Pyrite framboids in the Permian–Triassic boundary section at Meishan, China: Evidence for dysoxic deposition
Pyrite framboids in the Permian–Triassic boundary section at Meishan, China: Evidence for dysoxic deposition
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DOI：
10.1016/j.palaeo.2007.06.005
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发表时间：
2007-09
期刊：
影响因子：
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通讯作者：
W. Shen;Yangting Lin;Lin Xu;Jian-feng Li;Yasheng Wu;Yongge Sun
中科院分区：
文献类型：
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作者：
W. Shen;Yangting Lin;Lin Xu;Jian-feng Li;Yasheng Wu;Yongge Sun
中国眉山二叠纪-三叠纪全球层型中的黄铁矿藤状证据表明，二叠纪晚期的大规模灭绝与底栖氧气水平的急剧下降密切相关。草莓的大小和丰度是根据酸残留物和样品抛光切片上的原位测定的。 24e层（24层的上层）和25、26和29层顶部的薄黄铁矿纹层中富含草莓状晶层，24e和28层中很少见，但27层中不存在。它们具有较窄的尺寸分布，平均直径为4.6μm至8.7μm，与缺氧/缺氧条件下形成的相似。黄铁矿草莓状体的丰度和平均直径表明沉积的氧化还原条件从上部缺氧（床层 24e）和下部缺氧（黄铁矿层，床层 25 和 26）到氧化（床层 27），再到上部缺氧（床层 28）和下部缺氧（床层 29）。我们的发现证实了二叠纪-三叠纪过渡期间发生的全球缺氧海洋事件，表明与二叠纪-三叠纪海洋大规模灭绝有直接关系。
Pyrite framboid evidence from the Permian–Triassic global stratotype at Meishan, China, indicates the late Permian mass extinction is closely associated with a dramatic decline of benthic oxygen levels. Sizes and abundances of the framboids were determined from acid residues and in situ on polished sections of the samples. The framboids are abundant in the thin pyrite lamina on the top of Bed 24e (the upper layer of Bed 24), and Beds 25, 26 and 29, rare in Bed 24e and Bed 28, but absent in Bed 27. They have narrow size distributions with average diameters from 4.6 μm to 8.7 μm which are similar to those formed under anoxic/dysoxic conditions. The abundances and mean diameters of the pyrite framboids indicate redox conditions of deposition changing from upper dysoxia (Bed 24e) and lower dysoxia (pyrite lamina, Beds 25 and 26) to oxygenation (Bed 27), and again to upper dysoxia (Bed 28) and lower dysoxia (Bed 29). Our discovery confirms a worldwide dysoxic marine event during the Permian–Triassic transition, suggestive of a direct relationship with the Permian–Triassic marine mass extinction.