内蒙古东升庙一带花岗质岩体锆石年代学及其构造意义

ZIRCON GEOCHRONOLOGY OF GRANITIC MASS IN DONGSHENGMIAO OF INNER MONGOLIA AND TECTONIC SIGNIFICANCE

研究区位于华北地块北缘西段,是解析中亚造山带构造演化的关键部位。本文在野外地质调查基础上,应用TIMS锆石U-Pb测年法对东升庙一带主要花岗—闪长质侵入岩体进行分析,完善了原有工作成果。证实了该区存在太古代结晶基底((2 619±18)Ma、(2 563±21)Ma),并于古元古代中晚期(2.0Ga)经历了一次强烈的碰撞造山运动,造成了闪长质与花岗质岩浆侵位,以及1.9Ga的变质事件。而后又经历了中元古代伸展裂解、石炭纪中晚期洋壳俯冲((304±3.4)Ma、(320.5±2.9)Ma)和二叠纪—三叠纪碰撞拼合((227.6±4)Ma、(246±2.5)Ma)3个重要的构造事件阶段,并伴有大规模岩浆侵入。

Located in the west part of northern margin of North China Block（NCB）,the study area is the key part to interpret tectonic evolution of Central Asian Orogenic Belt. Based on the field geological investigation, it is TIMS Zircon U-Pb technology employed to analyze chronology of intrusive rock, we concluded that there should be craton crystalline basement （Neoarchean,2 619±18Ma,2 563±21Ma） in the study region. It experienced the strong collision orogeny in late Paleo-proterozoic （2.0Ga） and the metamorphic event of 1.9 Ga, which caused the intrusion of granitic and diorite mass, following with other three important large-scale tectonic stages i.e. Mesoproterozoic stretching cracking, Carboniferous oceanic crust subduction and Triassic-Permian collision split.