May 2020 Outcrop by The Rocky Mountain Association of Geologists

OUTCROP Newsletter of the Rocky Mountain Association of Geologists

Volume 69 • No. 5 • May 2020

The Rocky Mountain Association of Geologists

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Vol. 69, No. 5 | www.rmag.org

OUTCROP The Rocky Mountain Association of Geologists

1999 Broadway • Suite 730 • Denver, CO 80202 • 800-970-7624 The Rocky Mountain Association of Geologists (RMAG) is a nonprofit organization whose purposes are to promote interest in geology and allied sciences and their practical application, to foster scientific research and to encourage fellowship and cooperation among its members. The Outcrop is a monthly publication of the RMAG.

2020 OFFICERS AND BOARD OF DIRECTORS PRESIDENT

2nd VICE PRESIDENT-ELECT

Jane Estes-Jackson janeestesjackson@gmail.com

Peter Kubik pkubik@mallardexploration.com

PRESIDENT-ELECT

SECRETARY

Cat Campbell ccampbell@caminoresources.com

Jessica Davey jessica.davey@sproule.com

1st VICE PRESIDENT

TREASURER

Ben Burke bburke@hpres.com

Chris Eisinger chris.eisinger@state.co.us

1st VICE PRESIDENT-ELECT

TREASURER ELECT

Nathan Rogers nathantrogers@gmail.com

Rebecca Johnson Scrable rebecca.johnson@bpx.com

2nd VICE PRESIDENT

COUNSELOR

Dan Bassett dbassett@sm-energy.com

Donna Anderson danderso@rmi.net

RMAG STAFF DIRECTOR OF OPERATIONS

Kathy Mitchell-Garton kmitchellgarton@rmag.org DIRECTOR OF MEMBER SERVICES

Debby Watkins dwatkins@rmag.org CO-EDITORS

Courtney Beck Courtney.Beck@halliburton.com Nate LaFontaine nlafontaine@sm-energy.com Jesse Melick jesse.melick@bpx.com Wylie Walker wylie.walker@gmail.com

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Outcrop | May 2020 OUTCROP

RMAG 2020 ON THE ROCKS FIELD TRIPS Registration open for 1-day trips Details for 2-day trips coming soon to www.rmag.org Please note that trips may be rescheduled or cancelled based on government guidelines concerning the coronavirus (COVID-19).

Contact the RMAG office to get on wait lists for sold out trips.

June 27-28

September 12

(Date Tentative) Corral Bluffs Fossil Trip: The Rise of the Mammals Colorado Springs, CO Trip limit: 30 Sold out!

Paleozoic Impact Crater Field Douglas, WY Trip limit: 32

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August 8

November 7

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OUTCROP Newsletter of the Rocky Mountain Association of Geologists

CONTENTS FEATURES

DEPARTMENTS

6 RMAG 2020 Summit Sponsorship

8 RMAG April 2020 Board of Directors Meeting

12 Lead Story: What Lies Beneath – A Hidden Holocene Megadrought Record In Northwest Montana

10 President’s Letter

32 2020 RMAG Foundation Scholarship Awards 34 2020 Neal J. Harr Pick Award

26 RMAG Luncheon programs: Mark W. Longman and Barbara A. Luneau 28 RMAG Luncheon programs: Rachel Aisner-Williams 35 In The Pipeline

COVER PHOTO

ASSOCIATION NEWS

36 Welcome New RMAG Members!

2 RMAG Summit Sponsors

37 Advertiser Index

4 RMAG On the Rocks Field Trips

37 Outcrop Advertising Rates

Buffalo Rapids of the Flathead River, just south of Flathead Lake, Northwest Montana. The bedrock in the foreground are Mesoproterozoic rocks of the Belt Supergroup. The lighter colored cliffs are Pleistocene Glacial Lake Missoula sediments, and the mountains in the background are the northern Mission Mountains. Photo courtesy Michael Hofmann

8 Publish with The Mountain Geologist 9 RMAG-DWLS Fall Symposium Call For Papers 11 RMAG Golf Tournament 25 RMAG Educational Outreach 27 Sporting Clay Tournament 31 RMAG/Mines Practical Python Short Course

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OUTCROP | May 2020

RMAG Summit Sponsorship Summit Sponsorship is RMAGâ&#x20AC;&#x2122;s primary corporate sponsorship program and a vital component of RMAGâ&#x20AC;&#x2122;s financial support. Our Summit Sponsors receive a suite of valuable benefits, including free admission to educational and social programs and advertising opportunities not otherwise available. Join the heart of Rockies geoscience and become an RMAG Summit Sponsor today!

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2020 RMAG Summit Sponsorship Benfits Visit www.rmag.org or contact the RMAG office for more information. Sponsorship Level Contribution Level

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Event Advertising (included for all events except where noted) Company logo looping in PowerPoint presentation Company logo on 2020 Summit Sponsor signage at all events** Opportunity to offer RMAG approved promotional materials RMAG 2020 Events

Fall Symposium Event Tickets

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RMAG 2020 Events RMAG Luncheons Luncheon Tickets

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OUTCROP | May 2020

RMAG APRIL 2020 BOARD OF DIRECTORS MEETING By Jessica Davey, Secretary jessica.davey@sproule.com

Toelle, for helping RMAG test out the online platform! The Membership Committee has been busy planning virtual events for the Mentorship Program participants, so stay tuned for some fun and engaging events. The Publications Committee reported that the next few issues of the Outcrop are lined up, and the Mountain Geologist is in good shape for the remainder of the year. Thank you to everyone who has contributed articles! The On the Rocks Committee has had to postpone some field trips. Please keep an eye on your email and the RMAG website for important changes to the On the Rocks calendar. The Educational Outreach Committee is in a holding pattern as in-person events at K-12 schools will not happen this school year. A reminder that the Teacher of the Year Award application deadline is May 8th; please pass this information along to a teacher you think is deserving of this distinguishing award!

In a “normal” year, we would all be gearing up for field season. With our current stay at home measures in place for the time being, field season may look different this year. What measures are you taking to ensure your fieldwork and research is moving forward? The RMAG Board of Directors continued our social distancing measures in April by once again meeting online on April 15th. All of the Board Members were present. Debby and Kathy report that the RMAG office is operating remotely, and they are available to answer member questions. Treasurer, Chris Eisinger, and Treasurer-Elect, Rebecca Johnson Scrable report that the Summit Sponsorship program is still going strong; please consider participating in supporting RMAG this year. The Continuing Education Committee was proud to announce the first virtual luncheon went off without a hitch! A big thank you to our presenter, Brian

Publish with… Why contribute? • Reach a broad industry and academic audience • Quarterly peer-reviewed journal • Permanent archiving includes AAPG Datapages • Quick turn-around time • Every subdiscipline in the geosciences Expanded geologic focus: • Entire greater Rocky Mountain area of North America • West Texas and New Mexico to northern British Columbia • Great Plains and Mid-Continent region

Email: mgeditor@rmag.org https://www.rmag.org/publications/the-mountain-geologist/

OUTCROP | May 2020

Vol. 69, No. 5 | www.rmag.org

October 27, 2020

RMAG/DWLS Fall Symposium 2020

Call for Papers DEADLINE EXTENDED! Abstracts due May 15, 2020 The Rocky Mountain Association of Geologists and the Denver Well Logging Society are teaming up again to present the 2020 Fall Symposium on October 27, 2020 at the American Mountaineering Center in Golden.

