滇西北龙蟠—乔后断裂带桃源段晚第四纪活动特征研究

Late Quaternary activity characteristics of the Taoyuan section of Longpan-Qiaohou fault zone in northwest Yunnan

根据详细的野外调查和剖面测绘成果,结合区域第四系测年结果等资料,对龙蟠—乔后断裂带桃源段新发现的桃源断裂、刀郭断裂、合江村断裂及已知的龙蟠—乔后断裂等4条主要断裂的晚第四纪活动特征进行研究。成果表明,龙蟠—乔后断裂带桃源段在晚第四纪的活动特征明显,活动强度中等,龙蟠—乔后断裂和合江村断裂属全新世活动断裂,桃源断裂和刀郭断裂属晚更新世断裂;晚更新世以来,龙蟠—乔后断裂和刀郭断裂以左旋走滑运动为主,而桃源断裂和合江村断裂则表现为正断走滑为主。这些断裂的活动性都不同程度地影响着研究区及附近区域的地震风险和构造稳定性。新的调查研究成果为深入认识龙蟠—乔后断裂带桃源段的晚第四纪活动性提供了新的资料,并可为深入理解该区的地震地质特征以及工程建设地震安全性评价等提供基础地质资料。

Based on the detailed results of field survey,section mapping,and Quaternary dating data,the Late Quaternary activity characteristics of four major faults,i.e.,the new Taoyuan fault,Daoguo fault,Hejiangcun fault,and the known Longpan-Qiaohou fault in the Taoyuan segment of Longpan-Qiaohou fault zone were studied.The results show that the activity characteristics of the Taoyuan section of Longpan-Qiaohou fault zone in Late Quaternary are obvious and the activity intensity is medium.The Longpan-Qiaohou fault and Hejiangcun fault are Holocene active faults,while the Taoyuan fault and Daoguo fault are Late Pleistocene faults.Since the Late Pleistocene,the Longpan-Qiaohou fault and Daoguo fault are dominated by left-lateral strike-slip,while the Taoyuan fault and Hejiangcun fault are dominated by normal strike-slip.The activity of these faults affects the seismic risk and tectonic stability of the study area and its vicinity to varying degrees.The research results in this paper provide the new data for further understanding the Late Quaternary activity of the Taoyuan segment of Longpan-Qiaohou fault zone,and can also provide basic geological data for further understanding the seismic geological characteristics and seismic safety evaluation of engineering construction in the study area.