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Squeezing Blood from a Stone: Inferences Into the Life and Depositional Environments of the Early Archaean

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Squeezing Blood From A Stone: Inferences Into The Life and Depositional Environments Of The Early Archaean Jelte Harnmeijer A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Washington MMX Programs Authorized to Offer Degree: Center for Astrobiology & Early Earth Evolution and Department of Earth & Space Sciences Abstract A limited, fragmentary and altered sedimentary rock record has allowed few constraints to be placed on a possible Early Archaean biosphere, likewise on attendant environmental conditions. This study reports discoveries from three Early Archaean terrains that, taken together, suggest that a diverse biosphere was already well- established by at least ~3.5 Ga, with autotrophic carbon fixation posing the most likely explanation for slightly older 3.7 - 3.8 Ga graphite. Chapter 2 aims to give a brief overview of Early Archaean geology, with special reference to the Pilbara’s Pilgangoora Belt, and biogeochemical cycling, with special reference to banded-iron formation. Chapter 3 reports on the modelled behaviour of abiotic carbon in geological systems, where it is concluded that fractionations incurred through autotrophic biosynthesis are generally out of the reach of equilibrium processes in the crust. In Chapter 4, geological and geochemical arguments are used to identify a mixed provenance for a recently discovered 3.7 - 3.8 Ga graphite-bearing meta-turbidite succession from the Isua Supracrustal Belt in southwest Greenland. In Chapter 5 and 6, similar tools are used to examine a newly discovered 3.52 Ga kerogenous and variably dolomitized magnetite-calcite meta- sediment from the Coonterunah Subgroup at the base of the Pilbara Supergroup in northwest Australia. Possible implications for the origin of texturally similar banded- iron formation, which may represent a silicified analogue, are discussed. In Chapter 7, structures from ~3.45 Ga kerogenous meta-chert in the Barberton Greenstone Belt, and similarly aged neptunian fissures in the Strelley Pool Chert, are interpreted as likely oncoidal trace-fossils indicative of complex microbial biofilm formation in Early Archaean shallow marine environments. No abiotic analogues to these structures are known. Carbon isotope analyses of Early Archaean carbonate, graphite and kerogen from different environments are compared in the concluding synthesis. Systematic isotope trends argue against a significant abiotic Fischer-Tropsch origin for syn- sedimentary carbon. The picture that emerges, rather, is consistent with vigorous Early Archaean pelagic autotrophy, and a benthic biota dominated by fermentation, acetogenesis and methanogenesis. Access to electron acceptors was limited, and seems to have been restricted to sulphate and mineral ferric iron in shallow and deep marine environments, respectively. TABLE OF CONTENTS Page List of Figures ii List of Tables ix Preface xi Acknowledgements xiii Philosophical Introduction 1 1. Epistemic Challenges to Archaean Geobiology 1 Geobiological Introduction 27 2A. Carbon Metabolism & Biogeochemical Cycling 27 2B. Banded-Iron Formation: A Continuing Enigma 57 2C. Early Archaean Geology & The Pilgangoora Belt 85 Thermodynamic Modelling 165 3. Mimicking Biological Carbon Isotope Signatures in Fe-C-O-H Systems 165 Depositional Environments 207 4. A Metasedimentary Succession From the Isua Supracrustal Belt 207 5. An Early Archaean Deep-Marine Micritic Banded-Iron Formation 253 Life 423 6. Sedimentary Carbon Isotopes From the 3.52 Ga Coonterunah Subgroup 423 7. Early Archaean Oncoidal Trace Fossils 447 Conclusion 469 8. Concluding Synthesis 469 Bibliography 497 LIST OF FIGURES Chapter / Figure Number Page Chapter 1: Epistemic Challenges to Archaean Geobiology 1: Cover of