准噶尔盆地构造动力学过程

GEODYNAMICS PROCESS IN THE JUNGGAR BASIN

准噶尔盆地被古生代缝合线构造包围,周缘山系向盆地方向逆冲推覆,显示了盆地处于长期受压的构造环境;火山喷发由海相转变为大陆相,火山活动由强到弱,表明二叠纪以后,上地幔物质一直处于收缩状态,盆地整体持续下沉接受沉积,地壳增厚。二叠纪进入盆地演化阶段之后,经历了晚海西、印支、燕山和喜马拉雅四期构造应力场的作用,发生了南北向拉张变形、南北向和北西向碰撞挤压变形、南北向和北西向张压交替变形以及南北向压扭冲断、走滑和重力滑覆变形,形成复杂多样构造类型。

The Junggar basin is surrounded by Paleozoic sutures and the mountains around the basin have been thrust toward the basin,showing that this basin has been in a long-continued,compressional regime.The change of volcanic rocks from marine facies to continental facies and change of volcanism from strong to weak indicate that after the Permian the upper mantle materials had long been in a constrictive stage,and that the whole basin sank continuously to receive deposits,thus resulting in crustal thickening.During the basin evolution stage in the Permian,the basin was affected by the late Hercynian,Indosinian,Yanshanian and Himalayan phases of tectonic stress fields,resulting in N-S extensional deformation,N-S and NW collisional compressional deformation,alternating N-S and NW extensional and compressional deformations and N-S compresso-shear,thrusting,strike-slip and gravitational sliding deformation,and finally a great variety of complex tectonic types were formed.