期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2010
卷号：107
期号：19
页码：8543-8548
DOI：10.1073/pnas.0914065107
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The end-Permian mass extinction horizon is marked by an abrupt shift in style of carbonate sedimentation and a negative excursion in the carbon isotope ({delta}13C) composition of carbonate minerals. Several extinction scenarios consistent with these observations have been put forward. Secular variation in the calcium isotope ({delta}44/40Ca) composition of marine sediments provides a tool for distinguishing among these possibilities and thereby constraining the causes of mass extinction. Here we report{delta} 44/40Ca across the Permian-Triassic boundary from marine limestone in south China. The{delta} 44/40Ca exhibits a transient negative excursion of [~]0.3{per thousand} over a few hundred thousand years or less, which we interpret to reflect a change in the global{delta} 44/40Ca composition of seawater. CO2-driven ocean acidification best explains the coincidence of the{delta} 44/40Ca excursion with negative excursions in the{delta} 13C of carbonates and organic matter and the preferential extinction of heavily calcified marine animals. Calcium isotope constraints on carbon cycle calculations suggest that the average{delta} 13C of CO2 released was heavier than -28{per thousand} and more likely near -15{per thousand}; these values indicate a source containing substantial amounts of mantle- or carbonate-derived carbon. Collectively, the results point toward Siberian Trap volcanism as the trigger of mass extinction.
