Carbon cycle perturbation expressed in terrestrial Permian-Triassic boundary sections in South China
Carbon cycle perturbation expressed in terrestrial Permian-Triassic boundary sections in South China
复制标题
华南陆地二叠纪—三叠纪边界剖面的碳循环扰动
DOI：
10.1016/j.gloplacha.2015.10.018
复制
发表时间：
2017-01-01
影响因子：
3.9
通讯作者：
Vajda, Vivi
中科院分区：
文献类型：
--
作者：
Cui, Ying;Bercovici, Antoine;Vajda, Vivi
无机碳和有机碳的稳定同位素通常用于化学地层学中，以基于外源碳库的碳同位素特征主导其他变异来源的假设来关联海洋和陆地沉积序列。本文对中国南方黔西-滇东地区二叠纪-三叠纪界线（PTB）四个剖面的沉积物样品进行了C-13（delta C-13（org））有机质分析。这些值随后与发表的来自全球层型剖面和梅山点以及许多其他海洋和陆地剖面的碳酸盐δ C-13值（δ C-13（carb））进行了比较。在所有四个剖面中明显的类似同位素趋势的特征是在宣威组顶部负偏移2-3%o，我们尝试将PTB放置在那里。这种负向的转变也对应于植被的周转和真菌孢子的出现，这通常被解释为二叠纪末大规模灭绝事件期间分解者的扩散和复杂生态系统的崩溃。此外，三角洲C-13（org）的绝对值更极端的更远（海洋）存款。三角洲的C-13（org）的研究沉积物的值是更多的变化相比，同时代的813 Ccarb记录从海洋记录，特别是在灭绝地平线以下的间隔。我们认为，沉积环境的影响三角洲C-13（org）值，但持久的地理三角洲C-13（org）模式，通过灭绝事件在四个独立的部分是一个迹象，大气三角洲C-13信号留下了不可磨灭的印记，在二叠纪末灭绝事件的深刻生态系统变化的地质记录。(C)2015 Elsevier B. V.版权所有。
Stable isotopes of inorganic and organic carbon are commonly used in chemostratigraphy to correlate marine and terrestrial sedimentary sequences based on the assumption that the carbon isotopic signature of the exogenic carbon pool dominates other sources of variability. Here, sediment samples from four Permian-Triassic boundary (PTB) sections of western Guizhou and eastern Yunnan provinces in South China, representing a terrestrial to marine transitional setting, were analyzed for delta C-13 of organic matter (delta C-13(org)). These values were subsequently compared to published delta C-13 values of carbonates (delta C-13(carb)) from the Global Stratotype Section and Point at Meishan and many other marine and terrestrial sections. A similar isotopic trend evident through all four sections is characterized by a negative shift of 2-3%o at the top of the Xuanwei Formation, where we tentatively place the PTB. This negative shift also corresponds to a turnover in the vegetation and the occurrence of fungal spores, which is generally interpreted as a proliferation of decomposers and collapse of complex ecosystems during the end Permian mass extinction event. Moreover, the absolute values of delta C-13(org) are more extreme in the more distal (marine) deposits. The delta C-13(org) values for the studied sediments are more variable compared to coeval 813Ccarb records from marine records especially in the interval below the extinction horizon. We contend that the depositional environment influenced the delta C-13(org) values, but that the persisting geographic delta C-13(org) pattern through the extinction event across the four independent sections is an indication that the atmospheric delta C-13 signal left an indelible imprint on the geologic record related to the profound ecosystem change during the end-Permian extinction event. (C) 2015 Elsevier B.V. All rights reserved.