西准噶尔乌尔禾早二叠世中基性岩墙群LA-ICP-MS锆石U-Pb测年及构造意义  

Zircon LA-ICP-MS U-Pb Dating and Tectonic Settings Implication of the Early Permian Intermediate to Mafic Dyke Swarms in Urho Area, West Junggar

作　　者：王乐民[1] 晁文迪 李永军[2] 王冉[2] 范显刚 

机构地区：[1]新疆维吾尔自治区国土资源厅,新疆乌鲁木齐830002 [2]长安大学地球科学与资源学院,陕西西安710054 [3]陕西省核工业地质调查院,陕西西安710054

出　　处：《新疆地质》2015年第3期297-304,共8页Xinjiang Geology

基　　金：中国地质调查局地质矿产调查评价专项(1212011220619);国家自然科学基金(41303027);中央高校基本科研业务费专项资金(2014G1271058)联合资助

摘　　要：西准噶尔东部哈拉阿拉特山南麓乌尔禾地区新发现大量中基性岩墙群。岩墙群侵位于下二叠统佳木河组磨拉石建造中,展布方向与达尔布特大断裂延伸方向一致。岩墙群中采集的3个锆石U-Pb年龄样品测年结果分别为(286.3±4)Ma(n=18,MSWD=0.32,95%置信度),(286.5±5.6)Ma(n=10,MSWD=0.3,95%置信度)和(283.6±2)Ma(n=6,MSWD=0.57,95%置信度),误差范围内基本一致,据此确定该岩墙群形成于早二叠乌拉尔世(Cisuralian)亚丁斯克期(Artinskian)。中基性岩墙群具鲜明的与岛弧俯冲作用有关的地化特征,做为西准东部俯冲造山的地质记录,测年结果表明,西准东部的俯冲造山作用明显滞后于西部,整个西准地区俯冲造山作用结束的最终时限为早二叠世晚期。Intermediate to mafic dyke swarms are newly discoveried in Urho area,the south of Hala＇alat mountain which is located in the east of West Junggar.The dyke swarms intruded the Permian Jiamuhemolasse formation.The nearly NE—SW-trending dyke swarms are parallel to Darbut Fault. Three samples for LA-ICP-MS zircon U-Pb dating from the dyke swarms yielded an age of（286.3 ± 4） Ma（n=18, MSWD=0.32, 95% confidence）,（286.5 ± 5.6） Ma（n=10,MSWD=0.3, 95% confidence）and（283.6 ± 2） Ma（n=6, MSWD=0.57, 95% confidence）.The fact that the same in error range confirms the dyke swarms belong to the Cisuralian Epoch of Early Permian.The dyke swarms with characteristics of island-arc zone show that subduction in the east of West Junggar was posterior to the subduction in the west and middle of West Junggar.The final end of the subduction in West Junggar was in late Early Permian,rather than early Carboniferous previously thought.

关 键 词：西准噶尔 中基性岩墙群 LA-ICP-MS锆石U-PB测年 早二叠世 

分 类 号：P597.3[天文地球—地球化学] P588.124[天文地球—地质学]