西昆仑库地伟晶辉长岩和玄武岩锆石SHRIMP年龄:库地蛇绿岩的解体  

Zircon SHRIMP Age Determination of the Giant-crystal Gabbro and Basalt in Küda, West Kunlun: Dismembering of the Küda Ophiolite

作　　者：张传林[1] 于海锋[2] 沈家林[3] 董永观[3] 叶海敏[3] 郭坤一[3] 

机构地区：[1]中国科学院广州地球化学研究所,510640 [2]中国地质调查局天津地质矿产研究所,300170 [3]中国地质调查局南京地质矿产研究所,210016

出　　处：《地质论评》2004年第6期639-643,共5页Geological Review

基　　金：国家自然科学基金项目 (编号 40 3 0 3 0 0 7);中国地质调查局项目 (编号 2 0 0 113 90 0 0 70 )的成果

摘　　要：西昆仑“库地蛇绿岩“是中国西部地区研究程度较高的蛇绿岩之一。对这条蛇绿岩带的时代、构造背景至今存在很大分歧。笔者等在库地超镁铁岩体中 ,获得侵入于橄榄岩中的伟晶辉长岩锆石 SHRIMP年龄为5 2 5± 2 .9Ma,在库地一些克沟获得块状玄武岩锆石 SHRIMP年龄为 4 2 8± 19Ma,这表明库地超镁铁岩和库地一些克沟玄武岩不属于同一时代 ,因此它们可能形成的构造背景也存在差异 ,库地蛇绿岩应解体。Küda Ophiolite” in West Kunlun is one of the most studied ophiolites in West China. Controversies on its age and tectonic significance exist among geologists till now. In this paper, by SHRIMP age determination, the zircon U Pb age of the giant crystal gabbro, which intrudes into the ultramfic complex, is 525±2.9Ma (MSWD=1.2), so the ultramafic complex, which is an important part of the Küda ophiolite, must older than this age. Zircon U Pb age of the basalt is 428±29Ma. The ages of the gabbro and the basalt argue that the ultramafic complex and the basalt in Küda were asynchronous and the Küda ophiolite should be dismembered. The age data in this paper supply new information to study the Paleozoic evolution in this area.

关 键 词：SHRIMP 库地蛇绿岩 锆石 西昆仑 玄武岩 辉长岩 超镁铁岩 解体 年代 资料 

分 类 号：P597.3[天文地球—地球化学]