Carbonate-platform response to the Toarcian Oceanic Anoxic Event in the southern hemisphere: Implications for climatic change and biotic platform demise
Carbonate-platform response to the Toarcian Oceanic Anoxic Event in the southern hemisphere: Implications for climatic change and biotic platform demise
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DOI：
10.1016/j.epsl.2018.02.017
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发表时间：
2018-05-01
影响因子：
5.3
通讯作者：
Li, Juan
中科院分区：
文献类型：
--
作者：
Han, Zhong;Hu, Xiumian;Li, Juan
Toarcian Oceanic Anodenal Event（T-OAE，类似于183 Ma）是一次短期的环境扰动，伴随着碳同位素的大规模释放，导致了全球海洋-大气系统中碳同位素的显著负漂移。北方以外地区普遍缺乏特征性的T-OAE记录，这意味着该事件的确切环境影响和意义尚不确定。早托阿西期，北方半球西特提斯的许多生物碳酸盐台地被淹没或转移到非骨骼台地。然而，南半球的Toarcian碳酸盐台地的记录是罕见的，因此在T-OAE期间生物台地消亡的程度和意义尚不清楚。在这里，我们提出了高分辨率的地球化学和沉积学数据在两个Pliensbachian-Toarcian浅水碳酸盐岩台地部分暴露在西藏喜马拉雅山。这些剖面在古地理上位于南半球开放的东南热带特提斯边缘。西藏喜马拉雅地区的T-OAE在有机质中表现为负CIE。我们的沉积学分析的两个部分揭示了丰富的风暴存款内的T-OAE间隔，这强调了在T-OAE事件，在最近提供的证据从西特提斯部分的北方半球的变暖和热带风暴之间的密切联系。此外，我们的分析还揭示了广泛的生物碳酸盐平台消亡的溺水或改变为非骨骼碳酸盐与CIE的发病相一致。两者合计，我们的研究结果表明，快速和普遍的海水变暖响应碳释放可能发挥了重要作用，在突然的生物碳酸盐台地消亡，抑制/推迟生物台地重新开发沿着整个热带/亚热带特提斯边缘。(C)2018 Elsevier B. V.版权所有。
The Toarcian Oceanic Anoxic Event (T-OAE, similar to 183 Ma) was a profound short-term environmental perturbation associated with the large-scale release of C-13-depleted carbon into the global ocean-atmosphere system, which resulted in a significant negative carbon-isotope excursion (CIE). The general lack of characteristic T-OAE records outside of the northern hemisphere means that the precise environmental effects and significance of this event are uncertain. Many biotic carbonate platforms of the northern hemisphere western Tethys drowned or shifted to non-skeletal platforms during the early Toarcian. However, southern hemisphere records of Toarcian carbonate platforms are rare, and thus the extent and significance of biotic platform demise during the T-OAE is unclear. Here we present high-resolution geochemical and sedimentological data across two Pliensbachian-Toarcian shallow-water carbonate-platform sections exposed in the Tibetan Himalaya. These sections were located paleogeographically on the open southeastern tropical Tethyan margin in the southern hemisphere. The T-OAE in the Tibetan Himalaya is marked by a negative CIE in organic matter. Our sedimentological analysis of the two sections reveals an abundance of storm deposits within the T-OAE interval, which emphasizes a close link between warming and tropical storms during the T-OAE event, in line with evidence recently provided from western Tethyan sections of the northern hemisphere. In addition, our analysis also reveals extensive biotic carbonate-platform demise by drowning or changing to non-skeletal carbonates coincident with the onset of the CIE. Taken together, our results suggest that rapid and pervasive seawater warming in response to carbon release likely played a significant role in sudden biotic carbonate platform demise, and suppression/postponement of biotic platform re-development along the whole tropical/subtropical Tethyan margin. (C) 2018 Elsevier B.V. All rights reserved.