云南华昌山Pb-Zn矿床热液流体演化:方解石REE及C-O同位素证据  

Hydrothermal fluid evolution in the Huachangshan Pb-Zn deposit in Yunnan:Evidences of calcite REE and C-O isotope analyses

作　　者：唐波浪 刘英超[2] 岳龙龙 马旺 庄亮亮[2] TANG Bolang;LIU Yingchao;YUE Longlong;MA Wang;ZHUNAG Liangliang(Jiangsu Nanjing Institute of Geo-Engineering Investigation,Nanjing,Jiangsu 21004l,China;Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]江苏南京地质工程勘察院,江苏南京210041 [2]自然资源部深地动力学重点实验室,中国地质科学院地质研究所,北京100037 [3]地球科学与资源学院中国地质大学(北京),北京100083

出　　处：《地质学报》2023年第4期1178-1191,共14页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41922022,91962105,92162322);中国科学院A类战略性先导科技专项项目(编号XDA20070304);第二次青藏高原综合科学考察项目(编号2021QZKK0304);中国地质科学院地质研究所基本科研业务费项目(编号J2105);国际地质对比计划项目(编号IGCP-662)联合资助的成果。

摘　　要：云南华昌山Pb-Zn矿床是发育在典型褶皱逆冲带内的密西西比河谷型(MVT)铅锌矿床,矿体多沿断裂及断裂两侧分布。本次工作通过对华昌山矿区内关键平硐的编录,识别出4套不同属性的断裂,其中3套对应发育了三种不同期次的热液流体:无矿流体、含铜银流体、含铅锌流体。三期流体均发育热液矿物方解石,通过对三期方解石的原位稀土元素分析发现,这三期流体均是与岩浆作用无关的热液流体,且三期热液流体存在不同的稀土元素配分模式曲线图、不同的lg(Y/Ho)-lg(La/Ho)分布特征和不同的Yb/Ca(原子比)-Yb/La(原子比)分布特征,说明三期热液流体的来源属性不同或者同源但受不同作用的改造。三期方解石的碳、氧同位素值表明热液流体中的碳来自盆地海相碳酸盐岩的溶解作用,方解石的氧同位素特征表明三期流体均为盆地卤水,且铅锌成矿期的流体中混入大气降水。分析华昌山矿床的构造断裂活动和热液流体特征,本文认为区域逆冲断裂之后的张性断裂是控制华昌山铅锌矿床的控矿断裂。The Huachangshan lead-zinc deposit in Yunnan is a typical MVT lead-zinc deposit formed in the fold-thrust belt,with most of the ore bodies located along and on both sides of the faults.In this study,four sets of faults with different occurrences were identified by cataloguing adits,three of which have developed hydrothermal fluids that include a non-mineralized fluid,a copper-silver fluid,and a lead-zinc fluid.All of them develop hydrothermal calcite during the hydrothermal process.As a result of in-situ rare earth element(REE)analysis,it is concluded that calcites originated from hydrothermal fluids unrelated to magmatism.In addition,calcites display different REE distribution patterns,and different positions on lg(Y/Ho)-lg(La/Ho)and Yb/Ca-Yb/La(atomic ratios)coordinate diagrams.These data indicate that the three fluid sources are different or that they have been modified from cogenetic fluid.The carbon and oxygen isotopic values of the calcites indicate a tendency for dissolution and reprecipitation of marine carbonate rocks within the basin.The oxygen isotopic characteristics of calcites indicate that the three fluids originated from basin brines and lead-zinc fluid mixed with meteoric water.Based on the detailed analysis of the fault activities and hydrothermal fluid characteristics,it is considered that the tensile faults after regional thrust fault are the main ore-controlling faults in the Huachangshan lead-zinc deposit.

关 键 词：华昌山铅锌矿床 热液方解石 原位稀土元素 C-O同位素 控矿断裂 

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