西准噶尔萨尔托海花岗岩株锆石U-Pb年代学及地质意义  

U-Pb Geochronology of Saertuohai Granitic Stock in Western Junggar,NW China

作　　者：张丽敏[1] 李永军[1] 孙勇[1] 杨洋[1] 张胜龙[1] 

机构地区：[1]长安大学地球科学与资源学院,西部矿产资源与地质工程教育部重点实验室,陕西西安710054

出　　处：《新疆地质》2014年第1期35-41,共7页Xinjiang Geology

基　　金：中国博士后科学基金特别资助项目(2013T60869);国家自然科学基金项目(41273033);中国地质调查局项目(1212011220619)联合资助

摘　　要：新疆西准噶尔萨尔托海蛇绿岩与下石炭统呈逆冲断层接触,后被达尔布特走滑断层所改造,是西准噶尔地区时代最新、规模最大的蛇绿混杂岩带。萨尔托海岩株侵入于萨尔托海蛇绿混杂岩带之中,岩体岩性为肉红色二长花岗岩。对花岗岩样品进行测年,新获得LA-ICPMS锆石U-Pb年龄(309±3)Ma(2σ),代表了花岗岩结晶时代,较区域花岗岩基如庙尔沟、加甫萨尔苏等岩体的形成时代略老。综合蛇绿岩及区域岩体时代和岩石学特征等,认为该年龄限定了蛇绿岩侵位时代上限,揭示其属区域伸展背景的产物,标志着区域俯冲作用已经结束。因此,西准噶尔地区至少在309 Ma以后不存在俯冲作用,该认识有助于理解新疆北部多期次岩浆活动的时限和性质。The Saertuohai ophiolite from West Junggar in Xinjiang (NW China) contacts with the early Carboniferous strata by a thrust fault, which has been transformed by the Darbut strike-slip faults. It is the latest and largest ophiolitic mélange zone in Western Junggar, and is intruded by the Saertuohai granitic pluton which is mainly composed of red monzonitic granite. A zircon U-Pb age of 309±3 Ma has been obtained by our LA-ICPMS dating for the granite, and is considered to represent formation age of the granite. This age is similar that of the Yegezikala granite in the adjacent ar-ea, but is slightly older than the regional granitic batholiths including the Miaoergou and Japusaersu granitic plutons. Based on a combination of the formation ages and petrogeochemistry of the ophiolites and granites, it is interpreted that the Saertuohai granite was formed in an extensional setting indicating the termination of the subduction of the Paleozoic Junggar oceanic crust, and its age confines the upper limit time of the tectonic emplacement of the Darbut ophiolite. Con-sequently, no subduction may exist in the West Junggar region later than 309Ma. Our data may be valueable for under-standing the Paleozoic geological evolution of the West Junggar region.

关 键 词：西准噶尔 萨尔托海 花岗岩株年代学 锆石U-PB年龄 地质意义 

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