Comunicaciones congresos CMS

Congress and meeting communications

CĂŠsar Menor SalvĂĄn May 2015

Summary The present volume includes research communications submitted by Dr. CĂŠsar Menor SalvĂĄn to congress, meetings and workshops and published in proceedings and books of abstracts. The list is not comprehensive because, due to the lower relevance of congress communications outside the meeting with respect to peer reviewed papers and the characteristics and number of communications usually prepared by a researcher, some documentation is lost.

12th Biennial SGA Meeting 12–15 AUGUST 2013, UPPSALA, SWEDEN

Mineral deposit research for a high-tech world

Proceedings VOLUME 1

12th Biennial SGA Meeting 12–15 AUGUST 2013, UPPSALA, SWEDEN

Mineral deposit research for a high-tech world

Proceedings Volume 1 Edited by Erik Jonsson et al.

SGA 2013 Programme Scientific programme (see Table 1, p. xx for overview) 10.40-12.00 Aula, S3.5 Porphyry systems and epithermal deposits Role of porphyry copper models in exploration and discovery. Richard H. Sillitoe Hydrothermal alteration, SWIR-mineral mapping, vein distribution and age of the Haquira East porphyry CuMo deposit. Federico Cernuschi, John H. Dilles & Robert Creaser Fluid evolution in a super-giant porphyry Cu-Mo deposit: El Teniente, Chile. Jamie J. Wilkinson, Victoria H. Vry, Edward T. Spencer & José Seguel

10.40-12.00 room X, S3.1 Volcanic-hosted base and precious metal deposits Geochemical signature of the “zero-age chimney” formed on artificial hydrothermal vents created by IODP Exp. 331 in the Iheya North field, Okinawa Trough. Tatsuo Nozaki, Jun-ichiro Ishibashi, Kazuhiko Shimada, Yutaro Takaya, Yasuhiro Kato, Shinsuke Kawagucci, Takazo Shibuya & Ken Takai

Subseafloor structure of a submarine hydrothermal system within volcaniclastic sediments: a modern analogue for ‘Kuroko-type’ VMS deposits. Jun-ichiro Ishibashi, Youko Miyoshi, Hiroyasu Inoue, Chris Yeats, Steven P. Hollis, Juan C. Corona, Stephen Bowden, Shouye Yang, Gordon Southam, Yuka Masaki, Hillary Hartnett & IODP Expedition 331 Scientists

Hydrothermal systems related to intraoceanic arcs. Cornel E.J. de Ronde

10.40-12.00 room IX, S5 High-tech elements – deposits and processes A new type of magmatic Sc-Zr occurrence located in the Kiviniemi area, Rautalampi, Central Finland. Tapio Halkoaho, Marjaana Ahven & O. Tapani Ramo

Carbonatite-hosted, late-stage apatite as a potential source of heavy rare earth elements? S. Broom-Fendley, F. Wall, A.E. Brady, A.G. Gunn, S.R. Chenery & W. Dawes

Granite-related indium mineralisation in SW England Jens C.O. Andersen, Ross J. Stickland, Gavyn K. Rollinson & Robin K. Shail

Indium fractionation in the granites of SW England. B. Simons, J.C.O. Andersen & R.K. Shail

10.40-12.00 room IV, S2.5 Ore mineralogy and geometallurgy A comparative automated mineralogical analysis of the Nkout (Cameroon) and Putu (Liberia) iron ore deposits.

K.F.E. Anderson, G.K. Rollinson, F. Wall & C. J. Moon

Combining chemical analysis (XRF) and quantitative X-ray diffraction (Rietveld) in modal analysis of iron ores for geometallurgical purposes in Northern Sweden. Mehdi Parian & Pertti Lamberg Geometallurgical characterisation of Ni-PGE ores through automated mineralogy. K.S. Viljoen, T. Dzvinamurungu, G. Mishra, D. Rose, F. van der Merwe, T. Greeff, M. Knoper, H. Mouri & H. Rajesh

Geometallurgical characterization of ore type B2 (high silica ore) at the Kiirunavaara iron ore deposit, northern Sweden. Kari Niiranen & Andreas Böhm

Isotope constraints on the genesis of the Arroyo Rojo VMS deposit (Tierra del Fuego, Argentina). Biel. C., Colás, V., Subías, I., Acevedo, R.D. & Bilström, K.

Geology and massive sulfide deposits in the Mofjell group in the Rodingsfjallet nappe complex, Nordland, Norway. Bjerkgard, T., Marker, M., Slagstad, T. & Solli, A. Hydrothermal alteration and ore mineralogy at the Lombador massive sulphide orebody, Neves Corvo, Portugal: an on-going study. Joao RS Carvalho, Ana S Fernandes, Bruno B Moreira, Álvaro MM Pinto, Jorge MRS Relvas, Nelson Pacheco, Filipa Pinto & Ricardo Fonseca

Mineralogy, textures and new sulphur isotope data of the Cerro de Maimon VMS deposit ores, Dominican Republic. Joan Marc Colomer, Eloi Andreu, Lisard Torró, Joaquín A. Proenza, Joan Carles Melgarejo, Cevero Chavez, Ricardo del Carpio, Julio Espaillat & John F. Lewis

Hydrothermal alteration zonation in the massive sulfide-hosting footwall sequence of Lousal, Iberian pyrite belt. Ana S.C.Fernandes, Jorge M.R.S. Relvas & Joao X. Matos The Jörn granitoid complex, Skellefte mining district, Sweden: petrography, lithogeochemistry and emplacement sequence. Manuel J. González-Roldán, Rodney Allen, Emilio Pascual, Teodosio Donaire, Manuel Toscano & Hans Årebäck

Hydrothermal imprint along the southern Central Indian ridge. K. U. Heeschen, U. Schwarz-Schampera , C. Bartsch, H. Franke, and F. Henjes-Kunst & J. Hansen

Petrochemistry and element mobility within the upper Tyrone arc, Northern Ireland: identifying VMSprospective stratigraphic horizons. Steven Hollis, Stephen Roberts, Richard Herrington, Garth Earls & Mark Cooper Recent advances in structural geology, lithogeochemistry and exploration for VHMS deposits, Kristineberg area, Skellefte District, Sweden. Nils F Jansson, Tobias Hermansson, Mac Fjellerad Persson, Alexandra Berglund, Annika Kruuna, Pietari Skyttä, Kai Bachmann, Jens Gutzmer, Reia Chmielowski & Pär Weihed

Structural investigation and 3D modelling of the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, Bergslagen region, south-central Sweden. Tobias C. Kampmann, Pär Weihed & Michael B. Stephens Cu-Zn mineralisation at Vannareid, West Troms Basement Complex: a new Palaeoproterozoic VMS occurrence in the northern Fennoscandian Shield. V. Juhani Ojala, Harald Hansen & Hannu Ahola Occurrence of gold (electrum) in the Lousal mine, Iberian pyrite belt, Portugal. Daniel P. S. de Oliveira, Carlos J. P. Rosa, Fernanda M. G. Guimaraes, Joao X. Matos, Zélia Pereira, Vasco C. S. Frias, Diogo R. N. Rosa & J. M. Castelo Branco

Major volcano-sedimentary facies types of the Madneuli polymetallic deposit, Bolnisi district, Georgia: implications for the host rock depositional environment. Nino Popkhadze, Robert Moritz, Stefano Gialli, Tamar Beridze, Vladimer Gugushvili & Sophio Khutsishvili

Observation on gold-copper mineralization at Noungou, Burkina Faso. Reinhard P. Ramdohr & Tatiana L. Evstigneeva

Alteration mineral domains under Loma la Cuaba: new insights as to the origin of the mineralization in the Pueblo Viejo district. Torró, L., Proenza, J.A., Melgarejo, J.C., Carrasco, C.A., Domínguez, H.S., Nelson, C. & Lewis, J.F.

Vascular plant materials control the formation of shale-hosted massive sulphides in the Iberian Pyrite Belt.

Jesús Velasco-Acebes, César Menor-Salván, Sara Gismera-Díez & Fernando Tornos

S3.2 Sediment-hosted deposits Stable isotope studies of carbonate – hosted ore deposit in Cerro Minado, Huercal – Overa (Spain). Sandra Amores, Oriol Bertran, Ferran Buireu, Miquel Febrer, Joan Carles Melgarejo & Pedro Enrique–Gisbert

The silver-polymetallic Mangazeyskoe deposit (Russia, Sakha-Yakutia): evidence for an involvement of magmatic and basinal fluids from fluid inclusions and stable isotopes (C, O, S). Anikina E., Klubnikin G., Bortnikov N., Prokof’ev V. & Gamyanin G.

Vascular plant materials controls the formation of shale-hosted massive sulphides in the Iberian Pyrite Belt Jesús Velasco-Acebes*, César Menor-Salván, Sara Gismera-Díez and Fernando Tornos Centro de Astrobiología, CSIC-INTA, 28850 Torrejón de Ardoz, Madrid, Spain. *velascoaj@cab.inta-csic.es Abstract. The Iberian Pyrite Belt (IPB) is one of the biggest massive sulphide concentrations in the world.

The mineralization lies within a sequence called VolcanoSedimentary Complex, and it can be hosted by volcanic rocks (northern zone of IPB) or shales (southern one).

We propose that sulphides formation of southern part is due to paleogeographical changes and the onset of regional volcanism. Isotopic data of massive sulphides (33.2 to +4.1Å) suggest that exists a second source of sulphur beside hydrothermal fluids, insomuch as stockwork presents a G34S between -2.5 to +10Å New data of higher plant biomarkers indicate that biological crisis during D-C boundary was the responsible for the input of organic matter that sulphate-reducing bacterias used to supply the needed H2S to the basin.

Keywords. Iberian Pyrite Belt, Tharsis, sulphides, biomarkers, geomicrobiology

massive

1 Introduction. Geological setting The Iberian Pyrite Belt (IPB) belongs to the South Portuguese Zone (SPZ) and is located in the SW of the Iberian Peninsula. It is the largest volcanogenic massive sulphide province, with more than 80 massive sulphide deposits and 1750 Mt of ore (Sáez et al. 1996; Leistel et al. 1997; Tornos, 2006).

The stratigraphy of the IPB is rather simple. The basement is not exposed and the earlier most rocks are shale and sandstone of Famennian age, the PQ Group (>2000 m), deposited in a stable platform. The PQ Group is conformable overlain by the Volcano-Sedimentary Complex, which was deposited in an extensional marine continental basin, likely a back arc one. It includes two groups of volcanic rocks, alkaline to tholeitic basalt, and calc-alkaline andesite to rhyolite. These rocks occur as (crypto-) domes, flows and sills and are interbedded with abundant shale and chemical sediments, chert and massive sulphides (late Devonian-early Visean). The uppermost rocks are grouped in the Culm Group, a flysch-like sequence of Serpukovian-Bashkirian age that represents the infilling of the basin during the progradation of the Variscan front.

The massive sulphide deposits occur in both the northern and southern part of the Belt with different features. Those located in the northern IPB are invariably hosted by the apical part of felsic domes, in relationship with pumice- and glass-rich dacite to rhyolite of Early Tournaisian age. They are interpreted as being replacive and major examples include Aguas Teñidas, La Zarza or Aljustrel. The deposits in the southern IPB are much younger, of Strunian age, and exhalative on third order basins. This type includes deposits such as Neves Corvo,

Aznalcóllar-Los Frailes, Las Cruces, Lousal, SotielMigollas, Valverde or Tharsis (Tornos, 2006).

Current models suggest that the massive sulphides of the southern IPB formed during the DevonianCarboniferous boundary in response to major paleogeographic changes and the onset of volcanism in the area (Menor-Salván et al., 2010). In brief, crustal thinning and magmatism generated large hydrothermal cells synchronous with the accelerated diagenesis and dewatering of the PQ Group, which produced hydrothermal venting on the seafloor and formation of anoxic bottoms. Vented fluids were metal-rich but sulphur±poor and the massive sulphides formed due to the input of large amounts of H2S derived from the biogenic reduction of seawater sulphate (Tornos, 2006; Tornos et al., 2008). This is consistent with the sulphur isotope values; different compilations of G34S data in the IPB show that the sulphur isotope values are more restricted and positive in the stockwork zones (-2.5 to +10Å) than in the overlying massive sulphides (-33.2 to +4.1Å), indicating that the deep sulphur-likely inherited from the sulphides in the PQ Group or due to the abiogenic reduction of seawater sulphate-mixed with another one derived with more negative signatures, likely the anaerobic sulphate reduction by chemolithoautrotrophic microbes in an open system to sulphate.

Numerical modeling and isotope geothermometry suggest that the anoxic bottoms reached a steady state at temperatures around 60-110ºC, optimal for hyperthemophilic sulphate reducers.

The electron donor for reducing such a large amount of sulphate could be the organic matter supplied by the destruction of vascular plants in subaerial forests located nearby (Menor-Salván et al., 2010). Our goal is to provide possible evidences of the importance of terrigenous organic matter input in the flourishing of microbiological activity during the formation of the giant VMS deposits of the southern IPB. Two falsation criteria for our model are the lack of increase in higher plant molecular fossils coincident with the major inorganic geochemical changes and the lack of indicators of terrigenous organic matter input to the basin.

2 Higher plant indicators and related sulphide precipitation The Devonian-Carboniferous boundary is too a very important key when we talk about biomass destructions.

The biological crisis lead to extinction of about 21% of marine genera and a general vanishing of microfauna (McLaren and Goodfellow, 1990; Sepkoski, 1996). The

major biological crisis during DC boundary is called Hangenberg event, charactrized by geochemical, lithological and biological changes in all trophic levels, terrestrial and marine (Caplan and Bustin 1999). The paleoecological events during DC boundary could supplied the organic matter necessary to adjust the mass balance that explain the massive sulphide formation. We considered a simple biogeochemical reaction using anaerobic fermentation of hexoses as archetypical electron donor. Principal reactions to produce H2S are as follows: C6H12O6 (glucose) + SO42- ĺ 2CH3COO- (acetate) + H2S + 2CO2 CH3COO- (acetate) + SO42- + 3H+ ĺ H2S + 2CO2 + 2H2O H2S + 0.5Fe2+ + 0.25O2 ĺ ++ + 0.5FeS2 (pyrite) + 0.5H2O

It is possible to combine some reactions to produce pyrite at the same time that CO2 is released:

With this null hypothesis, we found in the organic extract of a shale sequence that cut the massive sulphide horizon, a strong increase in the cadalene relative concentration versus 1,3,6,7-tetramethylnaphthalene (Fig. 1), exactly coincident with the maximum increase of anoxicity (measured as V/Cr ratio) and the minimum G34S levels. 1,3,6,7-tetramethylnaphthalene has been selected because is a chemically similar molecule and its concentration remains constant along the entire sequence. Cadalene is a higher plant biomarker and its increase suggest a rise in the input of terrigenous organic materials.

