numbi has produced over 350 million barrels of oil and is now under waterflood. Beginning in 2004, a stratigraphic revision of over 100 wells included a comprehensive review of core-based depofacies and stratigraphy in seven wells that each have more-or-less continuous core though the reservoir. In the previous geological model, sandstones were correlated as continuous but thinning from the NW-SE trending field-bounding growth fault southwest to the structural crest. A more complex stratigraphy is now recognized; an unconformity truncates underlying units and has downlapping beds above. This new model honors the dynamic data collected during production and water injection. The overall depositional setting was a mesotidal barred coastline in an arid tropical environment. During transgression and regression, wave and tidal ravinement processes aggressively cannibalize the barrier and erode into the substrate. Recognition of wave and tidal ravinement surfaces in core is essential to understanding the resultant stratigraphic architecture. Palynological data from wells N-1 and M-1, collected in 1992, has been reinterpreted and incorporated into the core-based depofacies interpretations. Algal filaments and monospecific microforaminiferal assemblages are distinctive tidal flat indicators. Subtilisphaera is an opportunistic genus that flourished in lagoonal settings inimical to most other microplankton. Marine shelf assemblages are diverse, including Florentinia, Odontochitina, Aptea, Spiniferites, etc. These end member assemblages are often modified with palynomorphs reworked by ravinement processes as the barrier systems migrate. As the barrier moves landward during transgression, back-barrier deposits become exposed on the shoreface and are eroded by wave ravinement, with lagoonal and tidal flat palynomorphs being incorporated into marine assemblages.

Within the back-barrier lagoon, tidal ravinement scours down into the underlying shoreface sands, introducing marine elements into lagoonal assemblages. During regression, wave and tidal ravinement surfaces migrate seaward, again reworking material from underlying deposits. Resultant successions comprise marine shoreface sandstones alternating with tidal complexes (channel sandstones, tidal and floodplain mudstones, minor anhydrites). Without an understanding of the mechanisms that generate these alternations, a priori interpretations of palynomorph assemblages can be to be at odds with core-based depofacies.

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Early - Middle Miocene Transgressive - Regressive Cycle in Eastern Venezuela Basin: Foraminiferal Response to Relative Sea-Level Changes Sandra Crespo de Cabrera Paleogene sedimentation in the MaturĂ­n Sub-basin until the Oligocene Epoch took place in transitional to inner neritic conditions, under a passive margin tectonic regime. At the beginning of the Early Miocene, subsidence resulting from a change to a foreland basin regime, initiated a gradual and continuous drowning of the basin, with the subsequent migration of depocentres from the northeast towards the south and southwest of the study area. Relative sea level changes associated to the Early Miocene major transgressive cycle, resulted in a turnover in the foraminiferal biofacies. The scarce and low diversity microfauna that occurs in the upper Oligocene Naricual Formation, was replaced by a more diverse and specialised microfauna, as seen in the dark grey shales of the overlying Miocene Carapita Formation. The prolific nature of the Oligocene reservoirs in the Northern Monagas area prompted the micropaleontological characterisation of the Carapita Formation, which, in this petroleum system, constitutes the seal. The area is tectonically complex, making it unsuitable for drilling without the use of biostratigraphy, (especially foraminifera) to correlate and make prognosis of the reservoir depth during the drilling phase. The formation was predominantly deposited in bathyal conditions during the interval of time that spans the planktonic foraminifera Zones N5 to N12. The average thickness is approximately 12000 feet (~4000 m), though it varies greatly due not only to the unconformably nature of the top of this formation, but also to section repetitions through reverse faulting and thrusting. The predominantly bathyal deposition, which characterises most of this formation, changes to neritic at a depth varying from 800 - 1000 feet above the reservoir, in the interval of the N5 - N6 Zones. The assemblage changes from abundant planktonic foraminifera with benthics such as Cibicidoides compressus, Uvigerina rugosa, Lenticulina americana, Cyclammina cancellata, Valvulina flexilis, Martinotiella communis, Textulariella miocenica, among the most abundant significant, to Eponides parantillarum, Nonion atlanticus, Valvulineria venezuelana, Ammonia beccarii, Eggerella aff. scabra, Spiroloculina sp., Textularia sp., and Ammobaculites dilatatus. Another conspicuous lithological feature is the appearance of abundant glauconitic pellets, derived from condensed sections formed to the northeast, as a result of the advance of the transgression and the sequestering of siliciclastics to the south. This biofacies and mineralogical changes that occur in the lower part of the Carapita Formation, approximately 800 - 1000 feet above the reservoir in this lithologically uniform formation, constitute a useful tool for correlation and reservoir depth prognosis during exploratory drilling and basin analyses studies.

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Palynomorphs: A Tool for Solving the Geologic Problem of the Gulf of Mexico and its Mexican Petroleum Sub-Basins Origin Jaime Rueda-Gaxiola Redbed and salt sequences are the economic basement of the Gulf of Mexico petroleum sub-basins in Mexico, and they represent the beginning of the Mesozoic marine transgression which formed the petroleum systems. They have been analyzed using the palynostratigraphical method developed at the Mexican Petroleum Institute since 1975, based on macro- and microscopic analyses of the organic and inorganic components in palynological residues, and of the glycerinated alcohol in which they are preserved.

Pollenospores, dinoflagellates, achritarchs, tracheids, circular bordered pits, foraminifera linings, scolecodonts and, even nannoplankton found in the particular organic matter residue, allowed to obtain litho-, bio-, and chronostratigraphical data related to tectonosedimentary and diagenetical processes from: Cahuasas Formation (1969, in the Tampico-Misantla Sub-basin), Rosario Formation (1975, in the Tampico-Misantla Subbasin), Todos Santos Formation (1982, in the Southeastern Sub-basins and 1987 in the western Veracruz Sub-basin) and La Boca Alloformation (1989, in the Huayacocotla-El Alamar Basin) and some salt units (1970-1993, in the Southeastern Sub-basins). These data, and also that obtained in 1971 by Kirkland and Gerhard, from the caprock of the Challenger Knoll drilled in the center of the Gulf of Mexico, have been useful for understanding the Mexican oil sub-basins sedimentary and tectonic evolutions, and to propose the Triple Junction Model for the Gulf of Mexico origin. This model is based on the existence of a very important unconformity between the basement and the redbeds from the Middle Jurassic rocks in the Sabinas and Southeastern sub-basins of the Gulf of Mexico, and also between the Liassic rocks and the Middle Jurassic redbeds in the Huayacocotla-El Alamar Basin, which was related to the southeastern Tlaxiaco and Huamuxtitlรกn basins, as suggested by Salvador (1987). On the other hand, only in the Tlaxiaco Basin and in the northern part of the Tampico-Misantla Basin, the Liassic redbeds gradually change to the base of the transgressive marine Middle Jurassic-Middle Cretaceous sequence. Over the major unconformity, the redbeds are Middle Jurassic age and are slightly older than the evaporitic rocks deposited over the Gulf of Mexico marginal sub-basins (Sabinas, Tampico-Misantla and Southeastern sub-basins).

Therefore, the age of these sub-basins is slightly younger than that of the Gulf of Mexico.

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Microfossil Abundance and Diversity Histograms: The Key to Interpreting Maximum Flooding Surface Condensed Sections, Source Rocks and Seals Walter W. Wornardt Jr. The third order (0.5-3.0 Ma) maximum flooding surface (MFS) and its depositional facies, condensed section, is a critical biostratigraphic and chronostratigraphic element in Well-Log Seismic Sequence Stratigraphy. The MFS condensed section consists of this marine hemipelagic sediments, deposited under very slow rates of deposition during sediment starvation. It consists of the upper portion of the transgressive systems tract and the lower part of the high stand systems tract. The sediment starvation results from a rapid rise of relative sea level and the landward transgression of the shoreline. It is associated with the authigenic minerals and very high abundance peaks of planktonic microfossils such as foraminifers, calcareous nannofossils and dinoflagellates. Therefore MFS condensed sections are the time stratigraphic correlation horizons that link deep and shallow water sediment packages. Important chronostratigraphic species within the MFS condensed section permit an age in millions of years to be assigned to each MFS maximum flooding surface. Computer generated species diversity and individual abundance histograms are constructed from a high-resolution micropaleontological checklist. These histograms are used to recognize a thickness of rocks on a well log that represents the MFS condensed section. The MFS maximum flooding surface within this MFS condensed section is identified by the highest gamma and lowest resistivity peaks on the well log. A line drawn through these peaks represents the MFS maximum flooding surface at a specific depth on the well log. This depth in converted into seismic time with a two way time log or synthetic seismogram overlaid on a seismic profile, at the well trace and the well location, where it typically correlates with regionally continuous, high amplitude seismic reflectors. Computer generated species diversity and individual abundance histograms for an entire stratigraphic section not only identify the MFS condensed sections within different sequences but they form typical patterns that are associated with lowstand systems tracts. Examples of the utility of recognizing of the following condensed sections will be discussed: MFS CS =Maximum Flooding Surface, Sf cs =Slope fan complex, lc cs=Leveed Channel and Bf cs=basin floor fan complex condensed sections in the Gulf of Mexico, Egypt, Saudi Arabia, Venezuela.

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Early Oligocene Benthic Foraminiferal Paleoecology and Sequence Stratigraphy in the Eastern Gulf Coastal Plain Richard H. Fluegeman The sequence stratigraphy of the early Oligocene in the eastern Gulf Coastal Plain of Alabama and Mississippi has been the focus of research since the early 1980’s. The Red Bluff Clay and its correlatives have long been recognized as the lowermost Oligocene lithostratigraphic units in the region. The contact of the Red Bluff Clay with the underlying Shubuta Clay Member of the Yazoo Clay is considered by most workers to be the Eocene-Oligocene boundary. Interpretations of the sequence stratigraphy of this interval vary with the Yazoo-Red Bluff contact being viewed as a maximum flooding surface by some workers and as a sequence boundary by others. If the uppermost Yazoo Clay is a condensed section, the overlying Red Bluff Clay would be a part of the Highstand Systems Tract. If the Yazoo- Red Bluff contact is a sequence boundary, the Red Bluff Clay should be a part of the Transgressive Systems Tract. Nearly two decades of studies of this interval have failed to resolve the discrepancy satisfactorily. Benthic foraminiferal assemblages and planktonic:benthic (P:B) ratios can provide proxies for fluctuating sea level. Both the Yazoo Clay and Red Bluff Clay are rich in foraminifera which provide additional data for the study of the sequence stratigraphy of the YazooRed Bluff contact. Benthic foraminifera were collected from the upper Shubuta Member of the Yazoo Clay and from the Red Bluff Clay in the Mobil-Mississippi cores in Wayne County, Mississippi with the goal of understanding the detailed paleoecology of this interval. Samples were taken at 10 cm intervals through the upper Yazoo Clay and Red Bluff Clay. Samples collected from outcrops of this interval at Little Stave Creek and the St. Stephens Quarry in Alabama and along the Chickasawhay River in Mississippi were also processed for foraminifera. The benthic foraminiferal assemblage in the Red Bluff Clay is characterized by Cibicidoides pippeni, Cibicidoides cookei, Hanzawaia lobatulus, Lenticulina vicksburgensis, Siphonina advena, Spiroplectammina latior, Massilina cookei, and Uvigerina vicksburgensis. Subtle changes in species composition are present from sample to sample. This Cibicidoides-Hanzawaia assemblage benthic foraminiferal assemblage is characteristic of middle neritic environments in the early Oligocene and contrasts with the outer neritic Uvigerina-Bulimina assemblage collected from the upper Yazoo Clay. Planktonic-benthic (P:B) ratios are lower at the base of the Red Bluff than in the upper Yazoo but increase upwards through the Red Bluff before falling sharply in the upper half. The Yazoo-Red Bluff contact also marks the appearances of numerous species typical of the Vicksburg benthic foraminiferal fauna. The benthic foraminiferal assemblages collected in this study suggest that the Red Bluff Clay was formed as a part of the transgressive systems tract. It represents the earliest Oligocene transgression in the eastern Gulf Coastal Plain. ____________________________________ Geologic Problem Solving with Microfossils

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The Northern Apennines (Italy): A Perfect Mountain Belt for Solving Geological Problems with Microfossils R. Catanzariti; A. Cerrina Feroni; N. Levi; G. Ottria The Northern Apennines is a fold and thrust belt developed since the Oligocene by the progressive shortening of the foredeep domain connected with the eastward migration of the orogenic front. The erosion following the overall belt uplift (Upper MioceneHolocene) make outcropping only the middle-upper crustal levels, involved in a very complex polyphase structural stacking. The last is made up by detached sedimentary successions, mostly consisting of deep-sea deposits, and low grade metamorphic sheets.

The tectono-stratigraphic units (Ligurides) deriving from the Ligurian-Piedmont oceanic basin and its transition to the Adria plate margin are widespread in the Northern Apennines. In the Ligurides the superimposion of the Adria-verging Oligocene-Miocene deformations (Apenninic orogenesis) onto the Europe-verging Eocene deformations (Mesoalpine Phase) causes a very complex structural pattern. The stratigraphy of the oceanic (Internal Ligurides) and transitional (External Ligurides and Subligurides) units is often unconsolidated and however it is less defined with respect to the stratigraphy of the outermost successions belonging to the Tuscan and Umbria-Marche domains. From these conditions it derives that the Northern Apennines belt is extraordinary favorable for the application of the micropaleontology to solve several geological problems. In particular, because of their abundance in the Northern Apennines sedimentary successions, and the high chronostratigraphical resolution power, the study of the calcareous nannofossils is the most useful biostratigraphical tool. Here we discuss some examples of geological problems from Northern Apennines which have been solved through the application of the calcareous nannofossil analysis. Two case histories refer to the reconstruction of complex polyphase structures where thrust sheets composed by tectono-stratigraphic units showing similar facies and stratigraphic features have been defined. The third example refers to the fundamental contribution of the nannofossil biostratigraphy for the definition of the propagation modality (diachronous opening and closing) of the foredeep basins which follows the progressive shifting of the belt front since the Oligocene. Finally, the essential contribution of the calcareous nannofossil analysis for dating the Aveto Unit succession has been discussed. The stratigraphic succession of the Aveto Unit, belonging to the upper Subligurides, is characterized by calcalcaline volcanoclastic deposits which has been previously referred both to the Upper Eocene and the Lower Miocene. On the contrary, the nannofossil data indicate a Lower Oligocene age (MNP23 biozone) which allows a new interpretation of the Aveto Unit succession and related andesitic source area.

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The Use of Planktonic Microfossils to Resolve Tectonic and Paleogeographic Uncertainties in the Lower Cretaceous of Sonora, Mexico J. F. Longoria; Rogelio Monreal Carrera The Lower Cretaceous succession of the western flank of Sierra Las Azules, Sonora, Mexico, was studied. It is made of a heterogeneous alternation of limestone and shale dipping SE. This succession was considered by previous authors as a continuous and complete Lower Cretaceous section. We studied and sampled a west-east traverse containing abundant planktonic foraminifera and calpionellids indicative of the Aptian-Albian (K6 to K12 of the biochronologic scheme by Longoria, 1984, for the Gulf Coast Region). The distribution of these planktic microfaunas indicates that contrary to the previous work, the exposed succession is represented by five structural segments: S1A, S1B, S2, S3, S4 representing tectonic duplications of the Aptian-Albian succession. From W to E: Segment 1A: 500 m of a structurally complex lithic package; microfossils assemblages include: 1) Caucasella cf. hauterivica (biozone K-6/K-7); 2) Colomiella recta and Hedbergella trocoidea (biozone K-12/K-14); 3) Colomiella recta (biozone K-12/K-14). Segment 1B: 728 m thick, ranging from Upper Aptian (Clansayesian) to Upper Albian, representing the interval between biozones K-12 to K-15; microfossils assemblages include: 1) Hedbergella cf. trocoidea and Colomiella recta indicative of biozone K-12; 2) the first occurrence of Ticinella primula, C. coahuilensis, Colomiella sp. and Favusella washitensis and Favusella confusa indicative of biozones K-13 and K-14; 3) Colomiella sp, Favusella scitula, Hedbergella planispira and Ticinella bejaouaensis indicative of biozone K-14; 4) abundant Favusella washitensis, F. scitula and Ticinella breggiensis indicative of biozone K-15. Segment 2: 700 m of thin-bedded wavy limestone interbedded with shale and thin-bedded fine-grained sandstone, referable to the Upper Aptian (Clansayesian) and includes biozones K-12 to K-13.

The following biochronological determinations were obtained: 1) Hedbergella planispira and the lack of Colomiella implies biozone K-12; 2) The presence of Favusella sp. and Colomiella sp. indicates biozone K-13. Segment 3: 1050 m of shale with limestone intervals grading into a regular alternation of thin-bedded nodular limestone and shale, ranging from lowermost Aptian (Bedoulian) to uppermost Albian, representing biozones K-6/K-7 to K-15; microfossil assemblages include: 1) Hedbergella planispira and Ticinella breggiensis indicative of biozone K-15; 2) Hedbergella delrioensis and Ticinella primula corresponding to biozone K-14; 3) abundance of Colomiella sp.indicating biozones K-12 to K-13; 4) abundance of Globigerinoides ferreolensis indicative of biozone K-11; 5) the concurrence of Caucasella sp. and Globigerinoides gottisi indicative of biozone K-6. Segment 4: 625 m of resistant cliff-forming, thick- to massive-bedded fossiliferous limestone, ranging from Upper Aptian (lower Clansagesian) to Lower Albian and include biozones K-12 to K-13/K14; microfossil assemblages include: 1) the concurrence of Hedbergella trocoidea, H. cf. primula, and H. bejaouensis indicative of biozone K-14; 2) abundant Colomiella sp. representing biozone K-12. The use of microfossil was fundamental in deciphering the structural complexity of this area which otherwise had been regarded as a continuous, complete Lower Cretaceous section; biochronological determinations indicate an overturned stratigraphy in segments 3 and 4, younger to the west; the contacts S1/S2; S2/S3, and S3/S4 are tectonic; based on biochronological data segment 3 is overridden by segment 4. Microfossil assemblages of Sonora are remarkable similar to coeval succession in the Gulf of Mexico region. ____________________________________ Geologic Problem Solving with Microfossils

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The Role of Biostratigraphy in Subsurface Sequence Stratigraphic Models M. D. Simmons In order to reduce risk in exploration and production, geoscientists need to generate maps that accurately portray the geometry and distribution of reservoir, source and seal facies.

Ideally some of these maps should reflect the sediments as they were deposited for as precise a time interval as possible. Sequence stratigraphy is a technology that facilitates this through the construction of high-resolution chronostratigraphic charts, and subsequently, maps drawn on various key stratal surfaces (e.g. MFS, SB and MRS). A prerequisite for these products is a robust appreciation of the biostratigraphy of the stratigraphic interval being studied. A methodology that has successfully been applied to Middle East stratigraphy (see Sharland et al., 2001; 2004) is as follows: • Identify MFS through biostratigraphic, sedimentological and wireline log characters (these should represent downlap surfaces on seismic data), • Correlation of these MFS through biostratigraphic data with an appreciation of the correlation issues between different fossil groups, • Use biostratigraphically validated MFS as a basis for drawing chronostratigraphic charts across the region and interval of interest, constrained by biostratigraphic considerations, • Use a grid of such chronostratigraphic charts to map gross facies distributions for key stratal surfaces, interpolated with data points off the line of section, and including an appreciation of the basinward shifts at SBs and their duration. Palaeoenvironmental interpretation from biostratigraphic data is included here.

Facies maps can then be turned into Play Fairway polygons for reservoir, seal and source.

One of many interesting derivatives of this methodology is the confirmation of synchronous relative sea-level change (MFS) over wide areas. These MFS are derived from the rocks themselves rather than published charts.

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A Biozonation for Controlled Top Reservoir Approach: Avoiding Mud Loss and Stuck Drill Pipe in the Danish Chalk Fields Lea Holstein; David J. Jutson The chalk fields located in the North Sea, the Danish sector, include reservoirs of Danian and Maastrichtian age, overlain by a Tertiary claystone interval. In the early field development phase, when reservoir pressures are high, an intermediate casing is set at the top of the Danian chalk. Low reservoir pressures later in the field life, cause severe drilling mud losses when entering the reservoir with the drill bit, jeopardizing the operation. An alternative method was devised to set the casing some distance above the reservoir, in the overlying claystone. However, the claystone is overpressured and very plastic with a tendency to hydrate, resulting in drilling problems, such as e.g. a stuck pipe. The solution to the problem was found by setting the casing shoe in a less plastic, marly claystone interval of approximately 6 ft thickness, located immediately above the reservoir. This interval is competent, but difficult to identify by conventional means during normal drilling. A pilot study of the lower Tertiary claystone interval based on five wells from the Gorm field was initiated. This resulted in a biostratigraphic zonation being established with 7 zones and 9 subzones of events (some unconventional) which, together with lithological changes, could be used to identify the depth at which controlled drilling should be initiated to pick an optimum casing point. The top of the zonation was defined as a combination of a basin-wide deposited ash layer and the diatoms Fenestrella antiqua and Coscinodiscus spp. The remaining part of the claystone to the top of the marly interval was dominated by non-calcareous agglutinated foraminifera which, despite the paleoecological restriction of these taxa, proved to be stratigraphically consistent, not only on the Gorm field, but also on the neighbouring fields. The zone immediately above the marl was recognised by an influx of the relatively large reticulate radiolaria, e.g.

Cenosphaera spp, and this interval had 5 subdivisions based on calcareous benthic foraminifera as well as sponge spicules. The top of the marly claystone was marked by incoming Danian planktic foraminifera in a low diversity assemblage and, when penetrating the Danian chalk, the calcareous benthic and planktic foraminifera dominated in highly diverse assemblages. Subsequently, the zonation was applied to 12 wells in which the casing points were identified successfully. With emendations, it was applied to a further 14 wells on neighbouring fields. The zonation is now generally applied when drilling into depleted reservoirs. The formation tops can be predicted within 2 ft TVD accuracy in areas with good well control.

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Application of Micropaleontology to Water Resource Problems: Aquifer Stratigraphy in the Coastal Plain of Delaware (Middle Atlantic Region, United States) P. P. McLaughlin; R. N. Benson Stratigraphic correlation and characterization of aquifers involves many of the same challenges as the study of petroleum reservoirs: understanding the details of a subsurface stratigraphic succession over a geographically limited area. And, as in reservoir studies, biostratigraphy can be a useful tool in aquifer geology. In our recent work in the Coastal Plain of Delaware, we have examined the distribution and facies characteristics of aquifers that provide the drinking water for the majority of the state’s residents. The focus of this work has been in two intervals: the Lower to lower Upper Cretaceous nonto marginal marine aquifers of northern Delaware; and the Miocene shallow- to marginalmarine aquifers of central and southern Delaware. Our understanding of aquifer architecture in these intervals has been improved by the integration of micropaleontology with wireline log correlation, sequence stratigraphic concepts, and subsurface mapping, providing data for better management of these natural resources. Stratigraphic analysis of aquifers in the Lower to lower Upper Cretaceous section of northern Delaware is complicated by heterogeneous facies and a lack of marine marker beds. Pollen and spores are important keys to understanding the stratigraphic relationships of aquifers sands. The ?Barremian to lower Cenomanian non-marine deposits of the Potomac Formation are composed of fluvial and overbank sands, floodplain silts and clays with scattered lignites, and colorful clay-rich paleosols. By combining biostratigraphy with wireline-log correlation, two sandy aquifer-prone intervals, separated by a finer-grained confining layer, can be correlated over much of the area. The Potomac Formation is separated by an unconformity from overlying ?upper Turonian to lower Santonian marginal-marine sediments of the Magothy Formation. The Magothy Formation appears to be incised valley fill, with variable thickness reflecting relief on a basal unconformity.

Sands in the Magothy Formation are important aquifers, in places, but differentiation from the Potomac sands can be difficult based on wireline logs alone; biostratigraphy can provide useful stratigraphic criteria. The Miocene aquifers of central and southern Delaware occur within a section of interbedded sands, silts, and clays deposited in shallow- and marginal-marine environments along and near wave-dominated shorelines.

