鄂东南铜绿山矿田矽卡岩型铜铁金矿床的辉钼矿Re-Os同位素年龄及其地质意义  

Re-Os dating of molybdenite from Tonglüshan ore district in southeastern Hubei Province,Middle-Lower Yangtze River belt and its geological significance

作　　者：谢桂青[1,2] 赵海杰[1] 赵财胜[3] 李向前[2] 侯可军[1] 潘怀军 

机构地区：[1]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 [2]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 [3]中国地质调查局发展研究中心,北京100037 [4]湖北省三鑫金铜有限责任公司,湖北大冶435100

出　　处：《矿床地质》2009年第3期227-239,共13页Mineral Deposits

基　　金：国家重点基础研究课题(2007CB411407和2007CB411405);国家自然科学基金(40434011和40402011);中央级公益性科学院所基本科研业务费(K0816);中国科学院地球化学研究所开放室基金(200402);中国博士后项目的联合资助

摘　　要：鄂东南地区(斑岩-)矽卡岩型铜铁金多金属矿床是长江中下游地区金属成矿带的重要组成部分,铜绿山矿田以成矿类型齐全和矿体规模较大为特点,是鄂东南矿集区最重要的矿田。但目前对不同成矿元素的矽卡岩型铜铁金矿床的成矿时代、成岩成矿时差和构造背景的研究相对较少。本文利用Re-Os同位素定年方法对铜绿山矿田两个典型的大型铜绿山矽卡岩铜(铁金)矿床和大型鸡冠嘴矽卡岩(铜)金矿床进行了成矿时代的研究,获得了辉钼矿的Re-Os同位素年龄范围分别为(136.8±1.9)～(138.1±1.8)Ma和(137.1±1.9)～(138.8±1.9)Ma,等时线年龄分别为(137.1±1.9)Ma和(138.2±2.2)Ma,表明铜绿山矿田不同类型的矿床几乎同时形成;与矿田花岗闪长岩锆石SHRIMPU-Pb年龄(140.3±1.8)Ma在误差范围内基本一致,存在较短的成岩成矿时差,该成矿时代与鄂东南地区其他矿田的(斑岩-)矽卡岩型铜钼矿床和矽卡岩型铁矿床,以及长江中下游地区铜陵、安庆、九瑞矿集区(斑岩-)矽卡岩铜多金属矿床的形成时代基本一致。铜绿山矿田矽卡岩铜铁金矿床可能是在太平洋板块俯冲的撕裂或开天窗时,由于玄武质岩浆底侵和岩石圈减薄导致中国东部大规模侵入岩和成矿作用产物的形成。The （porphyry-）skarn Cu-Fe-Au polymetaUie deposits in southeastern Huhei constitute an important component part of the Middle-Lower Yangtze River metallogenic belt. The Tonglushan ore district is characterized by various types of mineralizations and large-sized ore bodies and represents the most important economic mineral district in southeastern Hubei Province. Nevertheless, little research work has been done on the timing of various skarn deposits and the genetic association of igneous rocks with mineralization as well as the tectonic frame- work of these deposit. Molybdenites from the Tonglushan skarn Cu- （Fe-Au） deposit and the Jiguanzui skarn Cu （Au） deposits yielded Re-Os model ages ranging from（136.8 ±1.9） to （138.1 ± 1.8）Ma and from （137.1 ± 1.9） to （138.8 ±1.9） Ma, respectively, with isochronal ages being （137.1± 1.9） Ma and （138.2 ± 2.2） Ma, which are considered to be reliable estimates for the timing of the Tongltishan and the Jiguanzui deposit. These data indicate that ages of various skarn deposits are almost identical to the zircon SHRIMP U-Pb age of （140.3± 1.8）Ma for the related granodiorite, almost the same as ages of other （porphyry-）skarn Cu-Mo deposits and skarn Fe deposits in southeastern Hubei Province and even those of the Jiurui Cu-Au （Mo）, the Anqing Cu-Fe- Mo （Au） and the Tongling Cu-Au ore districts in the Middle-Lower Yangtze River metallogenic belt. Combined with geological, geochemical and geophysical evidence, it is proposed that the skarn Cu-Fe-Au deposits in TongliJshan constitute a part of extensive igneous rocks and corresponding skarn Cu-Fe-Au mineralization that resulted from lithospheric thinning and basaltic magma underplating, which, in turn, were triggered by the roll- back and/or window of the downgoing slab related to the subduction of Pacific plate in East China.

关 键 词：地球化学 辉钼矿RE-OS年龄 矽卡岩铜铁金矿 铜绿山矿田 鄂东南地区 

分 类 号：P618.41[天文地球—矿床学] P618.31[天文地球—地质学]