西准玛依勒地区哈吉岩体和包体LA-ICP-MS锆石U-Pb测年及地质意义  

LA-ICP-MS ZIRCON U-Pb DATING OF HAJI GRANITE AND INCLUSIONS FROM MAYILE AREA IN WESTERN JUNGGAR, XINJIANG

作　　者：汪雅兵[1,2] 王振华[1] 韩玉萍[1] 佟丽莉[2] 杨高学[2] 

机构地区：[1]甘肃省国土资源规划研究院,甘肃兰州730000 [2]长安大学地球科学与资源学院,陕西西安710054

出　　处：《甘肃地质》2013年第3期12-18,共7页Gansu Geology

基　　金：国土资源大调查项目(XJZBKD2008-04)

摘　　要：LA-ICP-MS锆石U-Pb测年结果显示，哈吉岩体形成时代为278±3Ma，MSWD=0．43。包体年龄为291±4Ma．MSWD=0．32，在误差范围内完全一致，表明岩体和暗色微粒包体是同时代形成的。包体是岩浆混合作用的产物。是过冷的镁铁质岩浆混入到中酸性岩浆中经快速冷凝的结果。在岩浆混合过程中，基性的包体岩浆和中酸性的寄主岩浆通过化学扩散发生成分交换，使包体受到了花岗闪长质岩浆的改造和同化。这可能就是哈吉岩体及其包体LA-ICP-MS锆石U-Pb年龄相同的原因所在。哈吉岩体形成的时代属于西准噶尔后碰撞深成岩浆活动的范围330，265Ma之间．其形成和演化代表了准噶尔地区后碰撞幔源岩浆底侵作用导致大陆地壳垂向生长的过程。LA-ICP-MS zircon U-Pb dating of the Haji grantite and its enclaves in the Mayile area of the Western Jungaar indicates that the isotopic age of granite is 278±3Ma （MSWD=0.43）,and its enclaves is 291± 4Ma （MSWD=0.32）. It suggests that granite and enclave should be formed at the same period. Enclaves formed from magma mixing ,that is say ,cool magnesium-iron magma mixing into neutrality-acidity magma ,fast cooling formed it. In process of magma mixing,basic magma of enclaves and acid magma of host rock changed the ingredient by chemistry proliferation, enclaves with granite magma by assimilation and transformation. This is the reason why Haji granite and its enclaves have the same geologic time. Haji granite formation times belongs to range （330-265Ma） of post-collision magma activity in West Jungaar,and its formation and evolution stands for continental crustal growth that by post-collision magma underplating in West Jungaar.

关 键 词：哈吉岩体 微细粒包体 LA—ICP—MS锆石U—Pb测年 玛依勒 西准噶尔 

分 类 号：P597.3[天文地球—地球化学]