In the lower to middle Miocene section, aquifer sands are generally best developed in highstand systems tracts at the top of sequences. Multi-fossil group biostratigraphy (pollen, dinoflagellates, foraminifera, radiolaria, diatoms), combined with strontiumisotope control from two sites, allows correlation and mapping of aquifers across a twocounty area. The upper Miocene section is more complex, with a heterogeneous mix of estuarine, non-marine, and shoreface deposits with significant facies changes and/or cutand-fill features. Upper Miocene microfossil control more limited, mostly pollen and spores. ____________________________________ Geologic Problem Solving with Microfossils

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Wolfcampian (Lower Permian) Carbonate Microfacies and Fusulinid Biostratigraphy along Eastern Central Basin Platform, West Texas Gregory P. Wahlman; Douglas R. Tasker The integration of carbonate microfacies and fusulinid biostratigraphy from several cores with subsurface well log and seismic data enabled the reconstruction of Wolfcampian (Hueco Group, Lower Permian) stratigraphic architecture and reservoir facies along the eastern margin of the Central Basin Platform at 8790 Canyon (South Cowden) Field, Ector County, Texas. Fusulinid biostratigraphic analyses of the cores allowed the recognition and mapping of the Upper Pennsylvanian and Lower Permian carbonate depositional sequences along the platform margin. Microfacies analysis enabled detailed facies reconstruction. A regional unconfomity at the end of the Pennsylvanian (top Bursum) carved an escarpment along the Central Basin Platform margin. During the following Early Permian (Wolfcampian, Nealian) transgression, well-developed Lower Hueco reef-mound complexes with associated packstone-grainstone flanking facies were constructed along the face of the Bursum escarpment. The Lower Hueco reef-mounds show the first development and radiation of the tropical Permian reef community, which is composed of phylloid algae, calcisponges, Tubiphytes, laminar encrusting red algae, bryozoans, specialized brachiopods, and botryoidal radial fibrous cements. Reef flank beds are composed of packstones and grainstones dominated by fusulinids, and phylloid algal and Tubiphytes fragments. Capping shoal facies are similar but also contain abundant abundant dasycladacean algal fragments. During the subsequent midWolfcampian unconformity, the Lower Hueco shelf-margin complexes were exposed subaerially and meteoric leaching enhanced reservoir porosity in the buildups. The following Late Wolfcampian (Lenoxian) transgression created less accomodation space along the platform margin, and the overlying Upper Hueco is composed of a relatively thin sequence of well-bedded shelf and shelf-margin fusulinid-skeletal packstonegrainstone shoal facies. The post-Wolfcampian shelf-margin backstepped dramatically, and so the Hueco platform and platform-margin carbonates in the study area are overlain (and sealed) by Leonardian basinal shales with interbedded lithoclastic-fusulinid debris flows.

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Biostratigraphy while Drilling (BWD): How Well Site Biostratigraphy is Helping Statoil to Drill Better Wells and Save Money in the Norwegian Offshore Sector Alex Cullum; Iain Prince Real-time, well site analysis of microfossils is making a significant contribution to value creation. The biosteering of production wells provides the support to drill more ambitious wells with confidence. Precise stratigraphic control while drilling increases safety, saves money while drilling and greatly increases the long term potential of production wells. The analysis of microfossils contained in drill cuttings and other borehole rock samples is required for accurately subdividing successions of sedimentary rocks according to their geological ages. The results are used to assist the reconstruction of subsurface geology, the planning of well paths, making decisions during drilling operations, and maximizing future hydrocarbon recovery. During the last 5 years Statoil’s biostratigraphy team has gradually been introducing an additional service to the company, comprising ‘real-time’, well site microfossil analysis for the rapid, high precision age dating of successions as they are drilled – biostratigraphy-while-drilling (BWD). The advantages are many. The well site geologist gains stratigraphic confidence when biostratigraphic data are immediately to hand. Expensive offshore rig time can be saved by precisely locating casing depths, coring intervals and terminal depths. BWD can help avoid drilling expensive sidetracks. The successful completion of long horizontal sections biosteered within the required zone for optimum production improves subsequent drainage. Setting up a BWD project is a problem solving task.

This presentation will use case studies from three of Statoil’s producing fields to show a range of BWD challenges and solutions. The first case study shows how low cost Cretaceous micropalaeontology has replaced a multi million dollar well tool in the identification of a critical casing point above a high pressure and temperature reservoir.

The second shows how Jurassic palynology is applied to drill long production sections in a structurally complex reservoir. In the third case study palynofacies has been applied to help biosteer wells in a reservoir which is almost depleted of microfossils.

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Developments in Biosteering Techniques and their Application to Solving Reservoir-Scale, Subsurface Geological/Geophysical Problems Paul R. Marshall; Elisabeth A. Nairn The concept of biosteering (the use of microfossils to guide the steering of deviated and horizontal wells during drilling) was initially developed, by Fugro Robertson Ltd, in 1988, on location in the North Sea, in response to a requirement to overcome a geologically based drilling problem. Since that time there have been many further developments in techniques and applications. All of the developments discussed in this presentation have two elements in common: they are all related to the solving of geological (or geophysical) problems; and they are all completely dependent on microfossils. Some have been purposefully designed others have emerged to solve problems within hours of the problem first being encountered. All have resulted in enhanced exploitation. The selection of examples presented will illustrate the principles involved. All utilise only standard, accepted, straightforward biostratigraphic concepts.

All have been based on carbonate successions, but are equally applicable to fossiliferous clastics. The problems dealt with include poor stratigraphic resolution, lateral facies changes, inadequate sequence stratigraphic interpretation, subsurface structural geological uncertainty, the recognition of hiatuses (and their variability) and 3D planning, where other disciplines have failed to find answers. The solutions have all required microfossils, but the key elements are the skills of the micropalaeontologists extracting and interpreting the data.

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Recognition of Sub-Facies within a Miocene Canyon and Fan System by Use of Benthic Foraminiferal Assemblages M. Rogerson; H. Tijbosch; T. J. Kouwenhoven; G. J. van der Zwaan; B. J. O'Neill; C. J. van der Zwan; G. Postma; K. Kleverlaan The sedimentology and micropalaeontology of an exhumed Miocene age canyon and fan system from the Tabernas Basin (S. Spain) has been investigated. Four sections from the El Buho canyon encompassing proximal canyon, distal canyon and adjacent slope environments have been logged on a centimeter scale and the 150-595 micron size range of 157 samples have been examined for their benthic foraminiferal content. Two further sections from the time-equivalent fan have also been investigated, and benthic foraminiferal census data has been collected for a further 28 samples. The assemblages revealed are similar across all of the environments, but several taxa show sufficiently strong associations with a particular sub-facies to make highly promising potential indicator species. Individuals of Genus Cibicidoides (esp. C. dutemplei) dominate the assemblage in all samples, with the exception of a number of locations within the fan deposits. Here, deep-dwelling infauna dominate (Genus Globobulimina and Nonion soldanii), which may reflect enhanced supply of organic matter by transport down the canyon, as has been inferred from similar assemblages in the distal parts of modern canyons. Absence from canyon environments of several taxa (Cassidulina obtusa, Uvigerina rutila/striatissima and Cibicidoides robertsonianus) indicates that these species are not able to adapt to conditions in which sedimentary disturbance is common.

Presence of Cassidulina laevigata exclusively within energy minimum zones within the canyon itself indicates a strong preference of this species to environments with highly elevated food supply, but that are sheltered from direct disturbance. In addition, some general assemblage characteristics show significant, apparently environmentally controlled, trends. “Faunal Density� the relative proportion of tests to mineral grains in the 150-595 micron fraction, is found to be an effective initial guide to the relative sediment transport activity of locations. The relative proportions of epi- and infauna or of agglutinated and calcareous individuals both provide good, if subtle, indicators for the relative amount of environmental disturbance. The presence of good presence/absence indicators and unique assemblages within particular environments allows delineation of slope, canyon and fan environments with certainty within the Tabernas Basin by micropaleontology alone. Environmentally sensitive whole-assemblage indices give additional insight into disturbance periodicity, and provide a method by which further environments within the canyon can potentially be recognized. Benthic foraminiferal assemblage data therefore hold significant potential for the development of predictive tools for delineating environment of deposition within canyon and fan systems.

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New Microfacies Methods and Applications in Mudrock Characterization and Reservoir Modelling from the Early Paleocene of Mid Norway Craig Harvey; Nicholas Holmes The Ormen Lange Field was discovered in 1997 and is the second largest gas discovery offshore Norway. Ormen Lange is situated in the Møre Basin and the hydrocarbons now fill a north south trending Paleogene dome structure. The Early Paleocene Egga reservoir unit is widely thought to have been deposited by turbidites in a structurally controlled sub basin. Key to modelling of the Egga reservoir unit and field development is the nature and distribution of associated claystones. The depositional model and facies relationships within the turbidite sediments of the Ormen Lange Field has been significantly improved through the application and interpretation of foraminiferal facies analysis. The link between highest foraminiferal diversities and hemipelagic claystones has long been established. But new techniques in micropalaeontological facies analysis, presented here, have built upon the ‘Pelagic Index’ to better quantify the transitional facies between muddy turbidite and hemipelagic claystone end members. Recognition and correlation within chronostratigraphic boundaries of transitional claystone characteristics has been applied to the Ormen Lange Field and this has provided information on sequential depositional trends through Egga reservoir units 1, 2 and 3, and lateral changes in claystone character within each unit. Moreover trends of turbidite locus deposition have been identified. As such, integration of the micro-facies data has provided valuable input to the further evaluation of reservoir model scenarios. Using a de-sanded system, modelling of the background claystones has elucidated hitherto unobserved potential reservoir barrier/baffle levels and impacts on fault seal and compartmentalization issues.

Microfacies data will also be utilized operationally and impact future well planning and design.

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Barriers, Baffles and Biostratigraphy: The Integration of Production and Geological Data to Maximize Recovery from Glitne, the Smallest Stand-Alone Field in Norway Iain Prince; Arnfinn Kjøsavik The Glitne field to date is the smallest stand-alone field development in Norway. The field is located on the border to the UK sector, approximately 40 km North-West of Sleipner. Production started in August 2001, with an expected lifetime of 2 years and cumulative production of 4 million Sm³. The reservoir is a complex of submarine fans belonging to the Upper Heimdal sandstones of a Late Paleocene age. It consists of three main fan systems separated by impermeable shale barriers. These fans are partly stacked on top of each other. The maximum hydrocarbon column on the structure is 37m. The reservoir properties are good, with high permeability, porosity and net-to-gross. The original development of this field consisted of 4 horizontal producers and 1 vertical injector.

These wells were geosteered into the required zones using wellsite micropalaeontology. However, post drilling analysis showed that the wells had poor coverage of the uppermost sand unit (H1), partly due to a disappointing first well A-3H, which was intended to be one of the 2 main H1 producing wells. Simultaneous inversion data suggested that there were hydrocarbon filled sands above the A3H well. Dynamic simulations showed that little of the reserves in the uppermost sandstone unit were being drained by the existing wells, under the assumption that a barrier to vertical flow separated the attic oil form the underlying wells. In an attempt to clarify the sealing properties of these shales (and hence vertical communication within the reservoir), foraminiferal microfacies were completed. In addition, the seismic data was reprocessed using a High Frequency Imaging technique (HFI). This allowed the top of the HC-filled reservoir to be accurately resolved for the first time. The results of the integration between the new seismic data, biostratigraphical data and simulation modelling showed that the shale separating the H1 sands from those below were a major barrier and as such significant oil reserves were not being produced based on the existing well coverage. As a result a 5th horizontal well was successfully biosteered, with a horizontal section of 1200 m, into the uppermost sand unit. The original economic recoverable reserves were estimated to 4 MSm³, of the 14.6 MSm³ of oil in place. Economic reserves are now over 6 MSm³. Small IS beautiful.

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Micropaleontology and Lithology of Deep-Water Sediments: Application of Multiple Overlapping Foraminiferal Litho-Biofacies Theory to Cuttings-Based Analysis of Reservoir Properties Richard H. Fillon Deep-water foraminiferal assemblages contain: (1) indigenous benthics, (2) planktonics from surface habitats, and (3) allochthonous shelf benthics. Each of these categories of foraminifera carries information on the processes, lithology, and reservoir properties of deep-water ecotopes. Examination of the foraminiferal ecology of the most important deep-water lithofacies provides a sound basis for describing representative litho-biofacies occurrences. Key deep water litho-biofacies include: foraminiferally-barren / clean sand; agglutinated flysch-type fauna / turbidite; marginal-marine deltaic fauna / debrite; calcareous bank-turtle grass flat fauna / mixed siliciclastic-calciclastic basin margin; open marine outer shelf-upper slope distal prodeltaic fauna / hemipelagite; infaunal dysoxic basin fauna / hemipelagite; infaunal oxic-dysoxic interface fauna / sapropelite; deep water calcareous epifauna / unconfined lower slope and rise condensed hemipelagite; and plankton-rich ooze / condensed pelagite. In the petroleum industry micropaleontological samples are collected from well cuttings that contain a mixture of lithologies and foraminifera within, typically, 30 ft of drilled section. The biofacies represented in these mixed samples vary in their importance as indicators of lithologic parameters specifically related to reservoir quality. In applied studies using biofacies as proxies for reservoir quality it is therefore important to sort them by their significance from the unique perspective of reservoir quality assessment. Recognition of multiple overlapping lithobiofacies in well cuttings makes it possible to record multiple litho-biofacies within a single drilled sediment volume. One simple method for doing this employs biofacies significance cascade diagrams. These diagrams plot the vertical extent of each key biofacies in a wellbore, allowing interpreters to view individual component biofacies in a mixed sample and to experiment with different reservoir quality proxy and stratal heterogeneity models.

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Establishment of a Chronostratigraphic Framework for Stratal Correlation, Sedimentary Basin Geohistory Reconstruction, and Petroleum Exploration, Northern Gulf of Mexico Ernest A. Mancini Establishment of a chronostratigraphic framework based on an integrated biostratigraphic and sequence stratigraphic approach is fundamental to intrabasin and interbasin stratal correlation, to the reconstruction of the geohistory of a sedimentary basin, and in oil and gas exploration. Microfossil and macrofossil biozones and stratigraphic sequences are recognized in Jurassic, Cretaceous and Paleogene strata of the northern Gulf of Mexico.

Sequence recognition is based on stratal geometries, nature of sequence boundaries, facies stacking patterns, and large-scale shifts in major facies belts as observed from the study of physical surfaces and facies changes in outcrop and from the study of well log signature patterns and seismic relector configurations and terminations in the subsurface.

Sequences are controlled by the change in accommodation space resulting from stratigraphic base-level changes (eustatic and tectonic effects) and sediment supply and accumulation. Depositional sequences include lowstand, transgressive, and highstand systems tracts. T-R sequences are composed of aggrading and backstepping intervals of a transgressive phase (upward deepening section) and an infilling interval of a regressive phase (upward shallowing section), which are separated by a surface of maximum transgression. The aggrading interval marks the change from base-level fall and erosion to base-level rise and sediment accumulation. Transgressive events of the backstepping interval are widespread and provide regional correlation datums. Progradational events associated with the infilling interval represent major influxes of siliciclastic sediments and result in a loss of accommodation space. An integrated biostratigraphic and sequence stratigraphic approach provides for the correlation of stratigraphic sequences across the northern Gulf of Mexico and for the opportunity to show correspondance between sequences recognized in strata of the Gulf of Mexico to comparable stratigraphic sequences reported from Western Europe.

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Statistical Modeling of Ecological Signals (SMES): New Applications for Biostratigraphy and Environmental Geology Barrie Dale; Amy L. Dale; Iain Prince; Craig Harvey SMES is a new method for identifying ecological signals from assemblage counts of microfossils. The method was first developed by Dale & Dale to identify ecological signals from recent dinocysts, using a global database of cyst distributions that allowed testing of the signals against known environmental factors. SMES utilizes statistical methods based on correspondence analysis that were found to most accurately reflect and quantify the ecological signals expressed by the recent cysts (Dale & Dale 2002). Here we report on latest efforts to test and develop this method for solving geological problems. The first application of SMES to industrial biostratigraphy was reported at the joint meeting of AASP-BMS-NAMS in London, 2002 (Dale et al., in press). A palynology dataset was used from Paleocene sequences in four wells along an onshoreoffshore transect from the Norwegian North Sea provided by Statoil. The method allowed identification of the statistically most important species, and the relative position of these along the main axes suggested ecological trends (the coastal/oceanic being most dominant). Tracking these trends down-hole showed major shifts in each well that could be correlated between all wells; the shifts corresponded to flooding surfaces, and suggested orientation of the well sites relative to a paleo-shoreline. This first test strongly suggested this method to offer a quicker, more robust application for paleoenvironmental interpretations from the dinocysts than previously achieved by traditional methods. Within the past two years we have extended the biostratigraphic applications using data sets covering Late Cretaceous to Eocene in six wells from the deep water Norway/Greenland basins provided by Statoil and Shell. The SMES method proved equally applicable to these greatly extended geological intervals, even in older sequences lacking the ecologically significant cyst groups linked to the recent cyst distribution models. This was particularly important for identifying the paleo-shelf/slope break.

As important known oceanic indicator species of Impagidinium and Nematosphaeropsis diminished stratigraphically downhole (Campanian), the method allowed us to identify their ecological counterparts, suggesting previous oceanic indicators. Current applications include Early Cretaceous to Pliocene sequences from the Møre Basin using datasets provided by Statoil and Shell. The main objective is to identify relative water depth indicators as input to basin modeling. For the first time this includes both palynology and micropaleontology data. Results so far suggest the method probably could be applied to virtually any industrial dataset of microfossil assemblage counts, covering any geological time period. In addition to these biostratigraphic applications, we are exploring the use of SMES in environmental geology. An example is included here using dinocyst data on the time-scale of 10s to 100s of years, in short cores of bottom sediments, suggesting a correlation between eutrophication and the collapse of local fisheries along the southwest coast of Norway. ____________________________________ Geologic Problem Solving with Microfossils

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A New Approach for the Analysis of Assemblages within Biostratigraphical Data Glenn Johnson; Anthony Gary; Douglas Ekart The use of biostratigraphy to make drilling decisions in ‘real time’ requires the biostratigrapher to be able to confidently distinguish the target interval from those bounding it based on differences in their faunal or floral constituents. Determining the group or assemblage of taxa that are diagnostic of these intervals (i.e., biofacies) is a complicated procedure because (1) samples can contain a hundred or more taxa, (2) biofacies can vary over relatively short distances (e.g., from field to field), and (3) the differences in the assemblages representative of the target and bounding intervals are sometimes subtle. We have developed a new procedure based on fuzzy c-means clustering to assist the biostratigrapher in the discovery of assemblages that may be representative of biofacies and the taxa diagnostic of those assemblages. This method, although newly developed, has been successfully applied in a number of areas including the Gulf of Mexico, Norway/Greenland Sea basins and Northwest Africa. The high-level steps of this method for the analysis of biostratigraphical data are: 1. Mathematically define faunal/floral assemblages that are representative candidates of biofacies. This is done using the fuzzy c-means (FCM) algorithm (Bezdek, 1981). FCM, unlike hierarchical clustering methods, allows samples to be mixtures of multiple assemblages. In addition, in contrast to eigenvector-based methods, FCM does not require matrix inversion, so it is more applicable to biostratigraphical data sets, which can be notoriously sparse. 2. Calculate the relative proportions of each assemblage contained in each sample. FCM calculates each assemblage’s degree of association (i.e., membership) for every sample. Samples that are represented almost entirely by one assemblage will have a membership value near one for that assemblage and membership values approaching zero for all other assemblages. A sample that is a mixture of multiple assemblages will not have high membership values for any one assemblage. The membership values, ranging between zero and one, allow the biostratigrapher to better evaluate the reliability or confidence of the results and identify assemblages mixed by syn- or post-depositional transport or caving. The FCM model can be used to classify future samples of unknown affinity. 3. Transformation of the FCM results for well-site application. At the well site timely decisions are critical, so the quantitative FCM results must be transformed into a more qualitative or descriptive form that can be quickly applied by a biostratigrapher working at the microscope. We have developed a methodology that scores each taxon relative to its usefulness as a proxy for the assemblages defined by the FCM method. Taxa that are a good proxy or diagnostic of particular biofacies by virtue of higher abundance values are determined by the correlation between the taxon’s abundance and the sample membership values, and taxa that are diagnostic based on their presence or absence are determined by a fuzzy set extension of the concepts of Constancy and Biostratigraphic Fidelity (Hazel, 1970).

References: Bezdek, J. C., 1981, Pattern Recognition with Fuzzy Objective Function Algorithms, Plenum Press, New York, New York. Hazel, J. E., 1970, Binary coefficients and clustering in biostratigraphy, Geological Society of America Bulletin, v. 81, pp. 3237-3252.

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Amphistegina, Red Algae and Paleobathymetry: The Lower Tortonian Distally Steepened Ramp of Menorca, Balearic Islands (Spain) Guillem Mateu-Vicens; Pamela Hallock; Marco Brandano Test shape in rotaliid larger benthic foraminifers is strongly influenced by environmental conditions. For example, thickness to diameter ratios (T/D) in tests of Amphistegina spp. has been shown both empirically and experimentally to be strongly influenced by both solar irradiance and hydrodynamics, both of which typically decline exponentially with water depth. Trends in T/D for Amphistegina spp. from the Indo-Pacific region can be bathymetrically represented by the equation (F.1): Z = (T/D / 1.476)^-2.333; where “Z” represents depth in meters. Thus, as observed in previous studies, the most robust individuals are found in high-light, high-energy shallow waters, whereas thin, flat tests are typically found in deeper, oligophotic waters where wave and current energy is limited. The decline in light intensity with depth in the water column is mathematically defined by the function Iz = I0 * e^-kz, where “I0” is the intensity at the surface (i.e., 0 m, which can be represented as 100%), “Iz” is the light intensity at depth “z” (or percentage of surface irradiance reaching that depth), and “k” is the light-attenuation coefficient. We found high correlation values when we compared T/D data with depth from Indo-Pacific sites that occur in very clear, oligotrophic waters (k= 0.04-0.06).

Previous studies have used Amphistegina morphology to infer light and water energy conditions in paleoenvironments (i.e., lower Miocene facies from Palawan, Philippines).

In our study, we interpret paleodepths by comparing T/D data for Amphistegina from lower Tortonian, distally steepened ramp of Menorca (Balearic Islands, Spain) with the mathematical model (F.1) based on modern data from the Indo-Pacific region. T/D ratios were determined for 62 Amphistegina specimens from 24 thin-sections from 6 different localities on the Menorcan ramp. Using the bathymetry calculated using the morphometric data, each locality has been interpreted relative to a ramp depositional model. Inner ramp conditions are interpreted to represent paleowater depths from less than 10m down to 20-30m, while middle-ramp habitats are interpreted as 30m down to 60m.

This interpretation increases the precision of previous paleobathymetric interpretations for these ramp habitats. At ramp margin and slope localities, T/D values tend to be highly variable, representing mixtures of tests from different habitats, reflecting downshelf transport and accumulation processes. Comparing Amphistegina T/D distribution with red-algae generic distributions resulted in similar interpretations not only for paleodepth, but also for climatic and paleonutrient conditions.

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Application of a Statistically Derived, Integrated Biozonation to a Deepwater Miocene Gulf of Mexico Field Andrew R. Bowman; Garry D. Jones; Roger J. Witmer; Anthony Gary In an attempt to refine Unocal’s Gulf of Mexico deepwater Miocene biozonation, a statistically rigorous methodology was applied to the extensive micropaleontological database of wells penetrating the Miocene. Over a two year period, we analyzed, in an integrated manner, the stratigraphic distribution of calcareous nannofossil and foraminiferal species that resulted in improvements in age-dating and correlating for both exploration and development scale projects. Our approach was to first begin with a detailed evaluation and validation of bioevents of many hundreds of Miocene age taxa using hardcopies of species distribution charts (BugCAD plots), followed by analyses of results processed through specialized computer software (IPS and BioSlot). This process yielded the placement of the more common types of bioevents (species range tops and bases), and in addition aided in the discernment of new, useful, subordinate bioevents.

All bioevents were then analyzed using the ranking and scaling probabilistic sequencing method (RASC), and the correlation and scaling in time method (CASC). The RASC/CASC methods resulted in the most probable order, termed the “optimum sequence” for the Miocene age biostratigraphic events. This optimum sequence has been empirically validated by its successful application to correlations during drilling wells and in multiple-well projects on a development scale in a deepwater Gulf of Mexico field.

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Increasing Resolution in Exploration Biostratigraphy with Crossplots of RASC and CONOP Sequences F. M. Gradstein; O. Hammer; E. Anthonissen; G. D. Jones A combination of Ranking & Scaling (RASC) and Constrained Optimization (CONOP) increases stratigraphic resolution and correlation potential of fossil distribution range charts for wells through rapid identification of average and maximum event positions. The new methodology solves the problem that conventional zonations do not rank taxa according to the degree of diachroneity of range endpoints in a correlation scheme. The RASC and CONOP methods yield three types of results that complement each other: A. (RASC) Most likely optimum sequence of events; this is an ordinal composite standard, with events variances. B. (RASC) Scaling of the optimum sequence; this is a composite standard with interval zones. C. (CONOP) Composite standards with display of penalty (misfit) of events, according to three strategies: 1) event positions in the composite are unconstrained, and can move either up or down, not unlike RASC. 2) event positions in the composite are maximized, either stratigraphically upwards (for tops) or downwards (for bases), as in conventional graphic correlation seeking total stratigraphic ranges.

Using this strategy, events from the lower part of ranges generally move downwards in the composite standard, and events in the upper part of ranges upwards. 3) Event positions are not allowed to move, and are correlated as locally observed. Stratigraphic crossplots of the results with methods A or B versus C1, C2 and C3 show which events do not deviate much their stratigraphic position from well to well, and which ones do. The latter often also have above normal variance. Next, using combination of simple penalty rules and the variance values, microfossil events are grouped in three classes A, B or C according to their Relative Biostratigraphic Value. A-events show regionally stable stratigraphic event positions, relative to B-events, that show more crossovers; C- events are least useful for tracking a stratigraphic level.

