大陆俯冲带的深部流体及变质化学地球动力学——以苏鲁超高压变质带为例  

Fluids from the Deeply Continental Subduction Zone and the Metamorphic Chemical Geodynamics

作　　者：张泽明[1] 沈昆 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]山东省地质科学实验研究院,济南250013

出　　处：《地球学报》2009年第1期5-20,共16页Acta Geoscientica Sinica

基　　金：科技部973项目(2003CB716501);国家自然科学基金项目(40399142和40472036);中国地质调查局项目资助。

摘　　要：通过苏鲁超高压变质带的岩石学、矿物化学、地球化学和年代学研究,在大陆俯冲带深部流体与变质化学地球动力学方面取得了重要的创新性成果。研究证明大陆俯冲带的深部流体是高氧逸度、富硅酸盐的超临界流体,揭示出超高压变质极端条件下的流体-矿物(岩石)相互作用可以导致不活动元素发生溶解和迁移,可以导致金红石的Nb/Ta之间发生强烈的分异,提出俯冲到地幔深处的超高压榴辉岩是地球内部"隐藏"的超球粒陨石Nb/Ta比值的物质源区,与低球粒陨石Nb/Ta比值的物质源区大陆地壳和亏损地幔在化学成分上形成互补。By the studies of petrology, mineral chemistry, geochemistry and geochronology of the ultrahigh- pressure metamorphic rocks from the Sulu orogenic belt, some important achievements related to the metamorphic chemical geodynamics in the convergent plate boundary have been reached. They include that the fluids in the deeply subducted continental crust are the high oxygen fugacity and silicate-rich supercritical fluids, the supercritical fluids-minerals （rocks） interactions under the extreme ultrahigh-pressure metamorphic condition have resuited in the mobility of normally fluid-immobile elements, and the highly fractionation between Nb and Ta, and that the voluminous ultrahigh-pressure eclogites subducted into the deep mantle have higher Nb/Ta values than that of the chondrite and are the complementary suprachondritic reservoir capable of balancing the subchondritic depleted mantle and continental crust reservoirs.

关 键 词：大陆俯冲带 超临界流体 Nb/Ta分异 变质化学地球动力学 

分 类 号：P588.3[天文地球—岩石学] P595[天文地球—地质学]