东昆仑造山带家琪式斑岩型Cu-Mo矿床中花岗闪长岩的斜长石晶体群及其成矿意义  

Plagioclase Crystal Populations of the Granodiorite in the Jiaqi-style Porphyry Cu-Mo Deposit,Eastern Kunlun Orogen,Qinghai,and their Metallogenic Implications

作　　者：罗照华[1] 郭晶[1] 黑慧欣 王秉璋[2] 王涛[2] LUO Zhao-hua;GUO Jing;HEI Hui-xin;WANG Bing-zhang;WANG Tao(State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;Qinghai Geological Survey Institute, Xining 810012, China)

机构地区：[1]中国地质大学(北京)地质过程与矿产资源国家重点实验室,北京100083 [2]青海省地质调查院,西宁810012

出　　处：《矿物岩石地球化学通报》2018年第2期214-228,371,共15页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：青海省地质调查院科研项目(QHDZDCY-2014-01)

摘　　要：近年来,越来越多的作者接受火成岩由多种晶体群组成的新概念。本文以东昆仑造山带家琪式斑岩型Cu-Mo矿床中花岗闪长岩为例,试图阐明火成岩晶体群的涵义及其研究方法和意义。显微镜观察表明,花岗闪长岩的斜长石按其结晶习性可划分为5种不同类型,阴极发光图像分析证实了这一观察,并揭示了它们的生长过程。电子探针剖面分析揭示了横跨晶体切面的化学变化,进一步表明这些晶体具有不同的生长环境和生长过程,属于不同的晶体群。基于平衡热力学原理,推测晶体群来自5个不同的岩浆子系统,暗示形成花岗闪长岩的岩浆为多重岩浆房系统岩浆混合作用的产物,且混合岩浆经历了快速固结过程。这些认识对于探讨斑岩型矿床成因具有重要意义。In recent years,more and more researchers accept the opinion that igneous rocks are composed of crystal populations. In this article,taking the granodiorite in the Jiaqi-style porphyry Cu-Mo deposit,Eastern Kunlun orogen,as an example,we attempt to clarify the content of the term ＂crystal population＂,and indroduce the methodology and implications for studying crystal populations. The petrography and CL images indicate that plagioclase grains in the granodiorite can be subdivided into five types. Chemical variation across the plagioclase crystal grains by EMPA further suggests that these five types of crystals have crystallized in different conditions and processes so that they are of different crystal populations. According to principles of the equilibrium thermodynamics,the five crystal populations are likely to be derived from five different magma subsystems,which suggests that the parental magmas are the product of magma mixing of a multiple chamber system. The mixing magmas must have experienced a quickly solidification process. The new insights are important for revealing origin of the porphyry deposits.

关 键 词：斜长石 晶体群 成因矿物学 斑岩型矿床 透岩浆流体 东昆仑造山带 

分 类 号：P578.968[天文地球—矿物学]