This enables well-site paleontologists to predict with confidence what the chances are a particular horizon has been identified, using primary, secondary and ternary marker criteria. Since the methods target all data, not a regional ‘mindset’, correlation potential of wells is optimized. Four large datasets demonstrate the new findings, three from petroleum basins, offshore NW Europe using Last Occurrence and and Last Consistent Occurrence events of dinoflagellates and foraminifers, and one for the deep GOM, using LO, LCO, Acme, First Common Occurrence and First Occurrence events of nannofossils and foraminifers. The Cretaceous zonation, offshore Norway, based on 1758 records in 30 wells, contains 80 events in 17 interval zones; 60% are Atype taxa. The Cenozoic zonation, based on 1548 records in 27 wells offshore Norway, contains 102 events in 18 zones; over 75 percent are A-type taxa. The Cenozoic zonation for the North Sea, based on 1347 records in 30 wells, consists of 107 events in 19 zones, over 60% track in the A category. The Neogene zonation for the GOM (Mad Dog), using 1688 records in 13 wells, is based on 85 events in 15 zones; over 75% have high stratigraphically fidelity. Both the RASC and the CONOP zonations can be easily converted to biochronologies, using selected age calibration points, that give the likely age of the events in the basins.

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A Fuzzy Inference System for Modeling Biostratigraphical Concepts Anthony Gary; Glenn Johnson; Douglas Ekart Biostratigraphical models are based on the knowledge and experience of the biostratigrapher and, for the most part, they exist only conceptually within the biostratigrapher’s mind. The human brain is an extremely powerful instrument for abstract thought and concept development, but it also has some serious shortcomings when it comes to reliably applying those concepts, such as inconsistencies in the storage, use and transfer of concepts, and inefficiencies in applying complex relationships. To complement the strengths of the human mind in conceptualization and help address some of its deficiencies in applying concepts, we developed a modeling tool specifically for biostratigraphical data based on fuzzy logic. Fuzzy logic is an extension of fuzzy set theory that generally allows concepts to be more faithfully modeled than is possible with the modeling methods presently available for biostratigraphical data. Basically, fuzzy logic is a generalization of the logical process that geoscientist use almost daily in their work. Formal logic (i.e., binary logic), such as “if A and B co-occur, and C is absent then the interpretation is D”, is the decision-making foundation for geoscientists when interpreting geologic data. However, the nature of the physical systems that are commonly encountered in petroleum geology often require more than a strict application of formal logic. Biostratigraphers commonly deal with continuous variables (e.g., species abundances) and there is generally no one abundance value (i.e., threshold value) that turns a ‘no’ decision into a ‘yes’ decision, but there are instead changes in the degree of likelihood of either decision as abundance values change. For example, the occurrence of one or two marine dinoflagellates may only indicate a weak association with an open marine environment, but as their numbers increase the strength of the association grows until some point at which there is little doubt of the open marine interpretation based on marine dinoflagellates. A critical part of the biostratigrapher’s job is to determine the degree of association among a group of variables relative to a suite of possible interpretations and, then rectify these associations to produce a single “best” interpretation. This task is more reliably performed and with less ambiguity using a fuzzy (i.e., multivalent) logic modeling process than it is using the more common binary logic approach. We have successfully applied fuzzy logic models to solve industrial problems of the type described above, and as a result of those successes have developed a Fuzzy Inference System (FIS) that will allow industrial biostratigraphers to quickly build and apply their own fuzzy logic models. The FIS consists of three primary components: a graphical interface for the biostratigrapher to create functions that represent their concepts of linguistic variables, a rule-builder that allows the biostratigrapher to create common language structures to represent their concepts using the functions representing the linguistic variables and basic elements of logic (e.g., conjunction, disjunction and negation), and a fuzzy logic processor to deconstruct the common language structures and apply the appropriate fuzzy set mathematics. ____________________________________ Geologic Problem Solving with Microfossils

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Assemblage-Based Biozonations: A Key Tool in the Detection of Reworked Fossils Richard A. Denne Determining the age of oil-well cuttings samples with microfossils is problematic in wells with a significant amount of reworked fossils. As caving is a common problem in cuttings, species’ bases cannot be used with any confidence. If it is determined that some of the fossil markers are older than the overall assemblage would suggest, then a biostratigraphic zonation that utilizes assemblage events (e.g. downhole increases, dominance shifts, and morphologic shifts) and short-ranging species is needed to correctly determine the sediment’s age, especially if the age of the reworked fossils is only slightly older than the age of the in-place assemblage. In an example from the upper Pliocene, the well contained a large number of reworked nannofossils from the lower Pliocene and upper Miocene. Many of these reworked species have their extinction points within nannofossil zone NN16 or NN15 (e.g. Sphenolithus abies, S. verensis, Reticulofenestra haqii, R. pseudoumbilica, and Dictyococcites antarcticus), so a typical tops-based zonation could be very misleading. Utilizing abundances of relatively common species, three biohorizons were identified, all within zone NN16. The uppermost event was a downhole increase in Discoaster spp. which is correlated to the middle of NN16. This was followed by a horizon containing downhole increases of both Coccolithus pelagicus and Cycloperfolithus carlae. This event is correlated to the Sphenolithus abies extinction point in the lower portion of NN16. The third event was a large downhole increase in the numbers of Gephyrocapsa sp. “small”, which occurs in the basal part of NN16. A second example is a well that contained rare, but consistent, occurrences of upper Eocene nannofossils, including Discoaster barbadiensis, D. saipanensis, and Cribrocentrum reticulatum. The section was determined to be lower Oligocene (nannofossil zones NP21 – NP23) due to the rarity of several species common within the uppermost Eocene (e.g. Ericsonia formosa and Reticulofenestra umbilica), and the common occurrence of Reticulofenestra laevis, a species that is rare within the upper Eocene. As a number of the lower Oligocene marker species are common in the upper Eocene, this section was zoned using the highest consistent occurrences of several species (Discoaster tani tani, Reticulofenestra hillae, and Helicosphaera reticulata) and downhole abundance increases of more common forms (e.g. Helicosphaera compacta, R. laevis). In both of these examples, without a thorough understanding of the overall inplace assemblage found in a specific place and time and a biozonation that utilizes assemblage changes, the age of the section could have been determined to be either older than its actual age or left unzoned due to the reworked fossils present in the sediments.

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New Insight into the Palynology of the Cretaceous Otway Basin, South Australia, Based on the Application of Quantitative Biostratigraphic Methodologies Eric Monteil; Andrew Kelman In the Cretaceous Otway Basin of South Australia, as in many petroliferous basins, palynology is a key element in exploration and production. In order to maximise the value of palaeontological information, quantitative palynological data were processed and interpreted using the Integrated Paleontological System (IPS) software. This is the first time IPS software has been applied to Australian material. The Otway basin palynostratigraphy was re-assessed based on the review of existing consultant reports and new sample analysis of 25 petroleum exploration wells. IPS software provides numeric techniques to objectively extract patterns from paleontologic data. Suites of simultaneous events, which are not identifiable from conventional range charts or from observations at the microscope, are used to define palynological surfaces that can be correlated across the basin, over 400 km. Graphic correlation is used to date these surfaces and to constrain the sequence stratigraphic framework. Palynological surfaces were integrated with the sequence stratigraphic interpretation derived from seismic and well data to produce a new regional tectonostratigraphic framework for the basin (Krassay et. al., 2004). This project provides further evidence that the future of applied biostratigraphy must rely not only on the refinement of microfossil biozonation schemes, but also through the application of quantitative analysis to fully exploit basic raw data.

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Graphic Correlation and Sequence Stratigraphy of Two Sirt Basin (Libya) Wells William N. Krebs; Thomas D. Demchuk The graphic correlation method is a unique process for ordinating and calibrating various vintages of historical paleontological data from the Sirt Basin. Integration of the results from graphic correlation with geological and seismic data offers a good opportunity to resolve the depositional and tectonic history of the basin and identify reservoir-prone, seal, and source rock intervals. Through the interative graphic correlation process, a composite standard database and chronostratigraphic framework can be constructed by combining elements of all available paleontological data of disparate vintage and nomenclature. Graphic correlation analysis of paleontological data from two Sirt Basin wells has revealed that the Upper Cretaceous and Tertiary sections consist of numerous rock sequences that are separated by major depositional hiatuses. The most robust dataset is comprised of foraminiferal, nannofossil, and palynological datums from Well A. The section in this well spans the uppermost Cenomanian (Upper Cretaceous) to Tortonian (Upper Miocene). Graphic correlation of these data indicates that the well section can be divided into at least twelve sequences that are bounded by either hiatuses or faults. These sequences formed during periods of continuous depositon, whereas the hiatuses represent erosional unconformities, sediment bypass, or periods of slow sedimentation (condensed intervals). Depositional rates varied from high during the latest Cenomanian and latest Maastrichtian to low in the early Maastrichtian and Miocene. The thickest sequence was rapidly deposited during the early Oligocene. The duration of hiatuses may vary from as much as 20 Ma at the T/K boundary to about 1 Ma during the late Eocene. The paleontological data from Well B are much less detailed and do not yield comparable results. Nevertheless, some diachroneity of lithostratigraphic units may be interpreted, but final determination requires detailed integration with seismic data and possibly further biostratigraphic analyses. For example, the Sirt Fm. in Well A may be younger (early Maastrichtian) than it is in Well B (Campanian or older).

In fact, part of the Sirt Fm. in Well A may correlate to a condensed section at the base of the Kalash Fm. in Well B. In addition, the Paleocene section present in Well B may not be present or may correlate to a dolomite section of uncertain age in Well A. Unlike Well A, the post-Eocene section is either thin or absent in Well B. Furture graphic correlation analysis of other regional well data, and subsequent integration with other stratigraphic information, including seismic interpretation, will help refine and confirm these preliminary chronostratigraphic relationships.

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From Greenhouse to Icehouse: Evidence for Late Early Eocene Concomitant Cooling of Southern Ocean Surface Waters and Global Deep Waters from Dinoflagellate Endemism Henk Brinkhuis; Matthew Huber; Appy Sluijs; Jeroen Warnaar; Catherine E. Stickley; Jonathan P. Bujak; James C. Zachos ODP Leg 189 drilling around Tasmania retrieved ~continuous Eocene records from the Southern Ocean – Antarctic Margin. The shallow marine, pro-deltaic successions of Sites 1170, 1171 and 1172 include the interval representing the onset (~55 Ma) and termination (~50 Ma) of the Early Eocene Climatic Optimum (EECO). The end of the EECO is globally reflected in the oceans by the onset of increasingly cooler deep-water temperatures, and marks the onset of the trend towards the Icehouse world. Here we show that a strong increase of endemic Antarctic dinoflagellates precisely matches the termination of the EECO in the Southern (Pacific) Ocean. The record of these surfacedwelling organisms thus indicates that changes of surface water parameters, notably temperature, occurred near simultaneously with global deep-water temperature changes.

Moreover, the signal coincides with the return to heavier d13C-values, and atmospheric CO2 decline. Comparison of the field data with predictions from fully coupled climate model simulations, and a new basic understanding of Eocene Southern Ocean circulation, suggests that changes in carbon burial was driving changes in atmospheric greenhouse gasses, and the apparently coupled surface- and deep-water temperature signals.

Opening/deepening of Southern Gateways is/are refuted as possible mechanisms related to Eocene cooling. The Southern Ocean records are compared with similar data from the Northern Hemisphere, including new data from the recent Arctic drilling (IODP 302ACEX). It is shown that combined dinocyst records argue for strong atmospheric cooling at ~50 Ma, followed by several further, probably orbital paced steps towards the onset of major Antarctic glaciation at ~33 Ma.

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Planktonic Foraminifera Record of the Mid Albian Sea-Level Rise, Upper Magdalena Valley, Colombia Lizette Leon-Rodriguez Micropaleontological studies have been carried out for several years by petroleum companies in the Upper Magdalena Valley Basin, but up to now only few have made it to the main stream; here a novel research done based on previously measured and sampled stratigraphic sections. Descriptions and analysis of planktonic foraminifera from a lower Cretaceous unit in southern Colombia named “Tetuán Limestone”, has allowed the comparison between the stratigraphic distribution (range) of the planktonic foraminifera and ammonites. This appraisal presents the recognition and calibration with other fossil groups of two planktonic foraminifera interval zones: Ticinella primula and Biticinella breggiensis, with late mid Albian and early late Albian ages respectively. The “Tetuán Limestone” belongs to a large sedimentary succession that extends along the Upper Magdalena Valley (Huila Department), and is described as intercalations of micritic limestones and micritic concretions of thin to middle size, tabular and cuneiform beds with interbedded dark gray, laminated, calcareous claystones with common imprints of ammonites, bivalves and fish. The presence of marine planktonic foraminifera like Ticinella primula, T. cf. albiana, T. caronae, T. madecassiana, T. roberti, Biticinella breggiensis, Hedbergella delrioensis, H. gorbachikae, H. simplex, Favusella washitensis, within the claystones of the “Tetuán Limestone”, immediately above the mainly arenaceous and barren for planktonic microfauna of the Caballos Sandstone, points to a marine transgression at least from the late Albian to early Cenomanian. The residing water masses that occupied the accumulation enclosure were mostly warm; nevertheless, abundant and punctual presence of species like Whiteinella baltica indicates temporal incursions of cold currents. High microfaunistic affinities could be established among Colombian planktonic foraminifera associations and Mexican and Texan ones. Minor affinities were observed with the Tethys realm’s associations.

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Cyanobacterial Productivity, Variations in the Organic Matter and Facies of the Indidura Formation (Cenomanian - Turonian), NE Mexico Fabian Duque-Botero; Florentin Maurrasse Rock sequences of Cenomanian-Turonian age commonly assigned to the Indidura Formation in northeastern Mexico (Coahuila State) show distinct facies indicative of signifi cant spatial variability over the carbonate platform. Three stratigraphic sections where selected to characterize these differences. Las Delicias section (stratotype) is composed of 10-30 cm thick beds of very-pale orange biocalcirudites, without internal primary structures. Allochems consist of abundant echinoderms, pelecypods, ammonites, and fewer proportion benthic and planktonic foraminifera. Total carbonate (CaCO3) varies between 48 and 94 wt%, and total organic carbon (TOC) between 0.08 and .18 wt%. La Casita Canyon section, southeast of Las Delicias, consists of 3-30 cm thick interbeds of pale yellowish brown biocalcilutites and olive gray shales. Hand specimens show no apparent depositional internal structures, whereas abundant micro-bioturbation appears in thin sections. Allochems consist of sparse fragments of planktonic foraminifera and radiolaria concentrated in burrows. Total carbonate (CaCO3) varies between 0.8 % and 59.3 %, whereas TOC fl uctuates between 0.02 and 0.69 wt%. In contrast, the Sierra de Parras section, south of Las Delicias and west of La Casita, includes a sequence with well defined rhythms. They consist of 8-200 cm thick beds of light olive gray and brownish black, to olive black shales; and 5-100 cm thick marly biocalcilutites. Both facies exhibit similar internal structures arranged in nearly evenparallel “varve-like” dual lamination (<3 mm thick). Microscopically, they include few planktonic foraminifera scattered in the dark laminae. Epifaunal remains include only sporadic pelecypods ( Inoceramus radic Inoceramus ). Total carbonate (CaCO3) content varies from 43% to 78.3%, while TOC is relatively high between 7.3 and 2.91 wt%, more often higher than 20%. Microfacies in the Parras area reveal compositional differences in the laminae associated with varying abundance of microspheres or “micro-ooids” that we attribute to be of cyanobacterial origin. The precesence of cyanobacteria/bacteria induced sediments all through the rock sequence at Parras de la Fuente is indicative of oceanic conditions that lead to the development of sedimentary facies in which other organisms were not able to trive (competitive exlusion). Laminae developed from fluctuating cycles of calcareous cyanobacteria blooms, which remained dominant throughout the sequence. C organic–rich black shales and limestones of the Parras region further document unique paleoceanographic conditions, which were also characterized by strong dysoxic/anoxic bottom conditions and rhythmical production of cyanobacteria.

These conditions contrast sharply with prevailing paleoenvironments recorded at Las Delicias and La Casita where benthic epifauna, planktonic and nektonic organisms were able to thrive. Assuming that these facies are coeval, microfacies and TOC analyses of these rocks further demonstrate distinct spatial differences between these areas. ____________________________________ Geologic Problem Solving with Microfossils

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Calcareous Nannofossil Evidence of Significantly Elevated Primary Productivity during Aptian/Albian Ocean Anoxic Event 1b Emily Browning; David K. Watkins The enhanced burial of organic material on an ocean wide scale during Cretaceous Ocean Anoxic Events has been attributed to 1) intensified stratification of the water column and oxygen depletion in bottom waters, and 2) enhanced primary productivity in surface waters. Calcareous nannofossils are splendidly preserved in Aptian/Albian OAE1b sediment recovered from the Blake Nose, located off the eastern coast of the United States, during Ocean Drilling Program Leg171b. This nannofossil community preserves a record of surface water fertility during OAE1b. Results indicate surface water fertility was significantly increased prior to and during OAE1b. The abundance of small Zeugrhabdotus (known as Zeugrhabdotus moulladei or Zeugrhabdotus erectus) and Biscutum ellipticum, species that tended to dominate during periods of elevated surface water fertility, increased by over 100% before and during the OAE1b interval.

Watznaueria barnesae and Nannoconus tended to be dominant in oligotrophic or stable oceanic conditions, the abundance of both decreased significantly before and during the OAE1b interval. The robust elevation of surface water fertility is unambiguously demonstrated by sections of OAE1b in which small Zeugrhabdotus comprised over 40% of the nannoplankton community. Two species assemblages responded to fluctuations in surface water nutrient content. The species assemblage dominant in high surface water fertility included: small Zeugrhabdotus, Biscutum ellipticum, Prediscosphaera columnata, Rotelapillus crenulata, and Rhagodiscus angustus. The species assemblage dominant in oligotrophic conditions included: Watznaueria barnesae, Nannoconus, Retecapsa surirella, and Rucinolithus irregularis. It has been hypothesized that Cretaceous Ocean Anoxic Events resulted in a dramatic turnover of species in the planktonic community. Results indicate the genus Prediscosphaera possibly arose at the onset of OAE1b. The dramatic increase in surface water fertility associated with OAE1b may have provided a niche for the origination of this predominant Middle-Late Cretaceous nannofossil genus.

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Evolutionary Trends in Axopodorhabdus biramiculatus Amanda Ruth Dillon; David K. Watkins Nannofossil assemblages from the Upper Albian and Cenomanian of Blake Nose (ODP Leg 171B) preserve a record of morphologic variability in the coccolith Axopodorhabdus biramiculatus. Results show a gradual size increase of 45-50% over approximately three million years that is statistically significant to the 99% confidence interval. The onset of the change in size correlates to a rapid shift in δ18O in planktonic foraminfera toward more negative values and to the deposition of black shale. This increase in sea surface temperature and collapse of upper water column stratification seems to have driven the anagenetic size change in A. biramiculatus. The size stabilizes at the end of the Middle Cenomanian, and is synchronous to another short episode of black shale deposition. The extinction of A. biramiculatus in the Late Cenomanian corresponds to the onset of Oceanic Anoxic Event 2. Axopodorabdus biramiculatus comprises between >.2%-1% of the total assemblage in the Late Albian to the early Cenomanian, indicating that caution should be exercised when using this species as the definition of a zonal boundary.

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Tracking Geologic Changes from Global Biogeographic Patterns: The Resolution Power of Larger Foraminifera Martin R. Langer Biogeographic patterns of modern larger symbiont-bearing foraminifera are strongly constrained by a complex and intriguing mixture of geological history, physical oceanography and protistan biology. Among the primary factors that limit larger zooxanhellate-bearing foraminifera to tropical and subtropical localities, sea surface temperature has long been considered to be of particular significance. We have established a global data base for modern and Upper Cretaceous larger symbiont-bearing foraminifera to compare the extension of biogeographic provinces, to analyze pronounced shifts in patterns of diversity and to examine geological factors regulating shifts and pathways in the evolution of diversity through time. The spatial patterns that emerge from these studies are used to highlight some of the environmental variables exerting control over the biogeographic distribution of larger foraminifera in time and space. By analyzing high-resolution satellite temperature/nutrient data in addition to prevailing ocean current regimes in modern oceans and by comparing them to the biogeographic patterns observed we identify specific temperature and nutritional requirements, means of dispersal and dispersion capabilities of individual species of larger foraminifera. The biogeographic faunal patterns observed in modern oceans are subsequently used to assess the environmental constraints governing biogeographic provinces of their Cretaceous counterparts. The analysis of distributional patterns in Upper Cretaceous larger foraminifera exhibits prominent biogeographic patterns that reveal extensions over local, regional and circumglobal levels. It is shown that the factors regulating Cretaceous biogeographic extensions, hotspots of diversity and individual patterns of distribution, follow the same mechanisms as observed in modern oceans and can thus be used to track geologic changes and to solve geologic problems in earth history. Modern and Cretaceous patterns of diversity and sites of mass accumulations of larger foraminifera are compared and may ultimately lead to a better understanding and an increased interest in larger foraminifera as potential reservoirs.

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The Rupelian/Chattian Boundary in the Southern North Sea Basin: New Insights in the Glacio-Eustatic Driven Unconformity Ellen De Man; Stefaan Van Simaeys Recent quantitative analysis of benthic foraminifera, calcareous nannofossils and organic-walled dinoflagellate cysts (dinocysts) from several cored boreholes throughout the southern North Sea Basin led to the establishment of an integrated regional zonation scheme and the reconstruction of the paleoenvironment. A major change in paleotemperature and paleobathymetry coincides with the Rupelian/Chattian (R/C) transition: Shallow marine subtropical species at the base of the Chattian are in strong contrast with the neritic relatively cold upper Rupelian fauna (Van Simaeys et al., 2004). These records are indicative of a hiatus between the top of the Rupelian and the base of the overlying Chattian transgression in their type region, the southern North Sea Basin.

Despite the fact that regional biostratigraphies achieve high resolution, chronostratigraphic calibration of the classic R/C transition to international time scales remains problematic. This is foremost due to the marginal to restricted marine setting of the basin, the weak paleomagnetic signal and the near absence of traditional, age-indicative calcareous microfossils. The current ‘global’ criterion for the recognition of the R/C boundary, i.e. the demise of the planktonic foraminiferal genus Chiloguembelina (e.g., Berggren et al., 1995), is furthermore not applicable in the remote North Sea Basin. Detailed dinocyst studies have been completed from several mid Oligocene sequences in both hemispheres, and the results have been directly calibrated with the GPTS. This has allowed the recognition of a globally synchronous “Svalbardella migration phase”, calibrated against the interval represented by the upper half of chron C9n. The sudden abundance of this Arctic, cold-water taxon at lower latitudes is consistent with the reported timing of one of the major Oligocene deep-sea benthic foraminiferal d18O events, known as the Oi2b-event (Miller et al., 1998). This episode, representing ~500 kyrs of profound global cooling, is termed ‘Oligocene Glacial Maximum’ (OGM), and has a GPTS age of ~27.5 to ~27.0 Ma. The subsequent warming during magnetochron C8, known as the ‘Late Oligocene Warming Event’ (LOWE, Zachos et al., 2001), is expressed by a major drop in d18O values and has been globally recognized within deep-sea records. This series of extreme climate changes is reflected in the marginal marine southern North Sea Basin successions. Multiple lines of evidences show a one-to-one correlation between the OGM cooling interval and the R/C unconformity in the type region. This correlation suggests a scenario of global cooling, concomitant Antarctic ice-sheet growth and significant glacio-eustatic sea level fall, which caused sub-aerial exposure and erosion of the marginal to restricted marine settings. The subsequent warming phase induced the basal Chattian major sea level rise, depositing time-transgressive glauconitic sands, unconformably overlying the clayey upper Rupelian strata. This distinct warming is evidenced by a tropical to subtropical association of benthic foraminifera, known as the ‘Asterigerina Horizon’. Attributing the OGM, and the corresponding glacio-eustatic sea level fall, to the R/C unconformity in the southern North Sea Basin has considerable implications for the age assessment of the R/C boundary. Since the OGM correlates to the upper part of magnetochron C9n, the base of the Chattian unit-stratotype is not older then ~27.0 Ma.

