新疆西准噶尔北部布尔津县木斯塔巴岩体年代学、地球化学特征及地质意义

准噶尔是新疆北部古生代造山带的重要组成部分,以广泛发育晚古生代花岗岩为特征,是中亚造山带总显生宙陆壳生长作用非常显著的地区之一。根据最新获得的LA-ICP-MSU-Pb锆石年龄,木斯塔巴岩体锆石年龄为(303±2.0) Ma(晚石炭世),岩石地球化学分析,岩石具高硅(66.04%~70.4%),高碱(2.26~2.87),高铝(13.25%~15.46%),高钾(3.4%~4.58%),低镁,A/CNK=1.06~1.22,低固结(6.34~12.87),高分异(78.35~84.5),富轻稀土(LREE/HREE=3.57~12.97)和大离子亲石元素K,Rb,Ba,Sr,亏损高场强元素Nb,Ta,Ti,P,为过铝质高钾钙碱性系列花岗岩,具碰撞花岗岩特征,属额尔齐斯构造带的重要组成部分,其形成与板块俯冲作用关系密切。本区石炭纪花岗岩的数据与北准噶尔地区对比,显示晚石炭世额尔齐斯构造带闭合,进入后碰撞阶段。

Chronology,Geochemical Characteristics and Geological Significance of Burqin Mustarba Mass in Western Junggar Basin,Xinjiang

Junggar basin is the important part of the north Xinjiang Paleozoic orogenic zone,and is characterized by widely develop the Late Paleozoic granites,is one of the most striking area for Phanerozoic continental crust growth in Central Asian Orogenic Belt.Accoding to the latest LA-ICP-MS U-Pb data,the zircon age of Mustarba mass is (303±2.0) Ma(Late Carboniferous),the result of lithogeochemistry anylysis show that the rock are high in silicon(66.04%~70.4%), alkali(2.26~2.87),aluminum(13.25%~15.46%),kalium(3.4%~4.58%),have low magnesium,A/CNK=1.06~1.22,consoli- dation(6.34~12.87),and high differentiation (78.35~84.5),are rich in LREE(LREE/HREE=3.57~12.97) and large ion lithophile element such as K,Rb,Ba,Sr, and deplete in high field strong elements such as Nb,Ta,Ti,P , belongs to Per- aluminous series of high potassium calcium alkaline granites,have the characteristics of colliding granite,which is the im- portant part of Erzis tectonic belt,its formation is related with the plate subduction.Compared with the north Junggar area, the data of Carboniferous granite in study area show the Erzis tectonic belt closed during the late Carboniferous,and En- ter the post-collision phase.