新疆北山盐滩断裂南一带高级变质岩系的发现、地质热力学特征及其大地构造意义  

Discovery and thermodynamic characteristics of high-grade metamorphic rock series along the south of Yantan fault in Beishan,Xinjiang and its tectonic significance

作　　者：李永寿[1,2] 杨兴科[3] 马海州[1] 

机构地区：[1]中国科学院青海盐湖研究所盐湖资源与化学重点实验室,西宁810008 [2]中国科学院大学,北京100049 [3]长安大学地球科学与资源学院西部矿产资源与地质工程教育部重点实验室,西安710054

出　　处：《岩石学报》2016年第6期1688-1698,共11页Acta Petrologica Sinica

基　　金：国家重点基础研究计划"973"项目(2011CB403004);新疆维吾尔自治区1︰5万区域地质矿产调查项目(XJQDZ2006-16)联合资助

摘　　要：新疆北山盐滩断裂南一带从原划奥陶-志留系地层中解体出古老的角闪岩相-麻粒岩相变质岩和变质侵入岩体,主要岩性为黑云母斜长片麻岩、条带状混合岩、斜长角闪岩、及少量变粒岩、麻粒岩等。其中首次发现了代表中、下地壳深变质作用的中-高压基性麻粒岩。详细的野外调查、岩相学及矿物学研究表明,该基性麻粒岩主要由透辉石、紫苏辉石、褐色普通角闪石及拉长石组成。其演化经历了由麻粒岩相岩石经退变质反应而成为角闪岩相变质岩的过程。研究表明,该区麻粒岩中的单斜辉石及角闪石矿物学成因均属于变质成因,其中单斜辉石形成环境为高压型,而角闪石形成环境为中低压环境。麻粒岩相变质岩形成于约1.25GPa（42km埋深）以下的中高压-高压环境,其形成温度约841℃;而退变质作用下的角闪岩相变质岩应形成于650-657℃的温度范围之内,压力为0.460-0.495GPa之间,相应的代表埋深约为16.5km的中低压型环境。该区高级变质岩及其基性麻粒岩的发现,将对该区地壳成分、麻粒岩的成因与变质作用以及所处的大地构造背景演化等研究无疑将起到非常重要的作用。The high-grade metamorphic rock series,representing metamorphic product in the middle-lower crust,was first found in south of Yantan fault of Beishan,Xinjiang. It is consisted of plagioclase-gneiss,migmatites,amphibolites and a small quantity of granulites. Through detailed field survey,petrography mineral-chemical study,find that the basic granulite is consisted of diopsides,hypersthenes,brown hornblendes and labradorites. It has an evolution from the granulite facies rocks into amphibolite facies rocks by retrograde metamorphic reactions. Research shows that,the clinopyroxenes and hornblendes of those granulites in this area have metamorphic genetic,the clinopyroxene is formed in high pressure environment and the hornblendes formed in the middle and lowpressure environment. Based on mineral geothermobaromemter,the metamorphism P-T conditions of the granulite facies is 1. 25GPa（ 42 km depth）,the temperature is about 841℃,and the range of retrograde metamorphism temperature of amphibolite facies should be650 - 657℃,the pressure is 0. 460 - 0. 495GPa（ middle and low-pressure,16. 5km depth）. The discovery of the granulite-facies stratum in this area has an important significance on further study of formation and structure of deeper crust in the area and continental geodynamic mechanism in Xinjiang,China.

关 键 词：新疆北山 高级变质岩系 基性中-高压麻粒岩 成因矿物学 P-T条件 

分 类 号：P588.347[天文地球—岩石学]