西南天山南缘震旦纪后碰撞过铝花岗岩的地学意义  

THE SIGNIFICANCE OF THE SINIAN POST-COLLISION PERALUMINOUS GRANITES AROUND SOUTH MARGIN OF THE SOUTHWEST TIANSHAN

作　　者：魏永峰[1] 李建兵[1,2] 杜红星[3] 邓泽锦[1] 康江伟[3] 

机构地区：[1]四川省地质矿产勘查开发局区域地质调查队,四川双流610213 [2]成都理工大学,四川成都610059 [3]新疆地质矿产勘查开发局第八地质大队,新疆阿克苏843000

出　　处：《新疆地质》2010年第3期242-246,共5页Xinjiang Geology

基　　金：新疆拜城县老虎台一带1:5万区域地质矿产调查项目(XJQDZ2007-10)资助

摘　　要：西南天山南缘震旦纪后碰撞过铝花岗岩同位素U-Pb年龄成果为(601.5±3.4)Ma和(677.3±3.8)Ma.岩石高硅富碱,A/CNK值平均1.02,C-norm≤1.79,属高钾钙碱性系列过铝质花岗岩类.岩石ΣREE普遍较低,呈明显负铕异常,分布曲线为显著的"V"字型,轻重稀土分馏程度较弱.与洋脊花岗岩相比,明显富集Rb,Th,相对富集Ce,Sm,强亏损Ba,相对亏损Zr,Ta,Nb亏损不明显.地球化学特征表明,该花岗岩形成于后碰撞环境.结合区域资料,认为震旦纪后碰撞过铝花岗岩形成于塔里木运动后碰撞期,是塔里木微板块和伊犁微板块边缘发生相对水平剪切运动,岩石圈源岩熔融.塔里木运动下限可能延伸到晚震旦纪早期.The U-Pb isotope ages of the Sinian post-collision peraluminous granite around shouth margin of the southwest Tian Shan are（601.3±3.4） Ma and（677.3±3.8） Ma,separately,The rocks are high silicon and rich alkali,the granite mean ratio of A/CNK is 1.02,its C-norm is ≤1.79.So,the granite belongs to high K and Ca alkali granite.∑REE of peraluminous granite is usally low,with obvious Eunegative anomaly,and distribution plot of the rock is marked V model,fractionation of LREE and HREE of the rock is weak.Compared wth ocean ridge granite,it is charactered by high rich RbTh,relatively rich Ce and Sm,strong deficit Ba,relatively loss ZrTa,and normal Nb.the geochemical charactors of the granite described as above indicate the rock formated in post-collision period.Intergrated with regional data,it came into being of remelt of lithosphere during horizonetle strike-slip movemenet betweem the Tarim and Yili microplates and the lower-limit of Tarim movement may extend to as old as early stage of late Sinian.

关 键 词：西南天山 震旦纪 后碰撞 过铝花岗岩 

分 类 号：P588.121[天文地球—岩石学]