挪威超硅石榴石橄榄岩及俯冲隧道流/熔体-岩石相互作用研究

俯冲作用是板块构造运动的核心过程，也是实现地球浅部与深部物质和能量交换的关键方式。俯冲板片与地幔楔在不同深度发生复杂的流/熔体-岩石相互作用，诱发汇聚板块边缘的大规模构造、岩浆、变质和成矿作用。然而，在超硅石榴石稳定存在的地幔深度，俯冲隧道内流/熔体的属性，以及它们与地幔楔岩石发生相互作用的过程，仍是未解决的难点和关键问题。项目将以挪威西片麻岩省超高压造山带内产出的Otrøy超硅石榴石橄榄岩为研究对象，通过岩石学、矿物学和地球化学的综合研究，重点利用原位微区元素和同位素分析技术，查明该造山带橄榄岩的地幔属性，系统揭示不同造岩矿物和包裹体所记录的流/熔体活动痕迹和交代过程，厘清在深度>160 km的地幔楔和俯冲隧道内流/熔体的组成、性质和起源，并约束流/熔体-地幔楔岩石相互作用的过程与机制。研究结果将为进一步理解俯冲带壳幔相互作用、元素循环过程以及弧岩浆作用的深部启动机理提供重要约束。

Subduction is the essential process of plate tectonics, and is the key manner to exchange material and energy between Earth’s shallow and deep regions. Complex interactions between fluids/melts and rocks can occur between subducting slab and mantle wedge in different depths of subduction zones, and trigger large-scale tectonism, magmatism, metamorphism and mineralization processes at convergent plate margins. However, in the mantle depths where majoritic garnet is stable, the nature of fluids/melts in the subduction channel and their interaction processes with mantle wedge rocks remain the key unsolved question. This project will focus on the Otrøy majoritic garnet peridotite massif in the ultrahigh-pressure metamorphosed Western Gneiss Region in Norway, and carry out systematic petrologic, mineralogical and geochemical studies, especially using in situ analytical techniques. Based on the investigation of mantle nature of this peridotite massif, this study will aim to reveal fluid/melt mobility and metasomatism reflected by different minerals and inclusions, clarify the composition, property, origin of the fluids/melts, and understand the interaction processes and mechanisms between fluids/melts and ultra-deep (>160 km) mantle wedge peridotites. The research outcomes will provide key constraints on the understanding of crust-mantle interaction in subduction zones, element cycling processes and deep initiation mechanism of arc magmatism.