俯冲带超临界流体的元素迁移:实验研究进展和存在问题

Element Migration of Supercritical Fluids in Subduction Zones:Progress and Problems of Experimental Researches

超临界地质流体是富溶质的浓稠流体,它们既有含水熔体的组成和结构,又有接近富水流体的密度和粘度,因而具有超强的元素溶解和迁移能力。目前从俯冲板片脱出并引发地幔楔熔融和弧岩浆活动的流体性质还模糊不清,阐明板片流体的性质及其对元素迁移的关键控制因素,特别是对超临界流体研究程度的提高,可能为俯冲带元素迁移、物质循环和成矿等过程和机制的理解提供新的认识和视角。本文回顾和剖析俯冲带流体和超临界流体的形成以及它们对元素(特别是难溶元素)的迁移能力和关键控制因素的实验研究现状,提出亟待解决的重要科学问题。

Supercritical geological fluids are solute-rich fluids.They have composition and structure close to those of hydrous melts but density and viscosity close to those of aqueous fluids.These features of supercritical fluids result in their super capability of element dissolution and migration.So far the nature and composition of the fluids released from the subducted slab and then to trigger the melting of mantle wedge and the generation of arc magmas are still vague.Therefore,the key factors controlling element migration of the fluids released from the subducted slab,especially the improvement of investigation on the supercritical fluids,may provide new insights and perspectives for understanding the processes and mechanisms of the element migration,material recycling,and metallogenesis in subduction zones.In this paper,we have reviewed and discussed status of experimental researches on the formation conditions,migration capability and key controlling factors for the transfer of elements(especially insoluble elements)of the aqueous fluids and supercritical fluids in subduction zones.Finally,we have put forward important scientific issues to be solved urgently.