内蒙古乌拉特后旗查干花钼矿锆石U-Pb和辉钼矿Re-Os同位素年龄及其地质意义  

Zircon U-Pb and Molybdenite Re-Os Ages and Geological Significance of the Chaganhua Molybdenum Deposit,Urad Rear Banner,Inner Mongolia

作　　者：李光耀 李志丹 王佳营 李效广[1,2] 李超[3] 涂家润 谢瑜 丁宁[4] LI Guangyao;LI Zhidan;WANG Jiaying;LI Xiaoguang;LI Chao;TU Jiarun;XIE Yu;DING Ning(Tianjin Center,China Geological Survey,Tianjin 300170,China;Key Laboratory of Uranium Geology,China Geological Survey,Tianjin 300170,China;National Research Center of Geoanalysis,Beijing 100037,China;The First Monitoring and Application Center,China Earthquake Administration,Tianjin 300180,China)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]中国地质调查局铀矿地质重点实验室,天津300170 [3]国家地质实验测试中心,北京100037 [4]中国地震局第一监测中心,天津300180

出　　处：《现代地质》2020年第3期494-503,共10页Geoscience

基　　金：中国地质调查项目“内蒙古阴山地区资源远景调查评价”(12120113057300);“硬岩型铀钍等矿产资源远景调查与勘查示范”(DD20160129);“鄂尔多斯、柴达木等盆地砂岩型铀矿调查”(DD20190119);国家自然科学基金项目“内蒙古赵井沟过铝质花岗岩浆演化与铌钽等元素富集机制”(41502082)。

摘　　要：内蒙古乌拉特后旗查干花钼多金属矿为华北陆块宝音图岩浆弧内的一处具有大型规模的隐伏矿床。钼矿体呈隐伏状赋存于二叠纪花岗闪长岩体与宝音图群二云石英片岩外接触带,大致呈不规则厚层状、脉状及网脉状,近NW向展布。发育钾化、云英岩化和绿泥石化等围岩蚀变,具斑岩型矿床蚀变分带特征。对与钼成矿关系密切的花岗闪长岩开展LA-ICP-MS锆石U-Pb定年,获得加权平均年龄为(257.2±1.3)Ma,表明查干花花岗闪长岩体形成于晚二叠世。对辉钼矿开展了Re-Os同位素测年,获得辉钼矿Re-Os等时线年龄为(238.6±4.4) Ma,模式年龄为(240.0±1.6) Ma,限定查干花钼矿是印支早期构造-岩浆活动的产物。辉钼矿Re含量为64 502×10^-9~245 621×10^-9,推测其成矿物质为壳幔混合来源。The Chaganhua molybdenum(Mo)polymetallic deposit is a large concealed deposit in the Baoyintu magmatic arc of North China Craton.The Mo orebody is hosted within the exo-contact between the Permian granodiorite and the two-mica quartz schist of the Baoyintu Group.The orebodies are NW-trending,and occur as irregularly-thick layers,veins,or stockworks.The wall-rock alteration styles include potassic,greisen,and chlorite,consistent with the typical porphyry-type deposit.In this study,we separated and LA-ICP-MS U-Pb dated zircons from the Mo-mineralized granodiorite from Chaganhua.Our results yielded a weighted mean 206Pb/238U age of(257.2±1.3)Ma(n=32,MSWD=1.6),indicating that the Chaganhua granodiorite was formed in the Late Permian.In addition,molybdenite Re-Os dating yielded an isochron age of(238.6±4.4)Ma and a model age of(240.0±1.6)Ma(n=9,MSWD=0.27),which reveals that the Chaganhua Mo mineralization was the product of the Early Indosinian magmatism.Furthermore,the Re content of molybdenite ranges from 64502×10^-9 to 245621×10^-9,suggesting that the ore-forming material was sourced from a mixture of crust and mantle.

关 键 词：锆石U-PB年龄 RE-OS同位素定年 查干花钼矿 乌拉特后旗 内蒙古 

分 类 号：P597[天文地球—地球化学] P611.1[天文地球—地质学]