Charles Lyell’s Principles of Geology 8 2: The distribution of Archaean outcrop today 9 3: The beginning of geobiological history 10 4: Alteration, deformation and metamorphism of pillow basalt 11 5: Greenstone belt geomorphology 12 6: Greenstone belt cross-sections 13 7: Textural preservation through silicification 14 8: Archaean stromatoloids/lites 15 9: Life or non-life? 16 10: Early Archaean carbonaceous matter 17 11. Generalized scheme of the evolution of organic matter 18 Chapter 2A: Carbon Metabolism & Biogeochemical Cycling 1: Classification of life in terms of energy- and carbon sources 39 2: Central fueling and biosynthetic pathways aerobic heterotrophy 40 3: Assimilatory and dissimilatory nitrogen pathways 41 4: Schematic overview of metabolism 42 5: The carbon isotope record over time 43 6: Assimilatory and dissimilatory nitrogen pathways 41 Chapter 2B: Banded-Iron Formation: A Continuing Enigma 1: Assimilatory and dissimilatory nitrogen pathways 41 ii LIST OF FIGURES (cont’d) Chapter / Figure Number Page Chapter 2C: Early Archaean Geology & The Pilgangoora Belt 1: Biomarker sampling localities in the Pilgangoora Belt 119 2: Macronutrient element maps 120 3: FTIR search for sheet-silicate ammonia 121 4: Textural associations of Early Archaean kerogen 122 5: Chert alteration 123 6: Map of Pilbara granite-greenstone distribution 124 7: Pilbara satellite photo and structural domain map 125 8: Stratigraphic divisions of the East Pilbara 126 9: Lithological map of the Pilgangoora Belt 127 10: Stratigraphic section of the Pilgangoora Belt 128 11: Angular unconformities in the Pilgangoora Belt 129 12: Gorge Creek Group sediments 130 13: Basalt features in the Pilgangoora Belt 131 14: Selected Strelley Pool Chert lithofacies 132 15: Field photographs of neptunian fissures 133 16: Autochtonous units compared with fissure breccia 134 17: Autochtonous units compared with fissure breccia 135 18: Slump structure at SPC/neptunian fissure contact 136 19: Slump structure and terminal wall at SPC/neptunian fissure contact 137 20: Textural relationships within neptunian fissures 138 21: Carlindi granitoid – Table Top Formation contacts 139 22: Partially silicified dolomite spar in SPC 140 23: Types of carbonate occurrence in the SPC 141 24: Carbonate dissolution-silicification textures 142 iii LIST OF FIGURES (cont’d) Chapter / Figure Number Page Chapter 2C (cont’d) 25: Pre-metamorphic silicification in the SPC 143 26: Low-grade SPC assemblages 144 27: Higher-grade SPC assemblages 145 28: Ternary ACF diagram of basalt compositions 146 29: Ternary metamorphic AFM diagram of basalt compositions 147 30: T-xCO2 diagram in the Ca-Mg+Si+fluid system 148 31: Pilgangoora Belt metamorphic zonation diagram 149 32: Post-metamorphic haematite in drillcore 150 33: Earlier major structural and tectonothermal events in the Pilgangoora Belt 151 34: Later major structural and tectonothermal events in the Pilgangoora Belt 152 Chapter 3: Mimicking Biological Carbon Isotope Signatures in Fe-C-O-H Systems 1: Isotopic fractionation of carbon 182 2: Oxygen buffers and graphite stability 183 3: The ternary C-O-H diagram 184 4: Fugacities of CO2, H2O, O2, CO, H2 and CH4 as a function of P, T and fO2 185 5: Graphite precipitated through siderite decarbonation 186 6: Theoretical β-factors as a function of temperature 187 7: Isotopic fractionation of reduced carbon equilibrating with C-O-H fluid 188 8: Calcite-graphite isotopic fractionation 198 9: Reduced carbon in isotopic equilibration with carbonate 199 10: Closed-system equilibration between reduced carbon and carbonate 200 11: β-factors for a variety of carbonates 201 12: Isotopes of carbon produced during closed-system siderite decarbonation 202 iv LIST OF FIGURES (cont’d) Chapter / Figure Number Page Chapter 3 (cont’d) 13: Isotopic evolution of carbon during open-system siderite decarbonation 203 14: Isotopic evolution of carbon during open-system