内蒙古二道河子铅锌矿成因研究  

The Origin of the Erdaohezi Lead-Zinc Deposit,Inner Mongolia

作　　者：李进文[1] 梁玉伟 王向阳 张斌[1] 杨郧城[1] 佘宏全[1] 郭志军[1] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]内蒙古第一地质矿产勘查开发院,呼和浩特010020 [3]内蒙古根河市森鑫矿业开发有限责任公司,内蒙古根河022350

出　　处：《吉林大学学报（地球科学版）》2011年第6期1745-1754,1783,共11页Journal of Jilin University：Earth Science Edition

基　　金：中国地质调查局地质调查项目(1212011085260);国家重点自然科学基金项目(41030421);国家科技支撑计划项目(2006BAB01A10);内蒙古地质矿产勘查开发局综合研究项目(ND2007004)

摘　　要：基于矿床地质调查,并通过岩矿石地球化学和锆石U-Pb测年研究,探讨了二道河子铅锌矿床成因。该矿床赋存于中侏罗统塔木兰沟组中,受北西向断裂-裂隙构造控制,矿体多呈脉状,围岩以火山岩为主,夹有砾岩。据常量、微量、稀土元素和Pb、Sr、Nd同位素测试结果:火山熔岩中SiO2质量分数为48.01%～56.44%,岩屑晶屑凝灰岩中为69.09%～71.73%。前者稀土总量高于后者,两者稀土配分型式相似,均显弱负铕异常;而前者Pb、Zn、Cu等成矿元素的含量却远低于后者。火山岩富集Rb、U、Th等大离子亲石元素,Sr普遍亏损,相对亏损Nb、Ta以及Ti等高场强元素。火山岩ISr=0.704 925～0.706 632,εNd(t)=0.5～2.0,εSr(t)=8.5～32.8,tDM=619～730Ma。火山岩和矿石的Pb同位素组成十分接近,206Pb/204Pb=18.130～18.475,207Pb/204Pb=15.526～15.567,208 Pb/204 Pb=38.078～38.286,μ值为9.32～9.40。矿床主要围岩岩屑晶屑凝灰岩的SHRIMP锆石U-Pb年龄为(164.2±2.3)Ma,这表明火山岩为混有壳源物质的幔源岩浆形成。火山活动分为2期:早期表现为中(基)性火山喷发;晚期岩浆活动发生于中侏罗世晚期,形成酸性火山碎屑岩。成矿物质由与火山岩有关的岩浆系统提供,富集于晚期岩浆中。与成矿有关的侵入岩可能是晚期岩浆作用形成的次火山岩。矿床可能是岩浆分异的含矿热液沿火山岩中的断裂、裂隙充填交代形成,成矿时代为中侏罗世晚期—晚侏罗世。Controlled by NW-trending fractures,the Erdaohezi lead-zinc deposit occurs in volcanic rocks and conglomerate of the Tamulangou Formation in the Hailaer-Genhe Jurassic volcanic fault-depression basin.Its ore bodies are mainly of vein type.Based on geological and geochemical investigation of volcanic rocks and ores as well as dating of volcanic rocks,the authors studied the genesis of the ore deposit.An analysis of major elements,trace elements,rare earth elements and Pb,Sr and Nd isotopes has revealed that the content of SiO2 in the lava is 48.01%-56.44% and that of the lithic crystal tuff is 69.09%-71.73%,and that Pb,Zn and Cu values in the former are much lower than those in the latter.The two kinds of rocks have similar REE patterns,characterized by weak Eu negative anomalies.LILE such as Rb,U and Th are rich in the volcanic rocks,while Sr and such HFSE as Nb,Ta and Ti are relatively depleted.In the volcanic rocks,ISr=0.704 925-0.706 632,εNd（t）=0.5~2.0,εSr（t）=8.5-32.8 and tDM=619-730 Ma.In addition,the composition of Pb isotopes in volcanic rocks is very close to that in sulfide ores,their 206Pb/204Pb,207Pb/204Pb and 208Pb/204Pb ratios are 18.130-18.475,15.526-15.567 and 38.078-38.286 respectively,with μ values being 9.32-9.40.With the SHRIMP zircon U-Pb method,the lithic crystal tuff was dated at（164.2±2.3） Ma.These data indicate that the magma that formed the volcanic rocks was derived from the mantle with the mixture of a small amount of crustal materials,and the ore-forming materials came from the magma system.The volcanism had experienced two phases： early magma was mainly intermediate,whereas late magmatism occurred in late Middle Jurassic and formed acid volcanic clastic rocks.Ore-forming material was abundant in the late magma,which might have also formed sub-volcanic rocks related to the mineralization.Ore-forming fluids from late magma differentiation might have formed the ore deposit by filling and metasomatism along the fractures in volcanic rocks and conglomerate,and the minerali

关 键 词：铅锌矿 地球化学 SHRIMP锆石U-PB测年 矿床成因 二道河子 内蒙古 

分 类 号：P618.4[天文地球—矿床学]