TY - JOUR
T1 - Coupled δ44/40Ca, δ88/86Sr, and 87Sr/86Sr geochemistry across the end-Permian mass extinction event
AU - Wang, Jiuyuan
AU - Jacobson, Andrew D.
AU - Zhang, Hua
AU - Ramezani, Jahandar
AU - Sageman, Bradley B.
AU - Hurtgen, Matthew T.
AU - Bowring, Samuel A.
AU - Shen, Shu Zhong
N1 - Funding Information:
We are grateful to G. Andrews, G. Lehn, L. Kump, and T. Lyons for discussions that improved the study, and M. Ankney, A. Masterson, and A. Potrel for help in the laboratory. We also thank J. Higgins, K. Lau, anonymous reviewers, and Associate Editor M. Fantle for thoughtful comments and suggestions that improved the final version of the study. This work was supported by the David and Lucile Packard Foundation (Fellowship 2007-31757 ) and the National Science Foundation ( NSF-EAR 0723151 ) to ADJ and Key Research Program of Frontier Sciences ( QYZDY-SSW-DQC023 ) and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB26000000 , XDB18000000 ) to HZ and SSZ.
Funding Information:
We are grateful to G. Andrews, G. Lehn, L. Kump, and T. Lyons for discussions that improved the study, and M. Ankney, A. Masterson, and A. Potrel for help in the laboratory. We also thank J. Higgins, K. Lau, anonymous reviewers, and Associate Editor M. Fantle for thoughtful comments and suggestions that improved the final version of the study. This work was supported by the David and Lucile Packard Foundation (Fellowship 2007-31757) and the National Science Foundation (NSF-EAR 0723151) to ADJ and Key Research Program of Frontier Sciences (QYZDY-SSW-DQC023) and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB26000000, XDB18000000) to HZ and SSZ.
Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2019/10/1
Y1 - 2019/10/1
N2 - We report high-resolution, high-precision δ44/40Ca, δ88/86Sr, and 87Sr/86Sr records spanning the Permian-Triassic boundary (PTB) from the Meishan and Dajiang carbonate successions in south China. The goal of the study was to understand the behavior of Ca and Sr isotopes during a time period in Earth history characterized by severe biological and environmental perturbations, including a major mass extinction, flood basalt volcanism, ocean acidification, and sea level fluctuations. Dajiang displays negative δ44/40Ca and δ88/86Sr excursions and invariant 87Sr/86Sr ratios in the <60 kyr timeframe between the main extinction horizon and the PTB. The Meishan δ44/40Ca and δ88/86Sr records are generally shifted to higher values and display both synchronous and asynchronous trends relative to Dajiang. In addition, 87Sr/86Sr ratios at Meishan are significantly elevated and do not define a clear secular pattern. We reconcile diverse conceptual models for the dataset with the aid of supporting elemental and isotope measurements (e.g., Sr/Ca, δ13C, and δ18O), as well as sequential leaching experiments. The combined body of evidence indicates that Dajiang sediments experienced recrystallization and neomorphism under rock-buffered conditions that preserved primary signals. In contrast, the Meishan records display influences from both primary and secondary processes, including local differences in fractionation, fluid-buffered early marine diagenesis, and late stage diagenetic overprinting. The three isotopic records for Dajiang, and to some extent, the δ44/40Ca and δ88/86Sr records for Meishan, preserve information about the geochemistry of end-Permian seawater. We find that enhanced weathering of shelf carbonates during sea level fall provides the best explanation for rapidly decreasing seawater δ44/40Ca and δ88/86Sr values without affecting 87Sr/86Sr ratios.
AB - We report high-resolution, high-precision δ44/40Ca, δ88/86Sr, and 87Sr/86Sr records spanning the Permian-Triassic boundary (PTB) from the Meishan and Dajiang carbonate successions in south China. The goal of the study was to understand the behavior of Ca and Sr isotopes during a time period in Earth history characterized by severe biological and environmental perturbations, including a major mass extinction, flood basalt volcanism, ocean acidification, and sea level fluctuations. Dajiang displays negative δ44/40Ca and δ88/86Sr excursions and invariant 87Sr/86Sr ratios in the <60 kyr timeframe between the main extinction horizon and the PTB. The Meishan δ44/40Ca and δ88/86Sr records are generally shifted to higher values and display both synchronous and asynchronous trends relative to Dajiang. In addition, 87Sr/86Sr ratios at Meishan are significantly elevated and do not define a clear secular pattern. We reconcile diverse conceptual models for the dataset with the aid of supporting elemental and isotope measurements (e.g., Sr/Ca, δ13C, and δ18O), as well as sequential leaching experiments. The combined body of evidence indicates that Dajiang sediments experienced recrystallization and neomorphism under rock-buffered conditions that preserved primary signals. In contrast, the Meishan records display influences from both primary and secondary processes, including local differences in fractionation, fluid-buffered early marine diagenesis, and late stage diagenetic overprinting. The three isotopic records for Dajiang, and to some extent, the δ44/40Ca and δ88/86Sr records for Meishan, preserve information about the geochemistry of end-Permian seawater. We find that enhanced weathering of shelf carbonates during sea level fall provides the best explanation for rapidly decreasing seawater δ44/40Ca and δ88/86Sr values without affecting 87Sr/86Sr ratios.
KW - Calcium isotopes
KW - Chemical weathering
KW - Diagenesis
KW - Radiogenic Sr isotopes
KW - Stable Sr isotopes
KW - end-Permian
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U2 - 10.1016/j.gca.2019.07.035
DO - 10.1016/j.gca.2019.07.035
M3 - Article
AN - SCOPUS:85070264495
VL - 262
SP - 143
EP - 165
JO - Geochmica et Cosmochimica Acta
JF - Geochmica et Cosmochimica Acta
SN - 0016-7037
ER -