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本文简要总结了国家重点基础研究发展计划项目《二叠纪地幔柱构造与地表系统演变》的主要研究进展:(1)峨眉山大火成岩省形成于~259 Ma,持续时间小于1 Ma,是地幔柱头熔融的产物;塔里木大火成岩省为多阶段喷发(~300,~290,280 Ma),持续时间超过20 Ma,是孕育地幔柱活动的产物。(2)利用综合地球物理方法发现峨眉山大火成岩省内带上下地壳界面“消失”、下地壳增厚且具高波速特征、岩石圈地幔减薄,是地幔柱熔融产物在地壳不同深度底侵和内侵的结果。(3)完善了大火成岩省岩浆矿床的形成机理,构建了地幔柱成矿系统的基本框架,提出地幔柱结构、岩浆源区特征、结晶分异过程、硫化物饱和、地壳混染和岩浆侵位过程等是地幔柱成矿的关键控制因素。(4)从相对和绝对时间角度确证了西伯利亚和峨眉山大火成岩省分别对应于二叠纪末(PTB)和瓜德鲁普统-乐平统界线(GLB)生物灭绝事件;重建了华南二叠-三叠纪海水温度和p H值的演变历史,使甄别二叠纪末生物大灭绝的直接诱因成为可能。
This paper briefly summarizes the major research progress of “Permian mantle plume structure and surface system evolution” under the state key basic research development project: (1) The Emeishan large igneous province formed at ~ 259 Ma with a duration less than 1 Ma, Melted product. The large igneous province of Tarim is a multi-stage eruption (~ 300, ~ 290, 280 Ma) lasting more than 20 Ma, which is the product of mantle plume activity. (2) Using integrated geophysical methods, it is found that the interface of upper crust and lower crust in the Emeishan large igneous province is “disappearing”, the lower crust thickens and has the characteristics of high velocity and the lithospheric mantle is thinned. It is the result of mantle plume melting at the bottom of the crust The result of invasion and internal invasion. (3) Perfecting the formation mechanism of the magmatic deposits in the large igneous province, constructing the basic framework of the mantle plume metallogenic system, presenting the characteristics of the mantle plume structure, the characteristics of magma source region, the process of crystallization differentiation, sulfide saturation, crustal contamination and magmatic intrusion The bit process is the key control factor of mantle plume formation. (4) From the angle of relative and absolute time, it is confirmed that the large igneous provinces of Siberia and Mount Emei correspond to the extinction of PTB and GLB respectively; the reconstruction of South China Permian- The evolution of Triassic sea water temperature and p H values made it possible to identify the immediate cause of the Permian end extinction.