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Plio-Pleistocene Dinoflagellate Cysts from DSDP Hole 610A, Eastern North Atlantic, and Biostratigraphic Application to Shallow Marine Environments Stijn De Schepper; Martin J. Head This study presents the first high-resolution Plio-Pleistocene dinoflagellate cyst biostratigraphy for the eastern North Atlantic. DSDP Hole 610A (53 13’N, 18 53’W; Rockall Trough) was chosen for its high sedimentation rate (5cm/kyr), good magnetostratigraphic calibration (Clement and Robinson, 1987) and independent oxygen-isotope stratigraphy in the time-interval of 3.6 to 2.4 Ma (Kleiven et al., 2002). The combination of independent dating methods allows dinoflagellate cyst events to be calibrated with an accuracy of up to 50 kyr. Based on ca. 100 studied samples (sampling interval, ca. 1.5m), a relatively diverse flora is observed in the eastern North Atlantic during the Plio-Pleistocene. At least fifteen dinoflagellate cysts species have a range base or top in the studied time interval. The range bases and tops largely cluster in three main biostratigraphic events at ca. 4.0 Ma, 3.2 Ma, and 2.6 Ma. After 2.6 Ma, coinciding with the onset of Northern Hemisphere glaciation, the flora undergoes marked changes: species richness is almost halved and biostratigraphic markers become scarce. Moreover, the dinoflagellate record shows marked changes: e.g. between 2.6 and 2.2 Ma, the cold-tolerant species Habibacysta tectata and Bitectatodinium tepikiense replace the previously omnipresent Operculodinium centrocarpum sensu Wall & Dale (1966), commonly seen as an indicator for the North Atlantic Current. The dinoflagellate cyst ranges recognised in DSDP Hole 610A are applicable for dating deposits in the mid to high latitudes of the Northern Hemisphere. This has already proven successful in shallow marine deposits of the southern North Sea Basin (England, Belgium, The Netherlands), which lack magnetostratigraphic calibration, and generally have poor calcareous microfossil control. Indeed, Pliocene deposits from Belgium have recently been more accurately dated and placed within a basin evolution context (De Schepper et al., 2004; Louwye et al., 2004).

References: Clement, B.M. and Robinson, F., 1987. The magnetostratigraphy of Leg 94 sediments, pp. 635–650. In W. F. Ruddiman, R. B. Kidd, E. Thomas, et al., Initial reports of the Deep Sea Drilling Project, 94. U.S. Government Printing Office, Washington. Kleiven, H. F., Jansen, E., Fronval, T. and Smith, T. M., 2002. Intensification of Northern Hemisphere glaciations in the circum Atlantic region (3.5–2.4 Ma) – ice rafted detritus evidence.

Palaeogeography, Palaeclimatology, Palaeoecology 184, 213–223. De Schepper, S., Head, M. J. and Louwye, S., 2004. New dinoflagellate cyst and incertae sedis taxa from the Pliocene of northern Belgium, southern North Sea Basin. Journal of Paleontology 78(4), 625-644. Louwye, S., Head, M. J. and De Schepper, S., 2004. Palaeoenvironment and dinoflagellate cyst stratigraphy of the Pliocene in northern Belgium at the southern margin of the North Sea Basin.

Geological Magazine 141(3), 353-378.

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Arctic Drilling: IODP 302 A digital video on disk.

Introduction by Henk Brinkhuis.

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Geologic Time Scale 2004 James G. Ogg; Felix M. Gradstein; Alan G. Smith The geologic time scale is the framework for deciphering the history of the Earth. The Geologic Time Scale 2004 (GTS2004) program under the auspices of the International Commission on Stratigraphy (ICS) had three components: (1) International definition (“Global boundary Stratotype Section and Point” or GSSP) of divisions of geologic time, (2) High-resolution integrated stratigraphy, and (3) Numerical age scale for both boundaries and all major events within each stage. Half of the 20 Cenozoic stages are fixed by GSSPs, but only 8 of the 30 Mesozoic stages are officially defined. Therefore, the summary scale has selected the most probable boundary definitions being considered by the subcommissions of ICS. The Neogene Period (Holocene through Miocene) time scale has an ultra-high-resolution scaling from astronomical (Milankovitch) cycles.

Astronomical cycles tied to radiometric ages also scale portions of the early Paleogene, middle Cretaceous, and early Jurassic through late Triassic. Depending on the time interval, other portions merge selected high-resolution radiometric ages, seafloor spreading models, strontium-isotope segments, and geomathematical interpolation methods. In sharp contrast to Mesozoic, the majority of Paleozoic stages are defined by GSSPs. The glaring exceptions are the Carboniferous and the Cambrian, which have only a single intra-system GSSP. Boundaries of all international Precambrian eras and periods are fixed at assigned numerical ages (e.g., Archean-Proterozoic boundary = 2.5 Ga exactly), except for the uppermost Proterozoic period. This new Ediacaran period was assigned a basal GSSP in Australia in 2004. Most of the Paleozoic time scale is derived from a merger of selected radiometric ages (mainly U-Pb) with different geomathematical interpolation methods (constrained optimization known as CONOP, graphical correlation, and/or spline-fitting of integrated biozonations for each period).

Utilization of astronomical (Milankovitch) cycles for scaling is still in its infancy within the Paleozoic. Computed ages (rounded) for the BASES of geologic periods and selected epochs are: Holocene -- 11.5 ka; Pleistocene -- 1.8 Ma; Pliocene -- 5.3 Ma; Miocene -23 Ma (base of Neogene Period); Oligocene -- 34 Ma; Eocene -- 56 Ma; Paleocene -65.5 Ma (base of Cenozoic Era); Cretaceous -- 145 ±4 Ma; Jurassic -- 200 ±1 Ma; Triassic -- 251 Ma (base of Mesozoic Era); Permian -- 299 Ma; Carboniferous -- 359 Ma; Devonian -- 416 Ma; Silurian -- 444 Ma; Ordovician -- 488 Ma; Cambrian -- 542 Ma (base of Paleozoic Era); Ediacaran -- 630 Ma (youngest period of Precambrian). The compilation of GTS2004 involved a large number of specialists, and is summarized in A Geologic Time Scale 2004 (~600 pages with summary poster, Cambridge University Press). Summary diagrams and tables of GSSPs can be downloaded from the ICS website (www.stratigraphy.org), and the source data will eventually be accessed through the CHRONOS database system. ____________________________________ Geologic Problem Solving with Microfossils

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Biostratigraphy Breaking Paradigms: The Absence of the Mirador Formation in the Eastern Llanos of Colombia C. A. Jaramillo; M. Rueda; F. Parra; G. Rodriguez The two major oil fields in Colombia discovered in last 25 years are the Ca単o Limon and Cusiana fields. Ca単o Limon is located in the eastern region of the Llanos of Colombia while Cusiana is located in the Llanos foothills, both being part of a large foreland basin active since the Paleocene. In both cases the main reservoir is a sandstone that has been called the Mirador Formation. Isopach maps of the Eocene Mirador formation show that it extended from the Llanos foothills into the Llanos basin. However, recent data suggested that the Mirador did not occur in most of the Llanos basin. Here we reanalyzed previous biostratigraphic information and dated several new sections and wells in the Llanos and Llanos foothills using a new zonation for the region produced by the Colombian Petroleum Institute. Biostratigraphic results indicate that the Mirador Formation only is present in the Llanos foothills. In most of the Llanos, including Ca単o Limon, the Mirador formation is not present and there is a hiatus from the upper Cretaceous to the lower Oligocene. Absence of Mirador could be explained either by bypass or accumulation and erosion. These results imply a new paleogeography for the time of accumulation of Mirador, a different basin model evolution, and a different fluid migration history to explain how Ca単o Limon and Cusiana oil fields were filled.

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A Fresh Look at the Potomac Group across the Atlantic: Correlation of Angiosperm Pollen Records between the Eastern USA and Portugal Peter A. Hochuli; Ulrich Heimhofer; Stefan Burla; Helmi Weissert Mid-Cretaceous successions from the western Portuguese basin and from the Potomac Group of the Atlantic coastal plain (eastern US) yield the most prolific sites with excellently preserved early angiosperm mesofossils (e.g. Drinnan et al. 1990; Friis et al.

1999). Thus they contain the most important archives for the evolution of early angiosperms. Enclosed in thick terrestrial successions the ages of the fossil-bearing deposits are very poorly constrained. Detailed and continuous angiosperm pollen records from two well-dated sections in Portugal document the diversification of early angiosperms between the late Barremian and the middle Albian. The stratigraphic framework of these marginal marine successions is based on dinoflagellate cyst biostratigraphy and d13C chemostratigraphy, allowing for correlation with the marine stratigraphic scheme. The record of the angiosperm pollen shows a consistent increase in diversity and relative abundance of the monocolpate forms (“magnoliids” and/or monocots) between the Barremian and the middle Aptian. The early Albian is marked by the appearance of the morphologically more advanced forms (tricolpates, polycopates) attributed to the eudicots. In comparison, the classical angiosperm pollen record from the Potomac group shows a more discontinuous distribution of taxa (Doyle & Robbins, 1977, fig. 4). The simultaneous appearance of several species of tricolpate pollen grains and the ratio between the monocolpate and tricolpate forms at the lower boundary of zone II suggests the presence of a major discontinuity in the sedimentary record. Comparison with the dated sections from Portugal indicates an Aptian age for the basal part of the Potomac Group (lower part of zone I, Patuxent Fm.) and an Early Albian age for the upper part of zone I ( ?Arundel Clay). A Late Albian age can be attributed to the zones IIA and IIB (Patapsco Fm).

References: Doyle, J.A., and Robbins, E.I. (1977) Angiosperm pollen zonation of the continental Cretaceous of the Atlantic Coastal Plain and its application to deep wells in the Salisbury Embayment: Palynology, 1: 43–78. Drinnan, A. N., Crane, P. R., Friis, E. M. & Pedersen, K. R. (1990) Lauraceous flowers from the Potomac Group (midCretaceous) of eastern North America. Botanical Gazette 151: 370-384. Friis, E. M., Pedersen, K. R. & Crane, P. R. (1999) Early angiosperm diversification: The diversity of pollen associated with angiosperm reproductive structures in Early Cretaceous floras from Portugal. Annals of the Missouri Botanical Garden 86: 259-296.

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Warm Surface Water Events: Integrating New Pliocene Siliceous Microfossil Paleobiogeographic Data with other Southern Ocean Proxies Matthew D. Lutz; David M. Harwood New high-resolution diatom and silicoflagellate paleobiogeographic data recovered from Southern Ocean cores have the potential to refine and expand the history of southern high-latitude oceanographic variability.

High species diversity, environmental sensitivity, and temporal resolvability of marine diatom assemblages make them excellent indicators of past climatic change. Because the Southern Ocean is an important piece of the global climate puzzle that is not fully understood, the acquisition of new Southern Ocean proxy data is necessary. It is especially significant to collect more data from the early Pliocene, as it is the most recent period of elevated temperature conditions analogous to predicted global warming scenarios. This study presents high-resolution (10 cm sampling interval) diatom and silicoflagellate assemblage data from two high latitude sites (>65ºS) in the Southern Ocean (ODP Site 1165B and the Northern Gunnerus Ridge).

Silicoflagellate records from ODP sites 1165, 751, and 748 indicate discrete intervals of warmer sea surface temperatures during the early Pliocene, climaxing at ~3.6 Ma, ~4.2 Ma, and ~4.7 Ma. Analysis of diatom assemblage data and specific siliceous microfossil indices (e.g. Dictyocha/Distephanus, Eucampia antarctica intercallary/terminal valves, Chaetoceros vegetative cell counts, sea ice flora, etc.) has the potential to better define the timing, duration, and magnitude of these Pliocene warm events. This enhancement of temporal resolution will be achieved through the use of CONOP, a biostratigraphic analysis program, which will apply a composite section of the Southern Ocean diatom record to the data collected. The lack of corroboration among existing early Pliocene proxy records (δ18O, δ13C, terrigenous mass accumulation rates, and silicoflagellate paleotemperature reconstructions) suggest that oceanographic controlling factors are difficult to discriminate (e.g. the differentiation between sea surface temperatures and ice volume from δ18O isotopic values). Utilization of extant species within the diatom assemblages will help to constrain paleoceanographic interpretations, due to their correlative absolute values of sea surface temperatures, salinity, and sea ice extent. This refinement may help to resolve the factors influencing the variability in other proxy records and allow for more accurate modeling of global climate change, both past and future.

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Solar Influence on Climate and Diatoms in the Northeast Pacific Alice S. Chang; Andreas Prokoph; R. Timothy Patterson; Helen M. Roe Diatom abundance and sedimentary characteristics were investigated from a 46-year long laminated record from Effingham Inlet, an anoxic fjord on the southwestern coast of Vancouver Island, Canada. Radiometric dating and counting of annual sedimentary couplets dates the sediments from AD 1947-1993. Quantitative diatom counting and sediment grain size analysis indicate that total diatom abundance increased and larger grain sizes were present during years of low sunspot numbers. Spectral analysis reveals a prominent 11-year periodicity in diatom abundance that is attributable to the solar sunspot cycle of similar length. Higher spring (April/May) values of the North Pacific High pressure index during sunspot minima suggest that during this time, suppression of the Aleutian Low pressure system led to strengthened coastal upwelling and diatom production earlier in the year. These results indicate that the 11-year solar cycle may exert a significant, though indirect influence on marine primary productivity in the northeast Pacific.

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Salt Marsh Foraminifera as Sea-Level Indicators in New Brunswick and British Columbia: A Quantitative Approach to Assessing Regional Variability in Taphonomic Biasing and Preferred Faunal Habitat R. Timothy Patterson; Andrew P. Dalby; Helen M. Roe A stepwise linear regression analysis was carried out on both 0-1 and 0-10 cm surface samples from transects across the marsh at Little Dipper Harbour, New Brunswick. Only the 0-1 cm surface samples produced statistically reliable results (R2=0.705; Râ&#x20AC;&#x2122;2=0.609).

The distribution of foraminifera in this marsh are similar to the foraminiferal distribution previously observed in nearby Nova Scotia marshes. These results are in sharp contrast to the foraminiferal distribution in several British Columbia marshes where infaunal habitat and taphonomic biasing result in 0-10 cm surface samples producing the best results using stepwise linear regression. A fundamental difference in taphonomic biasing and the apparent preferred habitat of the same marsh foraminiferal species in these areas pose difficulties for researchers here and elsewhere who are attempting to develop transfer function training sets that can be applied over a wide area.

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Late Quaternary Foraminiferal Assemblage Changes in Relation to SeaLevel and Sequence Stratigraphic Principles on the Mixed SiliciclasticCarbonate Belize Margin Brooke Olson; Marek Leckie; Andre Droxler; Gerald Dickens Foraminiferal abundances and distributions yield a wealth of paleoecologic and biostratigraphic information, providing excellent tools to interpret the geologic record and date sediments. In purely siliciclastic systems, analysis of preserved foraminiferal sediment assemblages has proved invaluable in paleoenvironment and sea level history reconstruction, as well as sequence identification. However, few studies have investigated the utility of foraminiferal proxies in mixed siliciclastic-carbonate environments. In this study, planktic and benthic foraminiferal populations are used to investigate foraminiferal response to late Quaternary glacial-interglacial cycles on the central Belize mixed siliciclastic-carbonate margin relative to sea level, water masses, and sequence stratigraphic principles. The Quaternary is an ideal interval to accomplish these objectives, as the timing and amplitude of Quaternary sea level fluctuations are well established independent of sequence stratigraphic principles. This study is based on the analyses of a well-dated continuous 37.7 m long piston core, MD02 2532, collected 3 km offshore the central Belize Barrier reef in the distal slope of Gladden Basin at 333 m of water depth by the R/V Marion Dufresne (IPEV). A robust chronology is established using high-resolution planktic oxygen isotope stratigraphy, anchored by several nannofossil stratigraphic and tephrochronologic markers, as well as radiocarbon ages in the upper part of the core, and demonstrates that the core represents most of the Brunhes (about 0.7 Myr). Sediments spanning the last glacial cycle express planktic foraminiferal assemblage variations corresponding to glacial-interglacial water mass changes (e.g., temperature, salinity). Benthic assemblages indicate water depth and paleoenvironmental changes as well as varying influences of carbonate and siliciclastic provinces.

Observations made on the Belize margin will help the interpretation of older mixed siliciclastic-carbonate environments where eustatic sea level is not well constrained.

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Benthic Foraminiferal Responses to Eutrophication and Hypoxia/Anoxia in Norwegian Silled Fjord Basins: Development and Assessment of Quantitative Faunal Indices Katrine Husum; Elisabeth Alve Silled fjord basins along the Norwegian Skagerrak coast (NW Europe) are experiencing permanent or ephemeral hypoxia/anoxia. n some fjords, the oxygen depletion is clearly due to human-induced eutrophication or organic load from industry. In others, the depletion is naturally caused. For most fjords, however, it is still unclear if one or the other or a combination of both factors is responsible for the deteriorating oxygen conditions. Unique time series of oxygen measurements exist from some of these fjords enabling a close correlation between instrumental data and the modern and fossil benthic foraminiferal record. The main objectives of this study are to 1) generate new quantitative faunal indices for monitoring and documenting natural variability and possible effects of eutrophication, and 2) define pre-pollution baselines that will enable distinctions between human-induced and natural (e.g. climatic) environmental changes.

The modern records show that both the absolute and relative abundance of the opportunistic species, Stainforthia fusiformis (Williamson) increases with increasing organic load in the sediments until permanent anoxia kills it off. In areas where high organic flux causes the bottom water to turn hypoxic for several months per year, S. fusiformis makes up >80% of the live (stained) benthic foraminiferal assemblages. The fossil records in all investigated fjords show a dominance of calcareous foraminifera. A development towards less diverse assemblages dominated by Stainforthia fusiformis occurs at different times in different fjords during the 20th century. The absolute abundance of benthic foraminiferal tests follow the same pattern as that of the modern assemblages illustrating that the fossil record reflects the same response to organic enrichment as the modern fauna. The results clearly demonstrate how data on the distribution of living foraminifera in these areas are directly applicable to reconstructing past environmental changes based on fossil assemblages. In addition, the benthic foraminifera Stainforthia fusiformis has a very good potential as a quantitative index for reconstructing increased organic flux followed by hypoxia/anoxia in fjord basins.

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A Holocene - ?Late Pleistocene Lacustrine Record of Diatom and Chrysophyte Cyst Distributions for Catahoula Lake, Louisiana: Paleoenvironmental Significance L. A. Febo; J. H. Wrenn; W. N. Krebs Catahoula Lake is one of the largest, strangest, and most important freshwater lakes in Louisiana.

The lake is wet during much of the year except for July to late November when water levels are dropped by the Army Corps of Engineers, once a natural cycle, to promote vegetation growth on the lake bed that provides food for thousands of migratory water fowl. During the dry phase, we drove out onto the lake bed and drilled two cores to a maximum depth of 27 m and examined the longest core (Core 2) to determine the temporal and paleohydrological history. Diatoms and Chrysophycean stomatocysts are among a suite of four abundant siliceous microfossils recovered from sediment samples. Diatoms in surface samples contain an assemblage of 22 species, indicating conditions ranging from nutrient-rich lake water to total dessication. Downcore samples show abundance and assemblage variations. Some intervals have few to rare diatoms, which is probably due to dissolution since frustules are highly fragmented and other microfossils, such as phytoliths, show pitting. In the deepest sample yet processed (18 m), diatoms are as diverse and abundant as in the surface sample. Chrysophycean algae are a diverse group of planktonic marine to freshwater golden-brown algae that form siliceous resting cysts, or stomatocysts. Stomatocysts are sensitive indicators of pH and salinity and are useful for reconstructing lake nutrient conditions based on their diversity, abundance, and the diatom-tostomatocyst ratio through time. More than 300 stomatocyst taxa have been reported from tropical to polar latitudes, but they are most commonly studied and described in oligotrophic, temperate to high latitude lakes where they appear to be the most diverse. Our study adds the first data on the modern diversity, pH, salinity, and nutrient conditions for a humid-temperate to subtropical lake in south-central North America as well as the temporal variations in cyst assemblages. The pH of Catahoula Lake varies between 6.33 and 7.56 and has a salinity of < 2â&#x20AC;°. A conservative estimate from surface samples reveals approximately 30 stomatocyst taxa are present. Of these, three may be morphotypes of other stomatocyst taxa. Additionally, two of the 30 stomatocysts (Cysts 9 and 15) have been described in the literature according to the International Statospore Working Group (ISWG) guidelines in which stomatocysts are given numbers rather than names.

Therefore, we add 25 new stomatocyst taxa and tentatively assigned taxa letter names.

Numerically, the most abundant stomatocyst is Cyst O, which is similar to Cyst 135 but differs by possessing a longer secondary collar hook and a wavy tertiary collar. Diatoms are more abundant than stomatocysts in the surface sample, indicating relatively high nutrient levels for Catahoula Lake. In the deepest core sample (18 m), diatom and stomatocyst abundance is equal in diversity abundance to that of the surface sample. This core sample is 10 m below a level dated by 14C to ca. 6 kyrs B.P. This suggests that Core 2 provides an archive of paleolimnological history of Catahoula Lake for a significant portion of the Holocene.

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Biostratigraphic Characterization of the Carito Field, Northern Monagas, Venezuela Marta Carrillo; Diana Cabrera; Arelis Farias Reservoir characterization “… is a process for quantitatively assigning reservoir properties, recognizing geologic information and uncertainties in spatial variability” (Lake and Carroll, 1986). Biostratigraphy is a geological tool that integrated with other disciplines, such as sedimentology and seismic allows determination of the vertical and lateral variations of the different sedimentary facies. The Carito Field is structurally complex and stratigraphically heterogeneous reservoir that was deposited in a nearshore to fluvial enviroment. As a result high-resolution biostratigraphy study is required to integrated palynomorphs, nannoplancton calcareous and foraminifers to establish the Cretaceous-Tertiary boundary, and the maximum flooding surfaces, as well as its sequence boundary. The K/T boundary was possible to determine with the integration of biostratigraphy and chemostratigraphy analysis. By integration of the sedimentology, electric log signals, and 3D seismic lines is possible to define the sequence boundary. In these kind of deposits is necessary to define the paleobathymetric depth for each sample analyzed and don’t use interpretation by range of depth as used to. Sequence boundaries were defined by the absence of fossils, specially the marine origin, the electric log response, and characteristic sedimentary structures, as surface reactivation, clasts and abrupt contact between facies.

In the Cretaceous sequence the palynomorphs assemblages were the more diagnostic, because the deposits are more continental with few marine influence. The presence of foraminifers assemblages indicative of marine enviroments, and the ocurrence of dinoflagellates and nannoplancton calcareous, in the Tertiary sequence allow us to stablish twenty flooding surfaces and their maximum in seven sequences. These methodologies allow us to reduce the uncertainities in the geological model, and recognize the heterogenity of the reservoirs. Prediction of heterogeneous reservoirs permit more accurate explotation program in exploration and production.

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Using Fusulines to Determine Periodicity of Sequence Stratigraphy Cycles D. M. Burns Sequence stratigraphy models have been developed and studied for over a quarter of a century. These are used to predict lateral and vertical relationships among strata developed sequentially during relative sea level rise and fall. Causal mechanisms for the development of the genetically related strata have been cited as tectonism, glacio-eustasy and local basinal influences. One of the important goals when working with sequence stratigraphy and formations of interest is to determine the timing of repetition of the observed cycles. Most of the lower order (longer duration of formation) cycles are considered to be influenced by glacio-eustastic changes brought about by Milankovitch perturbations, astronomical variations in the attitude of the Earth and in its orbit.

Unfortunately, many stratigraphic sequences lack significant chronological components to enable assigning accurate ages to the cycles so that this connection can be made. The Pennsylvanian/Permian Casper Formation in southeastern Wyoming is being studied to determine the sequence stratigraphy developed along a paleo shoreline which separated onshore aeolian dunes from an offshore carbonate platform. Age control of the timing of the cycles was achieved by the analysis of fusulines. This genera was short-lived but highly evolved, first appearing in the Pennsylvanian as a rather simplistic test and becoming extinct in the Permian as a rather intricate lifeform. As a result of this, they are excellent for establishing highly accurate age control. These foraminifera occur in several of the limestone layers, and these limestone layers represented similar sections in successive cycles. As the fusulines are the only component in the formation with chronologic significance, the use of them was the only way in which to determine the periodicity of the cycles. As a result of this analysis, the cycles were determined to recur every 1.2 million years and can be interpreted to be a result of low frequency Milankovitch perturbations.

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The Foredeep Basin Evolution in the Northern Apennines (Italy) R. Catanzariti; A. Cerrina Feroni; N. Levi; G. Ottria The outer sector of the Northern Apennines fold and thrust belt is characterized by foredeep basin successions deposed since the Oligocene at the top of the sedimentary cover of the Adria plate continental margin (Tuscan and Umbria-Marche domains). The foredeep successions are overthrusted by the Ligurian stack, which is made up of the remnants of the Ligurian-Piedmont ocean and its transition to the Adria plate. Through all the belt the foredeep deposits are represented by thick silicoclastic turbidites (20004000 m) deposed in diachronous basins which developed in parallel to the belt trend (NNW-SSE). The foredeep turbidites are generally interposed between shaly and siltymarly deposits which mark the beginning and the closure of the foredeep sedimentation.

