论文部分内容阅读
班公湖-怒江带作为羌塘地块与拉萨地块晚中生代聚合而形成巨型构造带,其形成时代与如何汇聚是构造研究关键所在。本次研究选择班公湖—怒江带中段的安多—聂荣地块发育为研究区,对地块内部基底发育的近东西走向的韧性剪切带,开展了韧性剪切变形分析与同构造年代学研究。剪切带面理和线理测量分析指示北东—南西向构造挤压,其同构造矿物40Ar/39Ar的测试分析获得年龄约为167 Ma,表明班公湖-怒江带中段形成于中侏罗世中期北东—南西向汇聚的构造背景下。结合区域构造分析,东亚大陆西缘羌塘地块与拉萨地块在中侏罗世中期以北东—南西向碰撞聚合的构造方式完成大陆拼接,为东亚大陆西缘中侏罗世变形提供了直接构造证据。
As the giant Mesozoic belt formed by the convergence of the Late Paleozoic of the Qiangtang block and the Lhasa block, the Bangong-Nujiang belt formed the key to tectonic study. In this study, we selected the amphibole-Nie Rong block in the middle section of the Bangong-Nujiang belt as the study area, and developed ductile shear deformation analysis and syn-tectonics of the near-to-west ductile shear zone developed in the basement of the block. Geochronology. The analysis of shear banding and lineage instructs tectonism that the NE-NW strike tectonic extrusion, and the age of the 40Ar / 39Ar isotopic mineral is about 167 Ma, indicating that the middle part of the Bangong-Nujiang belt was formed in the Middle Jurassic Under the tectonic setting of the North-East-South-West convergence in the mid-world. Based on the regional tectonic analysis, the Qiangtang block and the Lhasa block in the western part of the East Asian continent were constructed by means of the continental collision in the middle-Middle Jurassic to the north-east-west collision, which provided a basis for the deformation of the Middle Jurassic in the western margin of East Asia Directly construct evidence.