云南羊拉铜矿床矿物组成、地球化学特征及其地质意义  

Mineral Composition,Geochemistry of the Yangla Copper Deposit in Yunnan and Their Geological Significances

作　　者：杨喜安[1] 刘家军[1] 韩思宇[1] 汪欢[1] 罗诚 刘月东 翟德高[1] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]云南迪庆矿业开发有限责任公司,云南德钦674507

出　　处：《现代地质》2012年第2期229-242,共14页Geoscience

基　　金：国家重点基础研究发展计划项目(2009CB421003;2009CB421005);高等学校学科创新引智计划项目(B07011)

摘　　要：云南羊拉铜矿床位于金沙江构造带中部,是三江地区一个十分典型的大型铜矿床。羊拉铜矿床的金属矿物为黄铜矿、黄铁矿、磁黄铁矿、方铅矿、自然铋、辉铋矿、毒砂、辉砷钴矿、辉钼矿等,根据金属矿物的共生组合,推测羊拉铜矿床为中高温热液矿床。羊拉铜矿床与羊拉花岗闪长岩体具有密切的成因联系,通过对羊拉铜矿床铜矿石稀土元素、微量元素的分布特征和羊拉花岗闪长岩的对比及S、Pb同位素组成的研究,表明成矿物质主要来源于地幔,部分来源于岩浆。早二叠世晚期金沙江洋盆向西俯冲形成了一系列逆断层。同时,金沙江洋盆向西低角度俯冲导致下地壳部分熔融,引发大规模的火山岩浆作用。在晚三叠世早期,构造背景由挤压环境到伸展环境的转折期,这些逆断层具有张性的特点,为后期的成矿热液提供了有利的容矿构造。持续上升的岩浆为地幔楔内的成矿流体提供了通道,岩浆内的部分成矿流体进入羊拉花岗闪长岩体附近的逆断层富集成矿。The Yangla copper deposit,situated in the middle section of Jinshajiang tectonic belt between Zhongza-Zhongdian plate and Changdu-Simao plate,is a representative and giant copper deposit that has been discovered in Jinshajiang-Lancangjiang-Nujiang region in recent years.Metalliferous minerals consist of chalcopyrite,pyrite,pyrrhotite,galena,bismuth,bismuthinite,arsenopyrite,cobaltite and molybdenite.Based on the mineral association,the paper infers that the deposit is a medium to high temperature hydrothermal deposit.There is a coupled relationship between Yangla granodiorite and copper mineralization in the Yangla copper deposit.A comparison of the REE and trace element compositions of the copper ores with those of the Yangla granodiorite,and S,Pb isotopic composition of the Yangla copper deposit indicate that the ore-forming fluids are derived mainly from the mantle,with minor contributions from the magma.In the late Early Permian,the Jinshajiang oceanic plate was subducted to the west,resulting in the formation of a series of gently dipping thrust faults in the Jinshajiang tectonic belt,meanwhile,accompanied magmatic activities.In the early Late Triassic,which was a time of transition from collision-related compression to extension in the Jinshajiang tectonic belt,the thrust faults were tensional,it would have been a favorable environment for ore-forming fluids.The ascending magma provided a channel for the ore-forming fluid from the mantle wedge.After the magma arrived at the base of the early-stage Yangla granodiorite,the platy nature of the granodiorite body would have shielded the late-stage magma from the fluid.The magma cooled slowly,and some of the ore-forming fluid in the magma moved along a gently dipping thrust faults near the Yangla granodiorite,resulting in mineralization.

关 键 词：羊拉铜矿床 矿物组成 稀土元素 微量元素 S、Pb同位素 云南 

分 类 号：P618.41[天文地球—矿床学]