The biostratigraphy based on the planktonic foraminifera assemblages analysis already allowed to confine the foredeep depositional system between the Oligocene (Macigno Fm) and the Middle Miocene (Marnoso Arenacea Fm). The systematic use of the nannofossil biostratigraphy allows the precise dating of the opening and closure shalymarly deposits of each succession of the foredeep migrating system. Through this approach the diachronous evolution of the foredeep basins and their eastward migration accompanying the progressive shifting of the compression front toward the outermost domains, have been identified. Between the Oligocene and the Middle-Upper Miocene, the deformation evolution of the Apenninic belt follows the diachronous eastward migration of the foredeep basins. In fact, in the Northern Apennine stack the single basins roughly coincide with the horses of the orogenic duplex structure which characterizes the foredeep successions; the duplex roof thrust corresponds to the basal overthrusting of the Ligurian stack, while the floor thrust is probably represented by the detachment level corresponding to the pre-foredeep shale and marl deposits. The reconstruction of the space-time evolution of the depositional system and its progressive deformation accompanying the belt front migration, has been performed trough the close integration between structural geology and biostratigraphy, and in particular, by the systematic study of the calcareous nannofossils for their high chronostratigraphical resolution power.

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The Reconstruction of Complex Structural Stackings at Upper Crustal Levels through Nannofossil Biostratigraphy: Two Examples from the Northern Apennines (Italy) R. Catanzariti; A. Cerrina Feroni; N. Levi; G. Ottria The Northern Apennines is a fold and thrust belt made up by three main structural domains: the lower one consists of the Adria plate margin sedimentary covers characterized by post-Oligocene foredeep deposits; the intermediate one is represented by the Ligurian Units, characterized by polyphase deformation (Mesoalpine and Apenninic tectonic stages); the post-Eocene Epiligurian Succession, regarded as thrust-top basin deposits. The first example regards the belt front-foredeep system which in the Northern Apennines is developed after the Upper Eocene continental collision; this system is characterized by a progressive shifting of the foredeep sedimentation and thrust deformation toward the outermost domains. The foredeep sedimentary sequences were accreted to the orogenic wedge with a piggy-back evolution and duplex structure. In each thrust sheet, the foredeep deposits are represented by thick sequences of turbiditic sandstones, which display analogous facies associations. In the study area, the overthrusting (main thrust, MT) between two tectonic units made up of foredeep sandstones, the Carigiola (CU) and Acquerino (AU) units, can be observed. The footwall consists of the CU, while the hanging wall is represented by the AU showing a duplex geometry, characterized by six horses. The whole structure is complicated by a late backthrust, which locally inverts the relationships between the tectonic units. The CU and AU units are respectively characterized by deposits of Aquitanian-lower Burdigalian and Lutetian-lower Aquitanian age. Because the strong facies convergence between the foredeep sandstones of the two tectonic units and the scarce outcrop-ratio, the reconstruction of the MT geometry has been mostly performed using the nannofossil biostratigraphy, documenting the presence of Lutetian-lower Aquitanian overlying Aquitanian-lower Burdigalian sediments. The second example regards the thrust-top basin deposits (Epiligurian Succession, ES) which are characterized by several chaotic levels and internal unconformities, indicative of the tectonic activity of the substrate; nevertheless the ES usually has been regarded as a poorly deformed stratigraphic succession. In the last years the use of the nannofossil biostratigraphy allows the recognition of internal thrust surfaces. In this setting, the dating of the main unconformities and tectonic phases in the ES gives tight constrains to understand the geodynamic evolution of the Northern Apennine belt. In the Enza Valley the ES is characterized by turbiditic sandstones alternating with hemipelagic slope marls and is affected by internal thrust deformations. The occurrence of these tectonic surfaces has been confirmed by the nannofossil biostratigraphy and, where the thrusts are covered by Quaternary deposits, the biostratigraphic data allowed the reconstruction of the thrust geometries through the systematic sampling of the outcropping deposits. ____________________________________ Geologic Problem Solving with Microfossils

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Ages of Maximum Flooding Surfaces, Sequences Boundaries in the Cenozoic and Mesozoic Walter W. Wornardt Jr. Maximum flooding surfaces can be age dated in millions of years before present (Ma) because of their association with important chronostratigraphic species within the maximum flooding surface condensed section within one third order depositional sequence. The (MFS) maximum flooding surfaces within a third order depositional sequence permits the recognition of the lowstand systems tract below the transgressive systems tract and highstand systems tracts above the maximum flooding surface. The maximum flooding surface is recognized by the bell-shaped curve that is formed from the increase and decrease in fossil abundance in the maximum flooding surface condensed section. It is also recognized at the highest gamma and lowest resistivity peaks on the well log. The depth of these peaks, converted to seismic time correlates with the regionally continuous, high amplitude seismic reflectors on seismic reflection profiles. In SEPM special publication No. 60, 1998, “Mesozoic and Cenozoic Sequence Stratigraphy of European Basins”, Hardenbol et al. recognized and dated 221 sequence boundaries from the Triassic to Recent. These sequence boundaries appeared on four “Sequence Chronostratigraphy/Biochronostratigraphy” charts that were included in this SEPM publication. On these charts they recognize 221 third order “SEQUENCES” bounded at the base and top with a sequence boundary. These sequence boundaries were designated by the first two, three or four letters of the stage name associated with the sequence boundary and a numerical age in Ma. Within each sequence, Hardenbol et al., 1998, indicated the position of the maximum flooding surface with a dashed line but choose not to age date these surfaces on the Cenozoic, Cretaceous and Jurassic charts. Therefore, the purpose of this paper is to recognize and date the Maximum Flooding Surfaces in Ma in the Cenozic, Cretaceous and Jurassic and to assign a specific numerical age and letter designation to each of these maximum flooding surfaces from the Jurassic to Recent. As such, future papers published will be able to refer these ages of all maximum flooding surfaces. Using a 36-inch scanner an image was created from the original Cenozoic and Mesozoic Sequence Chronostratigraphy and Biochronostratigraphy Chart published by Hardenbol et al. (1998). These images were digitized using the Neurolog™ software program to determine the ages of the maximum flooding surfaces. The ages of the sequence boundaries on the charts were used for calibration to determine the ages of the maximum flooding surfaces. The numerical age and the letter designation of the maximum flooding surfaces are shown with an * (asterisks) or ® (diamond) (Figures 16). Hardenbol et al. (1998), also did not recognize the fourth-order sequences and maximum flooding surfaces of Wornardt and Vail (1990, 1991) and Wornardt et. al.

(1998) including the 0.70, 0.60, 0.50, 0.40, 0.30 and 0.20 Ma. These sequences and maximum flooding surfaces have also been assign a specific numerical age and letter designation by a (®) in this paper (Figs. 1-6). ____________________________________ Geologic Problem Solving with Microfossils

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High-Resolution Biostratigraphy in Reservoir Sequence Analysis: A Risk Reduction Technology for the 2000â&#x20AC;&#x2122;s Walter W. Wornardt Jr. In the quest for hydrocarbons, both exploration and development programs can be greatly enhanced by applying high-resolution biostratigraphy to seismic sequence stratigraphic analysis.

The methodology, published in 1990 and 1991 by Drs. Vail and Wornardt provides the explorationist and explorationist with the capability to recognize, discover and evaluate new hydrocarbon reservoirs and to reduce the risk in managementâ&#x20AC;&#x2122;s decisions. Wells can be divided into third order depositional sequence boundaries, highstand, transgressive and lowstand systems tracts including prograding complex, forced regression, bottom-set turbidites, slope fan and basin floor fan complexes. It also identifies the third order depositional sequence and systems tract that is associated with the potential hydrocarbon reservoirs. Recently we applied high resolution biostratigraphic analysis at the reservoir level by recognizing and defining flow barriers fossil assemblages in the shales between individual reservoir sand flow unit base on abundance, tops, bases, absence, and superpositional relationships. This methodology is referred to as Reservoir Sequence Analysis. When applied to existing fields can increase the production, the life of the field and extend the area of the field. A standard-of-reference well, with well developed reservoir sands, within one or more third order depositional sequences are identified in order to establish a seismic sequence stratigraphic well-tie for the entire field. The Maximum Flooding Surface and Sequence Boundaries above and below the reservoir sands are identified and age dated on a welllog and seismic profile and/or workstation by integrating the high-resolution biostratigraphy, well-log signatures, paleoenvironments/paleobathymetric changes and seismic profiles. With in each Sequence the various systems tracts with their corresponding reservoir sands are identified and labeled. The flow barrier fossil assemblages in between the reservoir sands are identified from high resolution checklists are defined and labeled. The flow barrier fossil assemblages are identified and characterized in a second well in the same field and within the same third order depositional sequences. The same flow barrier fossil assemblages are correlated to the first standard of reference well. The same flow barrier fossil assemblages are identified in additional wells in order to: (1) Identify the relationship of the flow barrier fossil assemblages and the reservoir sands penetrated; (2) determine which reservoir sands are present, or not present; (3) determine which reservoir sands correlate from well to well; (4) determine the play concept (are sands parallel to strike, such as coastal belt, sheet and channel overbank sands or perpendicular to strike, such as, incised valley fill or slope fan channel sands; (5) predict the geometry, continuity and distribution of the reservoir sands both vertically and laterally. These systems tracts in additional wells with the same reservoir section can be correlated with a high degree of confidence, from upthrown to downthrown fault blocks, around salt domes, and updip with downdip. Examples will be discussed from various parts and age in the Gulf of Mexico and Nigeria.

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“Globalization” of Sequence Stratigraphy through Biostratigraphy Thomas D. Davies; Keith A. Knabe; Chengjie Liu; Yow-Yuh Chen; Ting-Chang Huang; John W. Snedden Biostratigraphy at ExxonMobil has played a key role in establishing a globally-calibrated sequence stratigraphic standard, which is based on the nomenclature published in SEPM Special Publication 60 (Hardenbol et al., 1998). Although this nomenclature was developed by the “Mesozoic-Cenozoic Sequence Stratigraphy of European Basins” project, we have applied this to other basins outside Europe, including basins offshore West Africa and the Gulf of Mexico. Using a standardized sequence nomenclature for all basins (based on sequence boundaries (SBs), maximum flooding surfaces (MFSs), and biohorizons) has reduced the inherent confusion associated with multiple, basin-specific stratigraphic schemes. This classification method is accepted as standard practice throughout our organization. High-resolution biostratigraphy, based on globally recognizable bioevents, is the best tool for correlating sequences within and between basins and, therefore, is critical to the sequence-identification process.

Our biostratigraphic standard is developed by combining bioevents from multiple microfossil groups (i.e., nannofossils, forams, and palynology) allowing us to identify and subdivide 3rd order sequences into numerous higher order (4th and 5th order) units/surfaces. As a result, the resolution of the industry nannofossil zonation of Martini (1971), for example, is greatly enhanced. Integrating these correlatable biohorizons with well log, seismic and other geologic data permits identification of MFSs and SBs, and provides geoscientists with a powerful integrative tool for hydrocarbon systems studies (e.g., improved reservoir, source, seal correlation and continuity, mapping, etc.). Benefits of a Standard include: • Uses a published chronostratigraphy that is relatively stable and tied to subsurface and outcrop control, • Develops common nomenclature based on SBs and MFSs, • Promotes and facilitates simple, uniform, clear and consistent communication within the Company, with other companies, governments, and contractors, • Promotes Database consistency through use of a Standard nomenclature, • Facilitates correlation of local/basinal events with regional/global events, • Encourages use and integration of biostratigraphy in seismic and other geologic studies.

We recommend that this methodology be adopted industry-wide.

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Reservoir-Scale Biostratigraphic Resolution in Near-Salt and Sub-Salt GoM Fields James H. Gamber; Jeffrey A. Stein A significant proportion of hydrocarbon fields currently being developed in deep water GoM are either subsalt or in close proximity to salt. The stratigraphy of these fields can be extremely complex and difficult to interpret due to a combination of syn- and postdepositional salt tectonics, poor seismic definition and ambiguous well log correlations.

However, the reservoir intervals generally comprise a broad range of biofacies or biozones that have proven useful for detailed correlation. The depositional context for these biofacies or biozones is defined through integration of microfossil assemblages with sedimentologic and sequence-stratigraphic criteria. The key to a useful delineation of facies is the application of a full suite of micropaleontological disciplines. Our multidisciplinary approach included foraminifera, calcareous nannofossils and, heretofore underutilized, palynology. Primary results are: â&#x20AC;˘ More precise age context for basin models â&#x20AC;˘ Enhanced recognition of allochthonous units including mass transport deposits, debris flows, slumps and post-depositional structural movements as important complications to reservoir prediction â&#x20AC;˘ Formation of field development models using reservoir-level cyclostratigraphic correlation based on subregional condensed sections, abandonment phases, and facies disconformities related to sequence boundaries. Of course, biostratigraphic, sedimentologic, sequence-stratigraphic work must have constant interplay. This offers mutually beneficial constraints on interpretation that optimizes the value of the individual datasets.

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High Resolution Biostratigraphy and Depositional Environment of the Miocene to Pleistocene Sequences in the Plataforma Deltana and Eastern Venezuelan Basin Dennis Alberto Sรกnchez Zambrano High-resolution biostratigraphy data is an important component for developing the sequence stratigraphic framework of sedimentary basins, especially those affected by complex interplay of regional tectonics. The Eastern Venezuelan Basin is structurally complex, with the presence of reactivated reverse faults and transverse faults of low angle with associated folding. The stratigraphical relationships between the study area and its vecinity show a wide variety of formational names due to lateral and vertical variations of facies complicated by tectonism. A Cretaceous para-autochthonous unit, corresponding to the Tala Thrust, overlaps the Lower Oligocene to Pliocene-Pleistocene autochthonous section in most of the area. This investigation has permitted to identify reservoirs, seals and stratigraphic traps. The most prospective sandstone facies of the Oligocene correspond to the Naricual Formation and the most prospective sandstone facies of the Early Miocene correspond to the lower section of the Capaya Formation. These results are of fundamental value to oil exploration in the study area. The main objective of this study is to estimate the upper water depth limits of selected species of benthonic foraminifera in reconstructing paleobathymetry with integrated assessment of modern microfaunal and sedimentological patterns, allowing identification of bathyal through littoral paleoenvironmental boundaries. The integration of the biostratigraphic studies with the seismic interpretation, well logs correlation and sedimentological studies, will improve our knowledge for future proposing prospective areas. Foraminiferal assemblages were studied from well samples of the Northern Monagas, Northern Anzoรกtegui and offshore Venezuela. A biostratigraphical scheme based mainly on benthic foraminifers, but also including planktic foraminifers, is proposed for the Miocene to Pleistocene interval, which enables correlation. The study area is divided into four provinces: Mata Grande, Tรกcata, Santa Bรกrbara and Plataforma Deltana. Each foraminifera biofacies has certain elements peculiar to its province. The sedimentological and foraminifera characteristic of the four provinces include: 1.- Fluvial/estuarine and 2.- Transitional barrier; composed of gray shales and sandstone. The benthic foraminifera association includes: Ammonia beccarii, Ammobaculites dilatatus, Valvulineria sp., Eggerella aff. scabra; 3.Prograding shoreface, characterized in the inner shelf sediments by the following biofacies: Nonionella atlantica, Amphistegina lessonii, Quinqueloculina seminulina, to increasing occurrences of Uvigerina peregrina, Lenticulina americana, Lenticulina senni, Bolivina multicostata, Gyroidinoides altiformis, in the middle and outer shelf; and finally 4.- Basin floor, composed of gray and black shales and the benthic foraminifera association include: Cyclammina acutidorsata, Cyclammina placenta, Cyclammina cancellata, Uvigerina rustica, Ammodiscus sp., Bathysiphon carapitanus and Uvigerina carapitana. This model provides the best understanding of the geohistorical and tectonic evolution of the area, and constitutes a powerful tool for hydrocarbon exploration.

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A Geologic Time Scale 2004: Why, How and Where Next!

Felix M. Gradstein; James G. Ogg This poster reviews Geologic Time Scale 2004 (Cambridge University Press, ~500 pp.).

We also indicate how it will be further refined. The Time Scale Project is a joint undertaking of F.M. Gradstein, J.G. Ogg, A.G. Smith, F.P. Agterberg, W. Bleeker, R.A. Cooper, V. Davydov, P. Gibbard, L.A. Hinnov, M.R. House (†), L.J. Lourens, H-P. Luterbacher, J. McArthur, M.J. Melchin, L.J. Robb, J. Shergold, M. Villeneuve, B.R. Wardlaw, J. Ali, H. Brinkhuis, F.J. Hilgen, J. Hooker, R.J. Howarth, A.H. Knoll, J. Laskar, S. Monechi, J. Powell, K.A. Plumb, I. Raffi, U. Röhl, P. Sadler, A. Sanfilippo, B. Schmitz, N.J. Shackleton, G.A. Shields, H. Strauss, J. Van Dam, J. Veizer, Th. van Kolfschoten, and D. Wilson, and is under auspices of the International Commission on Stratigraphy. Since Geologic Time Scale 1989 by Harland and his team, many developments have taken place: (1) Stratigraphic standardization through the work of the International Commission on Stratigraphy (ICS) has greatly refined the international chronostratigraphic scale. In some cases, traditional European-based stages have been replaced with new subdivisions that allow global correlation. (2) New or enhanced methods of extracting high-precision age assignments with realistic uncertainties from the rock record. These have led to improved age assignments of key geologic stage boundaries and other global correlation horizons. (3) Orbital tuning has greatly refined the Neogene, and improved parts of Paleogene and Mesozoic. (4) Statistical techniques of compiling integrated global stratigraphic scales within geologic periods. The construction of Geologic Time Scale 2004 (GTS2004) incorporated different techniques depending on the data available within each interval. Construction involved a large number of specialists, including contributions by past and present subcommissions officers of ICS, geochemists working with radiogenic and stable isotopes, stratigraphers using diverse tools from traditional fossils to astronomical cycles to database programming, and geomathematicians. Anticipated advances to the Geologic Time Scale during the next 4 years include: - A geologically realistic Precambrian scale; - Formal definition of all Phanerozoic stage boundaries; - Orbital tuning of polarity chrons and biostratigraphic events for the entire Cenozoic and Cretaceous; - A detailed database of high-resolution radiometric ages that includes “best practice” procedures, full error analysis, monitor ages and conversions; - Resolving age dating controversies (e.g., zircon statistics and possible reworking) across Devonian/Carboniferous, Permian/Triassic, and Anisian/Ladinian boundaries; - Improved and standardized dating of several ‘neglected’ intervals (e.g., Upper Jurassic – Lower Cretaceous, and Carboniferous through Triassic); - Detailed integrated stratigraphy for Upper Paleozoic through Lower Mesozoic; - Online stratigraphic databases and tools (e.g., CHRONOS network). The geochronological science community and ICS are focusing on these issues. A modified version of the time scale to accompany the standardization (boundary definitions and stratotypes) of all stages is planned for 2008. ____________________________________ Geologic Problem Solving with Microfossils

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StrataPlot – A New Graphic Correlation Tool Emil Platon; Paul Sikora As part of the National Science Foundation’s Cyberinfratstructure for the Geociences (GEON) initiative, the Energy and Geoscience Institute at the University of Utah has designed and developed a software application (StrataPlot) for the storage, retrieval, and graphing of biostratigraphic datums. StrataPlot is a stand-alone, Windows®-based application that employs the graphic correlation procedure first described by Shaw (1964). The major output of this software consists of a graph that displays the first and last stratigraphic occurrences of fossil species that are in common between an analyzed section and a composite-stratigraphical database representing composite stratigraphic ranges from hundreds or thousands of individual localities. When a new section is to be analyzed its datums are graphed against a selected composite standard. A successful interpretation results in the analyzed section becoming part of the composite standard against which future sections will be calibrated. StratPlot is a dynamic system that will continually refine its composite standards as the user adds more stratigraphic information.

StrataPlot provides a large number of user-friendly “on-screen” operations that greatly improve the efficiency of the interpretation process. StratPlot is currently undergoing beta-testing and will be publicly available in early 2005. It provides an integration and reference tool for professional paleontological queries within the GEON cyber-network.

Initially, StratPlot’s database will consist of approximately 2000 research localities that were studied by Amoco Exploration and later donated to EGI in 1999 by British Petroleum. Both StratPlot and the research localities database will be publicly available for user download in 2005 via EGI’ s newly installed GEON node. In addition, the database table structure has been modified to allow users that are not trained in paleontology (i.e., geologists/geophysicists in need of time constraints, or the general public) to make queries using either relative (e.g., “lower Eocene”) or absolute (e.g., “53.5 Ma”) age. Populating this new table structure based on recalibration of the StratPlot database against the latest time scales is an ongoing process that will continue into the first half of 2005.

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An Artificial Intelligence Machine for Paleoenvironmental Interpretation of Micropaleontological Data from Well Samples Emil Platon; Anthony Gary Several groups of marine microorganism are commonly used by paleontologists for chronostratigraphic and paleoecologic analyses of well samples. Given their adaptation, benthic foraminifera are best suited for deciphering the nature and dynamics of ancient paleoenvironments therefore, much of this paleoecological information resulting from micropaleontological analyses for the industry is limited to paleodepth-related data derived from benthic foraminifera. As all paleontologist know, there is much more potential environment-related information available through a more comprehensive analysis of the marine microorganisms, especially benthic foraminifera. Environmentâ&#x20AC;&#x2122;s productivity, sediment flow, pathway, and origin, nature of substrate as well as climate changes are among the features that could be added to the paleoecological interpretation of paleobiological data. Such information would aid in the integration of paleontological analysis into sequence biostratigraphic models. The development of several software packages and their associated databases help paleontologists perform stratigraphic analysis, multiple-well correlation, data storage, reservoir scale two well correlation, and limited paleodepth determination. Systems dedicated specifically to paleoecological interpretation of the micropaleontological data however, have not yet been produced and marketed. Recognizing the need for such technologies the Technical Alliance for Computational Stratigraphy of the Energy and Geoscience Institute (EGI) at the University of Utah, begun developing such a system. The software currently under development at EGI implements a Case Base Reasoning (CBR) technology. Results obtained with this system include information related to paleodepth, sediment flow, productivity, nature of substrate, and climate change. Paleoenevironment-related knowledge is stored in the form of cases in a relational, SQL database. Measurements relevant to environmental interpretation are automatically computed by the system for both the cases and samples to be analyzed. The analysis is done by comparing the micropaleontological assemblages of samples with those of cases for which an environment interpretation exists. If the highest similarity value computed during this process exceeds a threshold established by the user, the environmental solution attached to the corresponding case becomes the solution for the analyzed sample. When the best match is a similarity value that is lower than the threshold then the existing solution is only partially used. In this case, additional knowledge would need to be added by the user and/or discovered by the system so that a complete interpretation can become available for the analyzed sample. When a new solution is created in this way, the system stores the sample assemblage and the solution in the case base, thus increasing the systemâ&#x20AC;&#x2122;s knowledge base for subsequent analyses. ____________________________________ Geologic Problem Solving with Microfossils

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Computational Biochronology Peter R. Thompson Biostratigraphers provide age control for geological studies. No other method of age assessment is as widely used, amenable to virtually all situations, or as cost-effective.

The value of biostratigraphic age assignments, however, can be tarnished by its inherent subjectivity stemming from operator experience, biases and (mis)identification criteria.

Access to a large technical library can mitigate some of this subjectivity by increasing the operatorâ&#x20AC;&#x2122;s exposure to previous work on the fossil group, the age interval, or the geographic area. The goal is accuracy and reproducibility of results. Computational Biochronology is a database of microfossil age and paleoecological information driven by a graphic user interface. It is designed for the specialist or biostratigraphic coordinator familiar with micropaleontology but who does not have a large technical library available, is not familiar with an interval of the local geological column, or with a particular fossil group. The database contains over 97,000 foraminiferal, 18,000 calcareous nannofossil, 19,000 dinoflagellate, 13,000 diatom, 12,000 radiolaria, and 10,000 ostracod entries, along with less numbers of charophytes, calpionellids, conodonts, and palynomorphs. It has worldwide coverage and ages between Triassic to Recent from over 1,300 publications plus ODP data from recent CD-rom compilations.

Each speciesâ&#x20AC;&#x2122; entry incorporates published records of generic assignment, the authorâ&#x20AC;&#x2122;s zonal limits, paleoecological interpretation, geographic location, a full citation, and an internal 8-character computer code. Synonymy is managed through placing the same computer code on related species, and a utility program is included to capture the codes for imported datasets. A table of published ages for stages and biozones allows the user to choose between several current timescales. The purpose of the Computational Biochronology program is to the bridge the information gap between data collection and data interpretation. With it, the user can immediately judge to correctness of the identifications. Calculations determine individual sample ages for each microfossil group supplemented by an identification of potential contaminants from younger and/or older ages. The individual microfossil sample age sets are then merged with the other microfossil sets, and the combined age set is smoothed for its overall age trend. Diversity and paleobathymetry functions next evaluate only those taxa within the envelope of the selected age model. A basic sealevel curve can be constructed as foraminiferal paleobathymetry scaled by age control points. A list of intersecting faults can also be used to separate the age trend into smaller fault-bounded segments. Output can be in the forms of text, spreadsheet or graphics suitable for more advanced applications. Examples are provided to compare the results of the application to published age curves.

