峨眉山地幔柱主要研究进展及四川盆地二叠纪成盆动力学机制

Advances on the Understanding in the Emeishan Mantle Plume and Dynamic Mechanism of the Permian Sichuan Basin Formation

近年来峨眉山大火成岩省及其地幔柱成因研究取得了重要进展,但关于地幔柱在四川盆地的作用范围和二叠纪成盆动力学机制等方面存在认识分歧。基于大量文献调研并结合近期研究,采用深部地幔活动控制表层系统演变的研究思路,系统梳理峨眉山大火成岩省及其深部地质特征。地幔柱是诱发峨眉山玄武岩大规模喷发并形成大火成岩省的主导因素,但地幔柱仅对四川盆地部分地区具有直接影响,具体表现为地幔柱上涌引起地壳隆升并导致中二叠统茅口组顶部出现地层差异剥蚀和对盆地中南部二叠纪沉积的控制作用,而盆地中北部中晚二叠世—早三叠世拉张槽群和“凹凸相间”沉积-构造格局的形成则主要受控于南秦岭洋岩石圈板块的拉张。

In recent years,significant research progress has been made on the Emeishan Large Igneous Province(ELIP)and its genetic mechanism of mantle plume,but the scope of the mantle plume on the Sichuan Basin and the dynamic mechanism for the Permian sedimentary basin formation remain unclear.Based on a number of literature research and recent studies,and the idea that deep mantle activity controls the evolution of crustal surface system,the characteristics of Emeishan LIP and its deep geology are systematically reviewed.It is recognized that the mantle plume is the dominant factor that induces the large-scale eruption of the Emeishan basalts and formed the LIP,and has direct influence on some parts of the Sichuan Basin,which is manifested by the differential denudation of the top Middle Permian Maokou Formation.This was likely caused by the upwelling of mantle plume and its control on the Permian sedimentation and sedimentary facies distribution in the centralsouthern part of the basin.Formation of the extensional troughs,and the alternating high-and-low sedimentarytectonic framework in the central-northern Sichuan Basin during the Permian to Early Triassic may have been mainly controlled by the extension of the southern Qinling Ocean.