青海南山地区中压相系递增变质带初步研究  

A Preliminary Study on the Medium Pressure Facies Series Progressive Metamorphic Zone in Nanshan Area,Qinghai Province

作　　者：代雄 杨柳[1] 贺光兴 李佳奇[1] 易建[1] 邓华波[1] 

机构地区：[1]四川省冶金地质勘查院,成都610051

出　　处：《地质论评》2016年第5期1201-1210,共10页Geological Review

基　　金：中国地质调查局"青海省共和县文巴地地区J47E021015;J47E021016;J47E022016;J47E022017四幅1:5万区域地质矿产调查"项目(编号:12120113033019)的成果~~

摘　　要：青海南山地区位于东昆仑与西秦岭的重要衔接处,首次发现一套递增变质带,变质带由中心往外,变质强度逐渐递减,依次分别为：矽线石带、蓝晶石带、石榴子石带、黑云母带、绿泥石带。本文以石榴子石黑云母变粒岩为研究对象,通过岩相学研究并结合电子探针成分分析,显示石榴子石变斑晶具有微弱的生长环带,黑云母以高温铁质黑云母为主,利用石榴子石—黑云母温度计、石榴子石—黑云母—斜长石—石英压力计计算,获得石榴子石带的变质P—T条件为564℃,0.56GPa;蓝晶石带的变质P—T条件为667~670℃,0.68~0.71GPa,属于中压相系。应与印支期古特提斯洋闭合导致的地壳碰撞加厚有关。Well-developed progressive metamorphic zone is found in Nanshan area, located in the joint region between the East Kunlun and the West Qinling Orogenic Belt in Qinghai Province. From center to the rim, the metamorphic zone could be subdivided into sillimanite zone, kyanite zone, garnet zone, biotite zone and chlorite zone with the decreasing of metamorphic grade. Among them, garnet porphyroblasts in Gt--Bio granulite show weak growth zoning, and biotite are mainly high temperature ferrobiotite. Based on Gt--Bi thermometer and Gt-- Bi--PI--Q barometer, garnet zone has temperatures of 564℃ and pressures of 0. 56GPa, kyanite zone has temperatures of 667 -670 ℃ and pressures of 0.68 -0.71GPa, belonging to medium pressure facies series. Related to the crustal collision thickening of the closure of the Paleo-Tethys Ocean in the Indosinian.

关 键 词：递增变质带 中压相系 印支期 青海南山地区 

分 类 号：P588.3[天文地球—岩石学]