Other higher plant indicator, that suggest the contribution of gymnosperm plants, is the 2methylretene (Bastow et al., 2001). Enhanced level of this biomarker, corrected against 9-methylphenanthrene, confirm the major input of higher plant material (Fig.2) 4

C6H12O6 + 3SO42- + 1.5Fe2+ + 3H+ + 0.75O2 ĺ )H62 + 6CO2 + 7.5H2O

3

2-MR/9-MP

Clearest evidence for this reaction it is seen in Filón Norte of Tharsis, inside the laminated ores composed by siderite-pyrite, interpreted as biogenic mounds (Tornos et al. 2008).

If this model is not correct, we should not find evidences of higher plant and terrigenous organic matter increase coincident with the mineralization event in the vertical distribution of biomakers.

2

1

0 0

0.5

Cad/TMN

60

90

120

150

180

Depth (meters)

0.4

Figure 2. Vertical distribution of 2-methylretene/9methylphenanthrene ratio versus shale depth. Marked zone represents the pyrite orebody.

0.3

0.2

0.1

0 0

30

60

90

120

150

180

Depth (meters) 5.4

4.4

V/Cr

30

3.4

2.4

1.4 0

30

60

90

120

150

180

Depth (meters)

Figure 1. Cadalene/1,3,6,7-tetramethylnaphthalene ratio and V/Cr ratio versus shale depth. The marked zone correspond with pyrite orebody.

Other evidences found are the enhanced levels of retene and 1-methylphenanthrene (measured as x/9methylphenanthrene ratios). Taken together, this suite of biomarkers indicates high input of gymnosperm flora (Alexander et al. 1992). The retene/9-MP and 2methylretene/9-MP ratios showed a linear correlation along the shale depth, confirming that both biomarkers are related and possibly from the same biological source.

The study of the linear hydrocarbons is a proxy for the evaluation of the input of terrestrial organic matter.

The terrigenous/aquatic ratio (TAR, Peters et al. 2005) evaluates the proportion of C27-C31 n-alkanes versus lighter n-alkanes. Vertical distribution of TAR shows relative changes in the contribution of land flora versus marine input. As expected, we found a TAR increase in the interest zone, confirming the previous observation on aromatic terpene biomarkers ( Fig. 3)

molecular evidence in this direction is the decrease of higher plant parameter (van Aarsen et al., 2000), that indicate a disminution of abietane-class terpenoid generating gymnosperm respect to global land flora (Fig. 5).

3 2.5

TAR

2 1.5

3 Conclusions

1 0.5 0 0

30

60

90

120

150

180

Depth (meters)

Figure 3. Vertical distribution of terrigenous/aquatic ratio versus shale depth. Marked zone corresponds with pyrite orebody.

To confirm the information of n-alkane distribution, we evaluated the hopane/sterane ratio, measured as C30 ÄŽČ•-hopane/C29 sterane (Fig. 4). The increase of hopane/sterane ratio in the vertical distribution could suggest land input or/and aerobic bacteria rich facies. An increase in hopane together with anoxicity is a strong suggestion of bacterial rich land material, consistent with the vascular plant crisis during DC boundary.

The vertical distribution of land plant biomarkers, indicators or paleovegetation changes and indicators of terrigenous organic matter input showed a dramatic enhancement coincident with evidences of anoxia and strongly negative G34S levels. The organic and inorganic geochemical alteration coincides with the occurrence of shale hosted massive sulphide orebody.

Data suggests that the formation of massive sulphide orebody could be related with the major paleoecological changes during Devonian-Carboniferous boundary, Hangenberg event.

We interpret that these features could be applied to the rest of deposits in the southern domain in Iberian Pyrite Belt (IPB).

(X 0.001) 24 20

50

Ret/C19

16

40

12

hop/st

8

30 4

20

0 0

30

60

90

120

150

180

150

180

Depth (meters)

10

0.8 0 0

30

60

90

120

150

180

0.6

Figure 4. Vertical distribution of hopane/sterane in Tharsis shale. Marked zone represents the pyrite orebody.

It is interesting to evaluate the paleovegetation changes associated with the orebody horizon. The lower retene/cadalene ratio in the interest zone suggests an ecological change with declining gymnosperm flora. The global dramatic increase in cadalene and abietane class biomarkers (retene and 2-methylretene), together with inverse variation in retene/cadalene ratio is suggestive of land ecosystem alteration, possibly destruction (Mizukami et al. 2013). Future prospects that confirm a dramatic destructive process of land biomass include the study of vertical distribution of high molecular weight PAHs, a proxy of paleofires. It is possible also that the ecological change was a gradual vascular plant crisis, consequence of climatic changes. The declining in vascular plants could increase erosion and incorporation of land materials to the marine basin, with concomitant increase of molecular biosignatures of land plants. Other

HPP

Depth (meters) 0.4

0.2

0 0

30

60 90 120 Depth (meters)

Figure 5. Vertical distribution of proxies of paleoflora changes in the Tharsis shale sequence.

Acknowledgements Study funded by the project CGL 2011-23207.

References Alexander R, Larcher AV, Kagi, RI, Price, PL (1992) An oil-source correlation study using age-specific plant-derived aromatic biomarkers. In Biological Markers in Sediments and Petroleum; Moldowan, Albrecht and Philp ed. Prentice-Hall, NJ, USA. Bastow, TP, Singh, RK, van Aarsen, BKG, Kagi, RI (2001) 2methylretene in sedimentary material: a new higher plant biomarker. Organic Geochemistry 32: 1211-1217.

Caplan ML, Bustin RM (1999) Devonian±Carboniferous Hangenberg mass extinction event, widespread organic-rich mudrock and anoxia: causes and consequences.

Palaeogeography, Palaeoclimatology, Palaeoecology 148:187207.

Leistel JM, Marcoux E, Thiéblemont D, Quesada C, Sánchez A, Almodóvar GR, Pascual E, Sáez R (1997) The volcanic-hosted massive sulphide deposits of the Iberian Pyrite Belt Review and preface to the Thematic Issue. Mineral Deposita 33:2-30.

McLaren, DJ, Goodfellow, WD, (1990) Geological and biological consequences of giant impacts. Ann. Rev. Earth Planet. Sci. 18:123±171.

Menor-Salvan C, Tornos F, Fernandez-Remolar D, Amils R (2010) Association between catastrophic paleovegetation changes during Devonian-Carboniferous boundary and the formation of giant massive sulphide deposits. Earth and Planetary Science

Letters 299:398-408.

Mizukami, T, Kaiho, K, Oba, M (2013) Significant changes in land vegetation and oceanic redox across the Cretaceous/Paleogene boundary. Palaeogeography, Palaeoclimatology, Palaeoecology 369:41-47 Peters, KE, Walters, CC, Moldowan, JM (2005) The Biomarker Guide, Vol II. Second Edition. Cambridge University Press, Cambridge, UK. Sáez R, Almodóvar GR, Pascual E (1996) Geological constraints on massive sulphide genesis in the Iberian Pyrite Belt. Ore Geology Reviews 11:429-451.

Sepkoski, JJ, (1996). Patterns of Phanerozoic extinction: a perspective from global data bases. In: Walliser, O.H. (Ed.), Global Events and Event Stratigraphy in the Phanerozoic.

Springer, Berlin, pp. 35±51.

Tornos F (2006) Environment of formation and styles of volcanogenic massive sulphides: The Iberian Pyrite Belt. Ore Geology Reviews 28:259-307.

Tornos F, Conde, C. and Spiro, B. (2008) Formation of the Tharsis Massive sulphide Deposit, Iberian Pyrite Belt: Geological, Lithogeochemical, and Stable Isotope Evidence for Deposition in a Brine Pool Economic Geology 103:185-214. van Aarssen BGK, Alexander R, Kagi RI (2000) Higher plant biomarkers reflect palaeovegetation changes during Jurassic times. Geochimica et Cosmochimica Acta 64:1417-1424.

Organic Geochemistry: trends for the 21st Century 26th IMOG

- Vol. 2 -

AROMATIC TERPENE BIOMARKERS REFLECTS PALEOECOLOGICAL CHANGES AT THE DEVONIAN-CARBONIFEROUS BOUNDARY IN THE IBERIAN PYRITE BELT César MENOR-SALVÁN*, Sara GISMERA DIEZ, Jesus VELASCO-ACEBES and Fernando TORNOS Centro de Astrobiologia (CSIC-INTA). Ctra. Torrejón-Ajalvir km 4. 28850, Torrejón de Ardoz, Spain *) Corresponding author: menorsc@cab.inta-csic.es The Iberian Pyrite Belt represents one of the largest crustal sulphur anomalies, in the form of one of largest concentrations of volcano-sedimentary massive sulphide deposits on Earth. The massive sulfide deposits occur in both the northern and southern part of the Belt with different features. Those located in the northern IPB are invariably hosted by the apical part of felsic domes, in relationship with pumice- and glass-rich dacite to rhyolite of Tournaisian-Visean age. Major examples include Aguas Teñidas, La Zarza or Aljustrel. The deposits in the southern IPB, that comprises the giant depostist of Neves Corvo, Tharsis, Aznalcóllar-Los Frailes, Las Cruces, Lousal, Valverde and Sotiel-Migollas, are hosted by shale, exhalative and formed in anoxic third order basins (Tornos et al., 2008).The formation of shale hosted massive sulfide deposits (363-359 Ma) was just before or coincident with the Devonian-Carboniferous boundary. The inorganic geochemical data of the ore bearing interval are consistent with ore formation during a highly anoxic event that was coeval with the onset of submarine volcanism and major biological sulfate reducing activity, which explain the decrease in 34S found in the ore bearing shale along D-C boundary. In a previous work, we suggested that the source of electron donor that could explain the formation of massive sulfide should be the enrichment of the basin in land organic matter (Menor-Salvan et al., 2010). To elaborate this model, we measured the vertical distribution of aromatic biomarkers and proxies for terrigenous/marine origin of organic matter along a continuous sequence of shale. The sequence belongs to the lowermost Volcano Sedimentary Complex, equivalent to the Tharsis orebody. The results showed a strong increase in cadalene/1,3,6,7tetramethylnaphthalene

ratio

and

2-methylretene/9-methylphenanthrene

ratio

(Fig.1)

coincident with the higher anoxicity (measured as V/Cr ratio) and lower 34S values on the shale sequence, that corresponds with the D-C boundary. The values of HPI (higher plant index, Van Aarsen et al., 2000), retene/9-methylphenanthrene and 1-methylphenanthrene/9methylphenanthrene showed similar feature. The increase in pristane/phytane ratio also suggests an increase in terrestrial material to the basin, confirmed by a marked increase on

Vol. 2, page - 291 -

25th International Meeting on Organic Geochemistry

IMOG 2011 18 - 23 September Interlaken, Switzerland

Book of abstracts

www.imog2011.com

The 25th International Meeting on Organic Geochemistry Interlaken, Switzerland 18th – 23rd September 2011

Book of Abstracts

IMOG 2011 Secretary, Rapiergroup, 113-119 High Street, Hampton Hill, Middlesex, TW12 1NJ, UK email: IMOGsecretary@rapiergroup.com

Preface Dear Conference Delegates, The Book of Abstracts represents the work that will be presented at the 25th International Meeting on Organic Geochemistry, held in Interlaken, Switzerland from 18th – 23rd September 2011. The conference is organised under the auspices of the European Association of Organic Geochemists. A total of 586 abstracts were submitted for consideration by the Scientific Committee, of which most were accepted.

Some abstracts were withdrawn during the process of preparation of the abstract volume, leaving 580 papers to be presented at the conference.

The Scientific Committee selected 85 abstracts to be presented orally in either plenary or parallel sessions.

In this volume, abstracts of the oral presentation are numbered from 1 – 85 with the prefix ―O‖. The remaining 495 abstracts were accepted as poster presentations and grouped in themed sessions. The posters will be split, with half on view for Monday and Tuesday and the remaining half on view for Wednesday and Thursday. Each themes session will be ―open‖ on a specific day, when the presenting author will be available for discussion. During this specific day the author should be in attendance during the poster session. Abstracts of posters are numbered from 001 to 516 with the prefix ―P‖. Posters P001 to P126 are open for discussion with the presenting author on Monday; P128 to P251 on Tuesday; P254 to P377 on Wednesday and P380 to P516 on Thursday.

We hope that you will find this Book of Abstracts informative and wish you a successful and enjoyable conference.

ORGANISING COMMITTEE Volker Dieckmann - Shell, The Netherlands (Conference Chairman) Erik Tegelaar - Shell, The Netherlands (Chairman Scientific Programme) Pim van Bergen – Shell, Scotland Stefano Bernasconi, ETH Zurich, Switzerland Michael Schmidt, University of Zurich, Switzerland Carsten Schubert, EAWAG, Switzerland SCIENTIFIC COMMITTEE Erik Tegelaar - Shell, The Netherlands (Chairman) Jan de Leeuw – Royal NIOZ and Utrecht University, The Netherlands Sylvie Derenne - CNRS Paris, France Tim Eglinton - ETH Zurich, Switzerland Francois Gelin - Total, France Vincent Grossi - University of Lyon, France Raymond Michels - CNRS Nancy, France Richard Patience - Chevron, U.S.A. Ann Pearson - Harvard University, U.S.A. Alex Sessions - CalTech, U.S.A. Tom Wagner - Newcastle University, U.K. Heinz Wilkes - GFZ Potsdam, Germany

2

P-071

Structural characterization of 1,6-dimethyl-5-isopentyltetralin from Cretaceous conifer fossil resins and coals: a novel diterpene biomarker Cesar Menor-Salvan1, Marta Ruiz-Bermejo1, Bernd R.T. Simoneit2 1

2

Centro de Astrobiologia (INTA), Torrejon de Ardoz, Spain, Department of Chemistry, Oregon State University, Corvallis, United States of America (corresponding author:menorsc@cab.inta-csic.es)

Recently, the gas chromatographic-mass spectrometry (GC-MS) study of the individual components of Cretaceous ambers (fossil resins) shown the presence of a previously unidentified compound with a molecular peak at m/z 230 (Pereira et al. 2009; Menor-Salvan et al. 2010). This compound, one of the main components of the extractable fraction of amber, is also common in the associated sediments, plant fossils and coals of the amber deposit.

These authors suggested a 2,5,6-trimethyl-1butyltetralin structure for the molecule, interpretation based largely in the fragmentation pattern observed in mass spectrum. In order to confirm this structure, we carried out the isolation and purification of the molecule from amber of the Cretaceous deposits located at Basque-Cantabrian Basin (Cantabria, Spain). For purification, the crude amber extract was fractionated by sequential elution in silica gel column followed by semi-preparative high performance liquid chromatography of the fraction containing the target compound and purity testing using GC-MS. The pure compound, a colorless oil, was then characterized by nuclear magnetic resonance (NMR).

Using the NMR and fragmentation data, we could infer a 1,6-dimethyl-5-isopentyltetralin structure (Fig. 1) for the unknown compound, discarding the structure previously suggested in the literature.

of diterpenoids of the labdane class, as communic or agathic acids. The association with conifer fossil resins and the possible diterpene precursor suggest a coniferous botanical origin. Therefore, the presence of 1,6-dimethyl-5-isopentyltetralin in the sedimentary record could be indicative of conifer resin contribution to the organic matter.

