上扬子北部褶皱带的构造应力场演化规律

Tectonic stress field evolution in fold belts in the northern Upper Yangtze region

在对大量逆冲与平移断层运动学详细分析与观测的基础上,本文利用实测断层擦痕矢量数据组进行了区域应力场反演,根据对断层叠加关系的分析及叠加褶皱的验证,划分出上扬子北部经历过3期挤压构造应力场演化,从早到晚分别为:第1期北西—南东向挤压应力场,第2期近东西向挤压应力场和第3期北东—南西向挤压应力场。结合相关的地质现象,认为在这3期挤压应力场作用下分别形成了晚侏罗世末—早白垩世初的湘鄂西隔槽式褶皱带、早白垩世末—晚白垩世初的川东隔档式褶皱带和南大巴山弧形褶皱带。由此表明,上扬子北部褶皱带的形成顺序为湘鄂西隔槽式褶皱带→川东隔档式褶皱带→南大巴山弧形褶皱带。

Based on kinematic analysis and measurements of reverse and wrench faults,stress field analysis is undertaken by using fault-slip datas from the northern Upper Yangtze region. The fault overprinting and superposed folds demonstrate that three phases of stress fields from the NW-SE compression,nearly EW compression to NE-SW compression occurred in the region. Analyses of geological phenomena suggest that the first phase of compression is responsible for the western Hubei and Hunan chevron syncline-box anticline belt of latest Late Jurassic to earliest Early Cretaceous,the second one is responsible for the eastern Sichuan chevron anticline-box syncline belt of latest Early Cretaceous,and the third one is responsible for the southern Daba arcuate fold belt of latest Early Cretaceous to earliest Late Cretaceous. All of these indicate that the fold belts in the northern Upper Yangtze region experienced the evolution from the western Hubei and Hunan fold belt,the eastern Sichuan fold belt to the southern Daba arcuate fold belt. Southern Daba arcuate fold belt,Eastern Sichuan chevron anticline-box syncline