东昆仑东段金水口石榴堇青石花岗岩成因——石榴子石证据  

Evidence from Garnet for Genesis of Garnet-Cordierite-Granite in the Jinshuikou Area,Eastern Segment of the East Kunlun Mountains

作　　者：孟繁聪[1] 田广阔 段雪鹏 范亚洲[1] 任玉峰 MENG Fan-cong;TIAN Guang-kuo;DUAN Xue-peng;FAN Ya-zhou;REN Yu-feng(Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China)

机构地区：[1]中国地质科学院地质研究所

出　　处：《矿物岩石地球化学通报》2018年第2期192-204,371,共13页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(41272052);中国地质调查局项目(12120114080101,12120115027001,121201102000150005-08)

摘　　要：为了查明东昆仑东段金水口地区的石榴堇青石花岗岩的成因和地质意义,对其中的石榴子石进行了岩相学和矿物化学研究。根据石榴子石的产状和成分,在该花岗岩中初略识别出岩浆型和转熔型两种成因的石榴子石。前者较少,与长石、石英共生,细小,自形,不含矿物包裹体,富MnO贫MgO,具MnO成分环带;后者较多,与黑云母共生,晶粒较大,它形,常含矿物包裹体,贫MnO富MgO,不具MnO成分环带。两种石榴子共存表明花岗岩为原地深熔成因或混合岩化成因,表明该地区的白沙河岩组片麻岩在早古生代曾经历过减压升温过程。In order to constrain the tectonic setting and genesis of the garnet-cordierite-granite in the Jinshuikou area,eastern segment of the East Kunlun Mountains,petrography and mineral chemistry of the garnet has been studied in this paper. There are two types of garnet in the granite： magmatic and peritectic. The former granet is rare and usually associated with quartz and feldspar. This type of garnet occurs as fine-grained,euhedral to subhedral crystal without mineral inclusions. It is enriched in MnO and poor in MgO,with MnO compositional zoning. The latter is bigger in size,and xenomorphic,containing minerals inclusions. It is poor in MnO and enriched in MgO,without MnO composition zoning. This type of garnet is abundant and commonly associated with biotite. The coexistence of the two type garnets indicates that the granite formed through anatexis or migmatization,indicating that the the Jinshuikou area has experienced decompression and heating processes in the Early Paleozoic.

关 键 词：石榴子石 花岗岩 深熔作用 金水口 东昆仑 

分 类 号：P578.947[天文地球—矿物学]