A Mesoarchean shift in uranium isotope systematics

Autor(es):Mostrar menos -

Wang, Xiangli ^{[1, 2]} ; Planavsky, Noah J. ^[3] ; Hofmann, Axel ^[4] ; Saupe, Erin E. ^{[1, 5]} ; De Corte, Brian P. ^[6] ; Philippot, Pascal ^{[7, 8]} ; LaLonde, Stefan V. ^[9] ; Jemison, Noah E. ^[10] ; Zou, Huijuan ^[1] ; Ossa, Frantz Ossa ^[4] ; Rybacki, Kyle ^[11] ; Alfimova, Nadezhda ^[12] ; Larson, Matthew J. ^[6] ; Tsikos, Harilaos ^[13] ; Fralick, Philip W. ^[14] ; Johnson, Thomas M. ^[10] ; Knudsen, Andrew C. ^[6] ; Reinhard, Christopher T. ^[11] ; Konhauser, Kurt O. ^[15]

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^[1] Univ S Alabama, Dept Marine Sci, Mobile, AL 36688 - USA

^[2] Dauphin Isl Sea Lab, Dauphin Isl, AL 36258 - USA

^[3] Yale Univ, Dept Geol & Geophys, POB 6666, New Haven, CT 06511 - USA

^[4] Univ Johannesburg, Dept Geol, ZA-2092 Johannesburg - South Africa

^[5] Univ Oxford, Dept Earth Sci, S Parks Rd, Oxford - England

^[6] Lawrence Univ, Dept Geol, Appleton, WI 54911 - USA

^[7] Univ Paris Diderot, CNRS, Sorbonne Paris Cite, Inst Phys Globe Paris, 1 Rue Jussieu, F-75238 Paris - France

^[8] Univ Montpellier, UMR 5243, Geosci Montpellier, CNRS, F-34000 Montpellier - France

^[9] CNRS, European Inst Marine Studies, Domaines Ocean UMR6538, Technopole Brest Iroise, F-29280 Plouzane - France

^[10] Univ Illinois, Dept Geol, Champaign, IL 61820 - USA

^[11] Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 - USA

^[12] St Petersburg State Univ, Univ Skaya Nab 7-9, St Petersburg 199034 - Russia

^[13] Rhodes Univ, Geol Dept, ZA-6140 Grahamstown - South Africa

^[14] Lakehead Univ, Dept Geol, Thunder Bay, ON P7B 5E1 - Canada

^[15] Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB T6G 2E3 - Canada

• Tipo de documento: Artigo Científico
• Fonte: GEOCHIMICA ET COSMOCHIMICA ACTA; v. 238, p. 438-452, OCT 1 2018.
• Citações Web of Science: 9

Resumo

Oxygenic photosynthesis fundamentally transformed all major biogeochemical cycles and increased the size and complexity of Earth's biosphere. However, there is still debate about when this metabolism evolved. As oxygenic photosynthesis is the only significant source of O-2 at Earth's surface, O-2 -sensitive trace element enrichments and isotopic signatures in Archean sedimentary rocks can potentially be used to determine the onset of oxygenic photosynthesis by tracking shifts in the oxidative capacity of Earth's surface environment. Here, we present an extensive new Archean U isotope record from iron formations, organic-rich shales, and paleosols. Variability in delta U-238 values gradually increased from Archean to Phanerozoic, consistent with current view of gradual oxidation of Earth's surface. In addition, statistical analysis on available delta U-238 data indicates a turning point of delta U-238 variability at roughly 3.0 billon years ago. We suggest that such a turning point in delta U-238 variability indicates the initiation of relatively large-scale oxidative weathering of U(IV)-bearing minerals, implying that oxygenic photosynthesis may have evolved before 3.0 billion years ago. (C) 2018 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 15/16235-2 - Evolução da vida e oxigenação da Terra primitiva: uma perspectiva a partir da América do Sul
• Beneficiário: Pascal Andre Marie Philippot
• Modalidade de apoio: Auxílio à Pesquisa - Programa SPEC