Spectroscopic characterization: 1 H NMR (CDCl3, 400 MHz) δ 6.97 (s, 1H), 6.96 (s, 1H), 2.89 (m, 1H), 2.70 (m, 2H), 2.55 (m, 2H), 2.27 (s, 3H), 1.88 (m, 2H), 1.67 (m, 1H), 1.34 (m, 2H), 1.27 (d, J=7.02 Hz, 3H), 0.97 (d, J=6.25 Hz, 6H) 13 C NMR (CDCl3, 100 MHz) δ 140.3, 139.7, 134.8, 133.3, 127.8, 126.0, 38.2, 33.1, 31.1, 29.2, 27.4, 26.8, 23.6, 22.7, 20.8, 19.8. + EI-MS m/z (%) 230 (M , 25), 215 (M-CH3, 14), 173 (29), 159 (100), 143 (13), 128 (12), 115 (7).

References: Pereira, R., de Souza Carvalho, I., Simoneit, B.R.T., de Almeida Azevedo, D., 2009. Molecular composition and chemosystematic aspects of Cretaceous amber from the Amazonas, Araripe and RecĂ´ncavo basins, Brasil. Organic Geochemistry 40, 863-875.

Menor-Salvan, C., Najarro, M., Velasco, F., Rosales, I., Tornos, F., Simoneit, B.R.T., 2010. Terpenoids in extracts of Lower Cretaceous ambers from the Basque-Cantabrian basin (El Soplao, Cantabria, Spain): Paleochemotaxonomic aspects. Organic Geochemistry 41, 1089-1103.

Fig. 1: Structure of 1,6-dimethyl-5-isopentyltetralin, isolated from Cretaceous amber.

The biochemical precursors of this molecule are not identified, but taking into account the structures identified in the amber extracts and the preservation of original biomolecules, the origin of the 1,6-dimethyl5-isopentyltetralin could be the oxidative degradation

215

P-383

Accumulation and degradation of plastic pollutants and diisopropyl-naphthalenes during composting of organic household waste Cesar Menor-Salvan Centro de Astrobiologia (INTA-CSIC), Torrejon de Ardoz, Spain (corresponding author:menorsc@cab.intacsic.es) Composting of household and urban organic waste received much attention by municipal authorities due to its utility in the recycling and volume reduction of waste. According with the waste management plan of the Spanish Government (Plan Nacional Integrado de Residuos 2007-2015, PNIR), in Spain, the 45-53% of the solid urban waste are composed by food or gardening residues and most of these waste is processed in 65 composting plants that generated 720.000 tons of compost in 2006. This compost is used mainly for agriculture and gardening. Following this effort, the market of small units for homebrew compost using household waste increased in parallel with the ecological education of the public and now is a widespread practice. In spite, little attention has been received the molecular composition of compost (Spaccini and Piccolo, 2007). Also, the non-beneficial effects of application of compost on the soil quality or incorporation of contaminants to farm products is still not very well understood. In this sense, Gonzรกlez-Vila et al (1999) noted the increase of phthalate esters in juice of tomatoes growth in compost-amended soils, together with changes in the lipid composition, suggesting a potential risk in the use of compost in the food industry.

Following this line of evidence and the potential use of composting units as a model of concentration and early diagenesis of terpene biomarkers, the study of the organic solvent extractable fraction of compost, generated using household units, was carried out. For 3 this study, a small compost unit (1,5 m ) situated in an urban environment was filled exclusively with food and gardening residues free of paper, plastic or noncompostable debris during five years. Yearly, samples of compost were extracted in dichloromethane/methanol 3:1 and analyzed by gas chromatography/mass spectrometry (GC-MS)

anthropogenic compounds found are the diisopropylnaphthalene isomers (DIPNs). The DIPNs could be accumulated in compost from the food residues, as consequence of migration from cardboard or paper packages (George et al. 2010; Sturaro et al., 1994).

DIPNs and phthalates are effectively degraded during compost maturation: 15.4% of total extract after 1 year, 0.9 % after 5 years with only phthalates remaining.

On the contrary, bisphenol A show resistance to degradation with accumulation on compost (0.1% of total extract after 1 year, 0.59% after 5 years).

Further study is necessary in order to understand the fate of organic pollutants during composting and to evaluate possible risks of the use of poorly maturated composts in agriculture.

References George, S.C., Volk, H., Romero-Sarmiento, M.F., Dutkiewicz, A., Mossman, D.J., 2010. Diisopropyl naphthalenes: Environmental contaminants of increasing importance for organic geochemistry studies. Organic Geochemistry, 41, 901-904.

Gonzรกlez-Vila, F.J., Almendros, G., Madrid, F., 1999.

Molecular alterations of organic fractions from urban waste in the course of composting and their further transformation in amended soil. The Science of Total Environment, 236, 215-229.

Spaccini, R., Piccolo, A., 2007. Molecular characterization of compost at increasing stages of maturity. 1. Chemical fractionation and infrared spectroscopy. Journal of Agricultural and Food Chemistry, 55, 2293-2302.

Sturaro, G., Parvoli, G., Rella, R., Bardati, S., Doretti, L., 1994. Food contamination by diisopropyl naphthalenes from cardboard packages. International Journal of Food Science & Technology, 29, 593-603.

Results and conclusion The main single components of the extractable fraction of compost (mean 29.6% of total compost) is constituted by plant lipids, n-alkanes and plastic contaminants. The plastic contaminants found are dominated by phthalate esters, followed by 2,4.ditertbutylphenol and bisphenol A. Other relevant

511

A368

Goldschmidt Conference Abstracts 2009

Modelling the Sn and W evolution in peraluminous leucogranites from the Central-Iberian Zone

Preservation under the Río Tinto extreme acidic conditions and a potential location on Aram Chaos, Mars

C. FERNANDEZ-LEYVA1*, C. RUIZ2 AND L. GONZALEZ1 1

Geological Survey of Spain (l.gonzalez@igme.es) (*correspondence: c.fernandez@igme.es) 2 Technical University of Madrid (UPM) Mining School, Spain (casilda.ruiz@upm.es) Leucogranites from Jálama Batholith show Sn and W mineralizations [1] commonly related to peraluminous granitic magma systems [2]. Equilibrium and fractional crystallization models have been obtained for two extraction assemblages (Fig. 1). The comparison of the models with the original leucogranite data permits to establish two distribution trends: a magmatic trend, which represents Sn and W concentration and another one from W enrichment, not reproduced by the modelling.

Therefore magmatic process could explain Sn mineralization whereas W mineralization can not be attributing at the same process.

Figure1: Comparison of the models with the leucogranite data [1] Ruiz et al. (2008) Chem. Erde 68-4, 337-450 [2] Haapala, I. (1997) J. Petrol., 38, 1645-1659.

DAVID C. FERNÁNDEZ-REMOLAR1, ELIZABETH JOHNSON2, TIM CLELAN2, KIM LICHTENBERG2, CÉSAR MENOR-SALVÁN1, MARY SCHWEITZER2, RICARDO AMILS1, VICTOR PARRO1 1 AND RAY ARVIDSON 1

Centro de Astrobiología (INTA-CSIC), Ctra Ajalvir km 4, 28850 Torrejón de Ardoz, Spain (fernandezrd@inta.es) 2 Marine, Earth & Atmospheric Sciences, North Carolina State University, USA (eajohns2@ncsu.edu) 3 Department of Earth & Planetary Sciences, Washington University at St Louis, USA (lichtenberg@rsmail.wustl.edu) MER, Mars Express and MRO have provided evidence in the form of sulfate deposits that some regions of Early Mars experienced episodic exposure to low-pH solutions. Spectral analysis shows the salts to be dominated by ferric oxides, with associated hydrated sulfates [1, 2]. Moreover, iron-rich caps appear topping different layers of this salty unit. This suggests that the cap may correspond to weathering horizons [1, 2], with dehydration and desulfation resulting in ferric oxide enrichment. A similar mechanism is observed in the acidic Rio Tinto system, where preservation of biological information can be traced over three terraces of different ages, and compared to that seen in the modern deposits of Río Tinto [3].

This results in deposition of a fine mineral coating over biological surfaces, where plant and animal tissues are permineralized and microbes are trapped inside ferric gels.

Paleobiological analysis of each of the sucessive iron rich terraces demonstrates both morphological and compositional information is preserved, even in the 2 Ma deposits. Here we show a multi-disciplinary geobiological approach combining structural, mineral and molecular methods to characterize preserved biological markers. These data can then be used to optimize our search for signatures of extinct life in these Mars acidic materials.

This research is being supported through the Project ESP2006-09487 provided by the Research and Innovation Ministery of Spain.

[1] Massé et al. (2008) JGR 113, doi: 10.1029/ 2008JE003131.[2] Lichtenberg (in prep.) JGR. [3] FernándezRemolar & Knoll (2008) Icarus 194, 72-85.

EPSC

EPSC Abstracts Vol. 9, EPSC2014-336, 2014 European Planetary Science Congress 2014 c Author(s) 2014

European Planetary Science Congress

Cold origins: Prebiotic Chemistry at the ice matrix C. Menor-Salván Centro de Astrobiología (CSIC-INTA). 28850 Torrejon de Ardoz, Spain. (cmenor@mtiblog.com / Fax: +34-949-327918)

Abstract The ice world experimental model (i.e., the chemical evolution in the range between freezing point of water and the limit of stability of liquid brines, ≈273 to 210 K) is summarized. Overall, the ice matrix is an adequate environment for the abiotic synthesis of nitrogen heterocycles (including nucleobases).

1. Introduction The origin of nucleobases and other heterocycles is a classic question in the chemistry of the origins of life.

The construction of laboratory models for the abiotic synthesis of nitrogen heterocycles in plausible natural conditions also aids the understanding and prediction of chemical species in the Solar System. If we support the idea of a prebiotic origin of nucleobases, a “cold origin of life” [1] or “ice world” is the preferred prebiotic environment because the nucleobases would be stable under cold conditions, and such an environment supports the relevance of eutectic water solutions of reactants in an ice matrix.

During the lasts years, we performed a series of experiments [2,3] which demonstrate the feasibility of the prebiotic synthesis of nucleobases at the ice matrix in the range of existence of eutectic solutions of organic solutes.

composed by methane-rich atmosphere and an ice pool (Figure 1), lead to the concentration of polycyclic aromatic hydrocarbons in water. If a nitrogen solute is present in eutectic solutions, as urea, the formation of pyrimidines (mainly uracil) and purines (mainly adenine).

CH4 / N2 C2H2 acetylene

N cyanoacetylene

The irradiation (by spark discharges or UV irradiation) of an atmosphere containing methane/ nitrogen or acetylene, lead to the formation of organic precursors whose fate depends on the environmental conditions. If a water pool is present at a temperature sufficiently low as freeze-thaw cycles are set, products of atmospheric irradiation could react with organic solutes, especially in the concentrated brines formed during the freezing process. The low temperature and freezing gives different results from the classic prebiotic chemistry simulations. Thus, the irradiation of a system

HCN

O NH2

H2N

CH• phenyl

O

NH2

H N

N cyanoacetaldehyde

Hydantoins

N

N

N

O

adenine H2N

NH2

HO

NH

phenylethyne

H2N

N

O

O

N H

OH N

OH cyanuric acid

NH

Aromatics

N N

cytosine HO

O

N N

OH

HO

N NH2

uracil

Pyrimidines

OH

Triazines

N

N N

OH

2,4,6-trihydroxy pyrimidine

NH2 N

NH2 ammeline

H2N

N

N N

ammelide

HO

2. Results

Amino acids?

Nitriles Carbonyl compounds

NH2 N

NH2 melamine

Figure 1: Summary of the products found by prebiotic chemistry simulations based on methane/nitrogen atmospheres and water in the temperature range between -25ºC and the water triple point. The cold conditions favor the formation of nitrogen heterocycles.

If acetylene (a molecule that has received little attention in the development of Prebiotic Chemistry) is present in the atmosphere, its photolysis products could react with efficient condensing agents, as urea, leading to the efficient formation of nitrogen heterocycles (Figure 2).

References [1] Eschenmoser, A.: Etiology of potentially primordial biomolecular structures: from vitamin B12 to the nucleic acids and an inquiry into the chemistry of life’s origin: a retrospective, Angewandte Chemie (International Ed. in English), vol. 52, pp. 12412–72, 2011.

Figure 2: Summary of the prebiotic chemistry of acetylene in presence of urea eutectic solutions.

3. Summary and Conclusions The cold prebiotic chemistry experimental model could contribute to the understanding of chemical evolution in cold water-rich planetary environments.

The experiments performed demonstrated that the synthesis of aromatic hydrocarbons, purines and pyrimidines and other nitrogen heterocycles of potential prebiotic interest (such as triazines and hydantoins) are favoured in the ice matrix by classic cyanide and cyanoacetylene pathways or by condensation of acetylene photolysis products.

Despite these results, the experimental prebiotic chemistry in the solute-concentrated solutions that fill the space confined by ice matrix has received relatively little attention in the elaboration of the models for the origin of organics in Solar System bodies and prebiotic evolution. Consequently, it is necessary to perform more experiments under plausible prebiotic conditions, especially if geochemical models support stable icy environments on the prebiotic Earth. The ice world constitutes an interesting prebiotic chemistry scenario that awaits further investigation

[2] Menor-Salván, C., and Marín-Yaseli, M.R.: Prebiotic chemistry in eutectic solutions at the water-ice matrix.

Chemical Society Reviews vol. 41, pp. 5404-5415, 2012.

[3] Menor-Salván, C., and Marín-Yaseli, M. R.: A new route for the prebiotic synthesis of nucleobases and hydantoins in water/ice solutions involving the photochemistry of acetylene. Chemistry: A European Journal, vol. 19, pp. 6488–97, 2013.

EPSC

EPSC Abstracts Vol. 9, EPSC2014-111-1, 2014 European Planetary Science Congress 2014 c Author(s) 2014

European Planetary Science Congress

An electrochemical cell model of the origin of metabolism C. Menor-SalvĂĄn Centro de AstrobiologĂ­a (CSIC-INTA). 28850 Torrejon de Ardoz, Spain. (cmenor@mtiblog.com / Fax: +34-949-327918)

between inorganic species could promote the biomimetic carbon fixation.

Abstract A dynamic system formed by the electrochemical coupling of iron metal and iron-sulphur species, derived from iron sulphide minerals, could promote carbon fixation by reductive carboxylation of thioacetate esters. Using a simple galvanic cell as experimental approach, the results suggest that the electrochemically active interfaces in plausible geochemical conditions could drive a simple protometabolism.

2. Results An electrochemical cell has been constructed using a cylindrical graphite reactor filled with granulated iron metal, a microporous clay barrier and pyrrhotite wet paste formed by pyrrhotite powder, containing 1 mmol of sodium sulphide (pH 9) and, optionally, 1 mmol of hydroquinone. Previously, 1 mmol of ethyl thioacetate was adsorbed by the pyrrhotite powder. A graphite electrode inserted in the pyrrhotite constitutes the cathode. The system was connected to a power supply at 1.1 V under a nitrogen atmosphere.

The organic solutes were analysed after three days of standing in anoxic conditions at room temperature; the analysis shows a significant quantity of lactic acid (Figure 1) with an estimated yield of 6.5% of the added ethyl thioacetate. Pyruvic acid was also detected, as well as glycolic acid and glycine.

