吉林敦化大石河钼矿床成因与辉钼矿Re-Os同位素测年  

Ore genesis and molybdenite Re-Os dating of Dashihe molybdenum deposit in Dunhua,Jilin

作　　者：鞠楠[1] 任云生[1] 王超 王辉[1] 赵华雷[1] 屈文俊[3] 

机构地区：[1]吉林大学地球科学学院,长春130061 [2]汪清华鑫矿业有限公司,吉林汪清133212 [3]中国地质科学院国家地质实验测试中心,北京100037

出　　处：《世界地质》2012年第1期68-76,共9页World Geology

基　　金：中国地质调查局项目"吉黑东部区域成矿规律综合研究"(1212011085485)

摘　　要：大石河钼矿床是近年来在小兴安岭—张广才岭钼成矿带南缘新发现的一个大型钼矿床。深部矿体产于似斑状花岗闪长岩体顶部,呈细脉浸染型;近地表矿体主要呈含辉钼矿石英脉,赋存于浅变质岩中。钼矿化受隐爆角砾岩筒及构造裂隙控制,矿化与蚀变具有明显的分带性,属斑岩型钼矿床。对采自矿区浅部矿体中的5件辉钼矿样品进行了Re-Os同位素测年,获得模式年龄(182.1±2.7)～(191.9±2.6)Ma,加权平均年龄(186.7±5.0)Ma,MSWD值为11.8,表明大石河钼矿形成于燕山早期。结合近年来小兴安岭—张广才岭钼成矿带上所获得的成岩成矿年龄数据,认为160～190 Ma是该钼成矿带的钼矿成矿作用的集中期。辉钼矿样品中Re含量为3.549～4.362μg.g-1,指示成矿物质为壳源。综合分析认为,大石河钼矿床为该区燕山早期大规模成矿事件的产物,形成于古亚洲构造域和环太平洋构造域叠加和转换期的构造环境。Dashihe deposit is one of the large-size molybdenum deposits recently discovered in the southern margin of Xiaoxinganling——Zhangguangcailing molybdenum metallogenic belt.Deep ore bodies in this deposit are located in the top of porphyaceous granodiorite,veinlet-disseminated in shape.The near-surface ore bodies mainly occurred in the low-grade metamorphic rocks as molybdenite-bearing quartz veins.Molybdenum mineralization was controlled by the explosive breccia pipe and the fissures,and the mineralization and alteration are obvious in zonaition,belonging to porphyry molybdenum deposit.Re-Os dating of five molybdenite samples collected from the shallow ore bodies showed that the model ages as 182.1± 2.7 Ma^191.9±2.6 Ma,with the weighted mean age of 186.7±5.0 Ma,and MSWD=11.8,which indicates the deposit formed in Early Yanshanian.Combined with other obtained lithogenic and metallogenic ages from the Xiaoxinganling——Zhangguangcailing molybdenum metallogenic belt,it can be inferred that 160~190 Ma is a concentrated period for large-scale molybdenum mineralization of this belt.The content of Re in the molybdenite is 3.549~4.362 μg·g-1,indicating ore-forming materials derived from crustal sources.Comprehensive analysis showed that the Dashihe deposit might be resulted by the large-scale mineralization events of the Early Yanshanian in the area,and formed in the tectonic environment during the superposition and transformation of Paleo-Asian and Circum-Pacific tectonic domains.

关 键 词：斑岩型钼矿 RE-OS测年 隐爆角砾岩筒 大石河钼矿床 敦化 吉林 

分 类 号：P618.65[天文地球—矿床学] P597.3[天文地球—地质学]