阿尔金山喀腊大湾地区中酸性侵入岩SHRIMP年龄及其意义

摘要

Kaladawan area of eastern Altun Mountains, is tectonically sandwiched between NE-trending Altun strike-slip fault and EW-trending northern Altun marginal fault. There outcropping s series of intermediate-acid intrusive rocks which were determined as Late Paleozoic era. In this paper, the authors for the first time take measurements of SHRIMP U-Pb zircon age of the intermediate-acid intrusive rocks and give a high quality age of 413 ~S14Ma. The results reflect that there happened a series strong magmatic intrusive activity in Early Paleozoic era. With other dating data of the intrusive rocks by othei methods in the area and with SHRIMP U-Pb zircon age of the intermediate-acid intrusive and ophiolite in Hongliugou area about 180km to the west of Kaiadawan area, the magmatic intrusive activity in Kaladawan area of eastern Altun Mountains can be divide to three stage as follows; pre-collision(520 ~500Ma) , syn-colli9ion(490 -470Ma)and post-collision(440 ~410Ma).%阿尔金山东段喀腊大湾地区位于北东向阿尔金走滑断裂北侧与东西向阿尔金北缘断裂所夹持的区域,该区广泛发育中酸性侵入岩,前人将其确定为晚古生代.本文运用锆石SHRIMP U-Pb方法对该区的中酸性侵入岩进行洲年,获得413～514Ma的年龄,确认喀腊大湾地区早古生代岩浆活动的存在.结合前人其他方法测年数据和红柳沟一带(喀腊大湾以西180km)中酸性侵入岩的SHRIMP测年资料和蛇绿岩的时代,将阿尔金山东段喀腊大湾地区中酸性岩浆活动划分为碰撞前岩浆活动(520～500Ma)、碰撞期岩浆活动(490 ～470Ma)和碰撞后岩浆活动(440 ～410Ma)三个阶段.