新疆巴楚地区早二叠纪基性岩墙中单斜辉石粗晶的稀有气体同位素研究

The early Permian Tarim large igneous province (LIP) is another confirmed LIP in China after the recognition of the Emeishan LIP, and is characterized by complex rock associations and abundant V-Ti magnetite mineral resources. Although many achievements have been made recently in the studies on the Tarim LIP, the geodynamic process of the magmatism and metallogenesis in the Tarim LIP and its relationship with mantle plume are yet to be fully understood. Using the nontraditional geochemical tracer of rare gas isotopes (He-Ne-Ar), this project will focus on the clinopyroxene macrocrysts in the early Permian mafic dykes from the Bachu area, Xinjiang, in combination with the traditional methods of major and trace elements as well as radiogenic isotopes (Sr-Pb). The properties and compositional characteristics of the mantle sources of the third (~ 280 Ma) magmatic episode in the Tarim LIP will be further discovered in order to discuss the interaction between a mantle plume and lithosphere during the evolution of the Tarim LIP. The final object of this project is to provide some constraints on unravelling the possible genetic linkage with plume-lithosphere interaction and metallogenetic effects of LIP events.

早二叠纪塔里木大火成岩省是我国继峨眉山大火成岩省之后又一个被学术界广泛认可的大火成岩省，以复杂的岩石组合和丰富的钒钛磁铁矿资源为特征。目前，关于塔里木大火成岩省的研究虽然已取得了许多的进展，但是对塔里木大火成岩省岩浆作用和成矿作用的深部动力学过程以及与地幔柱的关系仍然需要进一步的制约。本项目拟采用非传统的稀有气体同位素（He-Ne-Ar）地球化学示踪手段，对新疆巴楚地区基性岩墙中单斜辉石粗晶开展研究，并结合传统的主量、微量元素和放射性同位素（Sr-Pb）地球化学示踪方法，进一步揭示塔里木大火成岩省中第三期（~ 280 Ma）岩浆作用的地幔源区性质和特征，进而探讨塔里木地幔柱-岩石圈相互作用过程，为阐明地幔柱-岩石圈相互作用与大火成岩省成矿效应的深部控制机理提供约束。

早二叠纪塔里木大火成岩省以岩石组合复杂、岩浆作用持续时间长以及广泛分布的铁质玄武岩有别于其它大火成岩省，但其形成过程以及赋含的钒钛磁铁矿矿化与地幔柱的具体关系尚不清楚。本项目以塔里木大火成岩省西北部巴楚地区基性−超基性岩墙为主要研究对象，基于之前的研究成果，通过对其单斜辉石粗晶的微区原位分析以及Sr−Pb和稀有气体同位素（He−Ar）研究，结合橄榄石斑晶微量元素分析，进一步揭示塔里木大火成岩省中第三期（~280 Ma）岩浆作用的地幔源区性质和特征，阐明钒钛磁铁矿成矿作用与源区再循环俯冲洋壳物质加入的成因联系，为深入理解塔里木地幔柱-岩石圈相互作用过程提供了新的科学依据，并为建立地幔柱-岩石圈相互作用与大火成岩省成矿效应的深部控制机理提供约束。