西藏冈底斯南部陆陆碰撞早期成矿作用分析  

Study on the metallogenesis during the early stage of continental collision in southern Gangdese, Tibet

作　　者：黄文婷[1,2] 梁华英[1] 伍静[1] 王春龙[1,2] 邹银桥[1,2] 王秀璋[1] 许继峰[3] Charllote M ALLEN 

机构地区：[1]中国科学院广州地球化学研究所,中国科学院矿物学与成矿学重点实验室 [2]中国科学院大学,北京100083 [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 [4]Research School of Earth Sciences,Australian National University

出　　处：《岩石学报》2013年第4期1439-1449,共11页Acta Petrologica Sinica

基　　金：973项目(2009CB421000);中国科学院战略性先导科技专项(B类)(XDB03010302);中国科学院广州地球化学研究所135项目(Y234022A07);中国科学院重点国际合作项目(GJHZ1127);国家自然科学基金项目(41172080;41121002;41272099)联合资助

摘　　要：冈底斯带南部发育有大量的斑岩铜钼矿床和矽卡岩型铜铅锌多金属矿床,形成了斑岩铜矿带和多金属矿带。前人的研究表明,成矿带内的矿床形成年代大都小于30Ma,处于碰撞后期伸展构造环境。本文对冈底斯带中南部的甲龙矽卡岩型铁矿、撒当金银矿床(点)和多底沟矽卡岩型钼矿床(点)开展了年代学研究,结果显示:甲龙铁矿黑云母二长花岗斑岩的锆石LA-ICP-MSU-Pb年龄为61.1±0.4Ma,MSWD=0.94;撒当赋矿安山岩锆石LA-ICP-MSU-Pb年龄为62.6±0.5Ma,MSWD=1.51;多底沟钼矿床(点)3件辉钼矿Re-Os模式年龄为64.3±0.8Ma～69.2±3.3Ma,加权平均模式年龄为66.7±6.4Ma(MSWD=8.1)。三个矿床(点)的同位素年龄表明成岩成矿事件和印度-欧亚板块陆陆碰撞早期构造岩浆事件有关。结合前人工作,我们提出冈底斯中南部发生了大规模与陆陆碰撞早期岩浆事件有关的成矿作用,形成了大面积分布的矿床,具有良好的找矿前景,应引起更多关注。Many porphyry Cu-Mo and Cu-Pb-Zn polymetal deposits have been found in the southern Gangdese belt, forming a porphyry copper ore belt and a polymetal ore belt, respectively. Previous geochronologic results indicate that most deposits in the southern Gangdese belt were formed after 30Ma and in post-collisional extension evnironment. In this paper, we analyze zircon U-Pb age of igneous rocks closely associate with the Jialong skarn Fe deposit and the Sadang Au-Ag deposit, respectively, and molybdenite Re-Os age of the Duodigou skarn Mo deposit in the southern Gangdese. The Jialong biotite monzonite granite closely associated with skarn Fe deposit has zircon LA-ICP-MS U-Pb age of 61.1±0.4Ma with MSWD=0.94. The Sadang andesite closely associated with Au-Ag mineralization has zircon LA-ICP-MS U-Pb age of 62.6±0.5Ma with MSWD=1.51. The molybdenite Re-Os model ages of the Duodigou skan Mo deposit varies from 64.3±0.8Ma to 69.2±3.3Ma, with an average weight age of 66.7±6.4Ma, MSWD=8.1. Our new results suggest that the three deposits own their origin to the magmatic events triggered by early Indus-Eurasia collision. Our results, together with former work, reveal that the southern Gangdese has undergone large-scale mineralization associated with the strong magmatic activities during the early Indus-Eurasia collision. It is, therefore, suggested that the southern Gangdese could be an important target area for mineralization related to early Indus-Eurasia collision.

关 键 词：冈底斯带 陆陆碰撞 成矿时代 西藏 

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