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Carbon cycle inverse modeling suggests large changes in fractional organic burial are consistent with the carbon isotope record and may have contributed to the rise of oxygen

Krissansen‐Totton, Joshua and Kipp, Michael A. and Catling, David C. (2021) Carbon cycle inverse modeling suggests large changes in fractional organic burial are consistent with the carbon isotope record and may have contributed to the rise of oxygen. Geobiology . ISSN 1472-4677. doi:10.1111/gbi.12440. (In Press) https://resolver.caltech.edu/CaltechAUTHORS:20210330-100726783

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Abstract

Abundant geologic evidence shows that atmospheric oxygen levels were negligible until the Great Oxidation Event (GOE) at 2.4–2.1 Ga. The burial of organic matter is balanced by the release of oxygen, and if the release rate exceeds efficient oxygen sinks, atmospheric oxygen can accumulate until limited by oxidative weathering. The organic burial rate relative to the total carbon burial rate can be inferred from the carbon isotope record in sedimentary carbonates and organic matter, which provides a proxy for the oxygen source flux through time. Because there are no large secular trends in the carbon isotope record over time, it is commonly assumed that the oxygen source flux changed only modestly. Therefore, declines in oxygen sinks have been used to explain the GOE. However, the average isotopic value of carbon fluxes into the atmosphere–ocean system can evolve due to changing proportions of weathering and outgassing inputs. If so, large secular changes in organic burial would be possible despite unchanging carbon isotope values in sedimentary rocks. Here, we present an inverse analysis using a self‐consistent carbon cycle model to determine the maximum change in organic burial since ~4 Ga allowed by the carbon isotope record and other geological proxies. We find that fractional organic burial may have increased by 2–5 times since the Archean. This happens because O₂‐dependent continental weathering of ¹³C‐depleted organics changes carbon isotope inputs to the atmosphere–ocean system. This increase in relative organic burial is consistent with an anoxic‐to‐oxic atmospheric transition around 2.4 Ga without declining oxygen sinks, although these likely contributed. Moreover, our inverse analysis suggests that the Archean absolute organic burial flux was comparable to modern, implying high organic burial efficiency and ruling out very low Archean primary productivity.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1111/gbi.12440DOIArticle
https://github.com/joshuakt/Carbon-isotopes-inverse-modelRelated ItemCode
ORCID:
AuthorORCID
Krissansen‐Totton, Joshua0000-0001-6878-4866
Kipp, Michael A.0000-0003-1844-3670
Catling, David C.0000-0001-5646-120X
Additional Information:© 2021 The Authors. Geobiology published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Version of Record online: 25 March 2021; Manuscript accepted: 09 March 2021; Manuscript revised: 08 February 2021; Manuscript received: 08 September 2020. DCC, JKT, and MAK were supported by NSF Frontiers in Earth System Dynamics award No. 1338810. This work was also supported by NASA Exobiology grant NNX15AL23G and Simons Foundation SCOL Awards 511570 and 511570FY20 to DCC. MAK acknowledges support from an NSF Graduate Research Fellowship and an Agouron Institute postdoctoral fellowship. This work was also supported by the NASA Astrobiology Program Grant Number 80NSSC18K0829 and benefited from participation in the NASA Nexus for Exoplanet Systems Science research coordination network. The authors declare no conflict of interest. Data Availability Statement: The Python code used for this analysis is available on the lead author's Github upon publication: https://github.com/joshuakt/Carbon‐isotopes‐inverse‐model
Funders:
Funding AgencyGrant Number
NSFEAR-1338810
NASANNX15AL23G
Simons Foundation511570
Simons Foundation511570FY20
NSF Graduate Research FellowshipUNSPECIFIED
Agouron InstituteUNSPECIFIED
NASA80NSSC18K0829
Subject Keywords:carbon cycle; carbon isotopes; organic burial; oxygen; Precambrian; weathering
DOI:10.1111/gbi.12440
Record Number:CaltechAUTHORS:20210330-100726783
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210330-100726783
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108581
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:30 Mar 2021 22:55
Last Modified:30 Mar 2021 22:55

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