1. Introduction One approach to the study of abiogenesis is the hypothesis of a protometabolic, complex chemical system that precedes the first living beings. The first metabolic systems could emerged from the interaction between sulphide minerals and/or soluble iron-sulphide complexes and fluids rich in inorganic precursors, which are reduced and derived from crustal or mantle activity. The role of iron sulphur proteins (which contain Fe-S clusters as active centers in the electron transfer reactions) and their occurrence in what are possibly the most primitive steps of oxidation of organic substrates, the carbon fixation by reductive carboxylation, and in the cell energy transduction machinery, have been an evidence used to connect the geochemical roots of the origin of life to the origin of biochemistry [1].

The structural similarity between the biological ironsulphur clusters and the crystal structure of iron sulphide minerals [2], the biomimetic activity of synthetic soluble Fe-S clusters [3] and the highly preserved biochemical reactions involved could explain why Fe-S clusters are found in all biological systems. In this sense, Fe-S clusters could trace the origin of life to the iron sulphide minerals as the roots of biochemistry [4]. In this work, we study the possible connection between the biochemical reductive carboxylation of thioesters and the geochemistry of the iron-sulphide system, by application of a new experimental approach: using an electrochemical cell to simulate how gradients

A b u n d a n c e T IC : M S C 2 3 .D \ d a ta .m s 1 .1 e + 0 7 1 e + 0 7

Lactic acid

9 0 0 0 0 0 0

Relative abundance

8 0 0 0 0 0 0 7 0 0 0 0 0 0

Pyruvic acid

6 0 0 0 0 0 0 5 0 0 0 0 0 0

Glycolic acid

4 0 0 0 0 0 0 3 0 0 0 0 0 0 2 0 0 0 0 0 0 1 0 0 0 0 0 0 0

1 2 12 . 5 0 1 3 . 0 0 1 3 . 5 0 1 4 15 . 0 0 1 4 . 5 0 1 5 . 0 0 1 5 . 5 0 1 6 . 0 0 1 6 20 . 5 0 1 7 . 0 0 1 7 . 5 0 1 8 . 0 0 1 8 24 .5 0

T im e - - >

Retention time (min)

Figure 1: Identified products obtained by carboxylation of ethylthioacetate coupled to the iron/pyrrhotite/sulphide electrochemical system. The major formation of lactic acid could be explained by reduction of newly formed pyruvic acid, catalysed by iron sulphides [5]

The control experiment without an external voltage source shows a significantly lower yield in the formation of lactic acid, suggesting that a low potential electron donor could be necessary for the process. To test this possibility, we performed an experiment using the same electrochemical cell design but without using an external voltage source and adding 1 mmol of hydroquinone (Eº = −0.699V).

Hydroquinone can act as analog of the biological ubiquinol and can perform electron transfer reactions on the surface of minerals [6]. The model biochemical reaction that motivates the selection of hydroquinone as an electron donor is the formation of pyruvate by direct carboxylation of acetic acid, promoted by (quinone) pyruvate dehydrogenase. The presence of hydroquinone promotes the synthesis of lactic acid, increasing the yield to 10.5% and suggesting that electrons can be transferred through iron sulfur clusters or surfaces, similar to the ubiquinol/iron-sulfur system in biochemistry. The experiments performed suggest a model for the reductive carboxylation of thioesters in abiotic and non-enzymatic conditions (Figure 2). Also, an electrochemical cell could be an approach to the experimental study of Origin of Life, as are ideal for the creation of electrochemical gradients and simulate an electrochemically active geochemical interface. Our work is the first experimental use of electrochemical cells within the sphere of abiogenesis and offers a potentially powerful model through which to explore emergent biochemical systems [5].

3. Summary and Conclusions Our experimental model shows that pyrrhotite (Fe7S8), in a soluble sulphur-rich environment and in the presence of soluble iron-sulphur clusters and newly formed FeS mineral precipitates, whose formation was induced by iron metal anodic oxidation, can promote the reductive carboxylation of simple thioacetic acid esters to form pyruvate/lactate under mild conditions. The reaction could be regarded as biomimetic of the pyruvate synthesis promoted by pyruvate ferredoxin oxidoreductase (PFOR) and favoured by the presence of low potential electron donors, such as hydroquinone, which suggests that the origin of ancient organic cofactors boosted the emergence of simple protometabolic systems. Overall, we showed experimentally that iron sulphides could be coupled with carboxylation in an emerging metabolism by means of an electrochemical gradient.

References [1] Beinert, H.: Iron-sulfur proteins: ancient structures, still full of surprises, J. Biol. Inorg. Chem., Vol. 5, pp. 2–15, 2009.

[2] Russell, M.J., Martin, W.: The rocky roots of the acetyl-CoA pathway. Trends Biochem. Sci. Vol. 29, pp.

358–363, 2004.

[3] Holm, R.H.: Electron Transfer: Iron–Sulfur Clusters. In Comprehensive Coordination Chemistry II; McCleverty, J.A., Meyer, T.J., Eds.; Pergamon: Oxford, UK, pp. 61–90, 2003.

[4] Russell, M.J.: The alkaline solution to the emergence of life: energy, entropy and early evolution. Acta Biotheoretica, Vol. 55, pp. 133–79, 2007.

Figure 2: Reductive carboxylation of a simple thioester, pulled by the iron-sulfur system (pyrrothite/FeS/SH-) in an electrochemical cell. The source of electrons is iron metal. Q: oxidized quinone; HQ: reduced quinone.

[5] Ibañez de Aldecoa, A.L., Velasco, F. and Menor-Salván, C.: Natural Pyrrhotite as a Catalyst in Prebiotic Chemical Evolution. Life, Vol. 3, pp. 502-517.

[6] Kung, K. and Mcbride, M.B. Electron Transfer Processes Between hydroquinone and iron oxides. Clay.

Clay Miner. Vol. 36, pp. 303–309, 1988.

EPSC

EPSC Abstracts Vol. 8, EPSC2013-PREVIEW, 2013 European Planetary Science Congress 2013 c Author(s) 2013

European Planetary Science Congress

Pyrrhotite catalyzes the synthesis of uracil under hydrothermal conditions A. L. Ibañez de Aldecoa and C. Menor-Salván Centro de Astrobiología (CSIC-INTA), 28850-Torrejon de Ardoz, Spain (menorsc@cab.inta-csic.com)

Abstract The hypothesis of a prebiotic origin for metabolic cycles in hydrothermal systems gained interest during last years. The experimental approach to support this hypothesis was oriented mainly to the formation of organic molecules in iron sulfide mineral surfaces from inorganic precursors. In this work, we explore the behavior of previously formed, prebiotically plausible organic molecules in iron sulfide rich, low temperature hydrothermal environments. Using urea as a starting point, we found that uracil and other nitrogen heterocycles could be synthesized using water-urea solution as precursor in a packed pyrrhotite bed reactor, simulating hydrothermal conditions.

1. Introduction Since the first proposals of a relationship between hydrothermal systems and origin of life [1], the experiments that replicate sulfide rich, hydrothermal chemistry confirmed the potential of these systems for the synthesis of organic molecules through carbon fixation. The main role corresponds to ferrous sulfide minerals [2]. These mineral phases can catalyze the formation of organic compounds from CO and thiols [3] in a hydrothermal environment, leading to the hypothesis of the chemoautotrophic origin of metabolism. About the role of this system in the prebiotic chemistry of nucleic acid components, it has been reported that iron sulfide minerals can catalyze the formation of purines and pyrimidines by formamide condensation [4]. We are interested in the possible role of iron sulfide minerals in hydrothermal environments in the prebiotic chemistry of organic molecules regarded as prebiotic precursors, as urea, amino acids and small organic acid. As an experimental model, we designed a continuous flow reactor with iron sulfide as immobilized phase and, in a first approximation, presented here, we used

aqueous solutions of urea as nitrogen source and tested if urea could be a source of nucleobases in iron sulfide rich hydrothermal systems. Urea was selected after its identification as a good precursor of nucleobases in icy systems [5].

2. Materials and methods 2.1 Pyrrhotite All pyrrhotite samples used were from the Gualba quarries (Barcelona, Spain), a Fe-Cu (Mo-Pb-Zn) sulfide rich skarn of Hercynian age. The pyrrhotite was characterized by electron microprobe analysis (EMPA-WDS) and X-ray diffraction (XRD). The composition found is Fe9S10 with dominance of hexagonal polytypes. The ore was selected from metamorphic origin in order to minimize the content of organic carbon. The Gualba pyrrhotite is strongly ferromagnetic; this circumstance has been used to the isolation of pyrrhotite from the ore paragenesis.

2.2 Experimental setup The experiments were conducted using empty HPLC 25x0.25 cm steel columns, filled with pyrrhotite powder. The powder was previously sterilized and extracted using dichloromethane and methanol to remove potential organic contaminants. The column was connected to an HPLC pump using peek tubing and connections. The pyrrhotite column was heated at 120ºC and flow adjusted to maintain a constant pressure of 200 bar (aprox. 0.1 ml/min). The aqueous solutions (10 ml total) were previously filtered through 0.22 microns filters and degassed. The effluent of reactor was freeze-dried and organic products were characterized using gas chromatography-mass spectrometry (GC/MS) after formation of trimethylsilyl derivatives.

3. Results

The formation of uracil was identified in a 0.1M solution of urea flowed through pyrrhotite reactor, with a yield of 3.5% of the total urea. The presence of succinic acid, a common prebiotic molecule, increased the uracil yield to 5.8%. The supplementation of the urea solution with glyoxal (0.1M) lead to the expected formation of hydantoin and 2-oxo-4,5-dihydroxyimidazolidine as major compounds, together with uracil, 5hydroxyhydantoin and succinic and fumaric acids (Fig 1).

extreme conditions of the system, which could degrade other molecules more complex or labile. For example, the potential cytosine could undergo rapid deamination to uracil under these conditions. Uracil remains in the system, as the most stable molecule of the nucleobase related heterocycles. This is specially highlighted by the use of urea as reactant, which, in cold conditions, leads to the formation of a rich assemblage of nitrogen heterocycles [5].

Acknowledgements We thank the invaluable help of Frederic Varela Balcells in the supply of pyrrhotite samples.

References [1] Holm, N.G., ed.: Marine hydrothermal systems and the origin of life, Origins of Life and Evolution of Biospheres, Vol. 22, pp. 1-242, 1992.

[2] Wächtershäuser, G.: On the chemistry and evolution of the pioneer organism, Chemistry and Biodiversity, Vol. 4, pp. 584-602, 2007.

[3] Cody, G.D., Boctor, N.Z., Brandes, J.A., Filley, T.R., Hazen, R.M. and Yoder, H.S.: Assaying the catalytic potential of transition metal sulfides for abiotic carbon fixation, Geochimica et Cosmochimica Acta, Vol. 68, pp.

2185-2196, 2004.

Figure 1: Synthesis of uracil and hydantoins from urea catalyzed by pyrrhotite (FeS) under simulated hydrothermal conditions.

To asset the mineral phase transformation, the worn out pyrrhotite was studied by X-ray diffraction. The new mineral phases identified were mainly pyrite, followed by siderite and minor iron oxides.

4. Summary and Conclusions This experiment could be added to those that highlight the catalytic properties of iron sulfide minerals in promoting prebiotic chemistry transformations. The ferrous sulfide mineral can catalyze the condensation of urea and/or urea and succinic acid degradation products to form uracil in a mechanism that still need to be elucidated. The presence of other prebiotic molecules could increase the organic diversity of the products. The presence of glyoxal leads to the formation of hydantoins as main product, together with uracil. The lack of other pyrimidines or purines could be a consequence of the

[4] Saladino, R., Neri, V., Crestini, C., Costanzo, G., Graciotti, M., and Di Mauro, E.: Synthesis and degradation of nucleic acid components by formamide and iron sulfur minerals. Journal of the American Chemical Society, Vol. 130, pp. 15512–15518.

[5] Menor-Salván, C., Roig Marin-Yaseli, M.; A New Route for the Prebiotic Synthesis of Nucleobases and Hydantoins in Water/Ice Solutions Involving the Photochemistry of Acetylene, Chemistry: a European Journal, Vol. 19, pp. 6488-6497, 2013.

EPSC

EPSC Abstracts Vol. 8, EPSC2013-PREVIEW, 2013 European Planetary Science Congress 2013 c Author(s) 2013

European Planetary Science Congress

Ice world: the origin of nucleobases in ice-liquid water coexistence conditions.

César Menor-Salván Centro de Astrobiologia (CSIC-INTA), Torrejon de Ardoz, 28850-Madrid, Spain (cmenor@mtiblog.com)

Abstract We could define the ice world as the chemical evolution in the range between freezing point of water and the limit of stability of liquid brines, ≈273 to 210 K. In this environment, the synthesis of nitrogen heterocycles using urea as nitrogen source and methane as precursor of active intermediates is favorable from a prebiotic chemistry standpoint, leading to a mixture dominated by pyrimidines and hydantoins. Hence, the synthesis in ice matrix constitutes an experimental model for the study of origin of nucleobases in Solar System bodies.

1. Introduction Despite the research into the photochemical transformations in ice from an astrochemical point of view, the study of the chemistry in the range of stability of the ice–water interface has not received much attention. This may be due to the scarcity of the defined conditions in the Solar System during the epoch of active prebiotic chemistry or the difficulties for demonstrating that these cold conditions existed in Hadean Earth. The evidence for a liquid water subsurface ocean on Saturn’s moon Europa[1] and the possible presence of water-ammonia eutectic brines or even a subsurface ocean in other outer giant planet satellites such as Titan[2] rekindled the interest in liquid water prebiotic chemistry. Moreover, the subsequent proposed steps for the emergence of cellular life have a limited temperature range, and a hot prebiotic Earth was regarded to be an unlikely environment for the origin of life by some authors[4]. Miller and Orgel stated in 1974 that the emergence of biological organization could only occur at temperatures below the melting point of the polynucleotide structure. After observing the instability of organic compounds in the prebiotic stages, these authors concluded that a temperature of 273 K would have been beneficial and that temperatures near the eutectic point of NaCl

solutions (251.3 K) would have been even better [5].

The low temperatures in planetary surface ices could be more conductive to the origin and the preservation of molecules that could be relevant for the emergence of life. In 1994, in one of the first explorations of the idea of an ice world-based origin of the life raw materials, Bada et al. [6] suggested that ice formations on early Earth could have preserved organic compounds against hydrolysis or photochemical degradation. Under plausible planetary conditions, the presence of liquid water at T<273 K within an ice matrix creates a potential reactor where the synthesis or polymerization of molecules of biological interest could occur. Within this context, we proposed a model of prebiotic synthesis in icy environments that could favor the origin of nucleobases.

2. Methodology The experimental setup and methods was detailed previously [7], [8]. Briefly, pure water or urea water solution in a sealed reactor under primordial methane containing or acetylene containing atmosphere, was subjected to freeze-thaw cycles in a temperature range between 5ºC and the ureawater eutectic point (-21ºC). The system was energized by means of spark discharges or ultraviolet irradiation (254 and 185 nm). Reaction products were separated and identified using gas chromatography-mass spectrometry.

