熊耳山沙坡岭钼矿辉钼矿Re-Os定年及东秦岭晚侏罗世钼矿化的识别  

Re-Os Isotope Dating of Molybdenite from the Shapoling Mo Deposit,East Qinling and Its Implication for Identification of Late Jurassic Mo Mineralization

作　　者：岳素伟[1] 邓小华[2] 姚军明[3] 孙亚莉[3] 

机构地区：[1]华南理工大学广州学院珠宝学院,广东广州510800 [2]北京矿产地质研究院,北京100012 [3]中国科学院广州地球化学研究所,广东广州510640

出　　处：《岩矿测试》2017年第3期305-317,共13页Rock and Mineral Analysis

基　　金：国家自然科学基金资助项目(41202050;41403032;41630313;41672079)

摘　　要：河南沙坡岭矿床位于华北克拉通南缘的熊耳地体,产在燕山期花岗岩与围岩太华超群的外接触带,为东秦岭最近发现的细脉浸染型钼矿床。矿体受断裂或围岩裂隙控制,呈细脉、网脉状产出,矿石类型包括细脉状、浸染状和块状。为确定沙坡岭钼矿床成矿时代,本文利用辉钼矿Re-Os同位素定年,研究表明:采集的6件辉钼矿样品Re-Os单样年龄为158.3±1.5~160.7±1.2 Ma,其加权平均值为160±1 Ma(2σ误差,MSWD=2.1),指示沙坡岭钼矿化发生于晚侏罗世,且早于花山岩基约30 Ma,指示与花岗岩基无关。另外,一件产于花山复式岩体的团块状辉钼矿样品Re-Os单样年龄为130.5±1.0 Ma,与赋矿的花山岩体成岩时代一致,同样与前人报道的辉钼矿年龄(125.4~129.4 Ma)基本一致,且不存在明显的单颗粒辉钼矿187Os迁移,表明部分钼矿化形成于早白垩世。因此,辉钼矿Re-Os同位素定年显示沙坡岭矿床存在晚侏罗世和早白垩世两期钼矿化。结合矿床地质特征、成矿构造演化,认为沙坡岭钼矿与熊耳地体的花山岩基、花岗斑岩以及相关热液矿床,均属于秦岭造山带陆陆碰撞过程中挤压向伸展转变体制的产物。The Shapoling Mo deposit is located in mass of the southern margin of the North China Craton. The deposit is hosted in a contact zone between granite and wallrocks of the Taihua Soupergroup,which is a recently found discovered vein dissemination type deposit in East Qinling. The ore-bodies are associated with quartz veins and controlled by subsidiary faults. The mineralization styles include veinlet and disseminated types. In order to determine the ageof the Shapoling Mo deposit, Re-Os isotopic dating of molybdenite was conducted. Six molybdenite samples yielded Re-Os ages ranging from 158. 3 ± 1. 5 Ma to 160. 7 ± 1. 2 Ma,with a weighted mean age of 160 ±1 Ma （2cr,MSWD= 2. 1）. The Re-Os age shows that the Mo mineralization occurred during the late Jurassic, earlier than theformation of Huashan rock mass （ about 30 Ma） . In addition, one molybdenite sample in Huashan rock mass yielded a Re-Os age of130. 5 ± 1.0 Ma,which is in accordance with the age of the Huashan pluton and molybdenite age （ 125. 4 - 129. 4 Ma） reported by a previous study. In conclusion, the Shapoling deposit contains two episodes of Mo mineralization from the early Cretaceous and Jurassic periods. Combining this with geological characteristics and tectonic-metallogenic evolution, it is suggested that Huashan rock mass, granite porphyr, and related hydrothermal deposits in theXiong？ er teerain are the products of extrusion to extension transitionduring continent-continent collision in the Qinling orogenic belt.

关 键 词：辉钼矿 RE-OS定年 沙坡岭钼矿床 东秦岭钼矿 

分 类 号：P597.3[天文地球—地球化学]