四川盆地熊坡背斜构造特征及其成因机制

基于地震剖面解释、数字高程模型、历史地震、测年数据及钻孔等资料，分析了四川盆地熊坡背斜的构造特征、运动学特征及其成因机制。结果显示：(1)熊坡背斜与蒲江-新津断裂空间展布上具有较强的一致性，表现出断层传播褶皱模型，变形显著，缩短量为7.2 km，缩短率约为30％；(2)熊坡背斜隆起于(1.0±0.2) MaB.P.之后，且中更新世早期及晚更新世曾发生过强烈活动，使背斜两侧第四系厚度产生明显差异；(3)蒲江-新津断裂现今地震活动明显且小震频繁，曾有Ms=5.0～5.9的地震历史记录；(4)来自龙门山与扬子克拉通的挤压应力以及断层-滑脱作用是形成熊坡背斜的主要应力机制。熊坡背斜并非均匀应力下连续变形的产物，而是由于断裂活动时发生快速抬升而形成的。

Structural Features and Genetic Mechanism of Xiongpo Anticline in Sichuan Basin

Based on seismic section, DEM, historical earthquakes, dating and drilling data, this study analyzed the structural features, kinematics characteristics and genetic mechanism of Xiongpo anticline in Sichuan basin. The results can be drawn as the following aspects: (1) the space distribution of Xiongpo anticline is same with that of Pujiang-Xinjin fault zone, presenting a model of fault propagation fold and its shorten is 7.2 km with shorten rate about 30%; (2) Xiongpo anticline uplifted after (1.0±0.2) MaB.P. and it was very active in Early Pleistocene and Late Pleistocene, causing Quaternary-thickness difference between two sides of Xiongpo anticline; (3) earthquakes especially small earthquakes happening in Pujiang Xinjin fault zone occurred frequently and there has earthquakes history of Ms ranging from 50 to 5.9; (4) the faulting-slipping and the crushing stress from Longmenshan to Yangtze craton are the main stress mechanism of Xiongpo anticline. It can be concluded that Xiongpo anticline formation is resulted from quickly uplifting when the fault is active rather than the product of uniform stress.