西藏蒙亚啊铅锌矿床矽卡岩矿物特征及其意义  

Characteristics and Significance of Skarn Minerals of Mengya'a Pb-Zn Deposit in Tibet

作　　者：邬秋敏 陈翠华[1] 涂宗林 张燕[1] 宋志娇[1] 赖翔 WU Qiumin;CHEN Cuihu;TU Zonglin;ZHANG Yan;SONG Zhijiao;LAI Xiang(College of Earth Sciences,Chengdu University of Technology,Chengdu,Sichuan610059,China;No.403 Geological Party,Sichuan Bureau of Geology and Mineral Exploration and Development,Emei,Sichuan614200,China)

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]四川省地质矿产勘查开发局四〇三地质队,四川峨眉614200

出　　处：《现代地质》2018年第5期874-886,共13页Geoscience

基　　金：四川省教育厅项目(SZX040);中国地质调查局项目(12120113036200);国家自然科学基金项目(41372093)

摘　　要：西藏蒙亚啊铅锌矿床是冈底斯北缘一个重要的层状或似层状矽卡岩矿床,来姑组为矿床的主要容矿层位。矿区矽卡岩矿物主要有硅灰石、辉石、石榴石、透闪石、阳起石、绿帘石和绿泥石等。根据矿物的共生组合及交代关系,推断矿床经历了4个成矿阶段:早期矽卡岩阶段、晚期矽卡岩阶段、石英-硫化物阶段和碳酸盐阶段。结合矿物手标本及显微镜下观察,通过对矽卡岩矿物的电子探针测试,分析石榴石、辉石和硅灰石的矿物特征,结果表明:西藏蒙亚啊铅锌矿床属钙质矽卡岩矿床,石榴石和辉石的组分变化较大,分别为And_(59.9～94.72)Gro_(0～37.87)(Pyr+Spe+Alm)_(0.87～6.78)和Di_(18.85～94.44)Hd_(3.39～70.58)Jo_(0.09～11.14),硅灰石的矿物组分为Wo_(99.00～99.44)Fs_(0.37～0.78)En_(0.07～0.23)。石榴石属钙铁榴石-钙铝榴石系列,且环带发育,辉石为透辉石-钙铁辉石系列,硅灰石组分较纯。西藏蒙亚啊矽卡岩为钙质矽卡岩,其矿床在形成过程中经历了热液流体的多期多阶段演化,矿床形成环境也并不是稳定的封闭体系。矽卡岩矿物成分特征表明,蒙亚啊铅锌矿床的成矿环境是一个低酸性的氧化-弱氧化环境。Mengyaa lead-zinc deposit in Tibet is an important stratified or stratoid skarn deposit in the northern margin of Gangdise.Laigu Formation,the main ore-hosting strata,provides the main metallogenic material.The main skarn minerals consist mainly of wollastonite,pyroxene,garnet,hopfnerite,actinolite,epidote,chlorite etc.According to the association combination and replacement relationship of minerals,the authors infer that Mengyaa lead-zinc deposit experienced four stages,i.e.,early-skarn stage,late-skarn stage,quartz-sulfide stage and carbonation stage.Combining with mineral hand specimens and microscopic observation and the electron microprobe analysis,the authors analyzed the mineralogical characteristics of garnet,pyroxene and wollastonite.The results of electron microprobe analysis show that Mengyaa lead-zinc deposit in Tibet belongs to calcareous skarn deposit;the composition of garnet and pyroxene changed greatly,which respectively were And59.9-94.72 Gro0-37.87(Pyr+Spe+Alm)0.87-6.78 and Di18.85-94.44 Hd3.39-70.58 Jo0.09-11.14;the mineral composition of wollastonite is Wo99.00-99.44Fs0.37-0.78En0.07-0.23.The garnets are mainly andradite-grossuthe,and the garnets always develop zoning structure.The pyroxene is diopside-hedenbergite series,and the wollastonite is pure.The skarn of Mengyaa deposit in Tibet is calcareous skarn.Its ore deposit experienced multi-stage and multi-order evolution of hydrothermal fluid during its formation,and the forming environment of the deposit also is not a stable close system.The mineral composition characteristics of skarn indicate that the metallogenic environment of Mengyaa Pb-Zn deposit was a low acid and oxidation-weak oxidation environment.

关 键 词：成矿环境 矽卡岩矿物特征 蒙亚啊铅锌矿床 西藏 

分 类 号：P618.42[天文地球—矿床学] P618.43[天文地球—地质学]