3. Results The sparking on a freezing dilute urea solution under a nitrogen/methane atmosphere leads to the formation of and cytosine, uracil as the main identified pyrimidines, in addition to adenine (Figure 1). The experiments showed that using the freeze-thaw conditions, the observed sequence of pyrimidine yield obtained was cytosine > uracil > 2,4-diaminopyrimidine > 2,4,6-trihydroxy pyrimidine.

purines is unclear, and the formation of ureido derivatives of carboxylic acids could be implicated.

The water-ice matrix played a dual role as a protective medium and a source of radicals for the photo-oxidation of purines and pyrimidines.

4. Summary and Conclusions

Figure 1. Origin of nitrogen bases in urea water-ice solution under methane atmosphere.

The formation of cytosine as the main pyrimidine suggests that the low temperature conditions could reduce the rate of deamination to uracil and favour subsequent chemical evolution steps. In our analysis of the gas mixture obtained after sparking a CH4/N2 mixture, the main product was acetylene, followed by unsaturated hydrocarbons and HCN, but no cyanoacetylene was found. To test if acetylene could be a precursor of nucleobases, icewater urea system under pure acetylene atmosphere were irradiated with ultraviolet radiation. The reaction products (Figure 2) contained hydantoins, pyrimidines and purines, including uracil, uric acid, xanthine, guanine and adenine. The highest yields corresponded to 5-hydroxyhydantoin,2-oxo-4,5dihydroxyimidazolidine, hydantoin, uracil, parabanic acid and uric acid. Additionally, cytosine, 6-methyluracil and iso-orotic and orotic acids were found in significant quantities. The presence of urea inhibits the formation of acetylene photopolymers.

The ice is a favorable matrix for the origin of nucleobases and other organic molecules of prebiotic interest, from precursors available in primordial conditions, as urea and acetylene or methane. The principal difference with prebiotic chemistry in hot conditions is that, in ice free environment, the atmospheric precursors tend to the formation of tholins and photopolymers and the inhibition of synthesis of nucleobases, which seems to be strongly favored in the zone of coexistence of ice and liquid water solutions enriched in organic solutes.

References [1] Chyba, C.F., and Phillips, C.B.; Europa as an abode of life, Origins of Life and Evolution of the Biosphere, Vol. 32, pp. 47-67.

[2] Tobie, G., Grasset, O., Lunine, J.I., Mocquet, A., and Sotin C.; Titan internal structure inferred from a coupled thermal-orbital model, Icarus, Vol. 175, pp. 496-502, 2005.

[4] Moulton, V., Gardner, P.P., Pointon, R.F., Creamer, L.K., Jameson, G.B., and Penny, D.; RNA argues against a hot start origin of life, Journal of Molecular Evolution, Vol. 51, pp. 416-421, 2000.

[5] Miller, S.L., and Orgel, L.; The Origins of Life on the Earth, Prentice Hall, New Jersey, 1974.

[6] Bada, J.L.; How life began on Earth: a status report, Earth and Planetary Science Letters, Vol. 226, pp.1-15, 2004.

Figure 2: Acetylene as precursor of nucleobases.

Analysis of the reaction products suggests that hydantoin was a product of direct synthesis from acetylene derived glyoxal and urea. 5hydroxyhydantoin was a product of both direct synthesis from glyoxylic acid and urea, and, in lesser extent, from photodegradation of purines and pyrimidines. The mechanism of formation of

[7] Menor-Salvรกn, C., Ruiz-Bermejo, M., Guzmรกn, M.I., Osuna-Esteban, S., Veintemillas-Verdaguer, S.; Synthesis of Pyrimidines and Triazines in Ice: Implications for the Prebiotic Chemistry of Nucleobases, Chemistry: a European Journal, Vol. 15, pp. 4411-4418, 2009.

[8] Menor-Salvรกn, C., Roig Marin-Yaseli, M.; A New Route for the Prebiotic Synthesis of Nucleobases and Hydantoins in Water/Ice Solutions Involving the Photochemistry of Acetylene, Chemistry: a European Journal, Vol. 19, pp. 6488-6497, 2013.

July 3rd–8th, 2011, Montpellier, France

Origins2011 International Conference

A tholin with lactate dehydrogenase enzyme-mimic activity César MENOR-SALVÁN*, Marta RUIZ-BERMEJO, Luis RIVAS, Susana OSUNA-ESTEBAN, Sabino VEINTEMILLAS-VERDAGUER Centro de Astrobiología (INTA-CSIC), Carretera Torrejón-Ajalvir Km 4.2, E-28850 Torrejón de Ardoz, Spain * menorsc@cab.inta-csic.es

Several ways are possible to generate tholins (i.e. complex organic materials generated by irradiation of CH4, CO or CO2 atmospheres, Sagan and Khare, 1979) by modification of physical conditions, composition or energy sources. Generally, the hydrolysis or pyrolysis of tholins release single molecules as amino acids, carboxylic acids or nitrogen heterocycles, but the nature and properties of their macromolecular structures received comparatively lesser attention (McDonald et al., 1994). After the fractionation of tholins in a hydrophilic and hydrophobic macromolecular fractions, we found that, despite its different chemical nature, hydrophilic tholin share some physicochemical properties with polypeptides (Ruiz-Bermejo et al. 2008). In a next step, we tested the ability of tholin to mimic intermediary metabolism reactions with prebiotic interest, a role that could be relevant in the origin of the metabolism, following the idea of a protometabolism without enzymes. In this sense, we show that some tholins generated by irradiation of CH4/N2 atmospheres could mimic the lactate deshydrogenase (LDH) activity. This paleozyme (catalyst in a hypothetical non-enzymatic origin of metabolism), could catalyze the oxidation of lactic acid to pyruvic acid, using NAD+ as electron acceptor, in the same conditions of purified LDH-D from Lactobacillus leichmanii, selected by its low activity and used as positive control. The dynamic light scattering and electrophoretic study of the active tholin suggest that a tridimensional configuration analog to the tertiary structure of proteins could be the basis of the catalytic activity.

A

B

O O

HO

Abundance (%)

Abundance (%)

O OH

OH pyruvic acid

lactic acid

6

8

10

Retention time

12

14

6

8

10

12

14

Retention time

Figure 1. Gas chromatogram showing lactate and the pyruvate synthesized using tholin exhibiting LDH mimic activity (A) and a negative control performed in the same conditions using an inactive tholin (B).

References Sagan C, Khare BN (1979). Tholins: organic chemistry of interstellar grains and gas. Science 277: 102–107.

McDonald GN, Thompson WR, Heinrich M, Khare BN, Sagan C (1994). Chemical investigation of Titan and Triton tholins. Icarus 108: 137–145.

Ruiz-Bermejo M, Menor-Salván C, Mateo-Martí E, Osuna-Esteban S, Martín-Gago JA, Veintemillas-Verdaguer S (2008) CH4/N2/H2 spark hydrophilic tholins: A systematic approach to the characterization of tholins. Icarus 198, 232-241.

July 3rd–8th, 2011, Montpellier, France

Origins2011 International Conference

Magnetically induced enantioselective crystallization of sodium chlorate with hydrophobic amino acid impurities at the water-air interface Susana OSUNA-ESTEBAN*, Maria Paz ZORZANO, César MENOR-SALVÁN, Marta RUIZBERMEJO, Sabino VEINTEMILLAS-VERDAGUER Centro de Astrobiología (INTA-CSIC), Carretera Torrejón-Ajalvir Km 4.2, E-28850 Torrejón de Ardoz, Spain *osunaes@cab.inta-csic.es

All the organic chemistry of terrestrial organisms is based on the L form of amino acids. Despite much effort devoted to elucidating how and why L-amino acids were preferentially selected with respect to the Denantiomer no clear solution has yet been obtained. Some enantioselective mechanisms have been proposed however none of them deal with organic molecules in plausible prebiotic Earth environments.

In 1985 Gilat ( Gilat and Schulman 1985, Gilat 1985) proposed the existence of what he named “chiral interaction” between chiral biomolecules (such as amino acids) and a polar solvent (such as water), in the presence of an interface, that leads to the formation of a magnetic moment of opposite direction for each enantiomer. He also suggested that the geomagnetic field of the Earth may have interacted with this hypothetical magnetic moment inducing an energy difference between the two enantiomers. To validate this hypothesis, is necessary a technique that is sensitive to tiny amounts of chiral hydrophobic amino acids located only at the upper molecular layers of a water solution. We propose to use the crystallization of sodium chlorate (Osuna-Esteban et al. 2008) as a probe for plausible amino acid enantiomeric excesses (e.e.) at this interface. Our results indicate that an upwards pointing magnetic field induces a detectable L e.e. at the water-air interface, whereas a downwards pointing field induces a D excess in these environments. These experiments suggest that the geomagnetic field of the Earth may have played a significant role on the prebiotic origin of homochirality inducing an e.e. on all hydrophobic chiral amino acids participating in the ocean-atmospheric chemistry of the primordial aerosol cycle.

Figure 1. Hydrophobic amino acid at the air-water interface in L (left) and D (right) conformation, with the hydrophobic residue R sticking out of the water. The electric dipole field associated with the zweitterion induces around the molecule a loop current of solution cations and anions. This current produces a magnetic dipole µ (here indicated as a vector) which points upwards for the L enantiomer, and downwards for the D enantiomer.

References Gilat G, Schulman LS (1985) Chiral interaction, magnitude of effects and applications to natural selection of L enantiomer. Chem. Phys. Lett. 121: 13-16 Gilat G (1985) Chiral interactions in biomolecules. Chem. Phys. Lett. 121: 9-12.

Osuna-Esteban S. Zorzano MP, Menor-Salvan C, Ruiz-Bermejo M, Veintemillas-Verdaguer S (2008) Asymmetric chiral growth of micron sized NaClO3 crystals in water aerosols. Phys. Rev. Lett. 100: 146102(4).

Astrobiology Science Conference 2010 (2010)

5290.pdf

Origin of life in Fe-poor oceans under a CH4-rich and SO2-poor atmosphere: II. Experimental evidence. Cesar Menor Salván1 and Hiroshi Ohmoto2. 1Centro de Astrobiologia, INTA-CSIC, Citra Ajahvir km. 4, 28850 Torrejón de Ardoz, Spain, menorsc@inta.es. 2Penn State Astrobiology Research Center & Department of Geosciences, The Pennsylvania State University, University Park, PA 16803, hqo@psu.edu.

Laboratory experiments carried out by various researchers during the past decades have shown that organic synthesis by Miller-Urey reactions or related mechanisms is not likely to have occurred if the prebiotic atmosphere was neutral or weakly reducing (i.e., CO2>CH4 N2>NH3, SO2>H2S, and H2>O2) Formation of a significant amount of complex organic molecules (i.e., tholins, amino acids, carboxylic acids, nitriles, and hydrocarbons) in the atmosphere requires methane as the main carbon bearing gas and an energy source (e.g., sparks, plasma- and electromagnetic discharge, and/or nuclear particles).

Our laboratory approach is consistent with theoretical investigations on the chemistry of pre-biotic atmosphere and oceans by Ohmoto and Menor-Salvan (see the accompanying paper). The aim is to investigate the fate of organic molecules, which were synthesized in methane-rich atmospheres by spark discharges, in Fe2+rich aqueous solutions. The atmospheres was varied in the CH4/N2/H2 ratios: 100/0/0, 10/90/0, 30/70/0, 50/50//0, and 40/30/30. Temperature of the atmosphere was thermostatized at room temperature. Organic molecules formed in the atmosphere continuously fell on a pool of liquid water (i.e., a simulated ocean) that contained either 0 or 10 mM of aqueous Fe2+. Temperature of the “ocean” was regulated at 0, 25, or 50°C. Aliquotes of the gas and solution were withdrawn every 3 (or 5) hours and analyzed for compositions using gas chromatography coupled with mass spectrometry. The chromatographic analysis was performed using a Hewlett Packard PLOT/Q GC column installed in a Turbomass Perkin Elmer GCMS system.

Our results indicate that the production of organic molecules in the atmosphere was dependent primarily on the partial pressure of CH4. However, for the production of HCN, N2 is necessary. Dominant products in the atmosphere acetylene and their volatile polymers (diacetylene), unsaturated hydrocarbons (dominated by ethylene, 1-propene, but-1-en-3-ine and 1,3-butadiine), hydrogen cyanide, acetonitrile and acrylonitrile. Gasphase reactions were nearly completed in the first 3-5 hours, which were subsequently followed by the formation of polymeric materials in aqueous or solid phase when the water was free of iron.

In contrast, presence of iron (II) in solution is found to destabilize hydrogen cyanide and acetylene that formed in the atmosphere. A previous study in our laboratory [1] showed that aqueous ferrous iron de-

creased the amounts of amino acids and polymeric materials which were formed by sparking methane/nitrogen/hydrogen atmospheres. Our results suggest that the main reason for preventing the organic molecules to increase polymerization in Fe-rich aqueous solutions is due to sequestration of cyanide by the formation of iron ferrocyanide (Fe4[Fe(CN)6]3, Prussian blue). Therefore, Fe2+-rich oceans are not favorable environments for a chemical evolution scenario based on atmospheric generation of organics. Furthermore, if the pre-biotic oceans had been Fe2+-rich, most of C and N in the atmosphere would have been sequestred as ferrocyanide, which would have resulted in reducing the amounts of C available for formation of acetylene and other unsaturated hydrocarbons.

Results of our experimental study support the idea that in an environment dominated by Fe-poor oceans, the classical Urey-Miller based prebiotic chemistry in a reducing atmosphere that was rich in CH4, N2 and H2 could be a significative contribution for the chemical evolution and life emergence on Earth.

Reference: [1] Ruiz-Bermejo, M.; Menor-Salván, C., Osuna-Esteban, S.; Veintenillas-Verdaguer, S. The effects of ferrous and other ions on the abiotic formation of biomolecules using aqueous aerosols and spark discharges. Orig. Life Evol. Biosph 37(6): 507-521 (2007)

Astrobiology Science Conference 2010 (2010)

5473.pdf

ORIGIN OF LIFE IN FE-POOR OCEANS UNDER A CH4-RICH AND SO2-POOR ATMOSPHERE: I. THEORETICAL APPROACH. Hiroshi Ohmoto1 and Cesar Menor Salván2. 1 Penn State Astrobiology Research Center & Department of Geosciences, The Pennsylvania State University, University Park, PA 16803, hqo@psu.edu, 2Centro de Astrobiologia, INTA-CSIC, Citra Ajahvir km. 4, 28850 Torrejón de Ardoz, Spain.

Current popular theory for the pre-biotic Earth postulates a weakly reducing atmosphere (CO2>CH4 N2>NH3, SO2>H2S, and H2>O2), which would have prevented organic synthesis through the Urey-Miller related reactions based on CH4 as the carbon source.

This theory was developed mostly on the assumptions that: (i) the atmospheric chemistry on early Earth was dictated primarily by volcanic emissions, (ii) composition of the average volcanic gas has remained essentially the same throughout geologic history, and (iii) UV photolysis of volcanic SO2 produced the anomalous isotopic fractionation of sulfur (AIF-S) in Archean sedimentary rocks. Most geologists have also assumed that the Archean oceans were rich in Fe, derived by submarine hydrothermal fluids on mid ocean ridges, to produce banded iron formations.