MAXIMIZING VALUE OF CORE AND FLUID ANALYSIS The technical program will be organized topically and will attempt to provide cross-disciplinary collaboration between the two societies. We welcome abstracts in the following categories: • Core facies modeling beyond cored well: capabilities and limitations • Recent improvements in core analysis techniques • Petrophysical calibration using advanced core analysis • Fluid Analysis: Advances & applications to reservoir characterization • Beyond basic core analysis: Geomechanics, wettability, etc. • New analysis of old cores/cuttings: capabilities and limitations • Case studies, Applications in Modeling, Improvements in reservoir characterization

American Mountaineering Center

We are interested in recent multidisciplinary studies, new core and fluid analysis technology, improved interpretations of core data showing improvements in petrophysical correlation and reservoir characterization, applications of fluid analysis linked to petrophysical interpretations and reservoir characterization, and new insights into petroleum systems using core and fluid analysis in US basins. We welcome abstracts for the technical talks with a minimum of 500 words and up to a single page in length. Send your abstracts today and join us for the RMAG/DWLS Fall Syposium 2020! Authors of accepted abstracts have the option to submit a 4-10 page technical paper with slides for course publication.

email: staff@rmag.org | phone: 800.970.7624 Vol. 69, No. 5 | www.rmag.org

1999 Broadway, Suite 730, Denver CO 80202

Send abstracts to: Ginny Gent ginny.gent@comcast.net

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PRESIDENT’S LETTER By Jane Estes-Jackson

Weathering the Storm

OUTCROP | May 2020

Another month has gone by and we are still acclimating to life during a pandemic. The RMAG, like so many other organizations, has had to adapt its activities to circumstances that are well beyond our control and changing almost daily. We continue to evaluate the situation and make adjustments as necessary. The monthly luncheon program has probably been the most profoundly impacted. I want to thank Dr. Brian Toelle, our scheduled speaker for the April luncheon, for graciously offering to present his talk online. This was the first online presentation in the history of the RMAG and it was a huge success. Our video conferencing software limits the number of talk participants to 200; the April talk sold out in two hours and had a waiting list. While it is a less than ideal substitute for a traditional luncheon gathering, it does provide a way for our members to stay connected and engaged, and the response that we received was overwhelmingly positive. The May, and (most likely) June luncheon talks will also be offered online, free to all current RMAG members. There appears to be a demand for these online offerings, and the Continuing Education Committee is diligently working on additional programs. With the coming of spring, many geologists’ thoughts naturally turn to field work. But that too has been impacted. Unfortunately we can’t be certain when social distancing measures will be lifted, so the On the Rocks Committee felt that it would be prudent to postpone the two May field trips until later in the year. At this time we are cautiously optimistic that the trips for June and later months will go on as planned, and we hope to open registration for them soon. The golf tournament will also be rescheduled

in late summer or early fall. The RMAG website is the best source of updated information regarding our upcoming events. Since late March we have been conducting our Board and Committee meetings using a version of Zoom provided by our phone service. And Zoom is great in that at least you can see faces. But it can’t replace the synergy of having a group of people in a room working together and building on each other’s ideas. It also can’t replace meeting a friend for coffee or lunch or a drink. I have to admit that staying home appeals to my introvert tendencies, and the first couple of weeks of self isolation weren’t a whole lot different than my normal life. But even introverts eventually crave some outside human contact, and as time goes on I find myself missing my friends and being with them in person. I am hopeful that before too long we will return to some semblance of normal interactions. Many members attend RMAG events for the networking opportunities, especially with this ongoing economic downturn, and that aspect is probably the most difficult to replace. Zoom Happy Hours may be an (albeit less than perfect) alternative. For me, face to face networking is much more effective and enjoyable and is difficult to replicate virtually. I am looking forward to the time, whenever that may be, when we can all be together again as a group. I really appreciate our Board and Committee members, and Kathy and Debby in our office, for rising to these challenging times. It has been a learning experience for all of us, and I think that the adaptations that we are implementing now have better prepared us for the future, regardless of what that looks like. Vol. 69, No. 5 | www.rmag.org

New Date!

Thursday, July 30th Arrowhead Golf Club

RMAG 2020 Golf Tournament 2:00pm Shotgun at Arrowhead Golf Club Registration includes entry, 18 holes of golf, cart, dinner, and chances to win contest & door prizes

Register Today! Teams of 4 and individuals are welcome to register at www.rmag.org Member Team: $600 Member Individual: $150 Non-member Team: $700 Non-member Individual: $175

Be an RMAG Sponsor! Details at www.rmag.org

email: staff@rmag.org | phone: 800.970.7624 Vol. 69, No. 5 | www.rmag.org

1999 Broadway, Suite 730, Denver CO 80202

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follow: @rmagdenver

LEAD STORY

WHAT LIES BENEATH A Hidden Holocene Megadrought Record In Northwest Montana BY MICHAEL H. HOFMANN

Department of Geosciences, University of Montana, Missoula, MT 59812; AIM GeoAnalytics, Missoula, MT 59801

INTRODUCTION Montanaâ&#x20AC;&#x2122;s Flathead and Mission valleys are known for their natural beauty. Some of the most stunning views are the result of recent geologic events that reveal themselves on the surface in awe-inspiring fashion. The towering mountains of the Mission Range, largely composed of metasedimentary rocks of the Mesoproterozoic Belt Supergroup, are bound by north-south trending normal fault(s) that have been active for millions of years and are evidence of the still ongoing tectonism in the intermountain seismic belt (Fig. 1, 2). Moraines, abandoned channels, and high terraces are scattered across the landscape and are now silent witnesses to the forces that affected the area during the last glacial maximum and the deglaciation during the latest Pleistocene (Fig. 3). In contrary, the record of the Holocene is largely hidden below the turquoise waters of Flathead Lake. Beneath these waters lays an astonishing sedimentary

for abrupt and dramatic climate changes is less well-documented. The relatively little attention that volcanic eruptions have received as possible drivers of pre-historic climate change is surprising, given the fact that significant multi-annual changes in global climate patterns have immediately followed large historic volcanic eruptions (Gillett et al., 2004; Church et al., 2005; Gleckler et al., 2006). The following is a brief look at a major drought record that coincides with the eruption of Mt Mazama (Crater Lake) in Oregon as it is reconstructed and quantified from integrated interpretation of high resolution seismic reflection profiles, piston cores, and

record that does not just give evidence of the ongoing tectonic activity in the region (e.g. Hofmann et al., 2006a), but also a dramatic climate change that occurred during the Holocene. Abrupt climate changes and drought events are common phenomenon around the world and have been recorded frequently throughout the Holocene (Laird et al., 1996; Forman et al., 2001; Alley et al., 2003). Such events are most commonly explained by variations in ocean circulation (Alley et al., 2003), solar forcing (Claussen et al., 1999), or internal variability of the oceanâ&#x20AC;&#x201C;atmosphere system (Schubert et al., 2004). In contrast, the effect of pre-historic volcanic eruptions as a possible driving mechanism

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Figure 1:

Location maps Aug 25, 2015 Flathead Swan Canada B River River A: Satellite images of the Flathead Lake northwestern United States Washington from August 25th 2015 (upper th image) and August 29 2017 Montana (lower image), respectively. Crater Lake Wildfire smoke from fires in Mt Mazama Idaho the vicinity of Crater Lake Oregon (Mt Mazama) during these days illustrates two potential airflow patterns to transport California Nevada wildfire smoke (and volcanic Aug 29, 2017 Canada ash) from southwestern Oregon to Flathead Lake in Flathead Lake northwestern Montana (dashed Washington lines highlight general airflow Montana direction). The white rectangle highlights area shown in figure Crater Lake Mt Mazama 1B. Satellite images from Idaho Oregon NASA (https://worldview. earthdata.nasa.gov). B: Map showing relevant California Nevada A geomorphologic and geographic features in the study area and mentioned in the text. Different shades of gray in the Flathead Lake basin represent the lake bathymetry with dark gray being deeper than 80 m (~260 ft) and lightest gray being less than 20 m (~65 ft) deep. Piston core locations are marked in white circles; cores mentioned in this manuscript are numbered (white number on black background); the locations of the seismic reflection data profiles are marked with dashed lines. BAB = Big Arm Bay; WHI = Wild Horse Island.

