内蒙古狼山山前断裂中段大地电磁探测研究

Study on Magnetotelluric Detection of the Middle Section of Langshan Piedmont Fault in Inner Mongolia

对一条穿过狼山山前断裂中段的宽频带大地电磁剖面进行精细化处理和二维反演,获得该断裂中段及其两侧地块的深部电性结构特征。结果表明,狼山山前断裂表现出明显的高低阻电性边界带,断裂西侧的狼山隆起上地壳表现出较为完整的高阻特征,中下地壳以低阻体为主;狼山山前断裂东侧的临河盆地浅部存在5 km厚的低阻沉积层,沉积层下方可能存在高阻基底。该分布特征表明狼山山前断裂是一条切割地壳尺度的深大断裂,同时具有孕育强震的风险。

In this paper,we finely process a broadband magnetotelluric profile passing through the middle section of Langshan piedmont fault and carry out two-dimensional inversion.We obtain the deep electrical structural characteristics of the middle section of the fault and the blocks on both sides.The results show that the Langshan piedmont fault presents an obvious high and low electrical resistance boundary zone.The upper crust of Langshan uplift on the west side of the fault shows relatively complete high electrical resistance characteristics.The middle and lower crust is dominated by low resistivity bodies.There is a 5 km thick low resistivity sedimentary layer in the shallow part of Linhe basin on the east side of Langshan piedmont fault,and there may be a high resistivity basement below the sedimentary layer.These distribution characteristics indicate that Langshan piedmont fault may be a deep and large fault cutting the lithosphere scale,and it has a risk of developing strong earthquakes.