银川平原基于地球物理资料三维建模的深部地质构造研究

Research on the deep geological structure in Yinchuan Plain: 3D modeling based on geophysical data

银川平原地质构造为一新生代断陷盆地,隶属于鄂尔多斯西缘裂陷带,被贺兰山隆褶带与陶乐-横山堡冲断带所夹持,同时受到鄂尔多斯地块西缘EW向拉张应力与阿拉善微陆块NE向的挤压应力,造就了该区现今复杂的地质构造特征,并且作为青藏地块、鄂尔多斯地块和阿拉善地块的分界及南北地震带的重要组成部分,银川断陷盆地成为中国大陆内活动性比较强的边界构造之一,历史上曾发生过多次强震。为解释银川断陷盆地深部地质构造,笔者以1∶20万区域重力资料为基础,钻孔、地震剖面、大地电磁测深剖面资料为约束,对银川平原进行2.5D人机交互反演,并以此成果为依据,构建了银川平原深部三维地质构造模型,为区域稳定性评价及地热资源勘探开发奠定坚实的基础。

The geological structure of Yinchuan Plain is a Cenozoic fault basin, which belongs to the western marginal zone of Ordos block, and is sandwiched between the Helanshan uplift belt and the Taole-Hengshanbao thrust belt. It is also subjected to the east-west tensile stress of the Ordos block and the northeastward compression stress of the Alxa micro-continent, which forms complex geological structural features of this area. As an important part of the Tibetan block, the Ordos block and the Alxa block, and the important component of the north-south seismic belt, the Yinchuan fault basin has become one of the more active boundary structures in China’s mainland, and had many strong earthquakes in history. In order to interpret the deep geological structure of the Yinchuan fault basin, the authors employed 1∶200,000 regional gravity data, drilling data, seismic section, and magnetotelluric profile data as constraints to perform 2.5 D human-computer interaction inversion in Yinchuan Plain. Based on this result, a deep 3 D geological model of the Yinchuan Plain was constructed, which laid a solid foundation for regional stability evaluation, exploration and development of geothermal resources.