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Mission Mountains

FIGURE 1:

Figure 2: LEAD STORY

Mission Mountains

WHI BAB

WHI

Photograph of Flathead Lake and the Mission Mountains The view is from Wild Horse Island (WHI) to the southeast across Big Arm Bay (BAB) of Flathead Lake (see Fig. 1 for location). The rounded, tree covered hill tops are the result of glacial erosion during the last glacial maximum. The Mission Mountains are uplifted along the N-S trending Mission fault (listric normal fault) that is located at the base of the high mountains dipping to the west. In Flathead Lake the fault has multiple splays that are further dissected by strike-slip faults (Hofmann et al., 2006a). A dextral strike-slip fault is mapped from outcrop and seismic to extend from WHI into BAB (dashed line). The shortest distance between the WHI peninsula in the center left of the photograph and the mainland across BAB is approximately 1.6 km (~1 mi). FIGURE 2:

depth conversion (Finckh et al., 1984; Mullins et al., 1996), resulting in useful reflections of the upper 60 m (~197 ft) of stratigraphy and a vertical resolution of approximately 10 cm (3.9 in). In addition to the existing seismic data set, 19 piston cores were recovered from Flathead Lake during two coring campaigns in 2000 and 2003 (Hofmann, 2005; Sperazza, 2006) (Figure 1b). Individual cores range from 5 – 11.5 m (~16 – ~38 ft) in length and penetrate the uppermost part of the stratigraphic sequence imaged in the seismic data set (Fig. 4). After collection, the cores were split

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accompanying hydrologic and geochemical modeling from Flathead Lake, Montana (Fig. 1).

METHODS

The seismic data set for this study consists of >270 km (>168 mi) of high resolution 3.5 kHz single channel seismic reflection data (Kogan, 1980; Hofmann et al., 2006a,b; Lankston, 2007, 2017). A constant velocity of 1.45 m/ms (4.8 ft/ms) for lake water and 1.5 m/ms (4.9 ft/ms) for unconsolidated lake sediments was applied to the seismic record for

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LEAD STORY Figure 3:

FIGURE 3: Morphologic and sedimentary record of Pleistocene lake level highstands and lake outflows (figure

modified from Hofmann, 2005) A: Elevation Profile along Highway 35 (southeast of Flathead Lake) showing Pleistocene or early Holocene lake terraces south of Flathead Lake. The 902 m (~2959 ft) terrace is the best developed lake terrace in the basin about 20 m (~65 ft) above the modern day lake level. B: Photograph of the imbricated boulders of Buffalo Basin (see Fig. 1 for location). Flow direction is to the south (left). Note person in the center of photograph for scale.

along their long axis, photographed, X-rayed, described, and sampled for further analyses, including total inorganic carbon (TIC) and grain size. Water samples for geochemical analysis were collected from six sites in Flathead Lake and one in Flathead River. Water was also sampled from depth at two sites within the lake by sampling the water trapped in the core tubes above sediment cores. Water samples were taken with syringes and filtered through 0.45 μm (0.000018 in) filters using ultraclean methods (Nagorski et al., 2003). Bicarbonate was determined by Gran titration and major and minor elements by Inductively Coupled Argon Plasma Emission Spectroscopy (ICP). Anions were determined by ion chromatography (IC). The pH of surface water samples was measured in the field and the lab. In general, surface water lake samples showed minimal variability for each constituent, approximately of a level comparable to the analytical error (~±10%), so an average value for each was used for modeling (Table 1). To determine the state of calcium carbonate saturation that might precipitate from Flathead Lake as a result of increased ionic concentration – in this study, the increase of ionic concentrations is directly

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Table 1 Average concentration of selected constituents in Flathead Lake surface water

linked to the decrease in lake water volume – the saturation index (SI) for calcium carbonate was calculated using Visual MINTEQ modeling software (Gustafsson, 2005). SI = log10 (IAP/Keq), where IAP is the ion activity product of the water and Keq is the equilibrium constant for the solid (e.g., calcite) at saturation, SI=0. At SI<0 the water is under saturated with respect to calcite and so calcite would not be expected to precipitate. At SI>0 lake water is over saturated

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Figure 4:

LEAD STORY

3.5kHz seismic reflection profile from Flathead Lake. Early Holocene strata (blue) is onlapped by post- early-middle Holocene strata (yellow). The reflector just below the unconformity coincides with the Mount Mazama tephra (MM; 7,630±80 cal yr BP). An older tephra, the Glacier Peak tephra (GP), provides additional age constraint for older strata. Cores FL-03-14K, FL-03-15K, and FL-03-16K (location on seismic profile and Fig. 1B) also show a progressively more significant hiatus from the basin center towards the margin. Letters B-F refer to different seismic stratigraphic units defined by Hofmann et al. (2006b) for the Pleistocene and Holocene lake infill. FIGURE 4:

(saturation remained at SI<0) as otherwise an increase in calcite would be expected in the sedimentary record. To determine the conditions at 7,600 cal yr BP during which the lake level starts to lower, the time and conditions that are required to decrease the lake volume by 25% but at the same time preventing carbonate precipitation (maintain saturation at SI<0), a simple hydrologic box model and the equilibrium chemical model MINTEQ were utilized. The hydrologic box model does not include changes in groundwater flow and only includes the relationship between surface inflow into the lake, lake surface evaporation, and surface outflow out of Flathead Lake. Historic annual average flow rates of Flathead River just upstream of Flathead Lake (USGS gauging station Columbia Falls just north of Flathead Lake) range between ~140 m3/s (~5,000 cfs (cubic feet per second)) during dry years and more than ~400 m3/s (~14,000 cfs) during years with high annual precipitation (Fig. 6A). Meteorological records from nearby weather stations in the watershed report

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and calcite would be expected to precipitate.

THE 7.6 KA EVENT

Sediment cores and 3.5 kHz seismic reflection profiles from Big Arm Bay (BAB) image an unconformity that is onlapped by younger strata below a depth of 15 m (~49 ft) below the present day lake level (Fig. 4). Within chronologic (samples from sediment cores FL-03-14K, FL-03-15K, and FL-0316K) and seismic data resolution, this unconformity occurs no more than 20 - 50 years after deposition of the Mount Mazama tephra (7,630 ± 80 calibrated years before present (cal yr BP); 2006; Zdanowicz et al., 1999; Hofmann et al. 2006b) and was formed when the lake level was at ~15 m (~49 ft) below the bedrock-controlled natural spillway elevation (878 m (2881 ft) above sea level), equivalent to a lake volume loss of about 25%. High resolution sample analysis from cores shows that no major change in inorganic carbon concentration (TIC) was observed across this unconformity (Fig. 5). This suggests that the lake waters were never over saturated OUTCROP | May 2020

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LEAD STORY

Figure 5:

Inorganic Carbon concentration of Flathead Lake sediments. Photograph (A) and X-radiograph (B) of a section of core FL-03-16K just above and below the Mount Mazama tephra. Lighter colors in the X-radiograph represent higher density sediments. There are no obvious calcite layers visible in the core record. (C) The inorganic carbon percentage measured from samples from core FL-00-9P for the same interval, varies between 0.2 and 1.6 percent but shows no significant increase just above the Mount Mazama tephra. The lighter gray shaded area highlights the core section displayed in the photographs; the darker shaded area outlines the Mount Mazama tephra. FIGURE 5:

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LEAD STORY

50 50 127.0 40

40 101.6

1952-2018 average

30 30 76.2 20 20 50.8 10 10 25.4

400-850cfs flow rates required to draw down lake during 7600 cal yr BP event

0 0 0

1952-2018 average

annual precipitation (in, cm)