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Stratigraphy to Seismic (StS): A Technique to Provide Digital Biostratigraphic Information for the Seismic Interpreter and its Impact on Geological Problem Solving Paul Watson; Elisabeth Nairn Stratigraphic data and interpretations have traditionally been presented in written text format with accompanying data charts, stratigraphic summary logs and well correlations and as a result only basic stratigraphic information tends to be utilised by geophysicists.

In the present day environment there is a need to streamline data presentation to add value to sequence stratigraphic interpretations by full integration of all stratigraphic and environmental data with the seismic. Fugro Robertson has facilitated this streamlining by the development of Stratigraphy to Seismic (StS). StS is a technique of providing stratigraphic interpretations in a digital format for integration with seismic data. The interpretations, as generated in any conventional stratigraphic report are displayed as a suite of pseudo wireline logs which are loaded into seismic software packages for posting on seismic sections. The interpreter, regardless of their scientific background can access information, which allows them to distinguish seismic features that are attributable to marked stratigraphic discontinuities. Four facets of stratigraphic interpretation are defined as curves, specifically interpreted geochronology (which can be based on a graphic correlation LOC), degree of discontinuity, palaeoenvironment and degree of reworking. The methodology and applicability of each of the curves is described in detail using examples from the extensive FRL database in areas as diverse as the UK, Norway, Brazil and Libya. Illustrations of the curve suites posted on seismic sections are provided to show the benefits to the interpreter. Further to this, worked examples of seismic interpretations showing the impact of the technique in solving geological anomalies are provided. These cover a number of problems from anomalous well correlations on good quality seismic to increased interpretation confidence where seismic data is of poor quality.

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Morphologic and Genetic Variations among Indian Ocean Calcareous Nannoplankton Alicia Kahn; Hui Liu; Marie-Pierre Aubry; Colomban de Vargas Molecular biology has revealed that calcareous nannoplankton speciation is much greater than morphological analysis would indicate. Small morphologic differences may characterize different species rather than reflect intra-specific variability. To test this hypothesis, we have integrated quantitative and qualitative morphologic variations in the families Rhabdosphaeraceae, Syracosphaeraceae, Calciosoleniaceae, and Calcidiscaceae with molecular phylogenetics. Here we focus on Rhabdosphaeraceaea for which we measured the length and number of rhabdoliths per coccosphere, plus cell diameter versus coccosphere diameter from filtered water samples collected in the Indian Ocean along a transect between Cape Town, South Africa, 35oS 20oE, and Port Hedland, Australia, 17oS 117oE. Well-established morphological species like Discosphaera tubifera show high intra-specific variability. On the contrary, morphological species such as Rhabdosphaera clavigera and R. stylifera show minimal intra-specific variability.

These latter two taxa have been considered synonymous by former authors but our work shows them to be two separate species, although some degree of hybridization may still occur between them. Total DNA was extracted from the samples used for morphological analyses. Various couples of primers targeting different taxonomic ranges within the coccolithophores were used to PCR amplify the LSU rDNA of chosen morphospecies, genus, or even families. Molecular phylogenies of the sequenced genes were interpreted in light of the morphological data, and ultimately used to inter-calibrate genetic and morphological variations at the species level. The use of combined morphogenetic datasets such as the one presented here will be a necessary condition to accurately define which characters of the coccoliths allow biological species recognition.

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Microstratigraphic Changes: A Methodology to Identify Stratigraphic Packages and Geologic Events Hermann Duque-Caro The here so-called microstratigraphy, is a tool which I have been using and improving since many years ago as a practical stratigraphic instrument for microscopic characterization and correlation in the subsurface stratigraphy of the Cretaceous and Tertiary basins of Colombia, particularly in those basins where the foraminiferal recovery is poor and/or badly preserved. It consists in distinguishing and defining stratigraphic packages based on changes and first occurrences of microelements in the sense of drilling (down bit). These changes and first occurrences (tops of packages) are defined by any variation in the physical characteristics observed in the washed samples, e.g. lithology, color, sedimentary minerals, microfauna, abundances, preservation, etc. Since the definitions of those packages always include physical, paleoenvironmental and chronostratigraphic parameters, they can be treated as time-rock units, which implicitly identify geologic events associated with the local basin evolution. Thus, the changes defining the tops or the bases of these units respectively mark the ends or the beginnings of these events and are very valuable for local and regional correlations and the logic and natural basis for intercontinental correlations. How microstratigraphy can be compared with other traditional tools, for example: micropaleontology and palynology? A major difference is that these traditional specialized tools always need a positive recovery of its diagnostic elements based on regional pre-established reference tables, which bear all of the problems dealing with intercontinental correlations and calibration with local stratigraphies. This microstratigraphic tool in contrast is independent and always starts with the microstratigraphic characterization of lithostratigraphic units as local time-rock units without depending on a positive recovery of conventional diagnostic elements to place the sample within a classic chronostratigraphic position. Hence, its results will always be positive and with a true local diagnostic. Another important aspect to remark of microstratigraphy is that due to the fact that the physical properties of the rocks with microfossil parameters are integrated it becomes a great support to geophysical interpretations searching for more accurate stratigraphic positions of their seismic and electric responses. The microstratigraphic packages and changes always will have a coincident seismic and electric response. As a result, this presentation will display an applied microstratigraphy in some Cretaceous and Tertiary basins of Colombia, particularly those with poor recovery or badly preserved record of foraminifera: the Aptian to Paleocene record of the Upper and Middle Magdalena basins, and the Eocene to Pliocene record of the Llanos Basin.

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Sample Preparation for Quantitative Analyses of Calcareous Nannofossils for Paleoceanographic Studies Chioma U. Udeze; John V. Firth; Thomas D. Olszewski Studies of living nannoplankton show that they have limited ecological preferences and thus are very good paleoceanographic indicators. The use of quantitative analyses to determine calcareous nannofossil accumulation rates has proved very useful as a proxy for understanding paleoproductivity and paleoceanographic reconstructions. However, most sample preparation methods in use still need to be improved in order to get an accurate representation of the accumulation rates of nannofossils. Different preparation techniques for the random settling method for quantitative analyses of calcareous nannofossils are briefly described and compared to each other. Preparation techniques applied to the present study include the modification of the random settling method by the introduction of an aliquot of microspheres to the settling chambers. The addition of the microspheres yields an independent estimate of nannofossil accumulation rate in addition to the original random settling technique and the two can be compared to each other. Other modifications tried to include the addition of sodium hexametaphosphate to aid in the disaggregation of flocculated particles and a wetting agent to reduce surface tension. These techniques can help determine how calcareous nannoplankton reflect productivity changes during different global climatic settings; data from the Eocene of the Western North Atlantic, where this technique has been applied, will be shown.

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Palynological Processing of Tropical Late Oligocene-Miocene Deep-Sea Fan Deposits: Angolan Basin, West-Central Africa Pi Suhr Willumsen; Barrie Dale; Iain Prince A palynological study of sediments from deep-sea fan deposits off the Congo River, Angola, West-Central Africa, shows that standard commercial palynological processing techniques have to be re-evaluated when one works with marine assemblages from late Oligocene to Miocene strata. As a part of a biostratigraphic and paleoeoclogical study we compared marine palynological assemblages from standard commercially processed preparations (treated with hot hydrochloric and nitric acids after treatment with hydrofluoric acid) and non-oxidized, minimally treated palynological preparations. This showed that especially the small brown cysts and dinoflagellate cysts genera with a protoperidiniacean affinity such as Sumatradinium, Trinovantedinium and Selenopemphix (De Verteuil and Norris 1992) are selectively removed by the standard commercial processing technique. Previously other palynologists have shown that species in the genera Sumatradinium, Trinovantedinium and Selenopemphix are stratigraphically important for dinoflagellate cyst assemblages of an early Neogene age (De Verteuil 1996; de Verteuil and Norris 1996). Furthermore, collation of modern and early Neogene dinoflagellate cyst assemblages is possible and can be useful in paleoecological reconstructions of marine depositional environments. From modern studies it is known that in tropical Central-West Africa round brown cysts and protoperidiniacean dinoflagellate cysts tend to thrive in upwelling influenced environments in the Congo Basin (Dale et al. 2002). Palynological techniques applied to material from deep-sea fan deposits therefore have to be retaining both biostratigraphic and paleoecological signals in marine palynological assemblages from this type of depositional environments.

References: Dale, B., Dale, A. and Fred Jansen, J.H. 2002. Dinoflagellate cysts as environmental indicators in surface sediments from the Congo deep-sea fan and adjacent regions. Palaeogeography, Palaeoclimatology, Palaeoecology 185, 309-338. De Verteuil, L. and Norris, G. 1992. Miocene protoperidiniacean dinoflagellate cysts from the Maryland and Virginia coastal plain. In: Head, M. J. and Wrenn, J. H. (eds), Neogene and Quaternary Dinoflagellate cysts and acritarchs. America Association of Stratigraphic Palynologists Foundation, Contribution Series, 391-430. De Verteuil, L. 1996. Data report: Upper Cenozoic dinoflagellate cysts from the continental slope and rise off New Jersey. Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 150, 439-454. De Verteuil, L. and Norris, G. 1996. Miocene dinoflagellate stratigraphy and systematics of Maryland and Virginia. Micropaleontology, Vol. 42, 166 pp.

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Telemicroscopy System for Calcareous Nannofossil Analyses Armando Antonio Scarparo Cunha; Amauri L. Bastos; Marcos H. P. Mauricio; Sidnei Paciornik Petrobras and PUC-Rio (Digital Image Processing Laboratory Group) has developed a telemicroscopy system that permits remote calcareous nannofossil analyses. The system consists of a fully motorized Axioplan 2-Zeiss Imaging microscope, with automatic illumination setting and auto focus controlled by a powerful software developed to run on a personal computer. The main procedural steps are: (a) sample processing and preparation of smear slides at the well-site; (b) automatic slide analyses and imaging by the system (microscope-videocamera-software/PC); (c) transmission of digital images from the well-site to the laboratory for image interpretation; (d) transmission of the biostratigraphic report back to the well-site in order to support drilling decisions. The images are captured by using a high-resolution video camera. The electronic images are easily and instantaneously transferred over Petrobras intranet from the well-site to Petrobras Research & Developement Center (CENPES) as soon as slide analyses are finished. At CENPES laboratory, images are evaluated by the biostratigraphers, who send back their biochronostratigraphic interpretation. This new methodology meets the need for increasingly rapid decision taking during drilling and coring operations, and permits horizontal well biosteering in near real time.

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Paleoecology of Southern Ocean Diatoms and Pliocene Climate Variation: High-Resolution Quantitative Biostratigraphy of ODP Legs 119 and 120 Rosemary Cody; David Harwood Advances in quantitative diatom biostratigraphy of the Southern Ocean have important implications for the nature of Antarctic climate variability, and may prove useful in resolving ongoing debate over possible episodes of significant ice sheet melt. This study focuses on one event between 4.4-4.1 Ma, applying a newly developed quantitative chronostratigraphic model to high-resolution analysis of diatom paleoecology from early Pliocene sections of ODP holes 751A and 748B on the Kerguelen Plateau. Sites are located near the limit of the sea ice zone and between the Antarctic Polar Frontal Zone and the Antarctic Divergence. This area corresponds to the open-ocean Antarctic assemblage of Pichon et al. (1989). Shifts in fossil phytoplankton assemblages over time reflect shifts in paleotemperature and paleoceanography. An elevated ratio of Dictyocha to Distephanus silicoflagellates in holes 751A-748B has been used to demonstrate a peak in warmth at ~4.3 Ma as well as 3 other lesser events, all apparently accompanied by shifts in the contemporary diatom assemblage. Quantitative diatom study is underway, which will improve our recognition and understanding of these associations. Diatom counts for 751A-748B are generated with a 10 cm sampling interval from smear slide examination under a light microscope at 500x. Early efforts have focused primarily on developing diatom biostratigraphy as a tool and assessing its potential value/ability to resolve patterns of climate variation and glaciation. Diatom assemblages are well preserved, extremely diverse and often highly specialized; they are therefore a potentially much more reliable and sensitive index of environmental change than the group of 8 silicoflagellate taxa. Numerous potentially valuable indicator species and diagnostic assemblages are apparent; these will be assessed using Q-mode factor analysis and clustering (various indices) and then compared to transfer functions proposed from late Pliocene to Recent studies. The age model for this study will be based on the new deterministic composite section for 26 Southern Ocean core sections and more than 150 taxa (300 events). The CONOP method represents a significant advance from biozone stratigraphy and should produce dramatically higher temporal resolution than a zonation based on relatively few zonal datum levels. This improved age constraint is essential for correlation between different sections and different proxy records, and will eventually resolve the timing, magnitude, and frequency of the controversial warm events. Furture work will add data from ODP 736 on the Northern Kerguelen Plateau to address the question of latitudinal variation.

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Oligocene-Miocene Paleoceanographic Events of Campos Basin, Brazil: Evidence from Deep-Sea Benthic Foraminifera ValquĂ­ria PorfĂ­rio Barbosa; Oscar Strohschoen Jr. The late Oligocene and early Miocene periods have generally been viewed as time of moderate global warmth and ice-free conditions. Several lines of evidence suggest that this time interval was possibly punctuated by several episodes of high-latitude cooling and continental glaciations. We present a quantitative and paleoecological study using deep-sea benthic foraminifera as a tool to identify climate and oceanographic oscillations across the Oligocene-Miocene boundary in Southern of Brazil. Benthic foraminifera have substantial scope in paleoceanographic studies and are recognized as one of the most important paleoecological and paleoenvironmental indicators because their abundance, wide distribution in all marine environments and their high sensibility to the past variability in deep water properties. Its wide employment in environmental reconstructions makes them a useful tool in industrial exploration mainly because their patterns of distribution can provide reliable clues for the understanding of marine environmental changes in the geological past. In this study we use the benthic foraminifera patterns of distribution to provide high-resolution records in the OligoceneMiocene boundary, including the Antarctic glaciation represented by Mi1 event.

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Paleoecological Interpretation of Benthic Foraminiferal Assemblages from Clastic Paleogene Environments Using Modern Analogues: Possibilities and Limitations Katrine Husum; Elisabeth Alve Benthic foraminifera comprise one of the most common, diverse and widespread microfossil groups in Late Paleozoic, Mesozoic and Cenozoic marine deposits.

Quantitative biostratigraphy is applied in a wide range of fields which are important for modern society oil exploration and production, engineering, and climatic as well as human impact studies. In the present project, we focus on benthic foraminiferal assemblages from Paleogene clastic deposits, in order to increase their usefulness in paleoecological interpretations. The Paleogene is of particular interest to the oil industry and it represents the youngest Period during which benthic foraminiferal assemblages taxonomically are substantially different from modern ones. We review the baselines commonly used for paleoecological interpretations of Paleogene benthic foraminifera and, combined with recent advances in our understanding of modern foraminiferal ecology, aim to establish sets of criteria that will maximize our possibilities of interpreting Paleogene assemblages. Numerous papers have been published on Paleogene benthic foraminiferal biostratigraphy, but to our knowledge, only about 50 of them attempt to interpret the paleoecology. Although most Paleogene foraminiferal species are now extinct, the interpretations are mainly based on modern analogues.

Besides using distribution patterns of modern foraminiferal assemblages to interpret the Paleogene paleoenvironments, e.g. paleobathymetry, the following faunal parameters are most commonly applied: simple measures of index, dominance, test species diversity, number of species and Fisher morphology, wall-structure, and the ratio between planktic and benthic foraminifera. Regardless of which parameters that are used it is always important to evaluate the assumptions on which the interpretations are based. For example, more recent studies of test morphology have pointed out that correlation between test shape and environment is loose and the former estimates that microhabitat assignment based solely on morphology is only correct in 75% of the cases (Jorissen, 1999; Van der Zwaan et al., 1999). This implies that any ecological interpretation based on microhabitat and test morphology (e.g. oxygen level, organic flux, water depth) is not straightforward. This study synthesizes paleoecological interpretations covering a shelf â&#x20AC;&#x201C; slope â&#x20AC;&#x201C; basin transect under different conditions and evaluates the robustness of the interpretations.

In addition, characteristic species, their abundance, and faunal parameters are summarized for every environmental setting.

References: Jorissen, F.J. 1999. Benthic foraminiferal microhabitats. In: B.K. Gupta (editor), Foraminifera. Kluwer, Dordrecht. Van der Zwaan, G.J. et al., 1999. Benthic Foraminifers: Proxies or Problems? A Review of Paleoecological Problems. EarthScience Reviews, 46, 213-236. ____________________________________ Geologic Problem Solving with Microfossils

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Dinoflagellate Cysts in Neogene Palynological Assemblages from the Deep Offshore of the Gulf of Guinea: More than Meets the Eye D. Michoux; S. Piriou The main biostratigaphic input to the understanding of the turbiditic systems forming the reservoirs of several fields of the Gulf of Guinea is usually provided by foraminifera and nannoplankton. Despite the presence of often extremely rich assemblages, palynology tends to take a back seat, as these assemblages are often dominated by terrestrial palynomorphs (pollen, spores, and freshwater algae) and do not always afford the necessary resolution in terms of chronostratigraphy and depositional environment, especially at reservoir scale. As for the example shown here, marine dinoflagellates, whose productivity may be low in the first place, are often diluted by the sheer abundance of the terrestrial material: if one excepts P. zoharyi which is considered to be transported from coastal waters, marine dinocyst frequency rarely exceeds 3%. The marine palynological signal is thus difficult to read, and frequency curves or marine/continental ratios derived from standard analytical procedures such as a count of 250 palynomorphs allow the recognition of only the main flooding events or condensed intervals. The recognition of more subtle events requires going beyond the frequency curves in order to fully exploit the palynological dataset. We present here a composite section covering the Late Miocene to uppermost Middle Miocene interval where discrete sediment packages yielded diverse marine dinocyst assemblages. Some contain â&#x20AC;&#x153;standardâ&#x20AC;? Gonyaulacoid genera such as Impagidinium, Operculodinium, Nematosphaeropsis and Spiniferites. An acme event of morphotypes related to the genus Capisocysta was also recorded. In addition, we present and illustrate here Peridinioid dinocyst assemblages, on which little emphasis seems to have been placed in an exploration context, even if numerous species are described and illustrated in the literature. 25 species have been identified so far. The development of this heterotrophic group of marine algae is commonly explained by the presence of upwelling currents. In the present case, they are commonly associated with Poaceae, freshwater algae (Pediastrum) and coarse phytoclastic material, suggesting a link with phases of fluvial activity during which a nutrient-rich plume extends far offshore. It is felt that Peridinioid dinoflagellate cysts show great potential for improving the biostratigraphic resolution, at least on a field-scale, and hopefully on a more regional scale when the taxonomy of this variable group has been firmed up.

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A Revision of the Reticulofenestrid Taxonomy and Biostratigraphy Eric de Kaenel A revision of the Oligocene-Pleistocene reticulofenestrid group is proposed based on an exhaustive taxonomic research from the first publication from Lohmann (1902) to the most recent publications dealing with terminology in the classification of the reticulofenestrids. A special attempt has been undertaken to find all published species of this group in the literature from the middle of the XX century, a period where most of the holotypes were illustrated by drawings and not yet by photo micrographs. Precise measurements of holotypes allow us to propose a very comprehensive classification based on key indications that will allow all nannofossil paleontologists to use this group for ecological or biostratigraphic studies. Several new species are described and new combinations proposed.

Keywords: coccolith, taxonomy, biostratigraphy, Crenalithus, Cyclicargolithus, Dictyococcites, Emiliania, Pseudoemiliania, Reticulofenestra.

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Oligocene - Miocene Dinoflagellate Cysts and Continental Palynomorphs in the Furrial Field, Eastern Venezuela Diana Cabrera; Solangel Alfonzo; Javier Helenes As part of PDVSA's exploration activities in the Eastern Venezuela Basin, 96 core samples were analyzed for palynology in the exploratory well No. 1 of the Furrial field.

The results show varied and abundant Oligocene-Miocene palynomorphs, two palynomorph assemblages are recognized in the section studied that help to determine the Oligocene-Miocene boundary in the Furrial field. The lowermost part of the section is assigned to the Magnastriatites - Cicatricosisporites dorogensis zone of Muller et al.

(1987) based on the ocurrence of the continental palynomorph Cicatricosisporites dorogensis and Jandufouria seamrogiformis.

The concurrent presence of the dinoflagellates Tuberculodinium vancampoe, Operculodinium centrocarpum, Polysphaeridium spp.and Homotryblium spp. indicate a late Oligocene age. The overlying interval is assigned to the Verrutricolporites rotundiporus - Echidiporites barbeitoensis zone of Muller et al. (1987) based on the presence of the pollen Psilatricolporites pachydermatus, Psilatricolporites divisus, Psilatricolporites triangularis, Bombacacidites brevis and Bombacacidites sp. A. The concurrent of the dinoflagellates Cribroperidinium tenuitabulatum, Spiniferites mirabilis, Lejeunecysta hyalina and Homotryblium spp. indicate an early Miocene age.

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Benthic Foraminifera from Early Carbonate Sediments of Chimana-El Cantil Formations: Biostratigraphic Use for Oil and Gas Exploration in Northeastern Venezuela Jacqueline Jouval Micropaleontological studies are performed on exploration wells with the purpose of providing age dating and paleoenvironmental interpretation of the sedimentary sequences for rig site intervention and regional studies. This work shows the results of a biostratigraphic study carried out of thin sections from side-wall cores and ditch cuttings in two wells in the North of Monagas area, Eastern Venezuela Basin. The wells penetrated the Lower Chimana-El Cantil formations constituted by an intercalation of siltstones, claystones and limestones. To determine the age and paleoenvironments of deposition of the carbonate levels, foraminiferal microfauna analysis were performed, revealing Aptian-Albian benthic microfauna of shallow-water environment like Orbitolina (Mesorbitolina) pervia, Nezzazata isabellae, Novalesia cf gracilis, Vercorsella sp, and Vercorsella cf arenata. This microfauna association was known in the Eastern Basin but has never been mentioned in wells from this area. However, these benthic foraminifers had been recognized in Western Venezuela carbonate sediments of the Cogollo Group, of the same age. The benthic foraminifers and miscellaneous organisms, contained in Chimana-El Cantil limestone samples were analysed during well drilling and have been later reviewed and specified. The main fossils observed are illustrated, in order for this benthic microfauna to be used as reference for future studies.

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Biostratigraphy Impact in the Geology Study during Exploration Drilling, Northwest Monagas Oilfields, Eastern Venezuelan Basin Rafael Ramirez; Olga M. V. Rodriguez; Dennis Alberto Sanchez Zambrano Hydrocarbon exploration in the Eastern Venezuelan basin has been carried out in areas of very complex structural styles and stratigraphy with a poor seismic resolution. The main oil reservoirs, Oligocene to Miocene, occurr in a stratigraphic column, where the micropaleontological content (foraminifera, calcareous nannoplankton and palynomorphs) has been used succesfully for chronostratigraphical and sedimentological correlation. These fossils groups have proved to be a powerful tool for the biostratigraphical control in exploration drillling, and stratigraphical reconstructions, in order to validate the seismic data, structural and stratigraphic model. This investigation shows the results of the integrated data from an exploration well located in the Nortwest Monagas, between Pirital and Santa Bรกrbara trends, versus the stratigraphic model proposed from a seismic interpretation. The results permitted the construction of a new chronostratigraphical-structural framework and the definition of paleoenvironmental conditions prevailing during deposition of the Oligocene to Miocene reservoirs.

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A Palynological Zonation for the Cretaceous - Tertiary of Colombia M. Rueda; C. A. Jaramillo Palynology is one of the main biostratigraphic tools used in Colombia. More than 20,000 palynological samples have been analyzed by the Colombian oil industry in the last 70 years. Current zonations used for the region have either low-resolution or do not apply to Colombian sediments. Lacking a reliable zonation costs millions of dollars derived from unreliable correlations, misfits in age determinations, and a general mistrust on the tool.

The need for a predictive zonation has become more evident recently because exploration has moved toward more complex or/and unexplored areas. In such areas, a good biostratigraphy can be a very important tool for field-mapping, well-drilling, testing structural interpretations, and correlating reservoirs. The Colombian Petroleum Institute established a five-year research program to produce a palynological zonation for Colombia. Graphic correlation and constrained optimization plus a number of data filters were used to produce the zonation. This zonation has 34 zones ranging from the Late Aptian to the Middle Miocene. The zonation has been successfully tested in several areas. We reinterpreted a recently well drilled in the Llanos foothills. The well was initially interpreted as reaching the Guadalupe formation. Our model indicated that the well only reached the Cuervos formation. A sidetrack and a new exploratory well in the area were subsequently drilled validating the proposed model. This example is a positive test that the zonation is reliable and can be applied to oil exploration.

