鄂尔多斯盆地西缘沙井子——平凉地区构造样式与形成机制  

Structural Style and Forming Mechanism in Shajingzi-Pingliang District on the Western Margin of Ordos Basin

作　　者：陈永振[1] 

机构地区：[1]西北大学地质学系大陆动力学国家重点实验室,陕西西安710069

出　　处：《地下水》2013年第2期124-127,共4页Ground water

摘　　要：探究鄂尔多斯盆地西缘沙井子-平凉段的构造样式与成因机制。以沙井子-平凉地区及其邻区7条地质剖面的野外观察以及钻井资料作为约束,综合利用重力资料和航磁资料,通过地震剖面解释和构造解析等方法对沙井子地区的构造样式进行研究。区内整体构造呈现出由四条近南北向的大型断层呈叠瓦状西倾东冲的构造格局,自西向东逆冲作用逐渐增强,出露地层变老;新生界和白垩系下覆的蓟县系、寒武系、奥陶系主体呈现出与冲断层相协调的构造形态;区域上白垩系广泛不整合覆盖于下伏不同时代地层之上,白垩系沉积前研究区的蓟县系-奥陶系已经作为一个相对独立的构造带存在。结论:沙井子地区的基本构造样式为西倾单向叠瓦状的冲断层组合形式。燕山期平板结构模式下的基底滑脱型单向冲断构造与喜马拉雅期的右旋剪切走滑构造的复合叠加,是沙井子地区现今构造样式形成的基本模式。To study the structural style and forming mechanism of Shajingzi - Pingliang district on the western margin of Ordos Basin. Using seven sections＇ tectonic characteristics in the area and drilling data as constraint, based on the gravity da- ta, aeromagnetic data, seismic section interpreting and tectonic analysis to do the research. Result： It is shown that the basic tectonic framework is controlled by the four main imbricate west dip thrust faults which are mainly near NS trending. The ob- duction enhanced gradually and outcropping strata become older correspondingly from west to east. Different tectonic zone are divided by imbricate - type thrust faults dip toward west, and in coordinately the Jixian - Ordovician formations deformed with the imbricate - type thrust faults dip toward west under the Cenozoic Erathem and Cretaceous formation. Cretaceous formation unconformably onlaps the different formation inferred that the tectonic pattern of Jixian - Ordovician formations has already been an undependent tectonic zone before the Cretaceous deposition. Conclusion the main pattern of the study area is the intra- basement decollement with imbricate - type thrust faults in the original plate structure model in Yanshan movement superim- posed with dextral shear slip fault during Himalaya movement.

关 键 词：鄂尔多斯西缘 沙井子地区 叠瓦状冲断层 滑脱面 构造样式 

分 类 号：P56[天文地球—构造地质学]