Volcanism and deep-ocean acidification across the end-Triassic extinction event
Volcanism and deep-ocean acidification across the end-Triassic extinction event
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DOI：
10.1016/j.palaeo.2015.09.046
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发表时间：
2015-12
期刊：
影响因子：
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通讯作者：
M. Ikeda;R. Hori;Y. Okada;R. Nakada
中科院分区：
文献类型：
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作者：
M. Ikeda;R. Hori;Y. Okada;R. Nakada
三叠纪末的灭绝事件标志着中生代的“五大”大灭绝事件之一。灭绝的最终原因被认为是中大西洋岩浆区（CAMP）的火山活动，但伴随生物更替的全球环境变化的根本性质仍然难以捉摸。在这里，我们目前的化学和矿物学研究在三叠纪末灭绝水平的深海燧石序列（犬山，日本）。经陆源物质标准化的贫化赤铁矿含量早于三叠纪末的灭绝水平，岩石颜色从砖红色到紫色发生了显著变化，这与已报道的赤铁矿岩石磁性记录一致。这表明自生赤铁矿的损失可能是由于底层水和下伏沉积物孔隙水的酸化。这一时间与CAMP火山活动的最初爆发相一致，表明温室气体的灾难性释放是深海酸化的一个原因。在三叠纪末的灭绝间隔，MgO/Al 2 O3，Fe 2 O3/Al 2 O3，和Al 2 O3/SiO2增加的颜色从紫色到灰红色的变化。这一趋势与干旱区风化CAMP玄武岩的趋势接近，表明它在三叠纪末灭绝事件后成为硅质岩中风尘的重要来源。这些时间关系支持CAMP的初始喷发，深海酸化和三叠纪末灭绝之间的同步性。硅质岩类似的岩石颜色变化可能对其他地质事件中的火山作用和深海酸化具有潜在的信息。
The end-Triassic extinction event marks one of the “big five” mass extinction events of the Phanerozoic. The ultimate cause of the extinction is considered to be volcanic activity at the Central Atlantic magmatic province (CAMP), yet the underlying nature of global environmental changes that accompanied the biotic turnover remains elusive. Here we present chemical and mineralogical studies across the end-Triassic extinction level of the deep-sea chert sequence (Inuyama, Japan). Depleted hematite content normalized by terrigenous material predated the end-Triassic extinction level with significant rock color change from brick red to purple, which is consistent with the rock magnetic records of hematite reported. This suggests the loss of authigenic hematite possibly due to the acidification of bottom-water and the underlying sediment pore-water. This timing is consistent with the initial eruption of CAMP volcanism, suggesting a catastrophic release of greenhouse gases as a cause of deep-ocean acidification. Across the end-Triassic extinction interval, MgO/Al2O3, Fe2O3/Al2O3, and Al2O3/SiO2increased with change in color from purple to dusty red. This trend became close to those of weathered CAMP basalts in arid area, implying that it became the considerable source of aeolian dust in cherts after the end-Triassic extinction event. These temporal relations support the synchrony among the initial eruption of CAMP, deep-ocean acidification, and the end-Triassic extinction. Similar rock color changes of cherts might have potential information for the volcanisms and deep-ocean acidification in other geologic events.