甘肃新疆交界地区四顶黑山镁铁质—超镁铁质岩的锆石U-Pb年龄及地质意义  

Zircon U-Pb ages of Sidingheishan mafic-ultramafic rocks in Xinjiang-Gansu border area and their geological significance

作　　者：王国强[1,2] 李向民[2] 徐学义[2] 余吉远[2] 武鹏[2] 

机构地区：[1]长安大学地球科学与资源学院,陕西西安710064 [2]中国地质调查局西安地质调查中心,陕西西安710054

出　　处：《地质通报》2012年第12期2046-2051,共6页Geological Bulletin of China

基　　金：中国地质调查局地质调查项目<北山-祁连成矿带地质矿产综合研究>(编号:1212011085077);<亚洲构造演化过程中几个关键时段火山岩研究>(编号:1212011120133)

摘　　要：采用高精度LA-ICP-MS锆石U-Pb同位素定年,获得甘肃新疆交界地区四顶黑山镁铁质—超镁铁质岩体中辉长岩的年龄为320.9Ma±3.0Ma,代表该岩体的形成时代为早石炭世,与镁铁质-超镁铁质岩紧密伴生的碰撞型花岗岩(二长花岗岩)的形成年龄为369.2Ma±2.7Ma,属晚泥盆世。结合区域研究资料对比,认为四顶黑山地区的碰撞作用应该在早石炭世之前结束,早石炭世已进入陆内裂谷岩浆作用阶段,为进一步探讨区域构造演化提供了更为丰富的年代学依据。LA-ICP-MS zircon U-Pb dating of gabbro in Sidingheishan mafic-ultramafic rocks yielded an age of 320,9Ma±3.0Ma, which indicates the emplacement age of Sidingheishan mafic-ultrarnafic rock. The zircon U-Pb age of the monzogranite （collisional granite） associated with the mafic-ultramafic rock is 369.2Ma±2.7Ma. Combined with previous studies of regional geology, the authors infer that the coUision period was ended before the early Carboniferous and Sidingheishan area entered into the stage of continental rift in early Carboniferous. The result obtained by the authors is important for the study of the tectonic evolution in this area,

关 键 词：镁铁质-超镁铁质岩 LA—ICP—MS锆石U—Pb年龄 四顶黑山 

分 类 号：P588.124[天文地球—岩石学] P597.3[天文地球—地质学]