黑龙江嫩江地区三合屯金矿区糜棱岩锆石LA-ICP-MS U-Pb年龄与成矿的关系  

Research on the relationship between mineralization and zircon LA-ICP-MS U-Pb dating of the mylonite from the Sanhetun gold deposit in Nenjiang region,Heilongjiang Province

作　　者：刘宝山[1] 寇林林[1] 张春鹏[1] 李成禄 罗健 韩仁萍[1] 李博文 LIU Baoshan;KOU Linlin;ZHANG Chunpeng;LI Chenglu;LUO Jian;HAN Renping;LI Bowen(Shenyang Geological Survey Center,China Geological Survey,Shenyang,Liaoning 110034,China;Research Institute of Regional Geological Survey of Heilongjiang,Haerbin,Heilongjiang 150036,China)

机构地区：[1]中国地质调查局沈阳地质调查中心,辽宁沈阳110034 [2]黑龙江省自然资源调查院,黑龙江哈尔滨150036

出　　处：《地质学报》2022年第3期954-970,共17页Acta Geologica Sinica

基　　金：国家重点研发计划项目(编号2017YFC0601305);中国地质调查局地质调查项目(编号DD20190156)联合资助成果。

摘　　要：三合屯金矿位于黑龙江省嫩江县境内,普遍认为其是韧性剪切带型金矿。本次对采自韧性剪切带中花岗质糜棱岩样品进行了锆石LA-ICP-MS U-Pb定年,以约束剪切带的活动时代,并为金矿化事件提供依据,获得糜棱岩中热液锆石增生边加权平均年龄为162 Ma。因此,矿区在燕山期晚侏罗世经历剪切变形,并且这期变形事件与前人研究的科洛镇-新开岭杂岩变形时间是吻合的,也与八大罕-嫩江断裂左行走滑运动时间基本一致。结合前人对邻区金矿床矿化时间的研究,三合屯金矿的成矿时间为燕山期早白垩世,晚于韧性剪切带的形成时间晚侏罗世。样品中继承性锆石(花岗质糜棱岩中核部锆石)最晚年龄显示晚三叠世岩浆侵入活动时间,因此认为,三合屯矿区原岩侵位时间为晚三叠世,变形时间为晚侏罗世,为三合屯金矿床的形成提供了基础条件。另外,本次测试锆石的Lu-Hf同位素结果表明:花岗质糜棱岩成岩物质主要来源于亏损地幔的新生地壳。The Sanhetun gold deposit is a ductile shear zone type gold deposit in the Nenjiang County, Heilongjiang Province. Zircons from the granitic mylonite collected in the ductile shear zone are dated by LA-ICP-MS U-Pb analysis to study the timing of the shear zone and relations with the gold mineralization. A weighted U-Pb age of -162 Ma is obtained from the rims of hydrothermal zircons from the studied mylonite. Thus, the shear deformation is defined in Late Jurassic, which is correlated with previous research on the deformation time of the Keluo-Xinkailing complex and the sinistral strike-slip time of the Badahan-Nenjiang fault. Taking into consideration previous studies on gold mineralization epoch, we propose that the Sanhetun gold deposit was formed in Early Cretaceous, after the Late Jurassic ductile shear deformation. The core zone of zircons from the granitic mylonite which have inherited zircon features represent a Late Triassic magmatic activity. The result also reveals the ductile deformation time of the Keluo complex is in Late Jurassic, rather than Late Triassic. It provides the basic condition for the formation of the Sanhetun gold deposit. The Lu-Hf isotopic analysis from the granitic mylonite in this study reveals a source of juvenile crust related to depleted mantle.

关 键 词：糜棱岩 热液锆石 锆石U-Pb年龄 LU-HF同位素 三合屯金矿 嫩江地区 

分 类 号：P618.51[天文地球—矿床学]