60 60 152.4

2000 2000 57

4000 4000 113

6000 6000 170

8000 8000 227

10000 10000 283

12000 12000 340

14000 14000 396

annual average flow (cfs, m3/s)

10.00

109 cm

150 cm

200 cm

Water budget <1 → lowering of lake level

0.10

0.01 0 0 B

present day minimum annual average inflow

1.00

1100 cfs 833 cfs 605 cfs

an average annual precipitation of 92 cm (36 inches) for the Flathead River catchment basin and 95.5 cm (37.6 in) for Flathead county (Fig. 6A). Low precipitation during dry years ranges from about 53 65% of the annual average precipitation, while during wet years precipitation peaks at about 150 - 160% of the annual average precipitation. Annual average evaporation rates range from 46 cm (~18 in) in the catchment to 109 cm (~43 in) in open, non-vegetated areas, such as right above the lake surface (LaFave, 2004). At these present conditions more than 90% of the lake inflow is surplus and flows out of the lake basin through the lower Flathead River (Fig. 6B). The hydrologic box model results suggests that at an open lake evaporation rate of 109 cm (~ 43 in), a minimum inflow of ~17 m3/s (605 cfs) is required to maintain the lake level at the natural spill point at 878 m (2881 ft). Inflow below ~17 m3/s (605 cfs) at this evaporation rate resulted in a lowering of the lake surface (Fig. 6B). By increasing the modeled evaporation rate to 150 cm (~59 in), the minimum discharge of Flathead River into the lake had to be increased to ~23 m3/s (833 cfs) to maintain the lake level at the spill point level. A modeled decrease in discharge to levels below ~23 m3/s (833 cfs) resulted in a progressive lowering of lake level (Fig. 6B). Finally, for even higher evaporation rates of 200 cm, the flow required to maintain the lake level exceeded ~31 m3/s (1100 cfs), or about 20% of modern day minimum average flow rates. Flow rates below this threshold again resulted in the lowering of the lake level (Fig. 6B). Using these historic observations and minimum modeled flows as a base line, figure 7 shows results from the physiochemically-coupled model suggesting that to drop the lake level 15 m below the natural spill

modeled water budget

Figure 6:

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2000 4000 6000 57 113 170 annual average flow (cfs, m3/s)

Hydrologic data for the Flathead Basin and water budget model A: Annual precipitation averages for Flathead county, MT (data from NOAA, https://www.ncdc.noaa.gov/cag/county/time-series) and average Flathead River flow rates at the Columbia Falls stream gauging station, upstream of Flathead Lake (https://waterdata.usgs.gov/mt/nwis/uv?site_ no=12363000) for the years 1952-2018. The flow rates required to draw down the lake level by ~15 m (~49 ft) as suggested for the 7,600 cal yr BP lowstand event, are less than 20% of the lowest recorded annual flow rate (gray box). B: Water budget model for Flathead Lake for different evaporation rates (109cm, 150cm, 200cm). A water budget of 1 is representative of an equilibrium between Qin (inflow) and Qout (outflow and a given evaporation). Values < 1 result in the lowering of the lake level, values >1 are surplus and flow out of the lake. At present the annual minimum inflow is ~140 m3/s (5000 cfs) (black dashed line). At present day evaporation rates of ~109cm (~43 in), an inflow of ~17 m3/s (605 cfs) is required to maintain the water budget in equilibrium. FIGURE 6:

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LEAD STORY just confined to the Flathead Lake basin but is recorded widely across the northwestern United States and western Canada (Fig. 8). Moreover, abrupt climate changes of different magnitude and effect at or near 7,600 cal yr BP also have been documented from many locations around the world and some examples are shown in figure 8. For example, the GISP2 ice core from Greenland revealed an increase of volcanic aerosols at about 7,600 cal yr BP, coinciding with the eruption of Mount Mazama and resulting in one of the highest SO4 residual concentrations during the Holocene (Mayewski et al., 2004); historic data and recent climate models show a convincing link between increased volcanic aerosol concentration, decadal scale cooling of ocean basins (Gleckler et al., 2006), and low precipitation rates in selected regions (McCormick et al., 1995; Chang and Wang, 2003; Gillett et al., 2004; Church et al., 2005); and planktonic foraminiferal concentration from the Irminger Sea show that the North Atlantic Sea Surface Temperature (SST) was reduced by about 3 – 6˚C (5.4 – 10.8˚F) at ~7,600 cal yr BP (Mayewski et al., 2004). This circumstantial evidence suggests that the increase in atmospheric concentrations of volcanic aerosols from the eruption of Mount Mazama resulted in climate changes around the globe, including northwest Montana. The atmospheric residence time of Mount Mazama aerosols was likely no longer than that of large historic volcanic eruptions and the primary cooling effect only lasted for several years (Chang and Wang, 2003). This rapid reduction in net heat flux to the oceans, however, can be sufficient to decrease the SST, which, in turn, can lead to multi-decade long decreases in oceanic evaporation rates and decreased atmospheric water vapor concentration that are decoupled from the primary cooling effect by the aerosols (McCormick et al., 1995; Church et al., 2005). Additionally, the duration of the low SST at ~7,600 cal yr BP may have been amplified by the downward movement of cold water into deeper ocean layers (Gleckler et al., 2006), reducing the rate of net heat export for many decades and, as a result, decreasing the rate of ocean surface evaporation. This assumed decade long decrease of oceanic surface evaporation would have resulted in a significant decrease in atmospheric moisture content that is

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point and to maintain calcite in solution (SI<0), the inflow into Flathead Lake likely fell to and remained for decades at a level well below the modern day minimum average discharge rate. Model results show that a SI<0 for calcite can be maintained by keeping the calcite concentration below a concentration factor of 2 for water temperatures between 4˚C (39.2˚F) and 10˚C (50˚F) (Fig. 7A). To prevent calcite concentrations to build up higher, it is required that the drawdown of the lake occurred within less than ~ 40 years, assuming a present-day evaporation rate of 109 cm (~43 in) (Fig. 7B). At higher modeled evaporation rates of 150 cm (~59 in) and 200 cm (~79 in) the drawdown had to occur even faster, within ~28 years and ~20 years, respectively. Longer lasting drawdowns would result in an increase of the calcite concentration factor above 2 and subsequent precipitation of calcite. To lower the lake level of Flathead Lake in such a short period of time, flow rates of the upper Flathead River had to be reduced to between ~12 m3/s (424 cfs) (evaporation rate of 109cm (~43 in)) and ~23 m3/s (833 cfs) (evaporation rate of 200cm (~ 79 in)) resulting in lowering the lake by about 15 m (~49 ft) in ~40 and ~20 years respectively (Fig. 7C). These model runs are directly coupled to the lake water chemistry that was constrained by the mineralogy and elemental composition of the core sediments (Table 1; Fig. 5). Using the relationship between historic precipitation in the basin and inflow to the lake (Fig. 6A), the modeled flow rates were translated to basin-wide precipitation. Doing so suggests that during this early mid-Holocene megadrought, precipitation dropped to less than ~50% of the historic average annual precipitation of ~95 cm/yr (37.7 in/yr) (Fig. 6A).

