南天山铜花山蛇绿混杂岩中斜长花岗岩锆石LA-ICP-MS微区U-Pb定年及其地质意义

Zircon LA-ICP-MS U-Pb age of plagiogranite from Tonghuashan ophiolite in Southern Tianshan Mountains and its geological implications

南天山铜花山蛇绿构造混杂岩带中发育有斜长花岗岩产于蛇绿岩的顶部,并且二者呈断层接触关系。本文采用锆石LA-ICP-MS微区微量元素分析和U-Pb定年,获得斜长花岗岩年龄为(406.5±5.0)Ma,侵位时代确定为早泥盆世,这一年龄代表了铜花山蛇绿岩形成的下限年龄。

In Southern Tianshan Mountains of the Tonghuashan ophiolitic tectonic belt,the plagiogranite is exposed at the top of ultrabasic rocks,showing fault contact relationship.The concordant age of（406.5±5.0）Ma was obtained for the plagiogranite by the zircon micro-domain LA-ICP-MS rare earth elements analysis and U-Pb age dating,indicating that the intrusive epoch of plagiogranite was Early Devonian,and that this age represents the lower limit age of the Tonghuashan ophiolitic formation.