However, recent geological and geochemical investigations by various researchers have raised a serious question regarding the validity of these assumptions.

For example, most H2O, C, N, and S on Earth may have been delivered >50 Ma after the accumulation of metals. Volcanic emission on the pre-biotic Earth probably occurred mostly under the oceans, rather than on land as today, because the land area was probably <20% of today. The typical fO2 values of pre-biotic magmas were probably 1±1 log unit below those of the fayalite+magnetite+quartz (FMQ) buffer, whereas those of modern subaerial volcanic gases are typically 1±1 log unit above FMQ. The AIF-S signatures in sedimentary rocks may have been produced by chemisorption reactions involving aqueous sulfate, H2S, organic matter and a variety of minerals during the early diagenesis of sediments under hydrothermal conditions, rather than by atmospheric UV reactions.

Using thermochemical data, we have computed gas-fluid speciation in the H-O-C-S-N-Fe system as a function of T (1400-200°C), PH2O (1000-1 bar), and fO2 (FMQ-3 to FMQ+3); an important constraint on the sulfur chemistry is the presence of pyrrhotite (FeS) in most igneous rocks. The results suggest that volcanic inputs to the pre-biotic atmosphere-ocean were dominated by reducing gases: H2>H2S>>SO2; CH4>CO2>CO; and NH3≈N2. We have demonstrated in the laboratory that Urey-Miller type organic synthesis readily occurs in atmospheres comprised of these reducing gases.

Our calculations also suggest that submarine hydrothermal fluids contain excess H2S over heavy met-

als (= Fe+Cu+Zn+Pb) at T >~250°C. Mixing of such fluids with O2-poor pre-biotic oceans would have resulted in the precipitation of all the heavy metals as sulfides (and carbonates) at sites of fluid discharge, whereas significant amounts of Fe precipitates as goethite in modern oceans. The excess H2S from the submarine hydrothermal fluids would have reacted with oceanic basalts at lower temperatures to form additional FeS and FeS2. Therefore, the pre-biotic oceans were likely to have been poor in both Fe and H2S. This is important for the origin of life, because our laboratory experiments have shown that polymerization of organic molecules to build complex organic molecules is inhibited by the presence of Fe2+ in water.

The effects of Fe in organic synthesis will be further discussed in an accompanying paper by Menor Salvan and Ohmoto.

Our study supports the atmospheric-synthesis scenario proposed by Urey-Miller for the origin of life on Earth.

A266

Goldschmidt Conference Abstracts

Critical influence of biogenic sulfur in the genesis of giant VHMS, Iberian Pyrite Belt

Cosmogenic-based physical and chemical denudation rates in the Idaho Batholith

D.C. FERNÁNDEZ-REMOLAR1, C. MENOR-SALVÁN1, MARTA RUÍZ-BERMEJO1, RICARDO AMILS1,2 AND F. TORNOS3

KEN L. FERRIER1,2, JAMES W. KIRCHNER1,3,4 AND ROBERT C. FINKEL2,1

1

Centro de Astrobiología (INTA-CSIC), Ctra Ajalvir km 4, 28850 Torrejón de Ardoz, Spain (fernandezrd@inta.es) 2 Centro de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, Spain 3 Instituto Geológico y Minero de España, c/Azafranal 48, 37001 Salamanca, Spain (f.tornos@igme.es) During the late Devonian-early Carboniferous, the Iberian Pyrite Belt was the loci of widespread hydrothermal activity and formation of volcanogenic massive sulfide deposits, making it the largest concentration of massive sulfides in the earth’s crust [1, 2]. The formation of these massive sulfides is currrently associated to subseafloor to seafloor precipitation by mixing of sulfur-depleted, metal-rich deep hydrothermal fluids of likely basinal derivation with seawater rich in biogenically derived reduced sulfur [2, 3]. Exhalative massive sulfides are better formed and preserved in anoxic oceanic bottoms, mainly three order basins filled with hydrothermal brines, i.e., brine pools [4]. The sulfides will result from the interaction of H2S, being produced through biogenic sulfur reduction, and the exhalated cations (H2S + M2+ → MS). This process demands reduced sulfur that can be mediated through Sulfur Reducing Bacteria. However, several questions remains unasked as the electron donor which would drive the reduction from SO4= to H2S. The combination of several evidences as the presence of organics (including pristane and phytane), mineral association to siderite and microbial structures and the low δ34S values suggest that the massive sulfides were produced by microbial activity as proposed in [3] and can shed light in those biogeochemical processes involved in the sulfide production.

[1] Leistel et al. (1998) Miner. Dep. 33, 2-30. [2] Tornos (2006) Ore Geol. Rev. 28, 259-307. [3] Tornos & Heinrich (2008) Chem. Geol. 247, 195-207. [4] Solomon et al. (2002) Geology 30, 87-90.

1

Department of Earth and Planetary Science, University of California, Berkeley, USA, 94720 (ferrier@eps.berkeley.edu, kirchner@eps.berkeley.edu) 2 Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA, 94550 (finkel1@llnl.gov) 3 Swiss Federal Institute for Forest, Snow, and Landscape Research (WSL), Birmensdorf, Switzerland 4 Department of Environmental Sciences, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland Chemical weathering plays a prominent role in many biogeochemical and geomorphological processes, supplying nutrients to soils and streams, promoting soil production, and drawing down atmospheric carbon dioxide. Rates of chemical weathering and physical erosion are thought to be coupled to one another, because rates of chemical weathering may depend on the rate at which physical erosion supplies fresh minerals to the soil, and rates of physical erosion may depend on the rate at which chemical weathering weakens bedrock and aids soil production. Several studies have found that chemical weathering rates are positively correlated with physical erosion rates, although the relationship varies substantially between studies.

Along two elevation transects in the deep, steep canyon of the South Fork of the Salmon River in the granitic Idaho Batholith, we have measured total denudation rates using 10Be concentrations in soil-borne quartz, and have split these rates into their physical and chemical components based on concentrations of chemically immobile zirconium in soil and parent rock. These rates are averaged over the long timescale of 10Be accumulation in soil-borne quartz, which at our field sites ranges from 5,000 to 26,000 years. Across our field sites chemical denudation rates (W) range from -5 ± 8 to 30 ± 4 t km-2 yr-1 and physical erosion rates (E) vary by more than a factor of four from 49 ± 4 to 218 ± 19 t km-2 yr-1. Most of our measurements are consistent with a power-law relationship between W and E, but several of the more rapidly eroding sites have slower chemical denudation rates than this relationship would predict, suggesting that chemical denudation rates at these sites may be damped by non-erosional factors (e.g., climate, vegetation) or that chemical denudation rates may in fact decrease as physical erosion rates approach limiting rates of soil production.

A620

Goldschmidt Conference Abstracts

Impact of sulfide separation on Ag and Mo budgets in arc magmas

Biomarkers preserved in fluid inclusions in quartz from the Berbes fluorite deposit (N Spain)

M.J. MENGASON*, P.M. PICCOLI AND P.A. CANDELA LMDR, Department of Geology, University of Maryland, College Park, MD 20742, USA (* correspondence: mengason@geol.umd.edu) To understand the impact of sulfide separation on the metal budgets of Ag and Mo in arc magmas, experiments have been performed on the partitioning of these metals among pyrrhotite, a rhyolitic melt, and an immiscible Fe-S-O liquid.

Previous experimental work on the partitioning of pyrrhotite and chalcopyrite with respect to Cu and Au in magmatic settings relevant to intrusion-related hydrothermal ore deposits, show a strong potential for the depletion of these metals by the segregation of the sulfide phases from silicate melts [1, 2, 3]. This sequestration of metals in sulfides may play a role in determining the relative abundances of these metals in associated deposits, or possibly even preclude ore formation. Evacuated sealed silica tube experiments were performed at 1042°C, log fO2 between FMQ and NNO, and log fS2 = -1bar. Partition coefficients for Ag and Mo between pyrrhotite and silicate melt (Ag 58±8 [1σSDOM]; Mo 35±3), and between Fe-S-O liquid and silicate melt (Ag 120±20; Mo 90±10) have been determined. Uncertainties represent one standard deviation of the mean. Based on these values, limits may be placed on the proportion of the initial metal budget that may be removed by the segregation of these sulfides.

During Rayleigh fractionation (F=0.1) where sulfides compose 0.1wt% of the assemblage, pyrrhotite would sequester Ag (13%) and Mo (8%) less effectively that the Fe-S-O melt (24% and 19% respectively). Although these reductions might lead to variations in the tenor of associated ore they appear to be unlikely to significantly inhibit ore formation on their own.

However if the magma metal budget is augmented through interactions with other magmas or by the assimilation of reduced sulfide-bearing sediments, the effects would be enhanced. Under the same conditions with 0.3wt % sulfides, po could remove 33% of the Ag and 21% of the Mo, whereas Fe-S-O melts could remove 51% of the Ag and 46% of the Mo. This suggests that exogenous additions of sulfur to arc magmas can affect their ore metal budgets.

[1] Jugo et al. (1999) Lithos 46, 573-589. [2] Lynton et al.

(1993) Economic Geology 88,s 901-915. [3] Simon et al.

(2007) Geochimica et Cosmica Acta 71, 1764-1782.

C. MENOR-SALVÁN1, F. TORNOS2, M. RUIZ-BERMEJO1, D. FERNÁNDEZ-REMOLAR1 AND R. AMILS1 1

Centro de Astrobiología (INTA-CSIC), Ctra Ajalvir km 4, 28850 Torrejón de Ardoz, Spain (menorsc@inta.es) 2 Instituto Geológico y Minero de España, c/Azafranal 48, 37001 Salamanca, Spain (f.tornos@igme.es) The Cantabrian Zone in North Spain includes several stratabound to vein-like fluorite deposits, forming a significant MVT district. The fluorite deposits replace Paleozoic limestone which are associated to an aureole of hydrothermal alteration including dolomitization and silicification. They are interpreted as formed from the reaction of deep basinal brines with limestone, with some mixing with coeval seawater. The outer hydrothermal aureole includes abundant euhedral quartz crystals hosting abundant and large fluid inclusions that are frequently infilled with hydrocarbons. The analysis of the hydrocarbons reveals the presence of biomarkers: acyclic isoprenoids, polycyclic isoprenoids and fatty acid esters.

Specifically, we found squalene, phytol and phytene, evidencing low maturation of organics.

Phytol

Sq Hopanoids Wax esters

Figure 1: GC/MS chromatogram (total ion count) of hydrocarbon inclusions in quartz from Berbes. Sq: squalene.

These results suggest that the hydrocarbons included in quartz source well preserved biomarkers which be of great interest for early Earth biosphere and planetary studies.

The genesis of these hydrocarbons is probably related with (a) dolomitization of the host rocks, or (b) hydrothermal degradation of underlying shale. Speculative, these processes would lead to the formation of nearby gas and oil fields.

International Journal of Astrobiology 6 (1) : 59–87 (2007) Printed in the United Kingdom doi:10.1017/S1473550407003679 f 2007 Cambridge University Press

European Astrobiology Network Association 2006 Meeting EANA – European Astrobiology Network Association 16–18 October 2006 Lyon, France

Early Earth Why on Earth ?

F. Albare`de LST, Ecole Normale Supe´rieure de Lyon, 46 Alle´e d’Italie, 6964 Lyon Cedex 7, France, e-mail: albarede@ens-lyon.fr The most troubled period of Earth’s history extends from the end of planetary accretion to the onset of plate tectonics: it is certainly the most important for understanding the origin of life but also still the most confusing for its near complete lack of observations.

Fundamental uncertainties arise both with the sequence of geodynamic processes that eventually lead to the triumph of plate tectonics and life and with the timing of events. The first issue is the very existence of a terrestrial magma ocean. The upper mantle of the early Earth must have been molten to depths in excess of 500 km by the release of the gravitational energy of planetary accretion, which includes the Moonforming impact and core segregation. However, this concept has been broadly rejected by geodynamicists for over 15 years on the ground that the major solid silicates (olivine, pyroxenes, and garnet) are denser than the magmas they crystallize from, while the role of buoyant plagioclase remains limited by the strong gravitational field of the Earth. This view holds that barren magma exposed to the surface quickly looses its heat by radiation into space and the Earth freezes in less than a million years. Evidence of 142Nd anomalies created by the extinct radioactivity of 146Sm (T1/2=103 My) gathered over the last three years showed this view to be incorrect and that a molten mantle existed until some 30 My after the formation of the nebula, a timing which happens to coincide with core segregation. The crux is likely to be the presence of a hydrosphere, which is unlikely to originate by outgassing of the Earth’s magma ocean: terrestrial material lost most of its volatile elements (e.g. 85 % of its K) and the interior of the planet certainly emerged bone-dry from the early stages of accretion. Water was therefore introduced from the outer Solar System at a late stage by the perturbing effect of giant planets on the orbits of icy objects. Water reacts with magmas and solid rocks to form hydrous minerals with low densities (serpentine, talc, and amphibole), which accumulated as a protective crust. Such a conductive boundary layer on top of the magma ocean extended the life of the magma ocean by a few tens of millions of years. An additional characteristic of the presence of water is the massive liberation of H2 upon oxidation of ferrous iron and its ensuing reaction with CO2 to produce CH4 and NH3. A remarkable incidence of these processes on the origin of life is the formation of prebiotic molecules. A second issue is how and when the Earth’s dynamic regime morphed into plate tectonics (or at least some early form of it) and why it did not bifurcate into a Mars-type regime of a thick lithospheric lid stagnant over the convective mantle, a situation far less propitious to create a biotic environment. Abundant granites are the hallmark of plate tectonics because they cannot be melts of the mantle and necessitate wet basalts as source rocks. Zircons are ubiquitous in granites but are highly soluble in basaltic melts. The discovery of

4.0–4.4 Gy old zircons in Jack Hills sandstones (Australia) therefore appears as smoking-gun evidence that at least some true granites existed, while their 176Hf isotope compositions indicate that the source of these granites (presumably hydrous basaltic rocks) formed very early in the Earth’s history. Continents rising above sea level constitute the major renewable source of nutrients (nitrate, phosphate) essential to maintaining life. This does not necessarily mean that continents were as widespread then as they are today and the case has recently been made that the rise of chlorophyll stepped up the capture of Solar energy, thereby increasing the rate of weathering and indirectly affected the rate of continental crust production. Conservatively, the point can be made that some continental crust existed by 4.3 Gy and that ‘a lot’ of it had come into existence by the time of the Isua rocks (3.85 Gy ago). Plate tectonics and life share water as a common thread, and water owes its presence on Earth to the strong gravitational field of the planet.

From suns to life : a chronological approach to the history of life on Earth M. Gargaud(1), D. Despois(1), F. Albare`de, J. C. Augereau, L. Boiteau, M. Chaussidon, P. Claeys, E. Douzery, P. Forterre, M. Gounelle, A. Lazcano, H. Martin, M. Marty, P. Lo´pez-Garcı´a, M. C. Maurel, T. Montmerle, A. Morbidelli, D. Moreira, R. Pascal, D. Pinti, J. Pereto, D. Prieur, J. Reisse, F. Selsis, M. Van Zuilen (1) Observatoire Aquitain des Sciences de l’Univers, L3AB, BP89, 33270 Floirac, France, e-mail: gargaud@obs.u-bordeaux1.fr We present, in a synthetic chronological frieze, the various events considered by the authors as relevant to the origins of life on Earth.

