西藏冈底斯中西段主碰撞期成矿事件——德新矿区花岗斑岩锆石U-Pb年龄证据  

Metallogenesis of the main collisional period in mid-western Gangdise:Zircon U-Pb geochronology of the granite porphyry in Dexin deposit,Tibet

作　　者：柯贤忠[1] 龙文国[1] 周岱[1] 王晶[1] 钟石玉 KE Xianzhong;LONG Wenguo;ZHOU Dai;WANG Jing;ZHONG Shiyu(Wuhan Center of Geological Survey, CGS, Wuhan 430205, Hubei, China;Hubei Geological Survey, Wuhan 430034, Hubei, China)

机构地区：[1]中国地质调查局武汉地质调查中心,湖北武汉430205 [2]湖北省地质调查院,湖北武汉430034

出　　处：《地质通报》2017年第5期772-779,共8页Geological Bulletin of China

基　　金：中国地质调查局项目<钦杭西段关键地区区域地质调查>(编号:12120113066400);<信宜-增城-龙川构造混杂岩带研究>(编号:12120114039201);<钦杭成矿带西段资源远景调查评价>(编号:12120113067200)

摘　　要：德新银铅锌矿床位于拉萨地块中部隆格尔-工布江达断隆带中段,是冈底斯银铅锌多金属成矿带上典型的热液型矿床之一。区内的铅锌矿化主要赋存于围岩裂隙和花岗斑岩中。利用LA-ICP-MS锆石U-Pb测年方法对区内含矿花岗斑岩进行年龄测定,获得^(206)Pb/^(238)U年龄加权平均值为57.7±0.5Ma(MSWD=1.6,n=15),代表花岗斑岩及与之相关的铅锌矿化形成年龄。综合区域地质背景,认为德新矿区与花岗斑岩有关的铅锌矿化形成于印度-亚洲大陆主碰撞时期,与纳如松多隐爆角砾岩型铅锌矿属同一岩浆成矿系统,冈底斯中西段存在(近)主碰撞阶段成矿事件。The Dexin Ag-Pb-Zn deposit,located in the Longgeer-Gongbujiangda fault-block uplift belt at the center of Lhasa Ter?rane,is one of the representative hydrothermal type deposits in the Gangdise Ag-Pb-Zn polymetallic ore-forming belt.The Pb-Znmineralization dominantly occurs in the fractures of wall rocks and the granitic porphyries.Zircons from the ore-bearing granitic por?phyry in Dexin were measured by the LA-ICP-MS U-Pb dating method,which yielded a weighted average206Pb/238U age of57.7±0.5Ma(MSWD=1.6,n=15)that represents the formation age of the granitic porphyries and the Pb-Zn mineralization in the graniticporphyries.With a comprehensive analysis of geological background,it is concluded that the Pb-Zn mineralization associated withthe granitic porphyries in Dexin and the cryptoexplosive breccia type Pb-Zn mineralization in Narusongduo were formed by thesame magmatic metallogenic system,and there were many magmatic-metallogenic events near/in the main Indian-Asian collisionalperiod in the mid-west part of Gangdise.

关 键 词：花岗斑岩 锆石U-PB 年龄 德新 西藏 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]