下扬子区三叠纪古地理演化

Evolution of paleogeography of Triassic of Lower Yangtze area

下扬子区在三叠纪期间接受了早-中三叠世海相碳酸盐沉积、中-晚三叠世海陆交互相和陆相湖沼沉积。沉积相带的空间分布和古地理格局的变迁明显地受到区域构造的控制。区内盆地发育与演化是在华南板块与扬子板块、扬子板块与华北板块相互作用的背景下进行的。早-中三叠世末期的印支运动是下扬子区构造古地理格局改变的决定性因素,使下扬子海盆闭合,沉积类型由海相沉积变为陆相沉积。下扬子区三叠纪古地理的演化特征也为板块碰撞提供了沉积证据。

Marine carbonate, marine-continental interbeded and continental sediments were accumulated in Lower Yangtze area during Triassic. The spatial distribution of sedimentary facies belts and the temporal changes of paleography were controlled by tectonics. Basin development and evolution in this area is related to the interactions of South China plate and Yangtze plate,as well as North China plate and Yangtze plate. Indochina movement occurred at the end of early-middle Triassic is the key control to the changes of tectonic-paleogeography, which led to the change from marine sedimentation to continental sedimentation. The characteristics of Triassic paleogeographic evolution of Lower Yangtze area also provide some sedimentary evidences for collision between Yangtze plate and North China plate.