These events have been tentatively ordered chronologically in accordance with actual knowledge within all the scientific disciplines involved in astrobiology. This frieze was originally published in November 2006 in a topical issue of Earth, Moon and Planets1 gathering nine articles written by 25 scientists (astronomers, geologists, biologists, and chemists) who have attempted to share their specialized knowledge concerning a common question: How did life emerge on Earth? Their ultimate goal was to provide an initial answer as a prerequisite to an even more demanding question: Is life universal? By adopting a chronological approach to the question of the emergence of life on Earth (the only place where we know for sure that life exists, even though nobody agrees on the general definition of ‘life’), it was possible to break down this question into several sub-questions that can be addressed by different disciplines. After an introduction, the main chapters of this review cover the following: the formation and evolution of the Solar System; the building of an habitable planet; prebiotic chemistry, biochemistry, and the emergence of life; the environmental context of the early Earth; the ancient fossil record and early evolution. The concluding chapter summarizes the highlights of

59

EANA 2006 Lyon Abstracts and simulated Mars conditions. The methanogenic archaea in pure cultures as well as in their natural environment of the Siberian permafrost represent high survival potential under these extreme conditions.

In contrast, these conditions were lethal for the reference organisms from non-permafrost habitats1,2. Our data suggest that in the scenario of subsurface lithoautotrophic life on Mars methanogenic archaea from Siberian permafrost could be used as an appropriate candidates for possible life on Mars.

1 Morozova, D. & Wagner, D. (2006). Stress response of methanogenic archaea from Siberian permafrost compared to methanogens from nonpermafrost habitats. FEMS Microbiol. Ecol. (submitted).

2 Morozova, D. et al. (2006). Survival of methanogenic Archaea from Siberian permafrost under simulated Martian thermal conditions.

Origins Life Evol. Biosph. (in press).

Halophiles from rock salt – a promising model for the search for extraterrestrial life?

G. W. Weidler, F. W. Gerbl, M. Pfaffenhuemer, C. Gruber, H. Stan-Lotter University of Salzburg, Department of Molecular Biology, Division of Microbiology, A-5020 Salzburg, Austria, e-mail: gerhard.weidler@sbg.ac.at Halophiles isolated from Permian rock salt might be promising model organisms for the search for extraterrestrial life, owing to the discovery of halite in meteorites, salts on Mars and the fact that several viable microorganisms have been isolated from Permo-Triassic rock salt (age 195 to 250 million years)1. In most cases these strains belong to the extremely halophilic Archaea. Two major strategies for the estimation of microbial community composition in ancient rock salt were used.

First, diversity was determined by molecular methods such as 16S rRNA gene amplification, clone library construction and phylogenetic analysis2. Second, a culture-dependent approach was started in 1999 with rock salt obtained from alpine salt mines. In this work 135 isolates have been examined with restriction fragment length polymorphism (RFLP) analysis of 16S rRNA gene fragments and with pulsed field gel electrophoresis (PFGE), as well as S1 Nuclease-PFGE to identify putative megaplasmids. It was possible to arrange all isolated strains into three groups according to RFLP patterns. Two RFLP groups were closely related to Halococcus sp. and one group was related to Halobacterium sp. PFGE and S1-PFGE analyses showed, according to whole genome restriction analysis and the presence of putative megaplasmids, that diversity is broader than RFLP analysis showed. Our results show that the diversity of cultivable organisms is, as expected, small, but examination of isolates by molecular methods showed that the closely related strains are more diverse than previously thought.

1 Stan-Lotter, H. et al. (2003). Int. J. Astrobiol. 1(4), 271–284.

2 Radax, C., Gruber, C., Stan-Lotter, H. (2001). Extremophiles 5, 221–228.

Growth of microorganism populations under experimental modelling of Martian and cometary nucleus subsurface conditions A. K. Pavlov(1,3), V. N. Shelegedin(2), M. A. Vdovina(1), A. V. Tretyakov(1) (1) Ioffe Physico-Technical Institute, St. Petersburg, Russia, e-mail : mariya.vdovina@mail.ioffe.ru; (2) St. Petersburg Polytechnical State University, St. Petersburg, Russia; (3) Russian Astrobiology Center, St. Petersburg, Russia Modern environmental conditions on Mars and cometary nuclei prohibit the existence of liquid water on the surface layer of Martian soil and cometary mantles because of extremely low atmospheric pressure.

However, according to observational data, a large amount of water ice is present in the Martian and cometary subsurface. In both cases the ice is subject to intensive sublimation if the surface is heated by Sunlight.

The surface layer which diffusion goes through is a porous material with a poor admixture of organic matter for Mars and high admixuture of organic for comets. In our experiment, we used a special vacuum

chamber in order to model the process of ice sublimation and vapour diffusion under heating. In order to model these processes we used a water ice sample covered by several centimetres of sand containing organic matter. Intensive sublimation was provided by radiation heating of the sand’s surface. We studied the possibility of the active growth of microorganisms in the vapour diffusion layer. Bacteria Vibrio sp. X were added to the sand. We performed several three-day experimental runs of the intensive sublimation of ice. As a result, we have recorded an increase of the bacterial population after each run. These results confirm the possibility of active metabolism and even reproduction of microorganisms under Martian and cometary surfaces.

Application of Solid-Phase Micro-Extraction (SPME) in the analysis of biomarkers in geological samples C. Menor-Salva´n, M. Ruiz-Bermejo, S. Osuna-Esteban, S. Veintemillas-Verdaguer National Institute for Aerospace Technology (INTA), Spain, e-mail: menorsc@inta.es Biomarkers are organic indicator compounds that could be used as tracers for geological and environmental processes1. These organic compounds can unambiguously be linked to a known biological precursor and include mainly hydrocarbons (derived from lipids and pigments), fatty acids and long-chain ketones and alcohols. Authors usually use the solid–liquid extraction of the samples as separation step, prior to the analysis of biomarkers by instrumental and chromatographic techniques. The properties of biomarker compounds are appropriate for the use of SPME as preparative step in the analytical process. It is a solvent-free technique that enables extraction and concentration steps simultaneously, using small quantities of the rock or sediment sample and allows the later application of classic extraction techniques in the same sample. SPME, coupled with GC-MS, has a higher efficiency and sensitivity than classic liquid extractions, reduces the process time and increases the cleanness of the technique. We used the SPME technique successfully for the organic analysis of natural samples with different geology and age and we found it applicable in the routine organic speciation of geological samples.

1 Simoneit, B. (2005). Mass Spectrom. Rev. 24, 719–765.

Light- and electron-microscopic analysis of Haloarchaea embedded in Austrian rock salt M. Dornmayr-Pfaffenhuemer(1), T. J. McGenity(2), M. N. Spilde(3), P. J. Boston(4), H. Stan-Lotter(1) (1) Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020 Salzburg, Austria, e-mail: marion.pfaffenhuemer@sbg.ac.at; (2) Department of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK; (3) Institute of Meteoritics, MSC03 2050, 1 University of New Mexico, Albuquerque, NM 87131-0001, USA; (4) Department of Earth & Environmental Science, New Mexico Tech, Socorro, NM 87801, USA Subsurface salt mines, such as those in Bad Ischl and Altaussee, Austria, are examples of sites where extremophilic microorganisms can be found. The most recent isolates from these salt mines are Halococcus dombrowskii1 and Halobacterium noricense2. In order to understand how these microorganisms are able to survive long periods of time embedded within sediments it is necessary to analyse the fine structures and the average chemical composition of the minerals where they were isolated. In this study a JEOL 8200 Electron Microprobe and a JEOL 5800LV SEM equipped with an Oxford Analytical ultrathin-window EDS and an Oxford Isis 300 X-ray analyser were used to analyse the ultrastructure and chemical composition of 250 million year old rock salt. The mineral structures, which occur at grain boundaries and in fluid inclusions, were examined for their significance as possible microbial habitats. In addition, haloarchaeal cells were embedded within salt crystals under laboratory conditions and subsequently analysed by light microscopy. The mineral structures of the ancient rock salt were examined for their significance as possible microbial habitats. Liquidfilled structures such as clay particles, fluid inclusions and grain boundaries are present; the chemical analysis of the liquid composition

69

80

EANA 2006 Lyon Abstracts temperatures below 500 xC in several active tectonic settings.

Biogeochemically, the process is important because it leads to reduction of H2O to H2. At the same time, catalytically active compounds such as magnetite are formed. H2 may be used together with CO2 and magnetite as a catalyst in Fischer–Tropsch Type (FTT) reactions. FTT processes may lead to the formation of CH4 as well as heavier hydrocarbons and other abiotic organic compounds. Serpentinization at temperatures below 300 xC is associated with high pH (pH 10–12). It is possible that the high pH may promote the formose reaction in natural environments and the abiotic formation of pentoses such as ribose, the carbohydrate constituent of RNA. Pentoses, and ribose in particular, are stabilized by borate that is scavenged from seawater by brucite – magnesium hydroxide that is yet another product of serpentinization reactions.

Origin of homochirality in an early peptide world A. Brandenburg(1,2), H. Lehto(1,3), K. Lehto(1,4) (1) Nordita, Blegdamsvej 17, DK-2100 Copenhagen, Denmark, e-mail : brandenb@nordita.dk; (2) AlbaNova University Center, 10961 Stockholm, Sweden; (3) Tuorla Observatory and Physics Department, University of Turku, Finland, e-mail: hlehto@utu.fi ; (4) Plant Physiology and Molecular Biology Laboratory, University of Turku, Finland, e-mail: klehto@utu.fi Life on Earth has chosen one of two possible chiral forms: amino acids left handed, and sugars right handed. Life may very well have been the other way around, and maybe it is actually the other way for some alien life forms still to be discovered. In our talk we review various approaches to achieving full homochirality, focusing mainly on the polycondensation of peptides but also addressing the polycondensation of polynucleotides. In the latter, autocatalysis and enantiomeric crossinhibition play key roles1,2, whilst in the former activation and epimerization are crucial3. The latter possibility may have been more relevant for the prebiotic chemistry on the early Earth, either in the porous structures in hydrothermal vents or in drying and wetting beach scenarios. This scenario may also be more readily amenable to laboratory investigations. The model captures effects similar to autocatalysis and enantiomeric cross-inhibition without, however, producing unreactive ‘waste’ product4. Finally, the spreading of chirality on the early Earth is discussed by solving a set of reaction-diffusion equations based on a polymerization model. It is found that effective mixing of the early oceans is necessary to reach the present homochiral5.

1 Sandars, P. G. H. (2003). Origins Life Evol. Biosphere 33, 575–587.

2 Brandenburg, A. et al. (2005). Origins Life Evol. Biosphere 35, 225–242.

3 Plasson, R., Bersini, H. & Commeyras, A. (2004). Proc. Natl Acad.

Sci. 101, 16 733–16 738.

4 Brandenburg, A., Lehto, H. & Lehto, K. (2006). Homochirality in an early peptide world. Astrobiology (submitted), http://arxiv.org/abs/ abs/q-bio/0610051.

5 Brandenburg, A. & Multama¨ki, T. (2004). Int. J. Astrobiol. 3, 209–219.

Photolysis of mixtures of gases containing cyanoacetylene or cyanubutadiyne Y. Trolez, J. Jeftic, J.-C. Guillemin Sciences Chimiques de Rennes, UMR 6226 CNRS-ENSCR, 35700 Rennes, France, e-mail : jean-claude.guillemin@ensc-rennes.fr Nitriles and particularly unsaturated nitriles play a determining role in —N) has been observed —C—C— Astrobiology. Cyanoacetylene 1 (H—C— in the atmosphere of Titan, in comae, in the Interstellar Medium (IM) and in numerous lab simulations of Planetary Atmospheres. The first —C—C— cyanopolyyne, cyanobutadiyne 2 (H—C— —C—C— —N), has been detected in the IM and in lab simulations of the atmospheres of Titan and the Primitive Earth. Several approaches leading to mixtures of products have been reported to detect it and to record its spectra1–3.

We have recently reported the first preparative synthesis of cyanobutadiyne 24. The photolysis of compounds 1 and 2 could have played a very important role in the formation of many compounds in the IM, in

comae or planetary atmospheres including the Primitive Earth. The photolysis of cyanoacetylene by itself or with various other gases has been reported5,6. Tricyanobenzenes and tetracyanocyclooctatetraenes have been obtained as well as the corresponding 1,4-adduct or diadduct with ammonia, phosphine (PH3), silane (SiH4), H2S, alkynes or alkenes.

Performing the same photolysis in gaseous phase with cyanobutadiyne 2 instead of cyanoacetylene 1, we have never been able to detect an adduct except with thiols. Even if the vapour pressure of cyanobutadiyne 2 is low at room temperature, very small quantities of vinylic or aromatic compounds can be easily detected by 1H NMR spectroscopy.

Similarly, the kinetic instability of cyanobutadiyne, which is much more important than the one of cyanoacetylene 1, cannot be proposed as an explanation, cyanobutadiyne being still easily observed in all the photolyzed samples.

1 Alexander, A. J., Kroto, H. W. & Walton, D. R. M. (1976). J. Mol. Spectrosc. 62, 175–180.

2 Haas, S., Winnewisser, G. & Yamada, K. M. T. (1994). Can. J. Phys.

72, 1165–1178.

3 Bizzocchi, L., Degli Esposti, C. & Botschwina, P. (2004). J. Mol. Spectrosc. 225, 145–151.

4 Trolez, Y. & Guillemin, J.-C. (2005). Angew. Chem. Int. Ed. 44, 7224–7226.

5 Ferris, J. P. & Guillemin, J.-C. (1990). J. Org. Chem. 55, 5601.

6 Guillemin, J.-C. et al. (1998). Chem. Eur. J. 4, 1074.

3-Amino-2-propenenitrile J.-C. Guillemin Sciences Chimiques de Rennes, UMR 6226 CNRS-ENSCR, 35700 Rennes, France, e-mail : jean-claude.guillemin@ensc-rennes.fr Cyanoacetylene has been observed in the Interstellar Medium, in comae, in Titan and in many simulations of planetary atmospheres. The presence of ammonia on the Primitive Earth has been the subject of strong debates. However, many compounds postulated as precursors or building blocks (a-aminonitriles, aminoacids etc.) easily give ammonia on hydrolysis or heating. Cyanoacetylene quickly and easily reacts with ammonia to form 3-amino-2-propenitrile in very good yields. In the area of Exobiologie, studies on 3-amino-2-propenitrile have been dramatically underinvestigated. We have developed a quite general study on the chemistry of 3-amino-2-propenenitrile1–3. We demonstrated particular properties on the chemistry, acidity and basicity in gas phase of this compound2. On the hypothesis that this compound could be formed in the IM or planetary atmospheres, we recorded its gas-phase infrared1 and microwave spectra3 to allow its detection in planetary atmospheres or in the Interstellar Medium.