VOLCANICALLY INDUCED CLIMATE CHANGE From the Flathead Lake data set it can be inferred that a severe 7,600 cal yr BP drought in northwestern Montana is intrinsically linked to the massive eruption by Mount Mazama, Oregon (Fig. 1). Importantly, the identification of this extreme decadal scale drought event at approximately 7,600 cal yr BP is not

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LEAD STORY

Modeled concentration factors and flow rates for the 7,600 cal yr BP lowstand. A: Saturation Indices (SI) for Flathead Lake water at different temperatures and concentration factors (1.0X is present conditions). Negative values are under saturated and positive values are over saturated. Calcite remains under saturated at concentration factors of 2 times or less for temperatures between 4째C (39.2째F) and 10째C (50째F). B: Relationship between concentration factor and years to lower lake level for three different evaporation rates (present day evaporation rate is 109 cm (~43 in). 150 cm (~59 in) and 200 cm (~79 in) are precipitation rates assumed for the time around 7,600 cal yr BP. C: Relationship between evaporation rates, average flow rates into the lake and the time it takes to draw down lake level to 15m (~49ft) below the natural spillpoint level. At an evaporation rate of 109 cm (~43 in), inflow into the lake has to be at a level below ~12 m3/s (424 cfs) to lower lake level. Higher inflow is permitted for higher evaporation rates, despite the need of lowering the lake level in a shorter time. FIGURE 7:

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LEAD STORY

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commonly transported by westerly airflow from the Pacific into northwest Montana. A decrease in precipitation to historic long lasting drought levels in the northwest (to <50% of present day average precipitation) as a result of the decreased moisture content, would have led directly to the observed lowering of the surface elevation of Flathead Lake. The cool SST anomaly produced by the volcanic eruption was likely reduced to background after several decades, restoring oceanic evaporation rates in the Pacific, and thus precipitation rates in the study area to normal mid-Holocene levels, preventing the precipitation of calcite in Flathead Lake. Unlike low latitude eruptions, such as that by Mount Pinatubo, the atmospheric dispersion of an eruptive plume from a mid-latitude volcano such as Mount Mazama (~43˚N) likely would be controlled by the strongly zonal air flow (e.g. polar jet stream) and would undergo a slower global dispersion of sulfate aerosols. Such a concentration of volcanic aerosols in the northern hemisphere higher latitudes, as proposed here for the Mount Mazama eruption, would result in significantly decreased northern hemisphere incoming solar radiation and an increase in the pole-equator temperature gradient. Northern hemisphere high-latitudes temperatures likely would decrease, causing winter-like conditions during the time of maximum aerosol concentration. It is possible that cooling the northern hemisphere in a manner such as this caused the post-7,600 cal yr BP drop in northern hemisphere SST (Mayewski et al., 2004) as well as the decreased evaporation and precipitation rates observed in many areas north of the equator (Fig. 8). Simultaneously, the increase in temperature gradient between the equator and the northern hemisphere polar region would have produced a southward shift in both the mid-latitude high pressure zone and the inter-tropical convergence zone (ITCZ) along with export of heat into the southern hemisphere, resulting in the anomalously warm conditions reported there during this time (Fig. 8). For example, dust levels in the Kilimanjaro region more than doubled during this time as a result of these changing conditions (Thompson et al., 2002) (Fig. 8b). To conclude, on the basis of the Flathead Lake

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LEAD STORY Compilation of Figure 8: climate studies. A: Precipitation intensity map for present day Northern Hemisphere January conditions; map modified from CCM0 model climate output visualization, Mercator projection (http://www.ncdc. noaa.gov/paleo/modelvis.html). Letters in squares refer to climate studies that recorded abrupt unusually wet conditions at ~7,600 cal yr BP; letters in circles refer to studies that observed an abrupt change to unusually dry or cool conditions at ~7,600 cal yr BP. (a) Increase in Alnus pollen percentage in Swift Lake, Alaska (Axford and Kaufman, 2004). (b) Increase in biogenic silica and several pigment peaks in Big Lake, British Columbia (Bennett et al., 2001). (c) Increase in organic carbon in Crowfoot Lake, Alberta (Leonard, 1986). (d) Erosional unconformity in Cartwright Lake, Alberta (Beierle and Smith, 1998). (e) Erosional unconformity in Flathead Lake, Montana (this study). (f) Increase in abundance of loess and dune deposits in Oregon (Sweeney et al., 2005). (g) Erosional unconformity in Great Salt Lake, Utah (Colman et al., 2002). (h) Increased varve thickness in Elk Lake, Minnesota (Bradbury et al., 1993). (i) Erosional unconformity in Lake Huron, Ontario (Moore et al., 1994). (j) Decreased percentage of benthic diatoms in Lake Titicaca, Peru and Bolivia (Baker et al., 2001). (k) Increased contrast between δ18O values of surface and thermocline dwelling foraminiferas in Amazon Fan deposits (Maslin and Burns, 2000). (l) High SO42- concentration in the GISP2 Ice Core, Greenland (Mayewski et al., 2004). (m) Change in foraminifera ratio in the Irminger Sea (Mayewski et al., 2004). (n) Decreased abundance of wood and peat samples in the Swiss Alps (Hormes et al., 2001). (o) Low δ18O values in the Soreq Cave, Israel (Bar-Matthews et al., 1999). (p) Increased percentage of dolomite in the Arabian Sea (Sirocko et al., 1993). (q) Increased dust concentration in Kilimanjaro ice cores (Thompson et al., 2002). (r) High δ18O values in a stalagmite from the Dongge Cave, China (Wang et al., 2005). B: Three examples of climate studies with state of climate proxy noted. Lower case letters in boxes and circles refer to references plotted on precipitation map. Gray shaded area highlights 7,600 cal yr BP event. FIGURE 8:

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LEAD STORY in the early Holocene (10,000-6,800 BP) interpreted from lake sediment core, southwestern Alberta, Canada: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 140, p. 75-83. Bennett, J.R., Cumming, B.F., Leavitt, P.R., Chiu, M., Smol, J.P., and Szeicz, J., 2001, Diatom, Pollen, and Chemical Evidence of Postglacial Climatic Change at Big Lake, South-Central British Columbia, Canada: Quaternary Research v. 55, p. 332–343. Bradbury, J.P., Dean, W.E., and Anderson, R.Y., 1993, Holocene climatic and limnologic history of the north-central United States as recorded in the varved sediments of Elk Lake, Minnesota: a synthesis: Geological Society of America Special Paper, v. 276, p. 309-328. Chang, F.-C., and Wang, C.-H., 2003, Did sulfur-rich volcanic eruptions affect drought episodes in Taiwan?: IAHS Publication, v. 281, p. 148-157. Church, J., A., White, N., J., and Arbaster, J., M., 2005, Significant decadal-scale impact of volcanic eruptions on sea level and ocean heat content: Nature, v. 438, p. 74-77. Claussen, M., Kubatzki, C., Brovkin, V., Ganopolski, A., Hoelzmann, P., and Pachur, H.J., 1999, Simulation of an abrupt change in Saharan vegetation at the end of the mid-Holocene: Geophysical Research Letters, v. 24, p. 2037-2040. Colman, S.M., Kelts, K.R., and Dinter, D.A., 2002, Depositional history and neotectonics in Great Salt Lake, Utah, from high-resolution seismic stratigraphy: Sedimentary Geology, v. 148, p. 61-78. Finckh, P., Kelts, K., and Lambert, A., 1984, Seismic stratigraphy and bedrock forms in perialpine lakes: Geological Society of America Bulletin, v. 95, p. 1118-1128. Forman, S.L., Oglesby, R., and Webb, R.S., 2001, Temporal and spatial patterns of Holocene dune activity on the Great Plains of North America: Megadroughts and climate links: Global and Planetary Change, v. 29, p. 1-29. Gillett, N. P., Weaver, A. J., Zwiers, F. W., and Wehner, M. F., 2004, Detection of volcanic influence on global precipitation: Geophysical Research Letters, v. 31, no.12, p. 12217-12221.

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datasets presented here and review of the global paleoclimate literature for this time period, it is inferred that the lake level lowstand observed in Flathead Lake at the time of the Mt Mazama eruption (~7,600 cal yr BP), is directly linked to this volcanic eruption. The volcanic eruption changed the climate across the northern hemisphere (Fig. 8). In the study area the volcanically induced atmospheric changes resulted in strengthened atmospheric westerly flow of unusually dry and cool Pacific air, severely limiting precipitation and producing the megadrought in northwest Montana.

