Constraining marine anoxia under the extremely oxygenated Permian atmosphere using uranium isotopes in calcitic brachiopods and marine carbonates

Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt

Wen-qian Wang
Feifei Zhang
Shu-zhong Shen
Bizzarro, Martin
Claudio Garbelli
Quan-feng Zheng
Yi-chun Zhang
Dong-xun Yuan
Yu-kun Shi
Mengchun Cao
Dahl, Tais Wittchen

The redox chemistry change in ancient oceans has profoundly shaped the evolutionary trajectories of animals. Uranium isotopes (δ²³⁸U) in marine carbonate sediments have widely been used to place quantitative constraints on the oxygenation state of the oceans through geological history. However, syndepositional and post-depositional diagenesis impose a positive and variable δ²³⁸U offset in the carbonate sediments relative to contemporaneous seawater, leaving uncertainties on quantification of anoxic seafloor areas in the past. Studies from modern settings suggest that Low-Magnesium Calcite (LMC) in articulate brachiopod shells are diagenetic resistant materials that may faithfully record the δ²³⁸U value of ancient seawater. However, this notation has not yet been validated in geological records. Here, we test this hypothesis by analyzing paired brachiopod shells and the host carbonate rocks from several Permian stratigraphic successions in South China. Forty-nine articulate brachiopod fossil shells and twenty-six host carbonate rocks from the Early Permian to the Late Permian were investigated. We performed a rigorous screening to monitor the diagenetic process that might have influenced the δ²³⁸U of the shells using a scanning electronic microscope, cathodoluminescent microscopy, and major and trace elements. We estimate that 53% of the shells preserve the primary seawater δ²³⁸U signals. Using the screened δ²³⁸U values of shells and bulk carbonates, we suggest there were four episodes of expanding marine anoxia during the Permian that are temporally coincident with periods of volcanism. The first two oceanic anoxic events occurred at a time when atmospheric pO₂ levels were predicted to be higher than today. The last two events are temporally coincident or immediately preceding the end-Guadalupian and the end-Permian mass extinctions, respectively, confirming previous suggestions that marine anoxia was a critical factor in driving marine animal extinctions.

Originalsprog	Engelsk
Artikelnummer	117714
Tidsskrift	Earth and Planetary Science Letters
Vol/bind	594
Antal sider	15
ISSN	0012-821X
DOI	https://doi.org/10.1016/j.epsl.2022.117714
Status	Udgivet - 2022

Bibliografisk note

Funding Information:
This study is supported by the Natural Science Foundation of China ( 42073002 , 91855205 , 41420104003 , 91955201 , 41830323 , and 4210030011 ), the Strategic Priority Research Program (B) of the Chinese Academy of Sciences ( XDB26000000 ), the Chinese Academy of Sciences ( QYZDY-SSW-DQC023 ), and the Fundamental Research Funds for the Central Universities ( 0206-14380145 ) and Frontiers Science Center for Critical Earth Material Cycling Fund . WQW also acknowledges funding from the China Postdoctoral Science Foundation (Grant No. 2021M691496 ). TWD acknowledges support from the Danish Council for Independent Research (DFF 7014-00295 ). MB acknowledges support from The Carlsberg Foundation ( CF18 1105 ) and the European Research Council (ERC Advanced Grant 833275-DEEPTIME ). We thank Drs. James N. Connelly and Álvaro del Rey for analytical support at the University of Copenhagen. We are grateful to Boswell Wing for the editorial handling of this manuscript and to two anonymous reviewers for constructive reviews that have helped improve the work. We are also grateful to Prof. Ethan L. Grossman from Texas A&M University for helpful discussions.

Funding Information:
This study is supported by the Natural Science Foundation of China (42073002, 91855205, 41420104003, 91955201, 41830323, and 4210030011), the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB26000000), the Chinese Academy of Sciences (QYZDY-SSW-DQC023), and the Fundamental Research Funds for the Central Universities (0206-14380145) and Frontiers Science Center for Critical Earth Material Cycling Fund. WQW also acknowledges funding from the China Postdoctoral Science Foundation (Grant No. 2021M691496). TWD acknowledges support from the Danish Council for Independent Research (DFF 7014-00295). MB acknowledges support from The Carlsberg Foundation (CF18 1105) and the European Research Council (ERC Advanced Grant 833275-DEEPTIME). We thank Drs. James N. Connelly and Álvaro del Rey for analytical support at the University of Copenhagen. We are grateful to Boswell Wing for the editorial handling of this manuscript and to two anonymous reviewers for constructive reviews that have helped improve the work. We are also grateful to Prof. Ethan L. Grossman from Texas A&M University for helpful discussions.

Publisher Copyright:
© 2022 Elsevier B.V.

ID: 320748909