峨眉山大火成岩省的形成机制及空间展布:来自沉积地层学的新证据

Generation and Spatial Distribution of the Emeishan Large Igneous Province: New Evidence from Stratigraphic Records

对西南地区茅口灰岩生物地层对比和峨眉山玄武岩与茅口灰岩之间的界面特征的研究表明,上扬子西缘茅口灰岩在玄武岩喷发前存在差异剥蚀,自西到东可分为深度剥蚀带(内带)、部分剥蚀带(中带)、古风化壳或短暂沉积间断带(外带)和连续沉积带;整个剥蚀区的范围同峨眉山玄武岩分布区基本一致。差异剥蚀是中二叠世晚期上扬子西缘一次快速地壳抬升和穹状隆起的结果,这说明峨眉山大火成岩省的形成与地幔柱活动有关。根据上升地幔柱地表抬升模型对峨眉山大火成岩省空间展布进行了讨论,并推算出该大火成岩省的规模。

The biostratigraphic comparison and sedimentological features of the Maokou limestone in SW China demonstrate that differential erosion and crustal uplift were developed prior to eruption of the Emeishan flood basalts. Four sedimentary zones are distinguished with the erosional degree decreasing from west to east. The erosion scope is coeval with the spatial distribution of the Emeishan basalts. It is suggested that differential erosion is caused by a rapid crustal uplift or doming related to the mantle plume activity. This paper discusses the spatial distribution of the Emeishan Large Igneous Province on the basis of the upwelling mantle plume-crustal uplift model and estimates the scale of Emeishan LIP.