川渝地区构造动力学演化与盆岭-盆山耦合构造分析

Tectonic dynamic evolution and analysis of basin-range coupling and basin-mountain coupling in Sichuan-Chongqing region,China

以构造动力学演化为主线,从拉张与挤压的辩证关系出发,提出了川渝地区构造动力学演化经历了挤压-区域拉张-陆隆伸展-再挤压的构造动力学演化过程;川渝地区在T3-J2期间为盆岭耦合构造格局,在当时山岭与盆地之间过渡的斜坡带前缘(大致相当于理县至都江堰地域),出现印支、燕山期滑覆构造,表现为山岭斜坡前缘逆冲叠瓦状断层与紧闭甚至倒转、平卧褶皱的出现;J3以来,构造动力学背景由伸展转变为挤压,形成基底卷入的厚皮构造,龙门山迅速崛起,四川盆地最终定型,形成现今见到的松潘甘孜高原-龙门山-四川盆地构成的盆山耦合构造格局。

From the dialectical perspective of extension and compression, this paper proposes that the Sichuan-Chongqing region has experienced a geodynamic evolution. The dynamic evolution of the main line began with compression, then regional extension, followed by uplift and stretching of the land, and finally by another stage of compression. The Sichuan-Chongqing region has experienced a geodynamic tectonic background of basin-range coupling between the Late Triassic to Middle Jurassic. During that period, sliding nappes of Indosinian and Yanshanian tectonic plates were found in the foreslope, an area roughly equivalent to the Dujiangyan-Lixian area serving as the transition zone between the range and the basin. The sliding of the Indosinian and Yanshanian results in the formation of imbricate thrusting faults, tight folds, and even the emergence of overturned and recumbent folds. Since the Late Jurassic, the shifting geodynamic tectonic background has resulted in the formation of many of the present day geologic landmarks in the Sichuan- Chongqing region after the Late Jurassic compression events gave way to the formation of the thick-skinned and basement-involved structure. After the basement structure formed after the Late Jurassic, many present day formations such as the Longmen Mountain rapidly rose, the Sichuan basin formed, and the basin-mountain coupling structure pattern consisting of the Songpan-Ganzi plateau- Longmen Mountain-Sichuan basin formed.