Anomalous Early Triassic sediment fluxes due to elevated weathering rates and their biological consequences
Anomalous Early Triassic sediment fluxes due to elevated weathering rates and their biological consequences
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DOI：
10.1130/g31203.1
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发表时间：
2010-11-01
期刊：
影响因子：
5.8
通讯作者：
Twitchett, Richard J.
中科院分区：
文献类型：
--
作者：
Algeo, Thomas J.;Twitchett, Richard J.
对16个近全球分布的海洋二叠纪-三叠纪边界剖面的分析表明，在二叠纪末危机之后，沉积物通量和岩性发生了系统的变化。相对于长兴期（二叠纪晚期），大陆边缘和台地剖面显示出更高的大块堆积速率（bar）和更丰富的粘土成分。这些模式在很大程度上超越了构造背景、层序地层因素和相的区域差异，据推测，这些模式是由于地表温度升高、降水酸度增加以及与陆地生态系统破坏有关的景观稳定性变化导致化学和物理风化加速，从而导致来自邻近陆地地区的侵蚀物质通量大幅（平均约为7倍）增加所致。这种沉积物激增可能是二叠纪海洋生物危机的一个促成因素，也可能是由于淤积和富营养化的有害影响而延迟恢复早三叠纪海洋生态系统的一个促成因素。同时期的深海剖面显示，由于远离大陆硅质碎屑源，且位于古碳酸盐补偿深度以下，二叠纪-三叠纪界线上的沉积物通量没有增加。
Analysis of 16 marine Permian-Triassic boundary sections with a near-global distribution demonstrates systematic changes in sediment fluxes and lithologies in the aftermath of the end-Permian crisis. Sections from continent-margin and platform settings exhibit higher bulk accumulation rates (BARs) and more clay-rich compositions in the Griesbachian (earliest Triassic) relative to the Changhsingian (latest Permian). These patterns, which largely transcend regional variations in tectonic setting, sequence stratigraphic factors, and facies, are hypothesized to have resulted from a substantial (average similar to 7x) increase in the flux of eroded material from adjacent land areas owing to accelerated rates of chemical and physical weathering as a function of higher surface temperatures, increased acidity of precipitation, and changes in landscape stability tied to destruction of terrestrial ecosystems. This sediment surge may have been a contributory factor to the latest Permian marine biotic crisis as well as to the delayed recovery of Early Triassic marine ecosystems owing to the harmful effects of siltation and eutrophication. Contemporaneous deep-sea sections show no increases in sediment flux across the Permian-Triassic boundary owing to their remoteness from continental siliciclastic sources and location below the paleo-carbonate compensation depth.