西藏班戈县拉青铜多金属矿床地球化学特征和年龄  

Geochemical characteristics,chronology and the significance of Laqing copper polymetallic skarn deposit,Bange county,Tibet

作　　者：董磊[1,2] 李光明[2] 黄瀚霄[2] 雍永源[2] 

机构地区：[1]中国地质科学院,北京100037 [2]成都地质矿产研究所,四川成都610083

出　　处：《地质通报》2013年第5期767-773,共7页Geological Bulletin of China

基　　金：国家重点基础发展计划课题<青藏高原南部矿床勘察模型与定位预测技术>(编号:2011CB403106);中国地质调查局青藏专项(编号:1212010918033)

摘　　要：拉青矿床位于班公湖-怒江缝合带南侧,属于矽卡岩型铜多金属矿床。矿区岩浆岩发育,矿化二长花岗岩为其成矿岩体。对二长花岗岩进行了LA-ICP-MS锆石U-Pb测年,获得年龄加权平均值为114.24Ma±0.87Ma,表明拉青矿床形成于早白垩世晚期。岩石地球化学数据分析表明,A/CNK值为1.15～1.17、A/NK值为1.53～1.59,为过铝质花岗岩,属于高钾钙碱性系列。轻稀土元素较重稀土元素富集,负Eu异常较弱。在微量元素蛛网图上,富集大离子不相容元素Rb、K、Th、U,亏损高场强元素Nb、Ti。R1-R2图解及Rb-(Yb+Nb)图解表明,拉青二长花岗岩形成于同碰撞构造环境。结合区域地质矿产资料初步认为,二长花岗岩体形成于班公湖-怒江洋消减闭合后羌塘板块与冈底斯板片碰撞拼合阶段,拉青矿床即是该同碰撞背景下形成的与二长花岗岩岩浆活动密切相关的矽卡岩铜多金属矿床。Laqing deposit located in the south of Bangong Lake-Nujiang suture is a skam type copper-riched polymetallic deposit. The intrusive rock is well-developed in the mining district, the monzogranite is closely related to mineralization. This paper is based on the data of zircon LA-ICP-MS U-Pb dating. The age of monzogranite is 114.24Ma＋0.87Ma, which imply Laqing deposit was formed in the late Early Cretaceous. The geochemistry results show A/CNK value is near 1.15-1.17 and A/NK value is 1.53~1.59. The rock which is ultraluminum type belongs to high-K calc-alkaline series. Laqing rock is enriched in FIP, EE and depleted in LREE, negative Eu is not obvious. In the spider diagram of trace elements,big ion incompatible elements Rb, K,Pb and Ti are rich, and Nb,Ti are poor. The R1-R2 and Rb-（Yb＋Nb） diagrams imply the monzogranite formed in the continental crust collision envi- ronment. According to regional geology and ore deposit geology data, it is considered that the deposit formed in the background of the Gangdese and the Qiangtang continental crust collision.

关 键 词：LA-ICP-MS U-PB测年 地球化学 矽卡岩型铜多金属矿 班公湖-怒江 拉青 西藏 

分 类 号：P618.41[天文地球—矿床学] P591[天文地球—地质学]