Stable carbon isotope signature in mid-Panthalassa shallow-water carbonates across the Permo-Triassic boundary: evidence for 13 C-depleted superocean
Stable carbon isotope signature in mid-Panthalassa shallow-water carbonates across the Permo-Triassic boundary: evidence for 13 C-depleted superocean
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DOI：
10.1016/s0012-821x(01)00398-3
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发表时间：
2001-08
影响因子：
5.3
通讯作者：
Masaaki Musashi;Y. Isozaki;T. Koike;R. Kreulen
中科院分区：
文献类型：
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作者：
Masaaki Musashi;Y. Isozaki;T. Koike;R. Kreulen
日本西南部的侏罗纪增生杂岩包含了主要沉积在古代太平洋或超级海洋泛海拉萨的古代洋中海山上的二叠纪-三叠纪石灰岩的外来岩块。本研究考察了日本西南部Kamura和Taho的二叠纪-三叠纪界线（PTB）上的这种开阔海洋浅水灰岩的稳定碳同位素组成（δ 13 C carband δ 13 Corg）。结果表明，两个剖面的δ 13 C碳值的长期变化几乎相同，在PTB上有一个显著的负尖峰。这证实了第一次，中泛地中海浅水碳酸盐岩的生物和化学地层相关，而不是以前研究的PTB部分从泛大陆的外围。在两个剖面中，δ 13 Ccarboccurs的负移与δ 13 Corg的负移平行，并且差值（Δ 13 C =δ 13 Ccarb −δ 13 Corg）在整个剖面中几乎保持不变。这意味着13 C贫化的水应该广泛发展，可能在全球范围内，在整个超级海洋泛地中海跨越PTB。这些发现表明，大量的12 C-富集的碳输入到海洋-大气系统中已经发生，并可能导致全球环境变化，可能与中生代最大的物种灭绝有关。
The Jurassic accretionary complex in southwest Japan contains exotic blocks of the Permo–Triassic limestone primarily deposited on ancient mid-oceanic seamounts in an ancient Pacific Ocean or superocean Panthalassa. This study examines stable carbon isotope compositions (δ13Ccarband δ13Corg) of such open-ocean shallow-water limestone across the Permo–Triassic boundary (PTB) at Kamura and Taho in southwest Japan. The results show an almost identical secular change in δ13Ccarbvalues with a remarkable negative spike across the PTB in both sections. This confirms for the first time that the mid-Panthalassa shallow-water carbonates are bio- and chemo-stratigraphically correlated not with previously studied PTB sections from the peripheries of Pangea. The negative shift in δ13Ccarboccurs parallel to that of δ13Corgin both sections, and the difference (Δ13C=δ13Ccarb−δ13Corg) remains nearly constant throughout the sections. This implies that the13C-depleted water should have developed widely, probably in a global extent, throughout the superocean Panthalassa across the PTB. These findings suggest that a large input of12C-enriched carbon into the ocean–atmosphere system has occurred and may have caused a global environment change probably relating to the greatest mass extinction in the Phanerozoic.