Zhang, S, Planavsky, NJ, Krause, AJ orcid.org/0000-0002-9771-8101 et al. (2 more authors) (2018) Model based Paleozoic atmospheric oxygen estimates: a revisit to GEOCARBSULF. American Journal of Science, 318 (5). pp. 557-589. ISSN 0002-9599
Abstract
Geological redox proxies increasingly point towards low atmospheric oxygen concentrations during the early Paleozoic Era, with a subsequent protracted rise towards present-day levels. However, these proxies currently only provide qualitative estimates of atmospheric O₂ levels. Global biogeochemical models, in contrast, are commonly employed to generate quantitative estimates for atmospheric O₂ levels through Earth’s history. Estimates for Paleozoic pO₂ generated by GEOCARBSULF, one of the most widely implemented carbon and sulfur cycle models, have historically suggested high atmospheric O₂ levels throughout the Paleozoic, in direct contradiction to competing models. In this study, we evaluate whether GEOCARBSULF can predict relatively low Paleozoic O₂ levels. We first update GEOCARBSULF by adopting the recent compilation of the δ¹³C value of marine buried carbonate and replacing the old formulation of the sulfur isotope fractionation factor with empirical sulfur isotope records. Following this we construct various O₂ evolution scenarios (with low O₂ levels in the early Paleozoic) and examine whether GEOCARBSULF can reproduce these scenarios by varying the weathering/degassing fluxes of carbon and sulfur, or carbonate δ¹³C. We show that GEOCARBSULF can, in fact, maintain low-O₂ (even 1–5% atm) levels through the early Paleozoic by only varying the carbonate δ¹³C within 2 standard deviation (SD) bounds permitted by the geological record. In addition, it can generate a middle–late Paleozoic rise in O₂ concentration, coincident with the diversification of land plants. However, we also argue that tracking atmospheric O₂ levels with GEOCARBSULF is highly dependent on carbonate carbon isotope evolution, and more accurate predictions will come from an improved C isotope record.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This is an author produced version of a paper published in American Journal of Science. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | atmospheric O2, GEOCARBSULF, Paleozoic, carbonate isotope, plant evolution i |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 01 Aug 2018 14:09 |
Last Modified: | 02 Aug 2018 09:54 |
Status: | Published |
Publisher: | American Journal of Science |
Identification Number: | 10.2475/05.2018.05 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:134001 |