桂中坳陷改造期构造样式及其成因

桂中坳陷的构造演化一般划分为原型期和改造期两大阶段。改造期主要属于挤压构造样式,目前的研究还相对比较薄弱。从大地构造动力学背景入手,结合区域地质事件,按照盆地发育世代与造山带演化阶段,综合近期野外地质调查与深层地球物理勘探成果等,分析了改造期挤压构造样式。主要有三大区域性冲褶变形构造系,包括大瑶山逆冲推覆构造系,右江逆冲推覆构造系以及雪峰山隆起南缘重力滑覆构造系。总体上,负向地形多褶皱紧闭,正向地形形成相对宽缓的箱状复式背斜褶皱;深层主要发育有基底断裂卷入引发的冲起构造以及与断层相关的断弯、断展、滑动等褶皱样式,浅层有逆冲推覆、纵弯、叠加等褶皱样式。目前桂中坳陷受到东西两侧剪切、向南拉张的应力作用。

Structural Patterns and Origin Of Tectonic Reformation in Guizhong Depression

The tectonic evolution process in Guizhong depression is divided into two stages, the primary and the late reformed ones. According to basin generation and orogenic stages, structural patterns of compression during reformation are analyzed by tectonic dynamics along with field survey,deep geophysics and tectonic events. Three faulted-folded deformation systems are suggested, including the Dayaoshan and the Youjiang napping systems, and the southern Xuefengshan Uplift gravity gliding system. In general, the negative landform usually shows tight folds and the positive landform usually shows box folds. The east-westward shear stress and southward tensional stress are present in Guizhong depression.