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Nannostratigraphy of Eocene Strata in the Talara Basin, Peru Yanina Narvaez The Talara basin, in nothwestern Peru contains the lithostratigraphic units Mogollon Formation and Talara Group. For many years, the age of the Mogollon Formation was not clearly defined because of its poor micropaleontological content. The Talara Group was defined previously by benthic foraminifera. To help clarify the age of these units, I completed a quantitative study of the distribution patterns of the calcareous nannofossils contained in them. I studied the nannofossil content of samples from seven wells drilled in the Talara Basin. Early Eocene calcareous nannofossils (NP13/NP12 zone) were found in the Mogollon Formation. Stratigraphic sections of the Talara Group of two wells analyzed contained Late and Middle Eocene nannofossils (NP20/NP17, NP16/NP15 and NP14 zones). The Middle Eocene calcareous nannofossils show variations through time. The relative abundance of warm-water species versus coolwater species provides a useful proxy interpreting Middle Eocene surface water temperature. These variations were probably due to the paleoclimatic changes at that time, but could also represent the influence of Andean tectonic activity.

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Middle Permian (Capitanian) Microfossils from the "Rader Slide", Guadalupe Mountains, West Texas Merlynd K. Nestell; Galina P. Nestell; Michael J. Sweatt A diverse assemblage of microfossils is present in a six meter turbidite sequence with three interbedded fossiliferous debris flows exposed in a well known road cut of the Rader Member (Bell Canyon Formation) in the Guadalupe Mountains of West Texas. The locality, known as the â&#x20AC;&#x153;Rader Slideâ&#x20AC;? in various guidebook stops, is located on U. S. highway 62/180 just southwest of the entrance to McKittrick Canyon. Each debris flow, derived from nearby Capitanian deposits, contains a distinct microfossil assemblage reflecting the depositional environment of the original source. The three debris flows and three thin limestone beds in the turbidite sequence, one above each of the three debris flows, were sampled. This study was undertaken to investigate if the microfossil assemblages in this interval were distinct enough to detect a time span in the deposition of the individual flows. Ten kilogram samples of each of the three flows and the three limestone interbeds were dissolved by dilute formic acid, leaving a small residue containing conodonts, small foraminifers, radiolarians, sponge spicules, and fish dermal plates and teeth.

Thin sections were made to study acid-soluble microfossils such as fusulinaceans and other foraminifers. The primary fossils used to differentiate rocks of Guadalupian age are species of the conodont genus Jinogondolella. Conodonts are relatively scarce in the first (or lowest) debris flow and common to abundant in the second and third flows. The first and third samples from the thin limestone beds produced extremely abundant conodont Pa elements including abundant ramiforms elements. The sample taken above the second debris flow had only a few broken conodont specimens. All of the conodonts appear to be morphotypes of one population of the species Jinogondolella postserrata. The conodont assemblage in the three debris flows appears to contain extreme variations of J. postserrata, whereas those morphotypes in the first and third thin limestone samples appear to be more uniform in shape. The first two debris flows contain the fusulinaceans Leella, rare Codonofusiella, Polydiexodina, and the small foraminifers Globivalvulina, Hemigordius, Baisalina, Abadehella, Deckerella, Neoendothyranella, Endotebanella, Geinitzina, and Polarisella. Dasycladacean algae, ostracods, sponge and bryozoan fragments are also present. The third debris flow contains abundant sponge spicules with scarce Leella and a distinct assemblage of small foraminifers including abundant nodosariids, and scarce Globivalvulina, Hemigordius, Baisalina, Abadehella, Neoendothyranella, and Endotebanella. The lower thin limestone bed contains a similar foraminiferal assemblage to that found in the first debris flow. However, the third thin limestone bed contains a similar assemblage to that found in the third debris flow with abundant nodosariids, very scarce other smaller foraminifers, Leella, and radiolarians. The sample taken above the second debris flow containing primarily abundant radiolarians is anomalous and appears to indicate a distinct change in water mass at the time of deposition. From this study, it appears that only the Jinogondolella postserrata conodont zone can be documented in this interval. The foraminiferal assemblage is not distinct enough to be time significant.

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Biostratigraphy: Recent Studies of a Pliocene/Pleistocene Section from the Tampico Misantla Basin, Southeastern Gulf of Mexico Héctor R. Ruiz; Julieta G. Martínez; Víctor O. Martínez; Rodolfo T. Guerra; Alberto T. Segura Hydrocarbon exploration in Tertiary siliciclastic sediments from the southeastern Gulf of Mexico has highlighted the importance of biostratigraphic studies in defining the geological setting of this relatively poorly known area of the Gulf of Mexico which is located in a province that has great potential for new hydrocarbon discoveries. In this study, ditch and conventional core samples from recent, PEMEX exploration wells have been analyzed for their foraminiferal and calcareous nannoplankton content to help define the biostratigraphic framework of the Pliocene/Pleistocene section from an area near the continental margin of the Tampico Misantla basin located offshore of Veracruz in eastern Mexico. The paleontological data was analyzed using a methodology that proportions a scheme to define the fossils that are used to determine the age of these sediments and those that help in the paleoenvironmental analysis. The assigned ages are based on First Occurrences (FO) and on limited occasions, Last Occurrences (LO) of planktonic foraminifera and calcareous nannoplankton. Occurrences of benthonic foraminifera were used for paleobathymetric interpretations. The documented index fossils for our age-determinations include the following: Gephyrocapsa oceanica, G. caribbeanica, Ceratolithus cristatus, Globorotalia truncatulinoides truncatulinoides (FO and LO of), Pulleniatina finalis and Globorotalia tumida flexuosa in the Pleistocene section, Inonion and Calabrian Stages; Discoaster brouweri and Globorotalia tosaensis tosaensis (FO) in the Late Pliocene, Gelasian Stage; Globorotalia miocenica, G. multicamerata, Globigerinoides obliquus extremus, Discoaster pentaradiatus and Discoaster tristellifer in Middle Pliocene, Piacenzian Stage: Globorotalia margaritae margaritae, Globoquadrina altispira altispira, Globigerina nephentes, Reticulofenestra pseudoumbilica and Sphenolithus abies in the Early Pliocene, Zanclean Stage and Sphaeroidinellopsis disjuncta and Globorotaloides variabilis to define the top of the Late Miocene, Messinian Stage. The integration of these data will result in a unified, biostratigraphic criteria for age-determinations and paleobathymetric interpretations of the Neogene in the southeastern GOM specifically for the Pliocene/Pleistocene section which will further our understanding of the stratigraphy of this under explored prospective interval in this region.

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Miocene Nannofossil Bioevent Summary with High Resolution Emphasis on GoM Events Stephan A. Root A review of the literature and some of the zonation schemes used within the U.S. oil industry suggests there may be in excess of 150 described and "inhouse" species that can be used to recognize over 250 potential nannofossil bioevents in the Miocene. This review attempts to rank the contribution of these species and their associated bioevents with an emphasis on the Gulf of Mexico. The species bioevents emphasized in this study include the highest occurrence (HO), which is the standard for well-site biostratigraphy; highest consistent occurrence (HCO); acme top (A); lowest consistent occurrence (LCO) and lowest occurrence (LO). The stratigraphic value of a species is dependent upon its ease of recognition (species concept and preservation), geographilc distribution, ecologic preferences, range duration and range consistency. Species with the highest utility are the primary markers. They tend to be distinctive and short ranging, with their associated bioevents geographically widespread and are emphasized in most of the published zonation schemes. In this study 11 HO's, 3 HCO's and 7 LO's are assigned a high utility.

Most species have a combination of some less desirable characteristics and have moderate (21 HO, 13 HCO, 12 LO), low (45 HO, 27HCO, 4 A, 4 LCO, 24 LO) or very limited (48 HO, 6 HCO, 5 LCO, 46 LO) utility. The final product summarized in chart form, compares the age assignment of these 250 bioevents, divided into the 4 utility rankings. It is hoped this chart will engender further discussion and additional studies to sharpen our focus and refine the position and applicability of these Miocene bioevents.

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The Age of Offshore Niger Delta Sediments Inferred from Palynological Evidence Olusola H. Amule; M. A. Sowunmi Sixty-six ditch cutting samples selected from interval 1060-10380 feet were investigated for palynomorphs with specific objectives of palynological zonations and age dating.

The samples were largely selected within shale horizons at 60 ft intervals within the paralic section of sand and shale intercalations. The selected samples were subjected to standard palynological sample preparation. Two alphanumeric palynozones (P800, P900) and three subzones (P880, P870, and P860) of Evamy et al. (1978) were recognized. They have been dated Upper Miocene to Recent based on the identified marker species such as Gemmamonoporites sp., Peregrinipollis nigericus, Cyperus type pollen, Podocarpus milanjianus, Echitriletes pliocenicus, Stereiosporites sp, Retisptephanocolpites gracillis and Multiareolites formosus. The relationship between age, basin modeling and evaluation is highlighted.

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Late Oligocene - Miocene Dinoflagellate Cysts from Deep-Sea Fan Deposits from Mid Latitudes: Angola, West-Central Africa Pi Suhr Willumsen; Barrie Dale; Iain Prince In this study of several offshore Wells from Angola, index dinoflagellate cysts are mapped and their biostratigraphic ranges are correlated with the terrestrial microflora transported into the deep-sea fan deposits. The aim is to establish a high-resolution biostratigraphic framework for the late Oligocene-Miocene interval that can assist in the interpretation of the depositional patterns of the Congo River deep-sea fan and eventual correlation between reservoir units in the Angola Basin. The Late Oligocene to Miocene dinoflagellate cyst assemblages from the Angolan Basin, comprise index fossils such as Distatodinium caterum, D. paradoxum and Chiropteridinium galea. Dinoflagellate cyst genera with a protoperidiniacean affinity such as Sumatradinium, Trinovantedinium and Selenopemphix (De Verteuil and Norris 1992) occur throughout the examined Angolan wells. Dinoflagellate cysts such as Sumatradinium soucouyantiae and S. hamulatum are also observed and these species have in the past been shown to be of biostratigraphic importance in other the early to middle Miocene zonations (De Verteuil 1996; De Verteuil and Norris 1996). These findings from tropical Angola, contrasts with previous studies that genera such as Chiropteridinium and Distatodinium are not found in the low latitude tropical material (Helenes & Cabrera 2003).

References: De Verteuil, L. and Norris, G. 1992. Miocene protoperidiniacean dinoflagellate cysts from the Maryland and Virginia coastal plain. In: Head, M.J. and Wrenn, J.H. (eds), Neogene and Quaternary Dinoflagellate cysts and acritarchs. America Association of Stratigraphic Palynologists Foundation, Contribution Series, 391-430. De Verteuil, L. 1996. Data report: Upper Cenozoic dinoflagellate cysts from the continental slope and rise off New Jersey. Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 150, 439-454. De Verteuil, L. and Norris, G. 1996. Miocene dinoflagellate stratigraphy and systematics of Maryland and Virginia. Micropaleontology, Vol. 42, 166 pp. Helenes, J. and Cabrera, D. 2003. Oligocene-Miocene palynomorph assemblages from eastern Venezuela. Palynology 27, 5-25.

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Biostratigraphic Characterisation of Ivorian Late Albian Sequences Victor Nda; Juliette Tea; Raphaël Yao; Adèle Atteba A high-resolution biostratigraphy study including micropaleontology (foraminifera and nannofossils analysis) and palynology has been carried out upon the Late Albian interval of petroleum offshore wells, in the Côte d’Ivoire (West Africa) sedimentary basin. This Late Albian interval yields abundant microfauna mostly composed of planktonic foraminifera. Microflora (spores and pollens) are generally abundant through all of the Albian interval, apart from the dinocyst specimens which are very rare to absent, as it is for the benthonic foraminifera. These Albian sediments are composed of claystone or marls interbedded with more or less loose sands layers and rare limestone stringers deposited in a coastal to external continental shelf environment. The study of planktonic foraminifera and miospores provided a remarkable succession of bio-events which are characteristic of this Late Albian interval. These biozones were calibrated with the electric and lithologic logs and also with the sequence chronostratigraphic chart of J. Hardenbol et al., 1998. This allowed us the opportunity to give more precision on the ages and palaeoenvironments determination, as well as the definition of the Late Albian depositional sequences. Thus, three (3) depositional sequences were identified: Al 10 (100 ma), Al 9 (100.6 ma) and Al 8 (101.5 ma).

Key Words: Biotratigraphy – High-resolution - Foraminifera – Miospores – Late Albian – Depositional sequence - Bio-event - Ivorian basin.

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High-Resolution Palynostratigraphy of a Sand-Rich Turbidite System, the Angel Formation, Carnarvon Basin, Australia J. G. S. Goodall; C. Hannaford; G. Scotford; M. Dâ&#x20AC;&#x2122;Cruz The Angel Formation of Tithonian age represents a sand-rich turbidite system, deposited both unconformably on a pre-rift topography at the basin margins and conformably within the basin centres. To aid detailed large scale stratigraphic correlations, an initial hypothetical model of lateral shale continuity within the sandy system was tested, using high resolution palynology (1-2m scale), demonstrating that isochronous 1-2m thick flooding surfaces within a third order cycle were correlatable over tens of kilometers in the subsurface. The data was also supported by reservoir pressure data and core data. A chronostratigraphic framework was constructed encompassing the last 3my of deposition of the Angel Formation, using the thin flooding surfaces as chronostratigraphic surfaces enabling the recognition of 3rd, 4th, 5th and 6th order turbidite sequences, each palynologically defined. Within the stacked third order cycle a key shale horizon has been recognized which is considered important in the construction of the chronostratigraphic framework. The recognition of this shale has implications for both underlying and overlying turbidite sand quality and distribution, this shale additionally has a predictive palynological response. The resultant work enables the mapping of individual turbidite cycles across the pre-rift topography and their connection with the more basinal deposits, enabling the recognition of offset stacking patterns of individual 6th order turbidite lobes and hence potential reservoir distribution. An additional consequence of the reservoir scale, high resolution palynological zonation has been the ability to biosteer at wellsite, with four horizontal wells drilled through individual 6th order turbidite cycles, some as little as 4m thick, with palynology successfully assisting drilling decisions in order to maximize reservoir penetration.

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Micropalaeontology and Palaeoenvironments of Saudi Arabian Upper Permian Carbonates and Reservoirs G. W. Hughes The Khuff Formation of Saudi Arabia consists of interbedded shallow marine carbonates and evaporates. It is exposed along the basement-flanking outcrop belt of central Saudi Arabia, and also forms important hydrocarbon reservoirs at depth in the east.

Micropalaeontological evidence suggests that the Khuff Formation in Saudi Arabia is of latest Permian to Early Triassic age. Micropalaeontological analysis has contributed new chronostratigraphic and palaeoenvironmental insights for the Khuff Formation. Late Permian foraminiferal facies include age-diagnostic species, despite the absence of the conventional fusulinid species. The Permo-Triassic boundary is characterised by (a) the extinction of Late Permian foraminifera (b) the presence of the spirorbid Spirorbis phlyctaena (c) a marked negative carbon isotope shift (d) a distinct soil level. This event lies at, or slightly above, the boundary between the Midhnab and Khartam Members in the outcrop belt and within the lower part of the Khuff B carbonate reservoir in the subsurface. Foraminiferal and calcareous algal biocomponents have been used to determine subtle palaeoenvironmental variations, both vertically and horizontally in the subsurface. The following biofacies have been established: Spirorbis-ostracodgastropod; Gastropod-brachiopod-ostracod; Ostracod-MizziaGymnocodium; Agathammina-Hemigordius; Agathammina-Hemigordius-Globivalvulina; NankinellaStafella; Bryozoa and Pachyphloia-Protonodosaria. Recognition of depositional cycles has also been assisted by identification of vertical stacking successions, or tiers. The reservoirs here considered display subtle palaeoenvironmental variations of an extensive, generally shallow marine, carbonate platform that ranged from intertidal to depths within intra-shelf basins that probably rarely exceeded storm wave base. An attempt has been made to apply the most recent understanding of Late Permian smaller foraminiferal taxonomy.

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Micropalaeontology and Palaeoenvironments of Selected Saudi Arabian Middle Jurassic Carbonates and Reservoirs G. W. Hughes The Middle Jurassic succession of Saudi Arabia is represented by the Dhruma and Tuwaiq Mountain Formations, of Bajocian - Bathonian and Callovian age, respectively.

Both formations contain carbonates that form important hydrocarbon reservoirs for Saudi Arabia. In the Dhruma, the Lower Fadhili reservoir is developed within carbonates of the Atash Member, while the Upper Fadhili and Hadriya reservoirs are developed in carbonates of the lower and upper Tuwaiq Mountain Formation respectively.

Macropalaeontological and micropalaeontological evidence has provided good chronostratigraphic control, and suggests a major unconformity at the Bathonian Callovian boundary, to lie within the upper Dhruma, above the Atash Member. This unconformity would place the Hisyan Member, the upper lithostratigraphic unit of the Dhruma Formation, into the basal part of the Tuwaiq Mountain Formation. The Atash Member of the Dhruma Formation contains microbiofacies characterised by the presence of Pfenderina trochoidea, Trocholina elongata, Nautiloculina oolithica, Redmondoides lugeoni, Trochamijiella gollehstanehi, Parurgonia caelinensis, Bositra buchi, Cladocorposis and Salpingoporella dinarica. The Tuwaiq Mountain Formation consists of the informal Baladiyah, Maysiyah and Daddiyah members, of which the Baladiyah contains the Upper Fadhili reservoir and the Daddiyah member contains the Hadriya reservoir. The Upper Fadhili reservoir contains Meyendorffina bathonica, Redmondoides lugeoni, Nautiloculina oolithica, Pfenderina trochoidea, Kurnubia wellingsi, Trocholina elongata and Trochamijiella gollehstanehi. The Hadriya reservoir contains Kurnubia wellingsi, Kurnubia palastiniensis, Trocholina elongata, Trocholina altispira, Trocholina palastiniensis, Nautiloculina oolithica, Redmondoides lugeoni and Cladocoropsis mirabilis and consists of a succession of prograding stromatoporoid and coral bioherms.

This new micropalaeontological evidence has enabled new biofacies units to be determined, of local isochronous value, together with establishing refined palaeoenvironmental interpretations and fine-scaled depositional cycles. These are of economic significance in terms of predicting trends of confirmed shallow facies belts as well as assisting in the prediction of potential locations of similarly good reservoir facies.

This information is also valuable for the development of reservoir-layering schemes to assist optimum exploitation of these internally heterogeneous reservoir carbonates.

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Micropalaentology and Palaeoenvironment of Late Jurassic Carbonate Formations and Reservoirs in Saudi Arabia A. Dhubeeb; G. W. Hughes The Upper Jurassic carbonates of Saudi Arabia include the Hanifa, Jubaila Formations and Arab D Member of Arab Formation. Numerous lithostratigraphic and sequence stratigraphic interpretations have been proposed but, despite their hydrocarbon exploitation since the 1930's, few detailed biostratigraphic studies were accomplished. A new composite stratigraphic range of the Saudi Arabia benthonic foraminiferal species is established. Macropalaeontological and micropalaeontological evidence has been used to constrain the ages of these three formations, and sedimentological evidence provides support for unconformities at their boundaries. Recent micropalaeontological and macropalaeontological studies have focussed on the recognition of palaeoenvironmentally-significant biofacies and their application towards the determination of highâ&#x20AC;&#x201C;resolution depositional cyclicity. The vertical succession of biofacies has revealed three depositional sequences from the Oxfordian to early Tithonian, each of which terminates with a coral-stromatoporoid biofacies. Integrated sedimentological and biofacies have also assisted in determining the transgressive and highstand systems tracts for each Formation. During the Late Jurassic, the current Arabian Peninsula lay on the south side of the Tethys, and was the site of an extensive, moderately shallow marine carbonate platform. Although the western flank of this platform has been removed during Tertiary uplift and erosion, the variety of palaeoenvironmentally-significant biofacies has led to the conclusion that the platform contained localised shoals that separated intra-shelf basins. These biocomponent influenced interpretations can be applied towards assisting exploration target location and in guiding reservoir development, by predicting the location and orientation of energycontrolled reservoir quality variations.

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Early and Middle Miocene Dinoflagellate Cyst Stratigraphy of the Pannonian and Vienna Basins, Central Europe Gonzalo JimĂŠnez-Moreno; Martin J. Head; Mathias Harzhauser Neogene stratigraphy in the central Paratethys area has been the focus of renewed interest in the past decade or so, owing to hydrocarbon prospects in the region. Parathethys extended over much of central Europe during the Early and Middle Miocene, and broad connections existed with the Mediterranean Sea and perhaps even with the Indian Ocean.

Normal marine conditions lasted until approximately 13 Ma, after which endemic marine conditions prevailed due to the closure of marine connections with the Mediterranean Sea. In the Late Miocene, freshwater conditions became established with the formation of Lake Pannon (not considered here). This is the first study to demonstrate the applicability of marine dinoflagellate cysts for detailed stratigraphic correlation in the Early and Middle Miocene of the Central Paratethys area. Two localities have been studied within the Vienna Basin: a 30-m thick section of middle Ottnangian (=middle Burdigalian) age at Strass-Eberschwang, representing the eastern Alpine foredeep of Upper Austria; and the 4-m thick holostratotype of the Badenian Stage (=late Langhian) at Badenâ&#x20AC;&#x201C;Sooss, Lower Austria. The 1183-m deep Tengelic-2 borehole, located in the Pannonian Basin in southern Hungary, close to the Mecsek Mountains and near the village of Paks, has also been studied. This borehole contains marine sediments of Badenian and Sarmatian (collectively Langhian and Serravallian) age. Dinoflagellate cysts and acritarchs from these three localities have been compared with assemblages of similar age from the Atlantic Ocean and Mediterranean Sea. Our results indicate that Cordosphaeridium cantharellus, Apteodinium spiridoides, and Exochosphaeridium insigne are characteristic of the mid Burdigalian; Cribroperidinium giuseppei and Palaeocystodinium miocenicum have highest occurrences near to the Langhianâ&#x20AC;&#x201C; Serravallian boundary, and many taxa present in the Langhian extend into the Serravallian, including Unipontidinium aquaeductum, Labyrinthodinium truncatum truncatum, Operculodinium? borgerholtense, Batiacasphaera sphaerica, and the acritarch Nannobarbophora gedlii. Increasingly restricted marine conditions are witnessed in the Serravallian of the Tengelic-2 borehole by a progressive reduction in species diversity. Cleistosphaeridium placacanthum, Pentadinium laticincinctum, and Hystrichosphaeropsis obscura are among the relatively few species surviving into the late Serravallian. Results have permitted the construction of a robust zonation that is compared with zonal schemes from the North Sea Basin, Mediterranean, and western North Atlantic.

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Environmental Regeneration of the Bilbao Estuary (N. Spain): Microfaunal and Geochemical Evidence Eduardo Leorri; Alejandro Cearreta; M. JesĂşs Irabien The Bilbao estuary was originally the most extensive estuarine area in northern Spain. However, the natural features of the Bilbao estuary have been dramatically modified by urban, industrial and port development. During the last 150 years, the Bilbao estuary has received wastes from many sources that have significantly degraded the environmental quality of the estuary. Estuarine restoration is being undertaken as part of a Revitalization Strategic Plan, which includes preventive measures and remedial action involving dredging of heavily contaminated surficial sediments. Despite these improvements, the unremoved contaminated sediments from the intertidal areas may act as a long-term source of heavy metals to the aquatic environment through sediment mechanical reworking and oxidation of anoxic sediments. Thus, these pollutants may continue to have significant environmental impacts even after discharge limits and clean-up procedures have been implemented. The record of recent environmental change preserved in the sediment from intertidal mudflats in the Bilbao estuary was studied by Cearreta et al. (Mar. Poll.

Bull. 44, 2002, 487-503). Three different environmental zones were distinguished based on its microfaunal and geochemical content. Initially, a pre-industrial zone; secondly, an older industrial zone; and finally, a younger industrial zone (extreme concentrations of metals / barren of indigenous foraminifera). Also, Cearreta et al. (Est. Coast. & Shelf Sci. 50, 2000, 571-592) analyzed surface sediments. They showed that heavy metal concentrations were highly dependent on proximity to sources of pollutants while living foraminifera were absent from surface sediments in the upper estuary, and were not abundant in the middle and lower estuary.

Based on these results, the present study evaluates the temporal evolution (geochemical and micropaleontological). For the geochemical analysis surface sediments were scraped off from 13 sites throughout the estuary and one locality in the open bay area in January 2000 and February 2003. Surface sediments consist of black sulphidic sandy muds, except the sample taken in the open bay area which was brown muddy sand. The micropaleontological samples were taken in January, May and November 2000, and February and May 2003. Although the species that have been found alive in the estuary are considered resistant to several polluting agents, we found only a reduced number of living individuals along the Bilbao estuary during the last 7 years. This is because their distribution reflects passive transport mechanisms from the open sea, omitting the possibility of their reproduction inside the estuary. These results have shown that there is still an ecological barrier that impedes the recolonization of the estuary by benthic foraminifera. The slight increase in the number of species living in the estuary, the recent presence of living foraminifera in the upper estuary and the decrease in heavy metal concentrations up to 50% during the last few years suggest the possibility of a satisfactory gradual recovery. Successful recolonization by benthic foraminifera may continue if the sediment conditions improve sufficiently in the Bilbao estuary. Foraminiferal assemblages could therefore be used as environmental quality indicators to assess the effectiveness of current regeneration schemes implemented under strategic local authority plans.

