豫西夜长坪钼矿床辉钼矿铼-锇同位素年龄及地质意义  

Molybdenite Re-Os isochron age of Yechangping Mo deposit in western Henan Province and its geological implications

作　　者：毛冰[1] 叶会寿[2] 李超[3] 肖中军[4] 杨国强 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]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实验室,北京100037 [3]国家地质实验测试中心,北京100037 [4]河南省地质矿产勘查开发局第一地质调查队,河南郑州450072 [5]中冶国际工程技术有限公司,北京100028

出　　处：《矿床地质》2011年第6期1069-1074,共6页Mineral Deposits

基　　金：全国危机矿山接替资源找矿项目(项目编号:20089949和200841019)资助

摘　　要：夜长坪钼矿床位于东秦岭-大别造山带,其赋矿围岩为中元古界官道口群龙家园组白云岩,辉钼矿化的主要类型为细脉状、网脉状、浸染状和条带状,围岩蚀变有透辉石化、金云母化、滑石化、绿泥石化、蛇纹石化、硅化和碳酸盐化,为斑岩-矽卡岩型钼矿床。选取5件辉钼矿样品进行了Re-Os同位素定年,获得模式年龄(145.4±2.1)Ma^(143.6±2.4)Ma,等时线年龄(145.3±4.4)Ma(2σ,MSWD=0.80),表明钼成矿作用发生于晚侏罗世—早白垩世。结合前人对东秦岭-大别造山带不同时期地球动力学背景的研究,笔者认为,夜长坪钼矿床形成于古太平洋板块向欧亚大陆板块俯冲的弧后岩浆带。The Yechangping Mo deposit is a porphyry-skam Mo deposit in the East Qinling-Dabie orogenic belt. Its ore-hosting wall rock is chert banded dolomite belonging to Longjiayuan Formation of Middle Proterozoie Guan- daokou Group, its main ore types are veinlets, stockworks, disseminations and banding, and its major wall rock alterations include diopsidization, phlogopitization, talcization, chloritization, serpentinization, silicification, potassic alteration and carbonation. Five molybdenum-bearing samples were selected for precise Re-Os dating, which yielded model ages ranging from （145.4 ＋ 2.1） Ma to （143.6 ＋ 2.4） Ma and an isochron age of （145.3 ＋ 4.4） Ma （20, MSWD= O. 80）, indicating that the molybdenum deposit was formed in the Late Jurassic-Ear- ly Cretaceous period. Based on a study of geodynamic settings of molybdenum deposits of different ages in the East Qinling-Dabie molybdenum belt, the authors hold that the geodynamic setting of the Yechangping Mo deposit is widespread magrnatism and back-arc extension caused by subduction of the palm-Pacific plate beneath the Eurasian continent.

关 键 词：地球化学 RE-OS同位素定年 斑岩-矽卡岩型钼矿 夜长坪 豫西 

分 类 号：P618.65[天文地球—矿床学]