黑龙江省漠河县洛古河多金属矿床成因与成矿时代  

ORE GENESIS AND METALLOGENIC AGE OF LUOGUHE POLYMETALLIC DEPOSIT IN MOHE AREA,HEILONGJIANG PROVINCE

作　　者：孙琦[1] 任云生[1] 杨群[1] 段明新[1] 郝宇杰[1] 

机构地区：[1]吉林大学地球科学学院,吉林长春130061

出　　处：《矿物岩石》2015年第3期20-28,共9页Mineralogy and Petrology

基　　金：中国地质调查局项目(1212011121081);国家重点基础研究发展计划项目(2013CB429802)

摘　　要：洛古河矿床为额尔古纳地块东北部的一个以铅锌为主、伴生铜钼的多金属矿床。为确定该矿床的成因、形成时代及构造背景,开展矿床地质特征研究和同位素测年工作。矿床地质研究表明,该矿床的主矿体主要呈层状、似层状和透镜状,赋存于额尔古纳河组大理岩与黑云母二长花岗岩的接触带附近;矿石中金属矿物主要为方铅矿、闪锌矿、黄铜矿、黄铁矿、辉钼矿,矿石构造以浸染状构造和细脉状构造为主;围岩蚀变类型主要包括矽卡岩化、硅化、绢云母化、碳酸盐化和绿帘石化。同位素测年结果表明,钻孔中矿体附近的黑云母二长花岗岩锆石U-Pb年龄变化范围为137 Ma±3 Ma^123 Ma±1 Ma,加权平均值为131.4 Ma±2.1 Ma(n=21,可信度95%);矿区内花岗斑岩锆石U-Pb年龄变化范围为129 Ma±1Ma^116Ma±2Ma,加权平均值为121.8Ma±1.9Ma(n=16,可信度95%);矽卡岩型多金属矿石中辉钼矿Re-Os模式年龄为127.1 Ma±2.1 Ma。综合分析认为,洛古河矿床属接触交代型多金属矿床,黑云母二长花岗岩为成矿岩体,成岩成矿时代为130 Ma^120 Ma,属大兴安岭北部早白垩世强烈构造岩浆作用的产物。结合区域构造演化及同时代同类矿床对比分析,初步认为洛古河多金属矿床成岩成矿作用发生于蒙古—鄂霍次克洋俯冲闭合后的造山后伸展的构造背景。The geological characteristics and isotope dating of Luoguhe lead and zinc polymetallic deposit in the northeast part of the Eerguna Block are studied so as to determine its ore genesis, metallogenic age and tectonic background. Major ore bodies exist in the contact zone between the biotite adamellite and the marble of Eerguna Group, and are mostly stratiform, stratoid and lenticular. The ore are mainly composed of galena, sphalerite, pyrite, chalcopyrite with crystalline granular texture, metasomatic texture and separation of solid solution texture. Polymetallic ore is showed by disseminated and fine vein-like structure. Country rock alteration types include skarn, silicification, sericitization, carbonation and chloritization. It is indicated that the biotite adamellite is closely related to the Luoguhe polymetallic deposit, and attribute to skarn genesis. Zircons from granite porphyry and biotite adamellite near the orebodies are used for LA-ICP-MS U-Pb isotopic dating; and molybdenite minerals are selected from the biotite adamellite ore to carry out the ReOs isotope dating. It shows that the U-Pb range of age is 137 Ma±3 Ma-123 Ma±1 Ma and weighted average age of zircon grains from the granite porphyry is 121.8 Ma± 1.9 Ma（n= 16, credibility is 95%） ;the U-Pb range of age is 129 Ma-F1 Ma-116 Ma±2 Ma and weighted average of zircon grains from the biotite adamellite is 131.4 Ma± 2.1 Ma（n=21 ,credibility is 95%）, and the Re-Os isotope model age of molybdenite is 127.1 Ma±2.1 Ma. Therefore,the biotite adamellite,granite porphyry and polymetallic mineralization belong to the same period of magmatic activity,and the metallogenic age is probably 130 Ma;120 Ma. According to the regional tectonic evolution and comparative analysis of same time and similar deposits, it is considered that the formation of Luoguhe polymetallic deposit is closely related to the Mongolia-Okhotsk Tectonic Domain, and formed in the extensional environment after collision orogeny.

关 键 词：矿床成因 成矿时代 构造背景 矽卡岩型矿床 洛古河多金属矿床 

分 类 号：P611.1[天文地球—矿床学] P597[天文地球—地质学]