同位素地球化学在峨眉山大火成岩省研究中的应用现状与进展

摘要

系统总结分析了峨眉山大火成岩省的同位素地球化学研究成果。总结前人研究资料中大量峨眉山大火成岩省（ELIP）中玄武岩和侵入体的同位素年龄数据，并结合生物地层学特征，确认我国西南峨眉山大火成岩省中的各个岩石单元的形成时代为251～263 Ma，其中基性超基性侵入岩体形成于约259 Ma，而作为峨眉山大火成岩省主体的峨眉山玄武岩系形成于251～253 Ma。Sr Nd、Re Os、Lu Hf 及 O同位素地球化学数据表明峨眉山大火成岩省的源区为地幔柱或者大陆岩石圈地幔（SCLM），其中峨眉山玄武岩与富含 Fe Ti 氧化物基性侵入体的 Sr Nd 同位素特征相似，具有与 OIB 相似的同位素性质；而含 Cu Ni 硫化物的基性超基性岩体的同位素特征接近地壳物质，可能与地壳混染作用有关。%The authors had systematically summarize and analyze the previous research results of isotopic geochemistry in Emeishan large igneous province (ELIP).According to the isotopic geochemical data of basalt and intrusions in ELIP,combined with its biostratigraphy,we propose a rough period of 251 263 Ma as the formation age of each rock unit in ELIP.Mafic-ultramafic instrusions in ELIP formed in ~259 Ma,and the basalts,which was viewed as the bulk of ELIP formed in 251 253 Ma. The isotopic geochemical data of Sr Nd,Re Os,Lu Hf and O indicate that the ELIP originate from either mantle plume or subcontinental lithosphere mantle (SCLM).The Emeishan basalts show similar Sr Nd isotopic characteristcs to the mafic intrutions which is rich of Fe Ti oxide;and the mafic-ultramafic instrusions bearing Cu Ni sulfides are closer to crust material,which might be related to crust contamination.