Sedimentary evidence for a rapid, kilometer-scale crustal doming prior to the eruption of the Emeishan flood basalts
Sedimentary evidence for a rapid, kilometer-scale crustal doming prior to the eruption of the Emeishan flood basalts
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DOI：
10.1016/s0012-821x(03)00323-6
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发表时间：
2003-08-25
影响因子：
5.3
通讯作者：
Wang, Y
中科院分区：
文献类型：
--
作者：
He, B;Xu, YG;Wang, Y
对峨眉山溢流玄武岩下伏的中二叠统茅口组进行了67个剖面的生物地层学和沉积学研究。结果表明，峨眉山大火成岩省侵位前存在穹隆状地壳减薄。茅口组变薄的碳酸盐岩被陆上不整合面覆盖，一般表现为岩溶古地形、古风化带，局部为残留砾石和底砾岩。物源分析表明，这些砾石和砾岩主要来源于上统茅口组。因此，地层减薄可能是由于区域隆升造成的差异侵蚀。茅口组的等厚度线描绘了一个近圆形隆起区，与实验和数值模拟预测的地幔热柱引起的地壳隆起一致。这一隆升的持续时间估计不到300万年，隆升幅度大于1000米。这些沉积记录为峨眉山溢流玄武岩形成的地幔柱启动模式提供了独立的支持证据。(C)2003 Elsevier B.V.保留所有权利。
Biostratigraphic and sedimentologic investigations in 67 sections have been carried out for the Middle Permian Maokou Formation that immediately underlies the Emeishan flood basalts in southwest China. The results suggest a domal crustal thinning before the emplacement of the Emeishan large igneous province. Variably thinned carbonates in the Maokou Formation are capped by a subaerial unconformity, which is generally manifested by karst paleotopography, paleoweathering zone, or locally by relict gravels and basal conglomerates. Provenance analysis indicates that these gravels and conglomerates were mainly derived from the uppermost Maokou Formation. Therefore, the stratigraphic thinning likely resulted from differential erosion due to regional uplift. Iso-thickness contours of the Maokou Formation delineate a subcircular uplifted area, in accordance with the crustal doming caused by a starting mantle plume as predicted by experimental and numerical modeling. The duration of this uplift is estimated to be less than 3 Myr and the magnitude of uplift is greater than 1000 m. The sedimentary records therefore provide independent supporting evidence for the mantle plume initiation model for the generation of the Emeishan flood basalts. (C) 2003 Elsevier B.V. All rights reserved.