四川西部里伍式富铜矿床黄铜矿Re-Os定年及其成矿意义

发布时间：2018-02-09 20:41

本文关键词： NTIMS Re-Os定年黄铜矿里伍铜矿江浪穹窿四川西部　出处：《地质学报》2017年12期 　论文类型：期刊论文

【摘要】：川西里伍式富铜矿系指产于扬子地台西缘和松潘-甘孜造山带接合带江浪穹窿中的呈层状-似层状或透镜状的富铜矿床。矿床地质特征、矿化类型及矿相学研究表明其为热液型矿床。为精确厘定热液成矿作用发生的时间,本文对占主体的块状-脉状矿石中的黄铜矿进行了高精度NTIMS Re-Os同位素定年,获得等时线年龄为150.2±4.9~151.1±4.8Ma(2σ),说明里伍式富铜矿主要形成于晚侏罗世,明显晚于赋矿围岩新元古界里伍岩群,与江浪穹窿边部出露的花岗岩体年龄较为接近;初始187Os/188Os比值为3.65±0.29,说明其金属成矿物质来源主要为大陆地壳,很可能主要来源于赋矿岩层里伍岩群。结合成穹构造—岩浆事件,本文认为早燕山期区域伸展构造背景下的岩浆热隆作用不仅为铜富集提供了热动力和部分流体,同时为矿体最终定位提供了良好的导矿—容矿空间,是里伍式富铜矿形成的关键因素。
[Abstract]:Wushi copper-rich deposit in Xili, Sichuan, is a layered, stratiform or lenticular copper-rich deposit occurring in the Yangtze platform western margin and the junction belt of the Songpan-Ganzi orogenic belt. The mineralization type and mineralogy indicate that the deposit is hydrothermal type. In order to determine exactly the time of hydrothermal mineralization, the chalcopyrite in the bulk vein ore is determined with high precision NTIMS Re-Os isotopic dating. The isochron age is 150.2 卤4.9U 151.1 卤4.8 Ma ~ 2 蟽 ~ (-1), which indicates that the Li-Wu-rich copper deposit was mainly formed in the late Jurassic, which was obviously later than the Neoproterozoic Liwu Group of ore-bearing surrounding rock, which is close to the age of the granite body exposed at the edge of the Jianglang dome. The initial 187Os-188Os ratio was 3.65 卤0.29, indicating that the metallogenic material was mainly derived from the continental crust and probably from the Wuyan Group of ore-hosting strata, combining with the Dome tectonic-magmatic events. In this paper, it is considered that the magmatic thermal uplift in the early Yanshanian regional extensional tectonic setting not only provides the thermal power and some fluids for copper enrichment, but also provides a good ore-conducting and ore-containing space for the final location of the orebody. It is the key factor for the formation of rich copper deposit in Liwu.
【作者单位】：中国地质调查局成都地质调查中心;国家地质实验测试中心;
【基金】：国家自然科学基金青年基金(41202067) 中国地质调查局矿产资源评价项目(1212011085139) 成都地质调查中心青年科学基金项目(所控基\[2015\]-05)资助的成果
【分类号】：P618.41

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