1 Benidar, A. et al. (2005). J. Phys. Chem. A. 109, 4705–4712.

2 Luna, A. et al. (2006). Gas-phase protonation and deprotonation of cyanovinyl compounds. Chem. Eur. J. (in press).

3 Askeland, E. et al. (2006). Microwave spectrum, structure and quantum chemical studies of a compound of potential astrochemical and astrobiological interest: Z-3-Amino-2-propenenitrile. J. Phys.

Chem. A. (in press).

Effects of Fe (II) in the formation of biomolecules in simulations experiments using spark discharges and aqueous aerosols M. Ruiz-Bermejo, C. Menor Salva´n, S. Veintemillas Verdaguer Centro de Astrobiologı´a (CSIC-INTA), Carretera Torrejo´n-Ajalvir, Km. 4,2, E-28850 Torrejo´n de Ardoz, Madrid, Spain, e-mail : ruizbm@inta.es The emergence of life is one of the most puzzling scientific problems. In this context, it has been proposed that aerosols played a major role on the origin of life on the Archean Earth. On the other hand, it is postulated that ancient sea had a salinity of 1.5 to 2 times the modern value, a pH=5–10 and the presence of the banded iron formations show that dissolved iron was present in excessive quantities in the early Earth.

Our experimental approach to synthesize abiotically organic molecules with biological interest consist in the simulation of an aqueous aerosol

EANA 2006 Lyon Abstracts in a plausible prebiotic atmosphere (CH4, N2 and H2) and in a plausible ancient sea (pH=5.8, salinity about 2 times the modern sea and Fe+2 0.01 M) and the simulation of storms using spark discharges. Using different sources of Fe (II) (FeCl2, FeCO3 or FeS) we observed the formation of some amino acids, hydroxy acids, di- and tri-carboxylic acids and heterocycles involved in biological process. Indeed, the presence of dissolved Fe+2 in our simulation experiments generates the formation of Prussian Blue, Fe4[Fe(CN)6]. This inorganic salt could be an important reservoir of HCN in the initial prebiotic conditions of Earth. However, in the experiments carry out in presence of insoluble FeS the formation of Prussian Blue is not observed but amino acids containing S are detected.

Chemical effects of gas–water interface: analysis and structural characterization of complex materials obtained from a CH4/N2/H2 atmosphere and an aqueous aerosol

M. Ruiz-Bermejo, C. Menor-Salva´n, E. Mateo-Martı´, J. A´ngel Martı´n-Gago, S. Veintenillas-Verdaguer Centro de Astrobiologı´a (CSIC-INTA), Carretera Torrejo´n-Ajalvir, Km. 4,2. E-28850 Torrejo´n de Ardoz, Spain, e-mail: ruizbm@inta.es It has been proposed that aerosols played a major role on the origin of life on the Archean Earth. Our experimental approach consists of the simulation of an aerosol in a plausible prebiotic atmosphere and the simulation of storms using spark discharges. The organic compounds with biological interest (i.e. amino acids, purine bases) are not present per se in the raw collected in simulation experiments otherwise as, generally, unknown precursors. Therefore, it is necessary to characterize the structure of these complex materials in order to clarify the nature of precursors and to find a plausible mechanism of synthesis. We used different spectroscopic techniques (IR, UV-vis, XPS, Solid State 13 C NMR spectroscopy) and other analytical tools (HPLC, GC-MS) to characterize the structure of our products. In our experiment, we obtained one water-soluble fraction (S) and one insoluble fraction (I). The bulk S fractions are constituted by polar units (containing carboxylic acids, amines, alcohols, and nitriles) with different molecular weights. It yields a relatively high amount of amino acids, purines bases and carboxylic acids. We propose the Strecker synthesis as the most likely mechanism in the formation of amino acids under our prebiotic conditions. However, the I fraction is an apolar solid that seems to be formed by large and rigid hydrocarbon chains. The presence of a —C) in the chains could be the punctual unsaturated bond (C—C, C— reason for the rigidity and the amine and hydroxyl group could allow the hydrogen bond among neighbour chains. The oxidative cleavage shows the presence of structures —C—C—C—C—C—.

Studies on prebiotic synthesis and ionophoric activity of model cyclic peptidomimetics K. Adamala(1,2), R. Ostaszewski(1,3) (1) Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland, e-mail: rysza@icho.edu.pl; (2) Faculty of Chemistry, University of Warsaw, Poland; (3) Faculty of Chemistry, Warsaw University of Technology, Poland Selective transport of ions and small molecules across cell membranes is crucial for the origin of the living cell’s homeostasis. Prebiotic synthesis of simple peptides or peptidomimetics must have been essential for formation of ion channels and pores in early cell membranes. We report our attempted synthesis of peptidomimetics with pore-forming activity, performed under prebiotic-like conditions. Synthesis was based on compounds already presented in a prebiotic Earth environment. The key-step of the total synthesis is the Ugi reaction, a four-component condensation reaction between an isocyanide, an amine, a carboxylic acid and an aldehyde, leading to the peptidomimetic structures. These products can be readily cyclized to final ionophoric compound. We suggest that upon proper substrate choice, intramolecular hydrogen bonds can be formed between side chains of amino acid used as

substrates for synthesis of peptidomimetic compounds. This hydrogen bond pattern can be responsible for stereoselective course of Ugi reaction. Ionophoric activity of cyclic compounds is confirmed by the standard mitochondria swelling assay and by data obtained by measuring picrate salts trans-phase transport of target compounds.

Oscillating prebiotic model: the theoretical substantiation and the program for experimental proof V. N. Kompanichenko(1,2) (1) Institute for Complex Analysis, 4 Sholom-Aleyhem Street, Birobidzhan 679016, Russia, e-mail: kompanv@yandex.ru; (2) Department of Chemistry, University of California, 1156 High Street, Santa Cruz, CA 95064, USA Various explored prebiotic models are able to self-complicate under certain conditions. However, the conducted experiments have not led to their transformation into a kind of simplest living units. According to the theoretically elaborated conception1, this transformation is possible through the intermediate stage – formation of oscillating (pulsing) prebiotic microsystem. Such a ‘bistate’ system may originate during non-equilibrium transition of a prebiotic microsystem from the initial into advanced state, in case there appears the balance between the states keeping through the oscillations around the highest ‘bifurcate’ point of transition. The system acquires the paradoxical way of organization – ‘stabilized instability’: the principally unstable point of bifurcation is ‘incorporated’ between two opposite but equal forces.

The regular oscillations to the initial and advanced states give the transformed microsystem the following properties, which are at the foundation of life: incessant inner fluctuations and re-arrangement of molecules; integrity through cooperative events; exchange by matter and energy with the outside world; forked structure consisting of two interrelated co-structures; repulsion of the co-structures from the central point of instability and their dichotomy at the end of cycle of the existence, etc. Experimenters are invited to begin experiments in this way. The aim of the experimental research is to obtain oscillating prebiotic microsystems, which are able to evolve to life. During the experiments various prebiotic models should be explored at the state of bifurcate transition and under oscillating conditions in experimental chambers.

1 Kompanichenko, V. N. (2004). Frontier Perspectives 13(1), 22–40.

Adsorption and thermal transformation of simple amino acids on oxides J.-F. Lambert, L. Stievano, I. Lopes, L. Piao, D. Costa Laboratoire de Re´activite´ de Surface, UMR 7609, Universite´ Pierre et Marie Curie, 4 Pl. Jussieu, 75252 Paris Cedex 05, France It has long been proposed that the surfaces of oxide materials may have played an important role in promoting and directing the synthesis of oligopeptides from amino acids, on the prebiotic Earth or in interstellar conditions. Mostly macroscopic level results have been obtained so far; the molecular environment of adsorbed amino acids is unknown. In particular, polymerization selectivities are hard to rationalize, so that one cannot evaluate the likelihood of the synthesis of ‘useful’ polymers.

In this study, simple amino acids were adsorbed on high surface area solid oxides (silica, alumina, saponite clay, Al-pillared saponites, goethite) with well-known surface structures. The adsorbed amounts were quantified as a function of pH. The adsorbed amino acids were characterized at the molecular level by vibrational spectroscopy, 13C NMR and DFT modelling. Thermal activation resulted in the clean formation of cyclic or linear dimers depending on water activity. Some hypotheses have to be reconsidered in view of our data. Even in the case of glycine, no less than four molecular environments are observed for the deposited amino acid: bulk a- and b-glycine, molecularly adsorbed zwitterions, and molecularly adsorbed neutral glycine. The systems studied exhibited a more complicated behaviour than anticipated, and thus a wider range of opportunity for the appearance of complex phenomena. Mixtures of two amino acids were also adsorbed on the

81

Goldschmidt Conference Abstracts 2007

A653

Generating the aromatic world: Synthesis of aromatic compounds in icy environments

Dating carbonate rocks with in situ produced cosmogenic 10Be: Why it often fails

C. MENOR-SALVÁN, M. RUIZ-BERMEJO, S. OSUNA ESTEBAN AND S. VEINTEMILLAS VERDAGUER

S. MERCHEL1, R. BRAUCHER1, L. BENEDETTI1, O. GRAUBY2 AND D. L. BOURLÈS1

Centro de Astrobiología (CSIC-INTA). Ctra. Torrejón-Ajalvir km. 4.2, Torrejón de Ardoz. E-28850 (Spain); (menorsc@inta.es)

1

The aromatic hydrocarbons are recognized as astrophysically important molecules and their presece in interstellar ices may contribute to the materials incorporated into planets, satellites, asteroids and comets. Ultimately, PAHs are recognized as key molecules in the study of the origin of life, due to their photochemical properties that could allow to PAHs to play the role of primitive pigment systems that drive synthesis of amphiphilic compounds; assemblies based on aromatic hydrocarbons were proposed as components of informational polymers, containers and mediators in metabolic pathways (1). The disponibility and stability of such aromatic compounds plus their capacity for self-assembly driven by pipi stacking interaction and weak forces made the aromatic hydrocarbons good building blocks for protocellular structures. Indeed, it has been demonstrated that amphiphyllic polycyclic aromatic compounds are capable to self-assemble and form bilayer structures (2). We demonstrate that complex mixtures of aromatic compounds could be synthesized in cold systems with water ice and methane as carbon source. Using spark discharges as energy source and generating a “ice reactor” by means of a cycle of freezing-melting we found benzene derivatives as acetophenone, benzaldehyde and benzonitrile and PAHs.

In situ produced cosmogenic nuclides have proved to be valuable tools for environmental and Earth sciences. Progress in the field of accelerator mass spectrometry (AMS) allows the determination of radionuclide concentrations as low as of 104105 atoms/(g rock) that makes quantifying Earth’s surface processes possible.

However, surface exposure dating of carbonate rocks using the cosmogenic radionuclide 10Be is still problematic. In order to investigate the reasons for this, we have performed extensive step-wise leaching of calcite-rich samples. Results on different grain size fractions clearly indicate the sources of atmospheric 10Be being small clay minerals. We demonstrate that partial-leaching procedures that result in moderate pH levels will not release 10Be (in-situ produced or atmospheric) due to the instant re-absorption on grain surfaces. Under strongly acidic conditions all absorbed atmospheric 10Be is leached from aluminosilicates giving abnormally high 10Be concentrations and consequently exposure ages that are too old (Merchel et al., submitted).

Now, that we understand the main obstacles in analysing 10 Be from carbonate rocks, the next steps are clear: We need to concentrate on samples that do not contain clay minerals.

This might require working on coarser grain size fractions or recrystallized material. Or we need to find a way to physically and/or chemically separate clay minerals from carbonates before dissolving them. This task is most challenging because clay is generally much more resistant to chemicals than carbonate minerals. After testing several analytical methods, i.e. XRD, IR, TEM-SAED, ICP-OES, SEM-EDX, we are still searching for a “simple and fast” method which could quantify clay concentrations in our samples and could help monitoring the efficiency of future separation procedures.

O O acetophenone

O

1-phenyl-1-propanone

O

N benzonitrile benzil

Naphthalene

O

2-methylnaphthalene Benzaldehyde

1-methyl-naphthalene

biphenyl

Figure 1: SPME-GC/MS chromatogram showing main aromatic compounds obtained in an icy environment.

References [1] Ehrenfreund P., Rasmussen J., Cleaves J., Chen L. (2006) Astrobiology 6, 490-520.

[2] Chen L., Geiger J., Perlstein J., Whitten D.G. (1999) J. Phys. Chem. B. 103, 9161-9169.

CEREGE, CNRS UMR 6635, Université Aix-Marseille III, F-13545 Aix en Provence, France (merchel@cerege.fr) 2 CRMCN-CNRS, F-13288 Marseille cedex 9, France

Acknowledgments: We thank I. Schimmelpfennig, L. Palumbo and P.H. Blard for their help during field work.

D. Borschnek is thanked for performing XRD, H. Miche for ICP-OES, and G. Camoin for optical microscopy at CEREGE. We also acknowledge the good collaboration with J. Huth (MPI for Chemistry, Mainz) in respect to SEM-EDX measurements. The AMS measurements at Gif-sur-Yvette would not be possible without G. Aumaître.

References Merchel S., Braucher R., Benedetti L., Grauby O., and Bourlés D.L. (2007), submitted to Quaternary Geochronology.

Ice as matrix for chemical evolution: Synthesis of polycyclic aromatic hydrocarbons in frozen environment by spark discharges.

C. MENOR-SALVÁN, M. RUIZ-BERMEJO, S. OSUNA ESTEBAN AND S. VEINTEMILLAS VERDAGUER. Centro de Astrobiología (CSIC-INTA). Ctra. TorrejónAjalvir km. 4.2, Torrejón de Ardoz. E-28850 (Spain); menorsc@inta.es It has been demonstrated that frozen water is a suitable matrix for high order chemistry, such as the oligomerization of nucleotides[1]. In this work we propose that frozen water with realistic temperature variations could be an attractive model in lower order chemistry, boosting the chemical evolution of the organic molecules synthesized by the effect of spark discharges on a suitable prebiotic atmosphere.

Our experiment creates a melting-freezing cycle of a liquid water pool under a CH4/N2/H2 atmosphere. After the generation of organic matter by means of spark discharges during 72 h, the system was maintained sealed and the melting-freezing cycle stablished during 3 months.

After that, the organic solution in the reactor device was analyzed by solid phase microextraction (SPME) coupled with GC-MS. We found a set of polycyclic aromatic hydrocarbons (PAHs) and other aromatic compounds as acetophenone or benzaldehyde (see figure).

PAHs are recognized as key molecules in the study of the origin of life, due to their photochemical properties i.e. as primitive pigment systems that drive synthesis of amphiphilic compounds [2]; with the freezing-melting cycle, we found a stable environment that could be conductive to the synthesis and accumulation of PAHs and prebiotic organic molecules on Mars, Europa, Titan or early Earth.

References [1] Trinks H., Schröder W., Biebricher C.K. (2005) Origins Life Evol. Biosph. 35, 429-445.

[2] Segré D., Ben-Eli D., Deamer D.W., Lancet D. (2001) Origins Life Evol. Biosph. 31, 119-145.