滇西大硐厂铅锌矿床成矿流体来源和成因  

The source of ore-forming fluid and genesis of the Dadongchang Zn-Pb deposit in the Western Yunnan,China

作　　者：杨佳飞 李文昌[1] 邓明国[1] 沙建泽 贾祯 陈俞宏 赵晓瑜 杨正良 YANG Jia-fei;LI Wen-chang;DENG Ming-guo;SHA Jian-ze;JIA Zhen;CHEN Yu-hong;ZHAO Xiao-yu;YANG Zheng-liang(Faculty of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650221,China;Yunnan Geological Survey Institute,Kunming 650216,China;Yunnan Nuclear Industry 209 Geological Brigade,Kunming 650034,China)

机构地区：[1]昆明理工大学国土资源工程学院,云南昆明650221 [2]云南省地质调查院,云南昆明650216 [3]云南省核工业二〇九地质大队,云南昆明650034

出　　处：《矿物学报》2023年第5期693-707,共15页Acta Mineralogica Sinica

基　　金：国家自然科学基金项目(编号:42272078,41762009);云南省重大科技专项(编号:202202AG050006)。

摘　　要：大硐厂Pb-Zn矿床是西南“三江”成矿带中南段腾冲地块内具有代表性的矽卡岩型矿床之一。本文拟通过对该矿床流体包裹体及C、O、S同位素研究,查明大硐厂矿床成矿物质/流体来源,探讨成矿流体性质及演化过程,揭示矿床成因。结果表明,大硐厂矿床成矿作用过程可划分为矽卡岩期、石英-硫化物期和碳酸盐期。成矿流体为H_(2)O-NaCl体系,含少量N_(2)、CO_(2)和CH_(4)。显微测温结果显示,矽卡岩期流体包裹体均一温度为340~464℃,石英-硫化物期为304~381℃,碳酸盐期为196~265℃,对应盐度分别为2.90%~15.76%NaCl eqv、3.87%~9.98%NaCl eqv和1.40%~8.81%NaCl eqv,均一温度和盐度伴随成矿流体的演化逐渐降低。C-O同位素结果表明,成矿流体主要来自于岩浆热液,流体迁移过程中可能受水/岩反应及大气降水作用的影响;硫化物δ^(34)SV-CDT值介于2‰~5‰之间,对比腾冲地块及毗邻的保山地块典型铅锌矿床S同位素研究结果,认为该矿床S主要来自深部岩浆。结合矿床地质、流体包裹体和C、O、S同位素特征,推测成矿环境的改变和流体混合可能是导致大硐厂铅锌矿床成矿物质发生大规模沉淀的主要因素。综合区域成矿背景,认为该矿床为陆陆碰撞造山环境下与深部燕山期隐伏岩体有关的矽卡岩型铅锌矿床。The Datongchang Pb-Zn deposit is one of the representative skarn-type deposits within the Tengchong block in the central and southern section of the"Sanjiang"metallogenic belt in Southwest china.In this paper,we have carried out researches of fluid inclusions and C,O,S isotopes of the deposit,in order to identify the source of the ore-forming materials/fluid in the Dadongchang deposit,and to discuss the properties and evolution process of the ore-forming fluid,and then to reveal the genesis of the deposit.The mineralization process of the Dadongchang deposit can be divided into the skarn stage,quartz-sulfide stage and carbonate stage.The ore-forming fluid is the H_(2)O-NaCl system,containing a small amount of N_(2),CO_(2)and CH_(4).Microthermometrric results show that homogenization temperatures and salinities are 340-464℃and 2.90%-15.76%NaCl eqv for fluid inclusions in minerals of the skarn stage,304-381℃and 3.87%-9.98%for those of the quartz-sulfide stage,and 196-265℃and 1.40%-8.81%for those of the carbonate stage,respectively.and the homogenization temperatures and salinities of fluid inclusions are gradually decreased with the evolution of ore-forming fluids.The C-O isotopic results show that the ore-forming fluids were mainly sourced from magmatic hydrothermal fluids which then could have been affected by the water/rock intereaction in the fluid migration process and meteoric water.Theδ^(34)SV-CDT values of sulfides vary from 2‰to 5‰.Compared with the results of S isotopes of typical lead-zinc deposits in the Tengchong block and the adjacent Baoshan block,it is believed that the S in this deposit was mainly sourced from the deep magma.Combined with characteristics of deposit geology,fluid inclusions,and C,O,and S isotopes,it is inferred that the change of its metallogenic environment and the mixing of fluids could be the main factors leading to the large-scale precipitation of metallogenic materials in the Dadongchang lead-zinc deposit.Based on the regional metallogenic background,it is considered

关 键 词：大硐厂铅锌矿床 流体包裹体 C-O-S同位素 成因机制 腾冲地块 

分 类 号：P597[天文地球—地球化学] P618.4[天文地球—地质学]