苦橄岩斑晶矿物的O-Li同位素研究：对峨眉山大火成岩省岩浆地幔源区的制约

岩浆地幔源区的性质和组成研究是大火成岩省成因研究的前沿课题之一。前人对于峨眉山大火成岩省高钛和低钛两类岩浆的地幔源区中是否含有与洋壳俯冲有关的榴辉岩/辉石岩组分存在不同观点，对于这些组分的具体来源缺乏深入认识。近年来，离子探针（SIMS）微区原位O-Li同位素分析技术的成熟为鉴别这些俯冲洋壳组分提供了坚实的实验基础。本项目计划对峨眉山大火成岩省内的大理、宾川、剑川、木里及Song-Da地区的高钛和低钛苦橄岩中的斑晶矿物开展O-Li同位素离子探针微区原位分析，并结合熔体包裹体成分、Sr-Nd-Hf同位素分析，揭示峨眉山大火成岩省的岩浆地幔源区中是否有与洋壳俯冲有关的榴辉岩/辉石岩组分以及这些组分的具体来源，并探讨高钛和低钛两类岩浆是否存在地幔源区差异。本项研究对探讨峨眉山大火成岩省地幔源区物质组成的不均一性、地幔柱-岩石圈相互作用过程，以及完善峨眉山地幔柱岩浆作用模型等方面具有重要意义。

The study of mantle source characteristics is one of the frontiers in continental large igneous province (LIP) research. The possible existence of eclogite/garnet pyroxenite related to subduction in the mantle source of High-Ti and Low-Ti magmas in the Emeishan LIP is still under debated. Further study is still needed about the origins of these enriched components. In situ analysis of O-Li isotopes using secondary ion probe with a multi-collection system (SIMS) is mature in recent years. This method makes tracing of subducted oceanic crust more reliable. In this project, we would carry out in situ analyses of mineral O-Li isotopes, combined with analyses of melt inclusion compositions and Sr-Nd-Hf isotopes of the High-Ti and Low-Ti picrites in the Emeishan LIP. The purpose of this study is to trace the possible existence of eclogite/garnet pyroxenite related to subduction in the mantle source of High-Ti and Low-Ti magmas in the Emeishan LIP. On the other hand, we will investigate the possible difference in the mantle source of High-Ti and Low-Ti magmas. A better understanding of the mantle source heterogeneity of the Emeishan LIP magmas and plume-lithosphere interaction process and further improvement of the model of Emeishan mantle plume magmatism can be achieved in our research.