devolatilization 204 Chapter 4: A Metasedimentary Succession From the Isua Supracrustal Belt 1: Geological map of metasediment outcrop 224 2: Stratigraphic section 225 3: Metasediment outcrop photographs 226 4: Metasediment photomicrographs 227 5: Cathode luminescence photographs of zircon separates 228 6: Shale- and Al2O3- normalized trace-element concentrations 229 7: Shale-normalized REE concentrations 230 8: Total REE, La/La* and Y/Ho ratios plotted versus Al2O3 231 9: Ce/Ce* versus Pr/Pr* diagram 232 10: Eu/Eu* versus Al2O3 233 11: K versus Rb concentrations compared 234 12: Chondrite-normalized Eu/Eu* versus Gd/Yb diagram 235 13: Ternary La-Sc-Th and Th-Zr/10-Sc discrimination diagrams 236 14: Zr/Ti – Nb/Y tectonic discrimination diagram 237 15: La/Th – Hf igneous provenance diagram 238 16: PAAS-normalized trace-element ratios compared 239 v LIST OF FIGURES (cont’d) Chapter / Figure Number Page Chapter 5: An Early Archaean Deep-Marine Micritic Banded-Iron Formation 1: Geological map of Pilgangoora Belt 313 2: Aerial photograph of micritic-BIF outcrop in Coonterunah Subgroup 314 3: Stratigraphic column of tephra-carbonate sequence 315 4: Outcrop photographs of Coonterunah sedimentary units 316 5: Thin-section photomicrographs of prominent 32cm carbonate unit 317 6: Thin-section and slab photographs of carbonate textures 318 7: Outcrop photographs of Coonterunah volcanoclastics 319 8: Thin-section photographs of Coonterunah volcanoclastics. 320 9: Outcrop photographs of carbonate silicification 321 10: Interflow metachert sediment atop basaltic subcrop 322 11: Photomicrographs of Ca-Mg±Fe amphibole 323 12: Photomicrographs of carbonate silicification textures 324 13: CaO – FeO* - MgO ternary diagram 325 14: Subsolvus relations for CaCO3-MgCO3 binary join 326 15: Ternary ACF phase diagram 327 16: Simplified P-T pseudosection
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  • Table of Contents. Letter of Transmittal. Officers 1910

    Table of Contents. Letter of Transmittal. Officers 1910

    TWELFTH REPORT OFFICERS 1910-1911. OF President, F. G. NOVY, Ann Arbor. THE MICHIGAN ACADEMY OF SCIENCE Secretary-Treasurer, GEO. D. SHAFER, East Lansing. Librarian, A. G. RUTHVEN, Ann Arbor. CONTAINING AN ACCOUNT OF THE ANNUAL MEETING VICE-PRESIDENTS. HELD AT Agriculture, CHARLES E. MARSHALL, East Lansing. Geography and Geology, W. H. SHERZER, Ypsilanti. ANN ARBOR, MARCH 31, APRIL 1 AND 2, 1910. Zoology, A. S. PEARSE, Ann Arbor. Botany, C. H. KAUFFMAN, Ann Arbor. PREPARED UNDER THE DIRECTION OF THE Sanitary and Medical Science, GUY KIEFER, Detroit. COUNCIL Economics, H. S. SMALLEY, Ann Arbor. BY PAST-PRESIDENTS. GEO. D. SHAFER DR. W. J. BEAL, East Lansing. Professor W. H. SHERZER, Ypsilanti. BRYANT WALKER, ESQ. Detroit. BY AUTHORITY Professor V. M. SPALDING, Tucson, Arizona. LANSING, MICHIGAN DR. HENRY B. BAKER, Holland. WYNKOOP HALLENBECK CRAWFORD CO., STATE PRINTERS Professor JACOB REIGHARD, Ann Arbor. 1910 Professor CHARLES E. BARR, Albion. Professor V. C. VAUGHAN, Ann Arbor. Professor F. C. NEWCOMBE, Ann Arbor. TABLE OF CONTENTS. DR. A. C. LANE, Tuft's College, Mass. Professor W. B. BARROWS, East Lansing. DR. J. B. POLLOCK, Ann Arbor. Letter of Transmittal .......................................................... 1 Professor M. H. W. JEFFERSON, Ypsilanti. DR. CHARLES E. MARSHALL, East Lansing. Officers for 1910-1911. ..................................................... 1 Professor FRANK LEVERETT, Ann Arbor. Life of William Smith Sayer. .............................................. 1 COUNCIL. Life of Charles Fay Wheeler.............................................. 2 The Council is composed of the above named officers Papers published in this report: and all Resident Past-Presidents. President's Address—Outline of the History of the Great Lakes, Frank Leverett.......................................... 3 On the Glacial Origin of the Huronian Rocks of WILLIAM SMITH SAYER.