豫西三门峡地区温塘断裂第四纪活动性研究

Study on the Quaternary Activity of the Wentang Fault in Sanmenxia Area,Western Henan Province

温塘断裂位于鄂尔多斯块体东南缘,是三门峡盆地的东边界控制断裂,准确厘定其活动性对于理解区域构造演化和判断三门峡地区地震危险性具有重要意义。运用野外地质地貌调查、联合钻孔剖面探测及光释光定年技术,对三门峡地区温塘断裂的活动性进行分析与研究。结果表明,温塘断裂南段出露地表,线性特征明显,断层最新活动时代为晚更新世;温塘断裂中段为第四纪隐伏断裂,断层活动时代为中更新世;温塘断裂北段断层出露,断层活动时代为中更新世。

The Wentang fault is located in the southeast margin of the Ordos block and is the control fault of the eastern boundary of the Sanmenxia Basin.The accurate identification of its activity is of great significance for understanding the regional tectonic evolution and assessing the seismic risk of Sanmenxia area.In this paper,the activity of the Wentang fault in the Sanmenxia area was analyzed and studied by field geological and geomorphological survey,joint borehole section and OSL dating technology.The results show that the southern segment of the Wentang fault is exposed to the surface with obvious linear characteristics,and the latest active age of the fault is late Pleistocene(34.7±2.3 ka).The middle part of the fault is Quaternary buried fault,the fault activity age is middle Pleistocene(137.49±17.0 ka).The fault of the north segment(Mianwa fault)is exposed and its active age is middle Pleistocene.