滇西北红山铜钼矿床辉钼矿Re-Os同位素测年及其成矿意义  

Re-Os dating of molybdenite from the Hongshan Cu-Mo deposit in Northwest Yunnan and its implications for mineralization

作　　者：孟健寅[1] 杨立强[1] 吕亮[1] 高雪[1] 李建新[2] 罗跃中[2] 

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,北京100083 [2]云南省地矿局第三地质大队,大理671000

出　　处：《岩石学报》2013年第4期1214-1222,共9页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划(2009CB421008);北京市优秀博士学位论文指导老师科研项目(20111141501);教育部新世纪优秀人才支持计划(NCET-09-0710);高等学校学科创新引智计划(B07011)联合资助

摘　　要：红山铜钼矿床是义敦岛弧南端格咱火山-岩浆弧中已探明规模最大的夕卡岩型铜矿床,近年来在其深部勘探过程中又发现斑岩型铜钼矿体。利用辉钼矿Re-Os同位素测年技术,分别对红山铜钼矿床中5件夕卡岩型矿石和1件斑岩型矿石中辉钼矿进行定年,首次获得红山铜钼矿床高精度成矿年龄。夕卡岩型矿石中辉钼矿Re-Os模式年龄为77.90～81.05Ma,加权平均值为79.32±0.87Ma,斑岩型矿石中辉钼矿模式年龄为80.71Ma,两者在误差范围内相一致;6件样品辉钼矿等时线年龄为80.0±1.8Ma,代表了红山铜钼矿床的成矿时代。辉钼矿中Re的含量为(4.074±0.035)×10-6～(94.21±0.75)×10-6,指示其物质来源以壳源为主,有少量幔源物质混入。红山铜钼矿床与格咱火山-岩浆弧燕山晚期岩浆侵入作用的高峰期及相关斑岩-夕卡岩型多金属矿床的成矿年龄一致,表明它们是弧陆碰撞的后造山伸展背景下同一区域地质事件的产物,该期夕卡岩-斑岩型铜钼多金属具有较大成矿潜力。The Hongshan Cu-Mo deposit is located in the Geza volcanic magmatic arc which lies on the southern part of the Yidun island arc in Sanjiang Tethyan area. The mineralization is dominated by skarn Cu, accompanying with granite porphyry Cu-Mo in deep. Re-Os isotopic dating technique on molybdenites collected from the skarn and porphyry type ores in the Hongshan Cu-Mo deposit have been applied to confirm the age of mineralization. The Re-Os dating of five molybdenite samples from skarn-type ore yields a Re-Os model age ranging from 77.90Ma to 80.05Ma, with an average of 79.32±0.87Ma and the isochron age of 80.0±1.8Ma. The Re-Os model age of the one molybdenite sample from porphyry-type ore is 80.71Ma. The ore-forming ages both skarn and porphyry type ores are identical within error. The Re content of molybdenites in Hongshan Cu-Mo deposit is （4.074±0.035）×10-6 ～ （94.21±0.75）×10-6, suggesting that the ore-forming material is mainly originated from crust and a little from mantle. The rock-forming and ore-forming ages of Hongshan Cu-Mo deposit and other polymetallic deposits occurred in Late Yanshanian are consistent. It is indicated that these deposits are formed under the same geodynamics background of late post-orogenic extension after Yanshanian arc-continental collision orogeny. The polymetallic mineralization in ～80Ma of Geza volcanic magmatic arc shows bright future for further prospecting.

关 键 词：红山铜钼矿床 RE-OS同位素定年 成矿物质来源 成矿地球动力学背景 

分 类 号：P597.3[天文地球—地球化学] P611.13[天文地球—地质学]