ACKNOWLEDGEMENTS

Funding for this research was provided by the National Science Foundation. Special thanks to Johnnie N. Moore, Michael Sperazza, and Marc H. Hendrix for their significant contributions to this research. Helpful suggestions and comments by reviewers Courtney Beck, Nathan La Fontaine, Jesse Melick, and Wylie Walker helped to improve this manuscript and are greatly appreciated.

REFERENCES

Alley, R.B., Marotzke, J., Nordhaus, W.D., Overpeck, J.T., Peteet, D.M., Pielke Jr., R.A., Pierrehumbert, R.T., Rhines, P.B., Stocker, T.F., Talley, L.D., and Wallace, J.M., 2003, Abrupt climate change: Science, v. 299, p. 2005–2010. Axford, Y, and Kaufman, D.S., 2004, Late Glacial and Holocene Glacier and Vegetation Fluctuations at Little Swift Lake, Southwestern Alaska, U.S.A.: Arctic, Antarctic, and Alpine Research, v. 36, p. 139–146. Baker, P., Seltzer, G., Fritz, S., Dunbar, R., Grove, M., Tapia, P., Cross, S., Rowe, and H., Broda, J., 2001, The history of South American tropical precipitation for the past 25,000 years: Science, v. 291, p. 640-643. Bar-Matthews, M., Ayalon, A., Kaufman, A., and Wasserburg, G., 1999, The Eastern Mediterranean paleoclimate as a reflection of regional events: Soreq Cave, Israel: Earth and Planetary Science Letters, v. 166, p. 85-95. Beierle, B., and Smith, D.G., 1998, Severe drought Vol. 69, No. 5 | www.rmag.org

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LEAD STORY study of recent sedimentation in Flathead Lake, Montana [M.S. thesis]: The University of Montana, 98 p. LaFave, J.I., Smith, L.N., and Patton, T.W., 2004, Ground-water resources of the Flathead Lake Area: Flathead, Lake, and parts of Missoula and Sanders counties. Montana Bureau of Mines and Geology Ground-Water Assessment Atlas 2A, 132 p. Laird, K. R., Fritz, S. C., Maasch, K. A., and Cumming, B. F., 1996, Greater drought intensity and frequency before AD1200 in the Northern Great Plains, USA: Nature, v.384, p. 552-554. Lankston, R.W., 2007, Revisiting the 1970 Flathead Lake seismic survey: The Leading Edge, v.26(8), p.1058-1063. Lankston, R.W., 2017, Overview of the Flathead Lake Seismic Survey. https://scholarworks.umt. edu/flathead/1 Leonard, E.M., 1986, Use of lacustrine sedimentary sequences as indicators of Holocene glacial history, Banff National Park, Alberta, Canada: Quaternary Research, v. 26, p. 218-231. Maslin, M.A., and Burns, S.J., 2000, Reconstruction of the Amazon Basin effective moisture availability over the past 14,000 years: Science, v. 290, p. 2285-2294. Mayewski, P.A., Rohling, E.E., Stager, J.C., Karlén, W., Maasch, K.A., Meeker, L.D., Meyerson, E.A., Gasse, F., van Kreveld, S., Holmgren, K., LeeThorp, J., Rosqvist, G., Rack, F., Staubwasser, M., Schneider, R.R., and Steig, E.J., 2004, Holocene climate variability: Quaternary Research, v. 62, p. 243-255.

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Gleckler, P.J., Wigley, T.M.L., Santer, B.D., Gregory, J.M., AchutaRao, K., and Taylor, K.E., 2006, Krakatoa’s signature persists in the ocean: Nature, v. 439, p. 675. Gustafsson, J.P., 2005, Visual MINTEQ version 2.32, based on the original MINTEQA2, v. 4.0 written in Fortran 77 code released by U.S.E.P.A. in 1999: http://www.lwr.kth.se/English/OurSoftware/ vminteq/index.htm Hofmann, M.H., 2005, Sedimentary record of glacial dynamics lake level fluctuations and tectonics: Late Pleistocene-Holocene structural and stratigraphic analysis of the Flathead Lake basin and the Mission Valley Montana United States America. [Ph.D. thesis]: The University of Montana, 258 p. Hofmann, M.H., Hendrix, M.S., Sperazza, M. and Moore, J.N., 2006a, Neotectonic evolution and fault geometry change along a major extensional fault system in the Mission and Flathead Valleys, NW-Montana. Journal of Structural Geology, v.28, p.1244-1260. Hofmann, M.H., Hendrix, M.S., Moore, J.N., and Sperazza, M, 2006b, Late Pleistocene and Holocene depositional history of sediments in Flathead Lake, Montana: evidence from high-resolution seismic reflection interpretation: Sedimentary Geology, v. 184, p. 111-131. Hormes, A., Muller, B. U., and Schluchter, C., 2001, The Alps with little ice: evidence for eight Holocene phases of reduced glacier extent in the Central Swiss Alps: The Holocene, v. 11, p. 255-265. Kogan, J., 1980, A seismic sub-bottom profiling

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LEAD STORY influences on accelerated loess accumulation since the last glacial maximum in the Palouse, Pacific Northwest, USA: Quaternary Research, v. 63, p. 261-273. Thompson, L.G., Mosley-Thompson, E., Davis, M.E., Henderson, K.A., Brecher, H.H., Zagorodnov, V.S., Mashiotta, T.A., Lin, P.N., Mikhalenko, V.N., Hardy, D.R., and Beer, J., 2002, Kilimanjaro ice core records: evidence of Holocene climate change in tropical Africa: Science, v. 298, p. 589–593. Wang, Y, Cheng, H., Edwards, R.L., He, Y., Kong, X., An, Z., Wu, J., Kelly, M.J., Dykoski, C.A., and Li, X., 2005, The Holocene Asian Monsoon: Links to solar changes and north Atlantic climate: Science, v. 308, p. 854-857. Zdanowicz, C.M., Zielinski, G. A., and Germani, M. S., 1999, Mount Mazama eruption; calendrical age verified and atmospheric impact assessed: Geology, v. 27, p. 621-624.

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McCormick, M.P., Thomason, L.W., and Trepte, C.R., 1995, Atmospheric effects of the Mt Pinatubo eruption: Nature, v. 373, p. 399-404. Moore, T.C., Jr., Rea, D.K., Mayer, L.A., Lewis, C.F.M., and Dobson, D.M., 1994, Seismic stratigraphy of Lake Huron – Georgian Bay and postglacial lake level history: Candian Journal of Earth Science, v. 31, p. 1606-1617. Mullins, H.T., Hinchey, E.J., Wellner, R.W., Stephens, D.B., Anderson, W.T., Dwyer, T.R., and Hine, A.C., 1996, Seismic stratigraphy of the Finger Lakes: a continental record of Heinrich event H-1 and Laurentide Ice Sheet instability: Geological Society of America Special Paper, v. 311, p.1-35. Nagorski, S.A., Moore, J.N., McKinnon, T.E., and Smith, D.B., 2003, Geochemical response to variable streamflow conditions in contaminated and uncontaminated streams: Water Resources Research, v. 39, p. 1044. Schubert, S.D., Suarez, M.J., Pegion, P.J., Koster, R.D., and Bachmeister, J.T., 2004, On the cause of the 1930s dust bowl: Science, v. 303, p. 1855-1859. Sirocko, R., Sarnthein, M., ErDo you have thin sections gathering dust in your closet lenkeuser, H., Lange, H., or hiding in a pocket of your thesis? Are your thin Arnold, M., and Duplessy, sections looking for a new home? The RMAG Education J.C., 1993, Century-scale Outreach Committee is creating a thin section library events in monsoonal climate for middle and high school teachers and would like your over the past 24,000 years: thin sections. We are willing to drive to you to pick Nature, v. 364, p. 322–324. them up. Sperazza, M., 2006, Acquisition and evaluation of sedPlease email your information to the RMAG office at imentologic paleomagnetic staff@rmag.org and someone from the Edudational and geochemical time-seOutreach Committee will contact you. ries data from Flathead Lake Montana: Implications for late Pleistocene and Holocene paleoclimate. [Ph.D. Thank you from the thesis]: The University of RMAG Educational Outreach Committee Montana, 291 p. Sweeney, M.R., Busacca, A.J., and Gaylord, D.R., 2005, Topographic and climatic

