东秦岭石窑沟斑岩钼矿床地质特征及辉钼矿Re-Os年龄  

Geological characteristics and molybdenite Re-Os isotopic dating of Shiyaogou porphyry molybdenum deposit in the East Qinling

作　　者：高亚龙[1,2] 张江明[3] 叶会寿[4] 孟芳[1] 周珂[1] 高阳[1] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室地球科学与资源学院,北京100083 [2]天津华北地质勘查局,天津300170 [3]武警黄金第六支队,三门峡472000 [4]中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点开放实验室,北京100037

出　　处：《岩石学报》2010年第3期729-739,共11页Acta Petrologica Sinica

基　　金：全国危机矿山接替资源找矿项目(20089949;200841019);公益性行业科研专项经费项目(K0801)的资助

摘　　要：在东秦岭钼成矿带最近探明的石窑沟大型钼矿床位于近东西向马超营断裂带与北东向石窑沟-焦园断裂带的交汇部位,获得钼金属储量10余万吨,平均品位0.068%。钼矿化呈细脉-网脉状分布于花岗斑岩体及其围岩熊耳群火山岩中,与矿化有关的围岩蚀变有钾长石化、硅化、绢云母化、黄铁矿化等,具有斑岩型钼矿床的一些基本特点。在矿床中选取5件不同矿化类型的辉钼矿样品,采用ICP-MS法进行Re-Os同位素定年,获得模式年龄131.3±2.4～134.3±2.6Ma,等时线年龄135.2±1.8Ma(MSWD=0.18),形成于早白垩世,与豫西熊耳山地区雷门沟、鱼池岭等钼矿床形成时代相近。据辉钼矿Re含量(8.242×10-6～30.24×10-6)推测,矿床成矿物质主要来自于下地壳。矿床为东秦岭-大别山地区中生代第三期钼成矿作用产物,形成于早白垩世中国东部岩石圈伸展环境。The Shiyaogou deposit is a large molybdenum deposit lately discovered in the East Qinling molybdenum belt. Emplaced along the intersection of the EW-trending Machaoying fault and the NE-trending Jiaoyuan fault,the Shiyaogou deposit has a proven reserve of more than 100,000 tonnes Mo,averaging grade of 0.068%. Mineralization of the deposit consists of quartz-molybdenite veinlets and stockworks which occur in the altered granite porphyry and Proterozoic Xionger Group. Hydrothermal alteration is well developed and is composed of potassic feldspar alteration,silicification,sericitization,and pyritization,typical of porphyry Mo deposits. Five molybdenite-bearing samples of different mineralizing types were selected for precise Re-Os dating,and the results yield Re-Os model ages between 131.3±2.4~134.3±2.6Ma and an isochron age of 135.2±1.8 Ma. The Re contents of molybdenite are (8.242±0.116~30.24±0.24) ×10-6,indicating that they were mainly derived from the lower crust. The age of the Shiyaogou molybdenum deposit is consistent with that of the Yuchiling and Leimengou Mo deposits in the East Qinling molybdenum belt,indicating that porphyry Mo mineralization was driven by the Early Cretaceous lithospheric extension in East China.

关 键 词：RE-OS同位素年龄 斑岩钼矿 岩石圈伸展 石窑沟 东秦岭 

分 类 号：P597.3[天文地球—地球化学]