色尔腾山山前断裂东段与西段转折处构造演化特征

色尔腾山山前断裂位于鄂尔多斯块体西北角,控制着临河凹陷（河套盆地西部）的持续沉降。对色尔腾山山前断裂东段与西段转折处构造演化模式的研究,有助于提高对正断层演化规律和区域地震风险的认识。本文在研究区大比例尺活动断裂填图的基础上,通过对重点区域进行无人机微地貌的测量、探槽开挖、钻孔资料与第四纪测年等方法获取数据,并运用构造地质学、地貌学和沉积地层学等理论,综合探讨断层转折处的构造演化模式及地震危险性。通过研究认为,近东西走向的色尔腾山山前断裂西段与北西走向的东段间以三角状的转换斜坡相连。现今的转折点为应力的积累区,具有较高的地震风险。水平拉伸力的持续作用使断层不断向盆地一侧迁移,同时使断裂转折部位更加平滑。

Tectonic Evolution of the Turning Point of the Eastern and Western Section of the Seertengshan Piedmont Fault

The Seertengshan Piedmont Fault (SPF) is located in the northwest corner of Ordos block, which controls the continuous settlement of the Linhe sag (western Hetao basin). The study of the tectonic evolution of the turning point between eastern and western segment of the SPF will help to improve our understanding of the normal fault evolution law and regional seismic risk. Based on the large-scale active fault mapping in the study area, we conduct the field survey of UAV micro-geomorphology in key areas, and combine trench excavation and Quaternary dating methods to explore the tectonic evolution patterns and earthquake hazard at fault turning point comprehensively. Through this study, we find that the EW-trending western segment of SPF and NW-trending eastern segment of SPF are connected by a triangular relay ramp. The turning point is the accumulation area of stress and has a high earthquake risk at present. With the continuous action of the horizontal tensile force, the normal faults migrate to the basin, and "cutting and straightening" makes the geometry of turning part smooth.