羌塘-三江古生代-中生代沉积盆地演化

Evolution of Sedimentary Basins in Qiangtang-Sanjiang from Paleozoic to Mesozoic

羌塘-三江构造-地层大区的古生代-中生代沉积盆地和构造演化受特提斯洋的控制.通过综合分析前人对羌塘-三江地区大量岩石地层、生物地层、同位素年代学及构造学等研究资料,对羌塘-三江构造-地层大区各分区古生代-中生代的沉积盆地类型进行了划分,并分析了各个沉积盆地的形成和演化过程,探讨了该区的大地构造演化:早古生代该区主体属于大洋环境;晚古生代随着特提斯洋向南东、北东方向的俯冲,该区开始发育一系列活动陆缘沉积盆地,产生金沙江弧后洋、澜沧江弧后洋和甘孜-理塘弧后洋,形成多岛洋弧盆系;中生代,随着特提斯洋向北东的俯冲消减,弧后洋逐渐闭合,羌塘-三江地区发生大规模弧-弧、弧-陆碰撞增生,逐渐转化成陆.随着白垩纪特提斯洋的闭合,印度板块与中国西部碰撞、造山,羌塘-三江地区发育陆内盆地.

The structure and evolution of Qiangtang-Sanjiang during Paleozoic-Mesozoic sedimentary basins were controlled by the Tethys.On the basis of the exploration of previous studies on lithostratigraphy,fossil assemblages,isotopic geochronology and tectonics of the study area,this paper classifies the sedimentary basins of Qiangtang-Sanjiang region,and analyzes the for-mation and evolution of each sedimentary basin.During the Early Paleozoic,Qiangtang-Sanjiang basins were mostly ocean envi-ronment;with the subduction of the Tethys Ocean to the northeastward and southeastward in Late Paleozoic,the active margin sedimentary basins developed in this area,forming Jinshajiang back arc-ocean,Lancangjiang back arc-ocean and Ganzi-Litang back arc-ocean and then the multiple island arc-basin systems of eastern Tethys system gradually formed.During the Mesozoic, with the subduction of the Tethys in Late Triassic in Qiangtang-Sanjiang,three arc-basins gradually closed,then large-scale arc-arc collision and arc-continent collision occurred in this area.This area eventually entered intracontinental evolution stage from the active margin sedimentary basins,Due to the close of Tethys in Cretaceous,the Indian plate and western China colli-ded,inland basins developed in Qiangtang-Sanjiang.