A Mesoarchean shift in uranium isotope systematics

Type Article
Date 2018-10
Language English
Author(s) Wang Xiangli1, 2, Planavsky Noah J.3, Hofmann AxelORCID4, Saupe Erin E.1, 5, de Corte Brian P.6, Philippot Pascal7, 8, Lalonde Stefan9, Jemison Noah E.10, Zou Huijuan1, Ossa Frantz Ossa4, Rybacki Kyle11, Alfimova NadezhdaORCID12, Larson Matthew J.6, Tsikos Harilaos13, Fralick Philip W.14, Johnson Thomas M.10, Knudsen Andrew C.6, Reinhard Christopher T.11, Konhauser Kurt O.15
Affiliation(s) 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.
Source Geochimica Et Cosmochimica Acta (0016-7037) (Pergamon-elsevier Science Ltd), 2018-10 , Vol. 238 , P. 438-452
DOI 10.1016/j.gca.2018.07.024
WOS© Times Cited 43
Keyword(s) Uranium isotope, Archean, Oxygenation, Oxygenic photosynthesis, Trace metal

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.

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Wang Xiangli, Planavsky Noah J., Hofmann Axel, Saupe Erin E., de Corte Brian P., Philippot Pascal, Lalonde Stefan, Jemison Noah E., Zou Huijuan, Ossa Frantz Ossa, Rybacki Kyle, Alfimova Nadezhda, Larson Matthew J., Tsikos Harilaos, Fralick Philip W., Johnson Thomas M., Knudsen Andrew C., Reinhard Christopher T., Konhauser Kurt O. (2018). A Mesoarchean shift in uranium isotope systematics. Geochimica Et Cosmochimica Acta, 238, 438-452. Publisher's official version : https://doi.org/10.1016/j.gca.2018.07.024 , Open Access version : https://archimer.ifremer.fr/doc/00638/74970/