深俯冲陆壳的P-T-t-熔流体演化轨迹:来自苏鲁超高压榴辉岩中多相固体包裹的约束

熔流体活动广泛而深刻影响俯冲带内构造变形、元素迁移、变质反应、壳幔相互作用和弧岩浆活动。准确厘定俯冲带内熔流体活动的期次、性质、来源、成分和机制是备受关注且亟待解决的科学难题。近期申请人在苏鲁桃行部分熔融超高压榴辉岩中新识别出大量发育主量元素成分环带的石榴石，各环带内保存不同类型的多相固体包裹体，为探究上述科学问题提供宝贵契机。拟以这些多相固体包裹体及寄主榴辉岩为主要研究对象，通过构造解析、岩相学、显微构造、矿物化学、相平衡热力学模拟、副矿物年代学和全岩地球化学等多方面综合研究，以准确估算多相固体包裹体的主微量成分并探明其成因机制，厘定熔流体活动的期次、性质、成分和时间，探明多相固体包裹体与寄主榴辉岩变质-熔融事件及P-T轨迹之间的耦合关系，最终重建超高压榴辉岩P-T-t-熔流体演化轨迹，从而深入理解深俯冲陆壳内熔流体的形成和演化规律。

Metamorphic fluid affects tectonic deformation, elemental migration, metamorphic reaction, crust-mantle interaction and arc magmatism in subduction zones extensively and profoundly. However, the scientific issue of accurately determining of the episodes, nature, origin, composition and mechanism of metamorphic fluid in subduction zones still raises considerable concern and needs to be solved urgently. Recently, the applicant newly identified garnets with major element zoning in partially melted ultrahigh-pressure eclogite from Taohang, Sulu belt. Various types of multiphase solid inclusions are preserved in every zone, which provides a valuable opportunity to explore the above scientific issue. Therefore, the applicant plans to take these multiphase solid inclusions and the host eclogite as the main object of the combined study of structural analysis, petrography, microtectonics, mineral chemistry, phase equilibrium modeling, accessory mineral geochronology, whole-rock geochemistry, in order to accurately estimate the main and trace element compositions of multiphase solid inclusions and ascertain their petrogenesis, to clarify the nature, compositions and timing of each episodes of the metamorphic fluid; combined with the metamorphic and anatectic events and the P-T path of the host eclogite, eventually reconstructing P-T-t-metamorphic fluid path of the ultrahigh-pressure eclogite, and further to assist understanding origin and evolution of metamorphic fluid in the deeply subducted continental crust.