新疆西天山七兴铅锌成矿特征、时代和地质意义  

Metallogenetic Features and Ages of the Qixing Zn-Pb deposit in the West Tian Shan of Xinjiang and Geological Implications

作　　者：薛春纪[1] 张权[1] 冯京[2] 王晓刚[3] 张兵[3] 万阈[3] 

机构地区：[1]地质过程与矿产资源国家重点实验室,中国地质大学地球科学与资源学院,北京100083 [2]新疆维吾尔自治区地质矿产勘查开发局,新疆乌鲁木齐830000 [3]新疆维吾尔自治区地质矿产勘查开发局第七地质大队,新疆乌苏833000

出　　处：《地质与勘探》2011年第5期794-808,共15页Geology and Exploration

基　　金：国家科技支撑计划(2011BAB06B02);高等学校学科创新引智计划(B07011);长江学者和创新团队计划(IRT0755)资助

摘　　要：近年新疆西天山新发现七兴铅锌矿,被认为是莱历斯高尔-3571矿田海西期成矿系列的有机构成。矿床形成于造山期后伸展背景,受垂直造山带走向的近南北向张性断裂-裂隙控制,石英-硫化物工业矿体呈脉状,与矿区近南北走向、成群分布的基性岩脉共/伴生,产在志留系粉砂泥岩层中。矿体与围岩界线截然,两侧围岩有硅化等热液蚀变,矿石的矿物组成较复杂,由石英、铅锌硫化物等十多种矿物组成,中-粗晶和交代结构,具有热液充填-交代成矿特点。成矿流体中温(108℃～324℃)、低盐度(0.71%～6.59%eq.NaCl),δ18OH2O V-SMOW=-0.10‰～7.50‰,δDH2O V-SMOW=-96‰～-102‰,主体为岩浆水。矿石δ34SV-CDT为较低的正值(2.9‰～4.8‰),88%～93%的硫由深源岩浆提供。矿石铅同位素组成变化范围极小,206Pb/204Pb=18.1893～18.1930,207Pb/204Pb=15.6185～15.6226,208Pb/204Pb=38.1113～38.1281,成矿金属来源与岩浆岩有关。成矿前辉长辉绿岩锆石SHRIMP U-Pb法测得186.2±8.4Ma成岩年龄;燕山早期构造伸展-岩浆活动-铅锌成矿在七兴矿区应为发生、发展、密切关联的连续地质过程。研究表明,七兴铅锌成矿不应是莱历斯高尔-3571矿田海西期成矿系列的组成部分,它是燕山期构造-岩浆-热液成矿的产物,无疑拓展了北疆金属找矿的时间域。The Qixing Zn-Pb deposit which was recently discovered in the West Tian Shan of Xinjiang is thought to be a part of the Lailisigao＇er-3571 Hercynian metallogenetic series.It formed in an extensional setting after orogeny.The vein-like Zn-Pb sulfide ore-bodies,paragenied or associated with some basic dikes which occur in nearly NS direction,occur in silty mud of Silurian strata and are controlled by the approximately NS faults and fractures normal to the orogenic belt.The orebodies are sharply bounded by wall rocks which have hydrothermal alteration such as silication.The Zn-Pb ore is composed of quartz,Zn-and Pb-sulfide and many other minerals,and shows a complex mineral composition.The minerals are middle-coarsely crystalline and replaced textures in the ores,characterized by hydrothermal filling-replacing in mineralization.The ore-forming fluid was middle temperature（108℃～324℃）,low salty（0.71%～6.59% eq.NaCl）,δ18OH2O V-SMOW=-0.10‰～7.50‰,δDH2O V-SMOW=-96‰～-102‰,and mainly from the magma.The ore δ34SV-CDT=2.9‰～4.8‰,and 88%～93% S was from the deep magma.The ore Pb-isotopic composition has a very small range of variation,with 206Pb/204Pb=18.1893～18.1930,207Pb/204Pb=15.6185～15.6226,208Pb/204Pb=38.1113～38.1281,and the metals in the ore were mainly related to the magma.The SHRIMP U-Pb age of zircons in the basic dikes is 186.2±8.4Ma.A Yenshan period tectonic extension – magma activity – Zn-Pb mineralization was a starting,developing and closely related geological process.Our work suggests that the Qixing Zn-Pb ore deposit is a product of the Yenshan period structure-magma-hydrothermal mineralization,rather than a part of the Lailisigao＇er–3571 Hercynian metallogenetic series.The Yenshan period metal mineralization in northern Xinjiang should be paid more attention.

关 键 词：矿床地质 流体包裹体 S Pb O H 同位素 锆石 U - 法 燕山期成矿 七兴铅锌矿新疆西天山 

分 类 号：P618.510.5[天文地球—矿床学]