Pattern of δ13Ccarb and implications for geological events during the Permian-Triassic transition in South China
Pattern of δ13Ccarb and implications for geological events during the Permian-Triassic transition in South China
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DOI：
10.1002/gj.1220
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发表时间：
2010-03-01
影响因子：
1.8
通讯作者：
Summons, R. E.
中科院分区：
文献类型：
--
作者：
Cao, C. Q.;Yang, Y. C.;Summons, R. E.
中国南方二叠系-三叠系界线上5个海相剖面的资料显示，从碳酸盐台地到低斜坡，不同相带的C-13-亏损碳酸盐岩（三角洲C-13（carb））的分布格局。三角洲C-13（碳水化合物）的逐渐减少是显而易见的，在所有部分和匹配的Sr-87/Sr-86从晚二叠世到印度（早三叠世）的相反的变化。锶和碳同位素数据中的这些互补趋势意味着，在二叠纪-三叠纪事件边界（PTEB）的增强大陆隆起和硅酸盐和有机质风化的延长期。PTEB处三角洲C-13（碳水化合物）的显著急剧下降在梅山的上斜坡环境中最为明显，在浅水环境中出现微弱下降，在最深的水环境中无法识别。我们认为，这种模式反映了增强的分层海洋条件的最新二叠纪海侵后立即。平台斜坡环境中PTEB处δ C-13（碳水化合物）的急剧下降可能是由于有机物（可能包括甲烷）呼吸作用形成的C-13贫化溶解无机碳（DIC）的深度选择性钙化。事实上，PTEB的大规模火山活动会增强富营养化和分层，从而减缓C-13耗尽DIC进入深水环境的混合。版权所有（C）2010约翰威利父子有限公司
Data from five marine sections across the Permian-Triassic boundary in southern China reveal a pattern of C-13-depleted carbonate (delta C-13(carb)) in different facies spanning carbonate platform to lower slope. A gradual decrease of delta C-13(carb) is evident in all sections and matched by an opposing change in Sr-87/Sr-86 from the Late Permian to the Induan (Early Triassic). These complementary trends in strontium and carbon isotope data imply an extended period of enhanced continental uplift and weathering of silicates and organic matter across the Permian-Triassic event boundary (PTEB). A pronounced sharp drop of delta C-13(carb) at the PTEB is most recognizable in the upper ramp environment of Meishan, occurs weakly in shallow water environments and cannot be discerned in the deepest water setting. We propose that this pattern reflects an enhancement of stratified-ocean conditions in the immediate aftermath of the latest Permian transgression. The sharp drop in delta C-13(carb) at the PTEB in the platform ramp environments likely resulted from the depth-selective calcification of C-13-depleted dissolved inorganic carbon (DIC) formed by respiration of organic matter including, perhaps, methane. Indeed, massive volcanism at the PTEB would have enhanced eutrophication and stratification thereby slowing the mixing of C-13-depleted DIC into deeper-water environments. Copyright (C) 2010 John Wiley & Sons, Ltd.