新疆东戈壁斑岩型Mo矿辉钼矿Re-Os年龄和成矿岩体锆石U-Pb年龄及其地质意义  

Zircon U-Pb Age of the Ore-bearing Granite and Molybdenite Re-Os Isotopic Age of the Donggebi Mo Deposit, Xinjiang and their Geological Significance

作　　者：吴云辉[1,2] 熊小林[3] 赵太平[1] 朱志敏[4] 李立[1,2] 

机构地区：[1]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]中国科学院广州地球化学研究所同位素地球化学国家重点实验室,广东广州510640 [4]国家海洋局第二海洋研究所,国家海洋局海底科学重点实验室,浙江杭州310012

出　　处：《大地构造与成矿学》2013年第4期743-753,共11页Geotectonica et Metallogenia

基　　金：国家973项目(编号:2014CB440802)资助

摘　　要：东戈壁Mo矿是新疆地区近年发现的超大型斑岩型矿床,Mo金属储量50.8万吨,它与矿体下伏的花岗质岩体(包括斑状花岗岩体和花岗斑岩岩脉)有密切的成因联系,矿区地表没有花岗质岩体出露,但在多个钻孔中可见。矿体石英脉辉钼矿Re-Os同位素等时线拟合年龄为233.2±2.2 Ma,加权平均年龄为235.4±2.5 Ma,斑状花岗岩锆石206Pb/238U加权平均年龄为237.0±4.7 Ma,花岗斑岩锆石206Pb/238U加权平均年龄为233.2±4.1 Ma。这些年龄测定表明东戈壁斑岩型Mo矿成岩成矿时代为晚三叠世,为印支期岩浆活动和成矿作用的产物。矿床的形成与花岗质岩浆的演化密切相关,花岗质岩体为东戈壁Mo矿床的成矿母岩。东戈壁斑岩型Mo矿的发现进一步说明了东天山印支期成矿事件的存在,结合区域上的岩浆活动,我们认为矿床形成于拉张伸展的构造背景,花岗质岩浆的形成可能与地幔物质的内侵有关。The Donggebi Mo deposit, located in Eastern Tianshan, Xinjiang, is a supper-large porphyry type deposit with a reserve of over 0.5 million tons of molybdenum. The porphyritic granite and the granitic porphyry underlying the ore bodies are believed to have played important roles in the Mo mineralization. The Re-Os isotope results for the molybdenites from the ores yield an isochron age of 233.2＋2.2 Ma and the weighted average age of 235.4~2.5 Ma. Zircon U-Pb ages of the porphyritic granite and the porphyry are 237.0~4.7 Ma and 237.0~4.7 Ma, respectively. These dating results indicate that the Donggebi porphyry Mo deposit and the related granites were formed in the late Triassic epoch. The granitic intrusion probably provided the ore-forming metals which led to the formation of the Donggebi deposit. The occurrence of the Donggebi porphyry Mo deposit demonstrates that the Indosinian orogeny is an important metallogenic period in East Tianshan. Based on the regional magmatism, we suggest that the Donggebi Mo deposit was related to a regional extension and the granitic magmas were produced by intrusion of mantle material into the continental crust.

关 键 词：东戈壁斑岩型Mo矿 Re Os年龄 锆石U—Pb年龄 印支期 东天山 

分 类 号：P597[天文地球—地球化学]