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Micropaleontological Proxies of the Recent Environmental Transformation in the St. Jones Estuary (Delaware, USA) Eduardo Leorri; Ronald E. Martin; Peter P. McLaughlin The St. Jones River is a small coastal river that extends from the coastal plain of central Delaware to the western shoreline of Delaware Bay. The lower reaches of the river are composed of microtidal (<2 m tides) brackish-water and salt marshes. Like so many other coastal and estuarine environments, these marshes have been (since at least the mid19th century) and are currently affected by major anthropogenic changes in the environment that have significantly degraded the environmental quality of the estuary.

Environmental monitoring programs provide â&#x20AC;&#x153;snapshotsâ&#x20AC;? of conditions at a single point in time, but many years of data are required to infer meaningful trends, which only provide insights into the last few decades. However, analysis of historical records in sediment cores provides a firm basis for interpretations of longer-term environmental trends and can provide a baseline against which continuous monitoring programs can be assessed. Benthic foraminifera provide a useful tool for such analyses. This study examines the benthic foraminiferal record of the St. Jones marshes to address two specific objectives: (1) to establish a historical context for environmental assessment by evaluating the degree of anthropogenic environmental changes in the marshes; and (2) to reconstruct the paleoenvironmental changes in this marginal marine environment during the last millennium following the postglacial rise of sea level. Study material includes 6 vibracores (up to 10 m in length), 2 Russian peat cores (up to 4.4 m in length), and 2 auger cores (up to 1.3 m in length) taken across the marshes. Preliminary results from the lower and middle portions of the estuary show that the basic assemblage is dominated by Arenoparrella mexicana accompanied by Jadammina macrescens, Trochammina inflata, and Trochammina ochracea, consistent with previous studies from Delaware marshes. In addition, we report, for the first time in Delaware marshes, calcareous taxa as dominant species in some intervals in the lower part of the estuary. This assemblage shows a high variability upwards in each core and between cores. Foraminifera are present but very scarce below 70 cm depth in cores from the middle and lower estuary. The upper 70 cm present a typical marsh assemblage. This suggests an increase in marine influence that may be correlated with the transgression that began with the end of the Little Ice Age about 150-180 years ago. The integration of these results with data from pollen analysis will allow us to reconstruct the environmental development of the St. Jones marshes during the later Holocene as well as the changes derived from European settlement.

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Foraminiferal Population Change as A Result of Increased Inflow into Nueces Bay, Texas Pamela Buzas-Stephens; Martin A. Buzas Ecosystem health in Texas bays and estuaries is dependent primarily on river inflow, especially in more arid regions. Foraminiferal populations were studied in Nueces Bay, Texas at five stations along a north-south transect toward the middle of the bay, where salinities were most constant (23-27 ppt). A first set of samples was taken from Fall 1998 to Spring 2002, during a period of low rainfall and hence low inflow (mean monthly discharge of .47-2564 ft3/s) from the Nueces River. The Central Power and Lighting Plant was in operation on the south shore of the bay, but the plant was closed in January 2003 due to budgetary considerations. Return flow from the plant consisted of large volumes of saline coolant water pumped from Corpus Christi Bay. Results of the 19982002 sampling revealed higher foraminiferal densities at the south shore, which is closer to river input, than at the north shore. Statistical analyses also showed that foraminiferal communities were different at the north and south shores. In addition, there was a high incidence of shell dissolution, mostly in Ammonia, at all stations. Populations of foraminifers were sampled again in March 2003, following the plant closing and a significant increase in inflow (mean monthly discharge of 19.69-16,170 ft3/s) due to higher precipitation. Salinity was lower at the south shore (12 ppt) than it was at the north shore (21 ppt). Preliminary data show that foraminiferal abundance is at least 2-3 times greater at each station, and that there is a low percentage of shell dissolution.

Ammotium replaces Ammonia as the dominant taxon at some stations. This paper documents the marked change in foraminiferal populations in Nueces Bay subsequent to high inflow. While these changes may not be permanent, the study emphasizes the utility of foraminifers for short-term habitat monitoring.

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Benthic Foraminifera Tests as Proxy Indicators of Sediment Pollution in the Macro-Tidal Red River Mouths (North Vietnam) Richard Hoefling; Christian Weiss; Heinz Juergen Tobschall Over the past decade reports of deformities of foraminiferal tests in lagoonal and tidal flat areas have become increasingly common. Benthic forams show a wide range of test malformations which may have been caused by pollution such as heavy metal contamination, or anthropogenic influences e.g. oil slicks, domestic sewage, change of physicochemical environment parameters and shortage of nutrients in the habitat. Until now only a few field studies and laboratory investigations concerning the causal mechanisms of such deformations have been carried out. Recent micropaleontological, sedimentological and geochemical studies in the macrotidal Halong Bay (clay-flats of the Red River Mouths, NE Vietnam) suggest that several taxa of the mostly cosmopolitan rotaliid foram genera Ammonia, Elphidium, Eponides, and Discorbia seem to be sensitive in-situ monitors of marine pollution in our study caused by the exploitation of Late Triassic coal-seams which led to a remarkable increase of As- and Zn-concentration in the clayey sediments. Also the C/N ratio reflects a high percentage of terrestrial organic material quite probably derivable from the coal exploitation. Microbial cells and biofilms attached to such contaminated sediments - mainly foraminiferal nutrients - quite probably initiate biomineralization reactions of foraminiferal tests at biofilm / sedi- ment interfaces. Especially high concentrations of As and Zn are known to be stressful and dangerous factors for microorganisms initiating toxic effects in microbial cells. The resulting morphologi- cal foram deformities include wrong coiling, aberrant chamber shape and size (particularly inflated last chambers), poor develop- ment of the last whorl, twisted chamber arrangement, additional chambers, protuberances, multiple apertures, irregular keel, twinn- ing, and lack of sculpture. The present preliminary observations need to be tested by more data derived from inductively-coupled plasma mass spectrometer (ICP-MS) studies concerning abnormal test mineralogy (e.g. stress dependent Mg/Ca ratios), and the setting of living cultures for microbiological and biomineralization studies.

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Palynologic Determination of Changes in Historical-Era Sedimentation and Vegetation in Marshes Flanking the St. Jones River, Delaware, USA Susanne Moskalski; Ronald Martin; Peter McLaughlin Pollen analysis in three cores from salt marshes on the St. Jones River in central Delaware show major shifts in vegetation over the last 500 years. Variations in pollen assemblages appear to reveal both natural changes in the plant community and anthropogenic changes related to European settlement. Age estimates derived from these changes allow assessment of the impact of post-European-settlement land-use practices on sedimentation in the St. Jones estuarine system. The area surrounding the St. Jones River has been continuously inhabited since 1650, when the English established the settlement of St. Jones Neck, while other portions of Delaware were settled as early as 1631. Prior to the advent of European agricultural practices, Delaware was thickly forested with mixed conifers and hardwoods. Clear-cutting for agriculture and fuel wood supply, beginning in the late 1600â&#x20AC;&#x2122;s, quickly denuded the area, which did not begin to recover until the second half of the 20th century. Preliminary analysis of the pollen record of three cores reflect a shift from this forested setting to one with a significant proportion of open areas. The lower, pre-settlement parts of the cores are dominated by Quercus, with abundant Pinus and Carya and common Graminae and Cyperaceae. The upper, post-settlement intervals are rich in Quercus, with common Pinus and Carya, but the abundances of Compositae are conspicuously higher. Alnus and Castanea are more common in the upper part of the cores, but Castanea abundances decline sharply above 65 cm. These shifts place the European agricultural horizon at a depth between 145 and 165 cm in the cores, and suggest that the American Chestnut Blight horizon occurs at 65 cm depth. Age estimates based on this horizon and radiocarbon dates from one core suggest a significant increase in sedimentation rates following European settlement.

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Reconstructing the Postglacial History of Georgian Bay, North American Great Lakes, Using Fossil Pollen and Protists Francine M. G. McCarthy; Steve M. Blasco; John H. McAndrews; Sarah H. Tiffin; C. F. Michael Lewis Microfossils have proven to be critical in unravelling the postglacial history of Georgian Bay, an arm of Lake Huron. The analysis of pollen and embryophyte spores provided a chronology, highlighting the very discontinuous nature of sedimentation in the basin.

This complex depositional history, in fact, confounded researchers in the 1960's and 70's who were unable to interpret the pollen succession, in what they felt should have been a more-or-less continuous sedimentary record since the retreat of ice sheets. We examined pollen and spores as well as thecamoebians and freshwater dinocysts from northwestern Georgian Bay near Tobermory and from Severn Sound; these, as well as published data, were interpreted not only to provide a chronology, but also to reconstruct paleoclimatic and paleolimnological conditions. Key findings include: 1) identification of a hiatus based on pollen stratigraphy between the end of the Nipissing Rise in the mid Holocene and anthropogenic siltation over the last few centuries, due to sediment starvation; 2) pollen evidence of regression producing a shoreline at least 50 m below the modern level of Georgian Bay around 7.5 ka BP (8200 cal yBP: near the pollen zone 2a/2b boundary); 3) thecamoebian evidence of brackish waters coincident with this lowstand below the elevation of the controlling (North Bay) outlet, recording closed basin conditions in Georgian Bay (low level Lake Hough); and 4) reconstruction of much colder, drier winters than are currently found in this region ~7.5 ka from the pollen data using transfer function analysis, but not substantially different mean July temperatures; meteorologically, this suggests a stronger influence of cool, dry arctic air/ much reduced flow of warm, moist tropical air from the Gulf of Mexico during the winter, resulting in substantially decreased snowfall, higher evaporation, and thus lower lake levels. These data and interpretations are consistent with micropaleontological and geochemical evidence for dry climatic conditions ~7500 yBP (~8200 cal yBP) cited by various authors for many parts of eastern North America, including the Greenland Ice Cap.

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Assemblages of Recent Large Benthic Foraminifera and Taphofacies Combined with Grain Characteristics as Indicators of Environmental Variables in Sea-Grass Beds, San Salvador, Bahamas Olivia C. Buchan; Ronald D. Lewis Sea-grass beds constitute an important environment in shallow-water, carbonate producing regimes. Grass blades baffle currents leading to sedimentation of fine sediment, and their root systems effectively bind the sediment preventing erosion. Sea- grass blades and associated benthic algae are substrates for a variety of epibionts including foraminifera. Despite the fact that sea-grass communities are a major source of organic matter, individual plants are rarely preserved as fossils, leaving virtually no direct record of plant assemblages or density. In contrast, the associated foraminifera have an exceptional fossil record. In this actualistic study, the composition and taphonomic state of foraminiferal assemblages is combined with conventional grain-size analysis and examination of other grain characteristics in order to identify subtle environmental differences within and between grass beds. Previous studies have examined algal and plant species as substrates, but only at a single site. In this investigation, six localities representing a range of vegetation densities, water depths, and water-energy conditions were selected: three in Grahams Harbor and three in the Snow Bay area. The Gaulins and South sites are low-density grass beds while Cut Cay, Dump Reef, and Snow Bay I and II are moderate- to high-density grass beds. SCUBA was used to record vegetation densities by counting individual algae and sea grass in 50x50cm grids located at 10m intervals along transects. The top 1cm of sediment was collected from each station, and one hundred individuals of each of the major genera of sea grasses and algae were collected for each locality. In the laboratory, vegetation was examined with a binocular microscope, and foraminifera were picked from the 2.0-0.5mm sediment fractions. Total foraminiferal density was recorded as the number of individuals per plant and per gram of sediment picked. Dead foraminifera were categorized by taphonomic condition: pristine, slightly altered, altered, and very altered. Preliminary results show that Thalassia and Halimeda are the favored substrates for phytal foraminifera. Cornuspiramia, Sorites, and Planorbulina are the dominant foraminifera on both of these, in proportions that vary according to locality. Total foraminiferal abundance and diversity in the sediment are highest at the Cut Cay and South sites and lowest at Dump Reef and Gaulins. This shows that vegetation density is not the only factor affecting total foraminifera abundance and diversity: the energy of the environment and nutrient supply may also play a role. Foraminifera are best preserved in Cut Cay and Snow Bay I and II. Lush stands of Thalassia with long blades (Snow Bay II) serve to protect delicate tests such as those of Sorites when they accumulate on the seafloor. At other sites, such as Gaulins and South, the taphonomic condition is highly altered. These are lower density grass beds, which expose tests to higher levels of transport. The foraminifera that dominate these areas, Archaias, Cyclorbiculina, and Valvulina, have thicker tests that can withstand harsher conditions. The close relationship between large benthic foraminifera and grass-bed vegetation makes the use of these microfossils an important tool in high-resolution paleoenvironmental interpretations.

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Foraminiferal Assemblages from Brazilian Environments Beatriz B. Eichler; Patrícia P. B. Eichler; André R. Rodrigues; Evelyn R. M. Pereira; Patricia B. P. Kfouri The ecology of foraminiferal and thecamoebians from the bays of Todos Santos/BA, Guanabara/RJ, Santos/SP, lagoon of Araruama/RJ, estuarine environments of Sao Sebastiao, Bertioga, Cananeia-Iguape/SP and Laguna/SC were compared through absolute and relative frequency of species. Their relations to temperature, salinity, dissolved oxygen, organic carbon were evaluated through cluster and MDS analysis (700 sediment samples). In Todos Santos Bay, Ammonia spp., Bolivina spp., Fursenkoina pontoni tolerates sediment with aliphatics whereas Elphidium spp. decreases under petroleum derived pollutants influence. In Guanabara Bay, Buliminella elegantissima, B.striatula, Bulimmina elongata flourishes under low oxygenated waters in organic enriched sediments. By the other hand, Quinqueloculina seminulum shows intolerance to low oxygen and Cassidulina subglobosa, Discorbis williamsoni are governed by lower temperature and higher salinities in the bar showing marine influence capable of renewing waters. In Araruama hyperhaline lagoon A. tepida, Triloculina oblonga, E. excavatum dominates with few marine species Poroeponides lateralis, Pseudononion atlanticum, Quinqueloculina lamarckiana, Pararotalia spp. São Sebastião channel and Laguna estuarine system presented Buccella peruviana as a coldwater species showing the influence of Malvinas currents. In relation to the petroleum pollutant outfall in São Sebastião, fauna are distributed along a gradient related to the distance from the outfall. The dominance of Ammonia spp., Bolivina spp., B. elegantisssima, F. pontoni in high organic sediments shows slightly contamination. Miliamina fusca denotes presence of freshwater, as well as its tolerance to polluted sediments. By the other hand, Hanzawaia boueana, P. atlanticum, D. williamsoni, D. floridana, Quinqueloculina spp, Pararotalia cananeiaensis, C. subglobosa, Elphidium spp, P. lateralis, Pyrgo sp. reflects high intensity currents. In Bertioga channel the same association occurs in euhaline environment together with Q. lamarckiana, Miliolinella subrotunda, Fissurina laevigata, transported from continental shelf. The Bertioga mixohaline environment are dominated by A. tepida, E. poeyanum, E. excavatum, whereas brackish rivers and mangroves in Bertioga, Santos Bay and Cananéia-Iguape estuarine system is populated by A. mexicana, H. wilberti, A. salsum, Gaudryina exillis, M. fusca, Paratrochammina sp., P. clossi, Polysaccammina ipohalina, Siphotrochammina lobata, Warrenita palustris, Glomospira gordialis, Ammobaculites ssp., Trochammina inflata.

The high organic sediments of Cananéia-Iguape mangroves, closer to fresh water presents thecamoebians as Difflugia protaeiformis, D. oblonga, Centropyxis aculeata and C. constricta.

Santos presented live species of B. elegantissima and Bolivina spp. reflecting the influence of sewage; and Discorbis spp, H. boueana, Quinqueloculina spp. closer to the ocean show that circulation patterns are related to cold fronts that occur periodically. The presence of live aerobics species shows that currents are efficient in renewing waters permitting well-oxygenated sediments. In Laguna, a choked coastal lagoon connected to the ocean via a narrow channel showed B. peruviana, B. striatula, C. subglobosa, P. atlanticum, Saccamina sphaera, Q. miletti, Q. patagonica, A. tepida, E. poeyanum as indicators of marine water intrusion. As a fresh water indicators Ammobaculites exigus, G. exillis, A. salsum showed low freshwater input and M. fusca together with the D. pyriformis, D. capreolata and C. marsupiformis showed the highest freshwater input in the region. It was also noted that M. fusca is the only species that tolerates pesticides contamination. ____________________________________ Geologic Problem Solving with Microfossils

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Foraminiferal Diversity Trends in the Sediments of the Brazilian Continental Shelf between 27ºS and 30ºS Patrícia Pinheiro Beck Eichler; Barun K. Sen Gupta; Beatriz Beck Eichler; Edmo J. Campos Preliminary results of a foraminiferal diversity (Shannon-Wiener function) study of surface sediments from the Brazilian shelf (lat. 27-30ºS, water depth 50-209 m) indicate effects of water mixing. The sediments were collected with a grab sampler in winter 2003 and summer 2004 along three W-E transects: (1) northern, Itajaí, in the South Brazilian Bight (SBB); (2) transitional, Santa Marta Cape; and (3) southern, Torres, on the South Brazilian Shelf (SBS). The SBB waters are produced by the mixing of Tropical Waters (TW, T >20ºC, S >36.4) and relatively colder and fresher South Atlantic Central water (SACW, T <20ºC, S <36.4), with a freshwater contribution through several estuaries along the SBB coast (Coastal Waters). The SBS is under the influence of the Brazil and Malvinas currents, major western boundary systems that converge near 40ºS; Subantartic Shelf Waters (SASW, T <15ºC, S 33.7-34), advected by coastal currents of southern origin, predominate during winter, whereas Subtropical Shelf Waters (STSW), transported by Brazil current, predominate in summer. Data from 25 stations show the presence of 41 benthic foraminiferal species with four conspicuous peaks of diversity.

Two peaks are on the shallower segments of the Itajaí (28 m, winter) and Torres (47 m, summer) transects, and are apparently related to freshwater intrusions. The assemblage is characterized by the presence of Pseudononion atlanticum, Ammonia sp., Bulimina marginata, Bolivina striatula, Arenoparella mexicana, Ammotium salsum and Gaudryina exilis. The two deeper-water (~130 m) diversity peaks are at the shelf break. On the Santa Marta Cape transect, a winter diversity peak and the occurrence of Uvigerina peregrina and Buccella peruviana are associated with SASW or Malvinas current. On the Itajaí transect, a summer diversity peak and the presence of Cassidulina subglobosa, U. peregrina and Hanzawaia boueana are apparently related to the influence of the South Atlantic Central water (SACW).

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Initial Results of an Integrated Micropaleontologic and Sedimentologic Study of Catahoula Lake, Louisiana J. H. Wrenn; L. A. Febo; R. A. Tedford; V. M. Bryant, Jr.; W. N. Krebs; R. M. Camors Catahoula Lake is the largest and most unusual freshwater lake in Louisiana. Its water level fluctuates + 6 m annually and lush vegetation covers the exposed lake bed during the summer.

Later in the year, hundreds-of-thousands of migrating waterfowl and shore birds stop to feed or over-winter in this Ramsar Wetland of International Importance. Dozens of archeological sites, some dating to Paleo-Indian time, occur on the lake shore. Curiously, the origin and age of this important lake basin and its deposits have never been studied. The goals of this study are to: 1) determine the type, thickness, and properties of the deposits, 2) evaluate the types and utility of microfossils present for unraveling the paleoclimatic and paleoenvironmental history of the lake, and 3) determine the absolute age of the deposits sampled. The geologic basin history will help explain the evolution of the lower Mississippi Valley, whereas the paleoclimate and paleoenvironmental record will assist archeologists in understanding the site occupancy record documented around the lake. Two core holes were drilled to a maximum depth of 27 m using a split-spoon rig. Core porosity, gamma-ray density (GRD), grain size, magnetic susceptibility (MS), and internal core structure were determined using a GeoTek Multi Sensor Core Logger (MSCL), X-ray imager, a Sedigraph, and techniques of traditional sediment analyses. Despite discontinuous sediment recovery, GRD and MS data permit the cores to be subdivided into four sediment packages and correlated. MS data suggests that extended periods of wet and dry, not attributed to annual lake level fluctuations, are recorded in the lake deposits. The upper 10 m of sediments in Core 2 consist of lacustrine silt and clay, whereas deeper, coarser sediments indicate fluvial deposition. Fine-grained sediments were encountered, but not successfully sampled, beneath a thick, basal gravel bed in Core 2. If they are lacustrine sediments, they indicate a more ancient lake is buried beneath the Holocene lake basin. Initial micropaleontologic study of core catcher samples revealed diverse palynomorphs (i.e., spores, pollen, and fungal debris) and biosiliceous microfossils (i.e., diatoms, phytoliths, chrysophycean cysts, and freshwater sponge spicules). Their abundance, diversity, and preservation fluctuate down core. A detailed, integrated micropaleontologic study will best reveal the paleoenvironmental and paleoclimatic record of the lake and its environs. Pollen analysis documents the development of bottomland forests (i.e., Type 92, 96, and 101 of the Society of American Foresters) dominated by Quercus, Planera aquatica, Salix, Carya, and TCT over the past 5,900 years. Poaceae, Asteraceae, Cyperaceae, and Cheno-Ams are the dominant herbaceous pollen. These herbs may have lived in openings around or within the forest and/or on the exposed lake bed during the summer. AMS 14C dating indicates sediments at 10 m are 5,700-5,900 years old. Since there are at least 30 m of undated sediments below this horizon and above the underlying (Miocene?) bedrock, it is likely that much older, possibly Late Pleistocene lacustrine, deposits are present in the basin. The average, long-term sediment accumulation rate is 1.5 - 1.7 mm/year during the past 5,900 years.

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Diagnostic Phytoliths from Mixed Hardwood Forest Plants and Soils, Catahoula Lake, Louisiana Rebecca A. Tedford; John H. Wrenn; Robin M. Camors The largest, natural freshwater lake in Louisiana, Catahoula Lake, is a unique lake characterized by wetting and drying cycles, which in turn influence seasonal variations in vegetation in and around the lakebed. These variations are manifested in a plant succession from herbaceous to woody-dominated communities on the lakebed. This water regime may have persisted in the lake for thousands of years during which sediment and abundant microfossils (e.g. diatoms, pollen, sponge spicules, and phytoliths) have been deposited. These microfossils provide an extensive record of both natural and anthropogenic change in the local and regional vegetation through time. Microfossils from sediment cores collected by Catahoula Lake Scientific Coring project (CATSCORP) are being studied with the goal of determining the environmental and climatic history of the lake. Phytoliths, microscopic opaline silica deposits that form within plant cell walls, are particularly useful at Catahoula Lake due to their abundance and resistance to dissolution. These biosiliceous bodies are of particular importance because morphologically distinct phytoliths can be used as proxies to indicate the presence of plants and associated plant communities in the fossil record. These plant signatures can then be used to interpret environmental conditions in and around the lakebed at the time of deposition. Phytolith production in the leaves and/or stems of 41 dominant plant species, representing 28 families, from the mixed hardwood forest environment surrounding Catahoula Lake were investigated with the aim of creating a Comparative Phytolith Atlas. Twenty-nine of the 41 taxa produced both distinctive and redundant phytoliths, in amounts ranging from minimal to abundant. A few of the phytolith producers exhibit distinctive morphologies, including Brunnichia ovata, Boehmeria cylindrica, Commelina diffusa, Cyperus erythrorhizos, Digitaria ciliaris, Diospyros virginica, Leptochloa fascicularis, Paspalum distichum, and Serenoa repens. Plants species were then divided into two main groups, the monocotyledons and the dicotylodons, and analyzed for phytolith production. In monocotyledons, short cells (e.g., bilobates and saddle morphotypes), elongates, and trichome phytolith types were commonly produced. Dicotylodons predominately yielded epidermal ground mass cells, stomatal complexes, cystoliths, and polyhedral plates.

Analysis of modern surface sediment samples indicate that the taxonomic value of identifying phytolith types observed in these two groups is particularly useful in distinguishing between shifts in forest and grassland communities, the influence of the lakeâ&#x20AC;&#x2122;s dynamic water regime (e.g., episodic flood events and shoreline advances and retreats) on sediment transport and phytolith distribution, and/or phytolith preservational bias that may exist. Modern phytolith distribution along with the Comparative Phytolith Atlas will then be used to study ancient phytolith assemblages recovered from lakebed and shoreline deposits. The aim of this study is to provide a framework for phytolith-based paleoenvironmental interpretation of sediment cores, collected by the Catahoula Lake Scientific Coring project from the lakebed and shoreline deposits. Future research will investigate taxa from the modern lakebed plant communities in order to expand the existing Comparative Phytolith Atlas.

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