赣中变质岩带的组成及构造变质变形特征

赣中变质岩带不是简单的一套震旦纪地层 ,而是由结晶基底中元古界中深变质岩系 (斜长角闪岩的Sm Nd全岩等时线年龄为 1113± 4 9Ma)和褶皱基底变质较浅的震旦系组成。两者之间以具热流体参与的混合岩化、韧性剪切带和递进变质三位一体组成的动热变质带接触。结晶基底经历了4期构造变质变形的叠加改造 ,每期构造变形都在变质岩石构造单元内留下各种变形形迹 ,变质作用表现为时间上的递进和空间上的叠加演化系列 ,是一套以众多的不平衡结构和多相共生混存的矿物组合 ,热变质带为一套动热变质塑性变形带 ,空间上依次形成绢云母—绿泥石带、黑云母带、石榴石带、十字石带以及夕线石带

Composition and structural metamorphism-deformation features of the central Jiangxi metamorphic zone

Thecentral Jiangxi metamorphic zone is not a simple suite of Sinian strata but composed of aMesoproterozoic medium- and high-grade metamorphic series (the whole-rock Sm-Nd isochronage of amphibolite is 1 113±49 Ma) as the crystalline basement and the low-grademetamorphic Sinian as the folded basement. Between them is a dynamo-thermal contactmetamorphic zone composed of migmatization, ductile shear zone and progressivemetamorphism, which occurred in the presence of hydrothermal fluids. The crystallinebasement underwent four phases of reworking by structural metamorphism-deformation. Thestructural deformation of each phase left various deformation markings. The metamorphismis manifested by an evolutionary series which was progressive in time and overprinted inspace and is marked by a mineral assemblage with many disequilibrium textures and manycoexisting minerals. The thermal metamorphic zone is a zone of dynamo-thermalmetamorphism-plastic deformation, and in space there appear successively thesericite-chloride zone, biotite zone, garnet zone, staurolite zone and sillimanite zone.