Research on the Genesis of High-Low Ti Basalt in ELIP

峨眉山大火成岩省(ELIP)位于扬子板块西缘，其主要组成部分为大陆溢流玄武岩。峨眉山玄武岩根据Ti含量被分为低钛玄武岩和高钛玄武岩，前人已经对峨眉山高低钛玄武岩地球化学和同位素特征进行了系统的研究，然而对高低钛玄武岩的成因机制还存在争议。文章对峨眉山高低钛玄武岩的地球化学、Sr-Nd同位素组成数据进行整理分析，以约束峨眉山高低钛玄武岩成因。研究结果表明：峨眉山低钛玄武岩和高钛玄武岩都来自于地幔柱熔融。峨眉山高钛玄武岩没有受到明显的地壳和岩石圈地幔物质污染，而峨眉山内带低钛玄武岩遭受到明显的地壳物质和岩石圈地幔物质污染。低钛玄武岩为尖晶石橄榄岩地幔熔融，高钛玄武岩为石榴石橄榄岩地幔熔融。峨眉山高低钛玄武岩成因的研究为深入理解峨眉山大火成岩省的形成机制及地幔柱–岩石圈相互作用过程提供了重要约束。The Emeishan Large Igneous Province (ELIP) is located on the western margin of the Yangtze Block, with its main component being continental flood basalts. The Emeishan basalts are classified into Low-Ti and High-Ti types based on Ti content. Previous studies have systematically investigated the geochemical and isotopic characteristics of these High-Ti and Low-Ti basalts, yet controversies remain regarding their genetic mechanisms. This paper compiles and analyzes geochemical data and Sr-Nd isotopic compositions of the Emeishan High-Ti and Low-Ti basalts to constrain their petrogenesis. The results indicate that both the Low-Ti basalts and High-Ti basalts of the Emeishan originated from mantle plume melting. The High-Ti basalts show no significant contamination by crustal or lithospheric mantle materials, whereas the inner-zone Low-Ti basalts exhibit evident contamination by both crustal and lithospheric mantle components. The Low-Ti basalts were derived from melting of spinel-bearing peridotite mantle, while the High-Ti basalts originated from garnet-bearing peridotite mantle. This study on the genesis of Emeishan basalts provides important constraints for understanding the formation mechanism of the ELIP and the interaction processes between mantle plumes and the lithosphere.