西藏羌塘盆地的构造沉积特征及演化

THE TECTONIC-SEDIMENTARY FEATURE AND EVOLUTION OF QIANGTANG BASIN IN NORTHERN TIBET

西藏羌塘盆地是特提斯构造域内晚古生代—中生代海相复合盆地。经历了晚古生代板块构造演化阶段、中生代板块构造演化阶段和新生代抬升剥蚀阶段 ,形成了晚古生代大陆边缘盆地、中生代南羌塘被动大陆边缘和北羌塘弧后盆地以及晚侏罗世之后的构造地貌盆地。受多期构造运动作用 ,盆地从北向南形成了北缘冲褶带、北羌塘变形带、中央碰撞隆起带、南羌塘变形带和南缘冲断带五个构造单元。变形由坳陷边缘到中心逐渐减弱 ,侏罗山式褶皱样式 。

Qiangtang basin is a marine composite basin of Tethys domain in Tibet during late Paleozoic-Mesozoic period. It underwent three major stages (the late Paleozoic plate tectonic evoloution, Mesozoic plate tectonic evolution and Cenzoic uplift-denudation) and formed different basins, including continental margin basin in late Paleozoic, southern Qiangtang passive continental margin basin and northern Qiangtang back-arc basin in the Mesozoic, and tectonic-morphologic basin after late Jurassic. By the effict of multitectonic movements, from north to south Qiangtang basin can be divided into five tectonic units:northern margin thrust-fold belt, northern Qiangtang deformation belt, central collisional uplift belt, southern Qiangtang deformation belt and southern thrust-fault belt. The deformation is weaker from depression margin to centre. Jura-type fold style shows that the deofmation of covering strata is a kind of decollement in shallow level.