Early Wuchiapingian cooling linked to Emeishan basaltic weathering?
Early Wuchiapingian cooling linked to Emeishan basaltic weathering?
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早期五家坪期变冷与峨眉山玄武岩风化有关？
DOI：
10.1016/j.epsl.2018.04.004
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发表时间：
2018
影响因子：
5.3
通讯作者：
Yuan Dongxun
中科院分区：
文献类型：
--
作者：
Yang Jianghai;Cawood Peter A;Du Yuansheng;Condon Daniel J;Yan Jiaxin;Liu Jianzhong;Huang Yan;Yuan Dongxun
晚古生代冰期末次冰期开始于瓜达鲁宾-洛平期(G-L)界线附近，与峨眉山大火成岩省侵位同步。利用CA-TIMS锆石U-Pb定年技术，获得了峨眉山大火成岩东部普安火山岩系最上层凝灰岩的年龄为259.51±0.21 Ma，制约了峨眉山火山活动的发生时间，为G-L界线提供了又一候选年龄。此外，我们还在中国西南的岩心剖面上测定了紧邻上覆的龙潭组基性粘土岩的年龄为259.69±0.72 Ma。这些年龄，连同龙潭组下部泥岩的源区风化趋势，以及汇编的古温度记录，表明最早的乌家坪期降温与末次二叠世冰期的开始相吻合。这种全球变冷与有机碳和碳酸盐碳同位素记录的正向变化有关，也可能与大气二氧化碳的减少有关。提出了一种假设的因果联系，即位于赤道湿润带的峨眉山省喷发后玄武岩的快速风化可能会加速大气CO2的消耗，导致气候变冷。我们的工作支持大型火成岩省份的长期气候降温效应。
The last glaciation during the late Paleozoic ice age commenced at around the Guadalupian–Lopingian (G–L) boundary and is synchronous with the emplacement of the Emeishan large igneous province. Using CA-TIMS zircon U–Pb dating, we obtained an age of 259.51 ± 0.21 Ma for the uppermost tuff from the Puan volcanic sequence in the eastern Emeishan large igneous province, constraining the timing of Emeishan volcanism and providing another candidate age for the G–L boundary. In addition, we determined an age of 259.69 ± 0.72 Ma for a basal claystone in the immediately overlying Longtan Formation from a drill core section in southwest South China. These ages, along with source weathering trends of mudstones from the lower Longtan Formation, and compiled paleotemperature records, indicate an earliest Wuchiapingian cooling coinciding with the onset of the last Permian glaciation. This global cooling is associated with positive shifts in both organic and carbonate carbon isotopic records and likely a decrease in atmosphericpCO2. A hypothesised causal linkage is proposed in which the rapid post-eruptive basaltic weathering of the Emeishan province in an equatorial humid belt may accelerate the atmospheric CO2consumption and lead to climate cooling. Our work supports the long-term climate cooling effects of large igneous provinces.