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Revisiting the Upper Cretaceous Niobrara Petroleum System in the Rocky Mountain Region By Mark W. Longman and Barbara A. Luneau, Denver, Colorado

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Denver Basin, for example, when warmer Gulfian waters flowed northward, they brought into the seaway the abundant coccoliths, copepods, and planktonic foraminifers that form the chalkier intervals. When arctic waters flowed predominantly southward in the seaway, carbonate productivity was limited and marlier, more organic-rich facies were deposited. Changes in water depth had little to do with the resulting Niobrara rock types, but the associated eddies, swirls, and current vortices did significantly impact chalk vs. marl deposition on a fine scale. New evidence supporting the importance of currents in the Seaway is five-fold: 1) Well-documented high-resolution interfingering of the chalk and marl facies on a scale of centimeters or less, which is far too thin to be controlled by sea-level fluctuations; 2) A lack of evidence for chalk-related highstands along the seawayâ&#x20AC;&#x2122;s margins (e.g., in Utah and Kansas); 3) Abrupt lateral changes in the thickness of chalkier deposits over distances of a mile or less; 4) Thin (<2 cm) organic-rich marls within the clean chalk benches that cannot be the product of sea-level changes; and 5) Study of modern ocean current flow patterns on deep-water hemipelagic deposits off New Zealandâ&#x20AC;&#x2122;s South Island and in the Mediterranean that have produced bedforms similar to some in the Niobrara seen on high-resolution cross sections (e.g., in the Denver Basin).

Our 1998 publication in The Mountain Geologist was based on a regional study of the Niobrara Formation across the Rocky Mountain region. That paper slightly preceded a burst of successful horizontal drilling and much new research into Niobrara stratigraphy and depositional processes. Isopach and facies maps we published as well as our depositional models for the Niobrara have proved useful, and we may have been ahead of the learning curve in attributing the chalk and marl benches primarily to current flow patterns in the Western Interior Seaway rather than eustatic sea level changes. Some lessons learned about the Niobrara in the 22 years since that paper was published will be the focus of this presentation. Our depositional model claimed that current flow patterns in the long, narrow Western Interior Seaway, specifically the flow direction of tropical Gulfian versus colder arctic currents, was the primary control on chalk vs. marl deposition. In the

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Facies and Sequence Stratigraphic Architecture of the Mural Limestone (Early Albian), Arizona Carbonate Response to Global and Local Factors and Implications for Reservoir Characterization By Rachel Aisner-Williams assemblages, and an 870 m-long low-angle leeward margin comprised of reef debris rudstone and grainstone shoal facies. Similar reef geomorphology and orientation is documented across the Gulf of Mexico and reflects the shelf-wide north to northeast-trending prevailing wind and current energies. Controls affecting reef formation and growth patterns include changes in accommodation space associated with low-amplitude global sea-level rise and regional thermotectonic subsidence, local accommodation space and nutrient fluctuations associated with the inner shelf depositional setting within a humid and

During this talk, we will explore the facies and sequence stratigraphic architecture of a multi-cyclic patch-reef and its associated ramp interior facies that formed during OAE 1b in the Mural Limestone, Arizona, USA. Ramp interior facies are comprised of bedded wackestone/packstone, rudist build-up and coral-algal patch-reef facies located north of Bisbee, Arizona at the Grassy Hill locality. The larger multi-cyclic patch-reef that developed coevally ~5 km to the south of Grassy Hill consists of a high-angle windward margin with a narrow ~70 m-long reef frame containing vertically zonated Microsolena, Actinastrea, diverse branching coral, and rudist

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RMAG LUNCHEON PROGRAMS and 4 record a second brief transgression and backstepping of reef facies followed by the final regression of shallow shelf carbonates that correlates to more robust patch-reef development in Sonora, Mexico. The patch-reef at Paul Spur is an excellent outcrop analog for productive patch-reefs in the Maverick Basin (Comanche Shelf) of Texas. Detailed facies mapping within these outcrop analogs highlights the greatest reservoir potential in leeward grainstones where primary porosity up to 15% is observed.

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siliciclastic-rich environment. Four aggradational to retrogradational high-frequency sequences (HFS) are documented in Arizona: HFS 1 and 2 represent the first pulse of patch-reef development in an overall 2nd-order marine transgression over the Sonora/ Bisbee Shelf. These sequences correlate to positive δ13C excursions associated with OAE 1b across the Gulf of Mexico and suggest that carbonate reefs persisted on the ramp interior during this time. HFS 3

RACHEL AISNER-WILLIAMS is a geologist with Occidental Oil & Gas based out of Denver. In her 9 years at Oxy, she has worked a number of Development, Appraisal & Reservoir Characterization projects in the Permian Basin in siliciclastic, carbonate and unconventional reservoirs. Her current role

is with Oxy’s Rock, Fluid & Geomechanics properties team where she focuses on core acquisition, interpretation and data integration for projects. Before beginning her career with Oxy, she worked as a Geo Tech for 5 years with CrownQuest Operating in Midland. Rachel holds a B.A. in Math from Smith College and an M.S.

in Geology from the University of Texas at Austin. She is a member and volunteer for RMAG, AAPG, SEPM and WTGS. Today she will take a break from the Permian and take us forward in time to the early Cretaceous, where she has been expanding upon her 2010 thesis work on carbonate patch reefs in Arizona.

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Introduce the python programing language for the geoscientist.

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Introduce python libraries that allow integration into other software programs through reading, manipulating, and writing LAS well logs and shapefiles.

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Provide hands on examples of the application of Data Mining, Machine Learning, and Data Analytics to solve problems faced by a petroleum geologist.

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By the end of the course students should be able to adapt the provided examples for use with their own data.

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RMAG Foundation Scholarship Awards After reviewing 51 scholarship applications from graduate students enrolled in 12 universities across the country and 1 undergraduate student, the Trustees of the RMAG Foundation have granted nine scholarships totaling $30,500 to the following students: GARY BABCOCK MEMORIAL SCHOLARSHIP

COLORADO SCHOOL OF MINES SCHOLARSHIP

Matthew Ellison, M.S. candidate at Utah State

Daan Beelen, Ph.D. candidate at CSM

“The Biggest Snowball Fight in Earth History: Sequence Stratigraphy and Facies Analysis of the Pocatello Formation, Idaho, USA”

“A Possible Late Cretaceous Impact Structure in Black Mesa, Arizona”

NORMAN H. FOSTER MEMORIAL SCHOLARSHIP

DUDLEY AND MARION BOLYARD SCHOLARSHIP AT UNIVERSITY OF COLORADO

Savannah Rice, M.S. candidate at Colorado School of Mines

Michael Frothingham, M.S. candidate at CU

“The Influence of PennsylvanianTriassic Salt Tectonics on Laramide Shortening in Central Colorado: A New Tectonic Model”

“Magmatic Fabric Influence on Crustal Seismic Anisotropy”

