南天山齐齐加纳克蛇绿混杂岩的SHRIMP年龄及其构造意义  

SHRIMP dating of the Qiqijianake ophiolitic mélange in the Kokshal region,southwestern Tianshan and its tectonic implications

作　　者：王莹[1] 黄河[1] 张东阳[1] 张招崇[1] ENCARNACION John 赵莉[2] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]美国圣路易斯大学地球和大气科学系,mo63108

出　　处：《岩石学报》2012年第4期1273-1281,共9页Acta Petrologica Sinica

基　　金：国家科技支撑计划(2011BAB06B02-04;2007BAB25B05);国家自然科学基金项目(0925006;40772045;40572047)联合资助

摘　　要：齐齐加纳克蛇绿混杂岩位于中国新疆西南天山阔克萨彦岭地区,主要由辉石橄榄岩,橄榄辉石岩,橄榄玄武岩,辉长岩,辉绿岩,基性熔岩等组成。它们以一系列构造碎片近东西向产出,断续沿长约5km,宽约500m。本文应用SHRIMP方法对该蛇绿混杂岩中玄武岩中的锆石进行SHRIMP锆石U-Pb测年,获得了399±4Ma的加权平均年龄,说明该蛇绿混杂岩形成于早泥盆世。结合前人的研究成果,我们推测齐齐加纳克蛇绿混杂岩与吉根蛇绿岩残片均为中亚造山带南天山蛇绿岩带的延伸,可能代表了一个多岛窄洋盆演化的产物,为南天山洋北向俯冲及其后的塔里木微板块与哈萨克斯坦-准噶尔板块陆陆碰撞形成的最后缝合带。Qiqijianake ophiolitic mélange is located in the kokshal region in southwestern Tianshan of Xinjiang,China,It mainly consists of pyroxene peridotite,olivine pyroxenite,olivine basalt,gabbro,diabase,basaltic lavas,which is exposed as a series of tectonic blocks with the length of 5km and width of 500m,In this paper,we report the SHRIMP U-Pb zircon data for basalt from the Qiqijianake ophiolitic mélange in studied area,It shows that the Qiqijianake ophiolitic mélange formed in the Early Devonian（399±4Ma）,In combination with previously published data,we infer that the Qiqijianake ophiolitic mélange and Jigen ophiolitic remnant are the extention of South Tianshan ophiolite zone in Central Asia,which may be the product of a narrow archipelagic ocean,It represents the suture of the northward subduction of South Tianshan Ocean and collision between the Tarim Plate and Kazakhstan-Junggar Plate occurred after the subduction.

关 键 词：齐齐加纳克 蛇绿岩 SHRIMPU-Pb测年 阔克萨彦岭 西南天山 

分 类 号：P597.3[天文地球—地球化学]