鄂尔多斯盆地西缘构造特征及其成因机制

Structural characteristics and forming mechanism in the western margin of the Ordos Basin

目的探究鄂尔多斯盆地西缘构造特征与成因机制。方法利用地震剖面解释、构造解析等方法进行研究。结果断裂以走向近南北向逆冲断层为主,其次为正断层与走滑断层,共分为4级。南北构造特征差异明显,北区为冲断体系,在桌子山段发育一系列西倾逆冲断层,铁克苏庙段发育断隆和前缘三角带,陶乐—横山堡段发育叠瓦状东倾逆断层;中区为逆冲推覆体系,在马家滩段发育薄皮构造,惠安堡段发育厚皮构造,甜水堡段发育叠瓦式逆冲推覆;南区为逆冲体系。西缘三叠纪—中侏罗世为陆相残延克拉通内叠合盆地;构造变形主要发生于侏罗纪末期,为陆内前陆盆地发育时期;早白垩世进入挤压期后伸展作用阶段;新生代北区处于伸展背景,而南区处于挤压背景,中区为它们之间的调节带。结论鄂尔多斯盆地西缘具有典型"南北分段"特点,其构造格局主要定型于侏罗纪末期。

Aim To study the tectonic characteristics and forming mechanism of the western margin of the Ordos Basin.Methods Based on the seismic section interpreting and tectonic analysis by this theory.Results It is shown that the fractures are mainly near NS trending thrust faults,followed by normal faults and strike-slip faults,which are divided into four levels.There are significant differences of structural characteristics from North to South,the North area is the thrust system,which are a series of west dipped thrust faults at Zhuozishan Mountain,faulted dome and triangular belt at Tiekesumiao and imbricated east dip reversed fault at Taole-Hengshanbu;the mid-area is the thrust nappe system,which are the thin skinned structure at Majiatan,the thick skinned structure at Huianbu and the imbricated thrust nappe at Tianshuibu;the south area is the thrusting system.It is concluded that the structure distortion mainly formed and it became a foreland basin in the Upper Jurassic.It is in a postcollisional setting in lower Cretaceous;the North area is in a postcollisional setting,but the South area is in a collisional setting,the middle area is the adjust part between the North area and the South area.Conclusion The tectonic characteristics is different from North to South,and the structure framework was mainly formed in the Upper Jurassic.