西南天山木扎尔特群长英质岩地球化学特征及U-Pb年龄的地学意义  

THE GEOCHEMICAL BEHAVIOR AND GEOLOGICAL SIGNIFICANCE OF U-PB DATING ON QUARTZ-FELDSPATHIC ROCKS IN EASTERN MUZHAERTE,SOUTHWEST TIANSHAN

作　　者：魏永峰[1] 邓泽锦[1] 李建兵[1,2] 杜红星[3] 孙涛 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]新疆维吾尔自治区地质矿产勘查开发局第八地质大队,新疆阿克苏843000 [4]核工业211队,陕西西安710024

出　　处：《新疆地质》2010年第2期125-129,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：西南天山南缘的木扎尔特群长英质岩原岩为英云闪长岩、花岗闪长岩、奥长花岗岩、石英二长岩.岩石地球化学特征表明:物源来自于下地壳,形成环境为大陆边缘.应用锆石LA-ICP-MSU-Pb定年法,在二云母二长片麻岩中获得3个年龄值.(1909±100)Ma代表片麻岩形成年龄,这是屹今为止,该地质体内发现的最古老同位素年龄;(617±30)Ma代表木扎尔特群形成后遭受第一期构造、变质和岩浆活动热事件的主体年龄,这一热事件持续约317Ma,在新疆称为塔里木运动;(281±31)Ma代表第二期构造、变质和岩浆活动热事件,与早二叠世末地壳深部调整,导致地幔热流上升,形成弥散型大陆热伸展构造有关.研究结果不仅确定了木扎尔特群可作为塔里木中央地块古元古代基底的代表,也为进一步研究塔里木盆地北缘地质演化问题提供了基础资料.Basing on protolith recovering,the protolith of the quartz-feldspathic rock in Muzhaert include continental tholeiite,tonalite,granodiorite,trondhjemite,adamellite and the protolith may contains clasolite considering the macro feature of it in field.Geochemical behavior of the magmatite rocks demonstrate the provenance comes from the crust and formed in the environment of the continental margin.The （1909±100） Ma in one of the three age which are obtained through LA-ICP-MS and U-Pb dating on zircon, was stand for the formation time of the gneiss which is the earliest isotope age founded in geologic body still for.The （617±30） Ma was the main age of the thermal event that undergoing the first structure, metamorphose and magmatic activity and these events last for 317 Ma which was called Tarim movement.The （281±31） Ma represent thermal event including the second tectogenesis,metamorphose and magmatic activity which are relevant to the movement that the mantle heat flow ascend and formed into dispersive thermal stretching continent in the end of the Early Permian period.This paper confirmed the Muzhaert as a representative of the palaeozoic era base in the center of Tarim and it＇s also supply a bond for the geologic succession on the north border of Tarim basin.

关 键 词：西南天山 木扎尔特群 长英质岩 U-PB 

分 类 号：P588.341[天文地球—岩石学]