巴楚隆起亚松迪断裂带构造特征及几何学模型

Structural characteristics and geometric models of the Yasongdi Fault Belt,the Bachu Uplift

基于地震剖面的精细地质解释,识别出塔里木盆地巴楚隆起亚松迪断裂带及邻区三期冲断-褶皱构造,并建立了其几何学模型。第一期活动的为沿中寒武统膏盐层滑脱的巴什托断裂,该断裂走向为NWW,形成于二叠纪之后、古近纪之前;第二期为基底卷入型的色力布亚断裂,该断裂走向为NNW,形成于晚中新世;第三期为分别沿中寒武统和古近系膏盐层滑脱的亚松迪深、浅层断裂,这两条断裂走向均为NW,形成于更新世—全新世。平面上,亚松迪断裂的发育位置受控于古近系膏盐层的分布范围。剖面上,与先存的巴什托断裂和色力布亚断裂的复合发育造成了亚松迪断裂带东、中、西三段不同的构造样式:东段发育断层传播褶皱(上)与突破型滑脱褶皱(下);中段发育断层传播褶皱(上)、突破型滑脱褶皱(中)和基底卷入构造(下);西段则发育滑脱褶皱(上)与断层转折褶皱(下),该段滑脱褶皱为亚松迪浅层断裂的西端点。最后,我们利用计算机数值模拟的方法对这三种冲断-褶皱模型进行了验证。

In this study,based on the analysis of seismic sections we identified three-stage development of thrust and fold structures and built up the geometric models of the Yasongdi and adjacent belts in the Bachu Uplift,Tarim Basin.Firstly,the NWW-trending Bashituo Fault was formed after the Permian but prior to the Paleogene,which slipped along the Middle Cambrian gypsum-salt layer.Then,the Selibuya Fault with a NNW strike characterized by basement-involved structures was formed in the Late Miocene.Finally,the Yasongdi Faults in the shallow and deep domains were developed during the Pleistocene to Holocene with the same NW trends,however,slipped along the Paleogene and Middle Cambrian gypsum-salt layers,respectively.In map view,the development of the Yasongdi faults is restricted by the extent of the Paleogene salt.Influenced by the rejuvenated Bashituo and Selibuya faults,the Yasongdi fault belt can be divided into three segments：the eastern segment is featured by the upper fault propagation fold and lower detachment fold;the central segment is mainly composed of the upper fault propagation fold,middle detachment fold,and lower basement involved structure;and the western segment consists of the upper detachment fold and lower fault bend fold.All the geometries of superposed folds described above have been reproduced by our numerical analog modeling.