MICHAEL S. JOHNSON SCHOLARSHIP

ROBERT M. CLUFF MEMORIAL SCHOLARSHIP

Jacquelin Lee, M.S. candidate at the University of Kansas

Thomas Martin, Ph.D. candidate at Colorado School of Mines

“ A novel approach to date continental sediment deposition and paleoclimate events using volcanogenic zircon in paleosols”

“Machine learning and advanced analytics of geoscience data, examples from deepwater core to fluvial outcrops”

OUTCROP | May 2020

Vol. 69, No. 5 | www.rmag.org

India Phillips, Rising Senior at Colorado College “ Using oxygen and carbon isotope rations of tooth enamel to understand niche partitioning among mammals after the CretaceousPaleogene mass extinction”

STONE-HOLLBERG SCHOLARSHIP Alison Hafner, M.S. candidate at Utah State Fault and fracture network behavior in a fluid-gas system: Analyses of fluid flow in natural CO2 reservoirs, Salt Wash Graben, UT”

PHILIP J. MCKENNA MEMORIAL SCHOLARSHIP

VETERANS MEMORIAL SCHOLARSHIP Chance Seckinger, M.S. candidate at Colorado School of Mines “ Lateral Heterogeneity of BasinPlain Turbidites of the Cloridorme Formation, Quebec, Canada”

In addition to cash awards, all scholarship winners will receive a one-year membership to RMAG, compliments of the Foundation. This allows an opportunity for them to engage with the organization, its members, and its various educational and social benefits.

Congratulations To These Outstanding Scholarship Winners!

Proudly developing Colorado’s energy potential through innovation, safety and a commitment to our community l e a r n m o r e at : w w w . c r e s t o n e p e a k r e s o u r c e s . c o m

2020 Neal J. Harr

Pick Award

The RMAG Foundation Pick Award is a tribute to the memory of Neal J. Harr who, in addition to being one of the most respected men in the oil and gas industry, served as the President of RMAG. Nealâ&#x20AC;&#x2122;s presidency was cut short by his death in 1979 from lung cancer at the age of 48. This award recognizes the outstanding senior class geology student from all ten Colorado colleges and universities. This year, we received nominations from eight schools as shown below.

These students will receive an engraved rock hammer commemorating their award. In addition, the Foundation will pay for a one-year membership to RMAG that will allow an opportunity for them to engage with the organization, its members, and its various educational and social benefits.

Hannah Runyon Colorado College

Hanna Janssen Fort Lewis College

Nicole Mejia-Mendoza Colorado Mesa University

Elizabeth Schaeffer Metro State University

Robert Johanson Colorado School of Mines

Blake Brazell University of Northern Colorado

Cody Delgado Colorado State University

Brock Arveson Western College University

OUTCROP | May 2020

Vol. 69, No. 5 | www.rmag.org

IN THE PIPELINE MAY 2, 2020

MAY 16, 2020

MAY 20, 2020

RMAG On the Rocks Field Trip. Corral Bluffs. Colorado Springs, CO. RESCHEDULED: SEPT. 12

RMAG On the Rocks Field Trip: Golden Rocks! The Geology & Mining History of Golden, CO. Rescheduled to Nov. 7.

RMAG Short Course. “Practical Python for Earth Scientists.” Catalyst Tech Center, Denver, CO. RESCHEDULED: OCT. 1

MAY 6, 2020

MAY 19, 2020

MAY 27, 2020

RMAG Luncheon. Speaker: Mark Longman. “Revisiting the Upper Cretaceous Niobrara Petroleum System in the Rocky Mountain Region”. RESCHEDULED TO MAY 13 (ONLINE)

DWLS Luncheon. Speaker Melanie Durand. “Crushed Rock Analysis Workflow Basin on Advanced Fluid Characterization for Improved Interpretation of Core Data.” Wynkoop Brewing Company, 1634 18th Street at Wynkoop, Denver.

RMAG Golf Tournament. Arrowhead Golf Club, Littleton, CO. RESCHEDULED: JULY 30

MAY 8, 2020 DIPS Luncheon. Speaker: Dr. Stephen P.J. Cossey. “PaleoCanyon Formation and Contemporaneous Oil Seepage near the Paleocene/ Eocene Boundary TampicoMisantla Basin, Eastern Mexico: Implications for Gulf of Mexico Exploration.” Members $25 and Nonmembers $30. For more information or to RSVP, visit www.dipsdenver.org.

ONLINE WEBINAR

MAY 13, 2020 RMAG Luncheon-Online 12-1 pm. Speaker: Mark Longman. “Revisiting the Upper Cretaceous Niobrara Petroleum System in the Rocky Mountain Region”. For registration details, visit www.rmag.org.

Vol. 69, No. 5 | www.rmag.org

OUTCROP | May 2020

WELCOME NEW RMAG MEMBERS!

Ron Birch

is a Senior Sales Representative at NOV in Denver, Colorado.

Aaron Peterson

is a Consultant in Denver, Colorado.

Rex Stout

Amy Richardson

works at Flat Water, Inc., and lives in Conifer, Colorado.

is a Geologist at Sinclair Oil & Gas in Salt Lake City, Utah.

Zachary Cassill

is a Senior Technical Analyst at ROGII in Cedar Rapids, Iowa.

James Van Meter

works at WPX Energy in Tulsa, Oklahoma.

Devin Hunter

Jonathan Schwing

is a Geologist at DJR Energy in Denver, Colorado.

is a Geologist I at Occidental and lives in Aurora, Colorado.

CALENDAR â&#x20AC;&#x201C; MAY 2020

Most events for the month of May are either postponed or cancelled due to restrictions and/or precautions relating to the COVID 19 pandemic. Please see Pipeline on page 35 for more details.

Experience Experience truly truly integrated integrated 3D interpretation 3D interpretation with truly integrated truly integrated with industry's most industry's most advanced advanced 3D with 3D interpretation interpretation with geoscience geoscience system industry's most industry's system most advanced advanced geoscience system geoscience system GVERSE Geomodeling 2017 GeoGraphix 2017 GVERSE Geomodeling 2017 GeoGraphix 2017

GVERSE GVERSE

Anthony Ford Account Executive, LMKR GeoGraphix

R TM

Email: aford@lmkr.com P: +1 (303) 996-2153, C: +1 (720) 210-8889

Ford Account Executive, LMKR GeoGraphix OUTCROP | Anthony May 2020 36

Email: aford@lmkr.com P: +1 (303) 996-2153, C: +1 (720) 210-8889

Vol. 69, No. 5 | www.rmag.org www.lmkr.com

www.lmkr.com

ADVERTISER INDEX

• Crestone Peak Resources �� 33 • Daub & Associates �� 24 • Donovan Brothers Inc. �� 24 • GeoMark Research �� 21 • GeoStar Energy Partners �� 28 • Great Western �� 29 • Hollowtop Geological Services �� 28 • Impac Labs �� 29 • LMKR �� 36 • Sinclair Petroleum Engineering, Inc. �� 26 • Sunburst Consulting �� 30 • Tracker Resource Development �� 35

OUTCROP ADVERTISING RATES 1 Time

2 Times

6 Times

12 Times

Full page (7-1/2” x 9-1/4”)

$330

$620

$1,710

$3,240

2/3 page (4-7/8” x 9-1/4”)

$220

$400

$1,110

$2,100

1/2 page (7-1/2” x 4-5/8”)

$175

$330

$930

$1,740

1/3 page horizontal (4-7/8” x 4-7/8”)

$165

$250

$690

$1,200

1/3 page vertical (2-3/8” x 9-1/4”)

$165

$250

$690

$1,200

1/6 page (2-3/8” x 4-7/8”)

$75

$120

$330

$600

Professional Card (2-5/8” x 1-1/2”)

$20

$34

$84

$144

OUTCROP | May 2020

Vol. 69, No. 5 | www.rmag.org