峨眉山大火成岩省动力隆升的沉积响应

The Emeishan basalts are the only large igneous province recognized by the international academic in our country. Numbers of studies on petrology, geochemistry, geophysics and chronology, which are related to the mechanisms of Emeishan LIP, had been done. However, the study on sedimentary reponses to the dynamic uplift, which is the independent and effective measure to discuss Emeishan LIP formation mechanism and dynamics process, is still poor. Therefore, based on the previous geological research, this study systematically carries out the research on sedimentology, provenance analysis, isotope dating and conodont biostratigraphy to Maokou limestone and the overlying clastic rock series, in an attempt to verify the spatial characteristics and control mechanism of the different initial depositional thickness and sedimentary facies. Moreover, through the top view of biotic zone of Maokou limestone, this study is helpful to quantitatively estimate the time and processed of dynamics uplift induced by deep mantle activity, which can prove the evidence of sedimentology and biostratigraphy to perfect the tectonic-sedimentary model of the Permian and fully recognize the processes and mechanisms that controlled the generation of the Emeishan LIP.

分布在中国西南三省的峨眉山玄武岩是我国唯一被国际学术界认可的大火成岩省，前人基于岩浆活动、地球化学、地球物理和年代学等研究取得了很多进展，但对动力隆升的浅部地质记录的研究尚且不足，而大火成岩省浅部地质记录特别是沉积响应研究是分析大火成岩省形成机制的一种可靠而独立的手段。因此，本项目以内带玄武岩下伏的茅口灰岩和砾岩为主要研究对象，以前期地质调查为基础，系统开展茅口灰岩沉积学、牙形刺生物地层学及碎屑岩系碎屑成分统计、同位素定年，查明茅口期灰岩原始沉积厚度差异和沉积相分异的空间特征和控制机理，制作茅口组灰岩顶部生物带俯视图，系统探讨深部地幔活动引起的地表动力隆升的时间和过程，为完善二叠纪的构造-沉积演化模型、全面认识峨眉山大火成岩省的形成过程和机制提供沉积学和生物地层学证据。

大火成岩省一直是国际地学界研究的热点，而分布在中国西南三省（云南、贵州、四川）的峨眉山玄武岩是我国唯一被国际学术界认可的大火成岩省。它具有较完整的岩浆-热液成矿系统并发育超大型钒钛磁铁矿，同时峨眉山玄武岩在晚二叠世的大规模喷发可能与瓜德鲁普世末和晚二叠世末的双生物大灭绝事件有关，因而引起国内外学者的广泛关注并已成为国际研究热点。本文对大火成岩省浅部地质记录（构造运动、沉积厚度、剥蚀程度、灾变沉积等）进行研究，进而分析大火成岩省形成机制。通过对ELIP玄武岩下伏地层进行研究，结合以近几年的野外地质调查和研究成果；同时选取分布于内带的盐源县巴折砾岩剖面、普格县西罗灰岩剖面、永胜县期纳灰岩剖面、盐源县白草坪灰岩剖面和会理县白果灰岩剖面五条主干剖面，开展沉积学、牙形刺生物地层学、碎屑成分统计和同位素年代学研究，分析研究区在玄武岩喷发之前的沉积环境，绘制沉积相展布图，完成主干剖面茅口组灰岩牙形刺和蜓类化石生物带划分和对比，绘制茅口组灰岩顶部生物带分布俯视图，定量分析ELIP动力隆升的浅表地质响应时间和过程。