南阳盆地朱阳关-夏馆断裂的浅部特征及活动性

SHALLOW STRUCTURE AND ACTIVITY CHARACTERISTICS OF THE ZHUYANGGUAN-XIAGUAN FAULT IN THE NANYANG BASIN

朱阳关-夏馆断裂是南阳盆地内1条重要的隐伏活动断裂,构造地貌显示清楚,与商县-丹凤断裂、铁炉子断裂共同构成东秦岭北部重要的北部边界,也是华北与华南地块的重要分界断裂。为了研究朱阳关-夏馆断裂的空间展布、断裂活动性以及浅部构造结构,针对该断裂采用了浅层地震勘探和钻孔联合剖面相结合的探测方法,跨断裂布设了3条浅层地震勘探测线和1条钻孔联合地质剖面。综合分析表明,朱阳关-夏馆断裂为1条走向NWW的正断层,钻孔联合地质剖面揭示的断裂上断点埋深为17.6~20.5m,最新活动时代为中更新世晚期。研究结果可为南阳市地震危险性评价以及该区的重大生命线工程选址提供地质和地球物理证据。

The Zhuyangguan-Xiaguan fault is a major fault in the Nanyang Basin.Together with the the Shangxian-Danfeng fault in the south and the Tieluzi fault in the north,it serves as the north boundary of the East Qingling Mountains,as well as the dividing line between North China and South China blocks.This work studied the spatial extension,activity and shallow structure of Zhuyangguan-Xiaguan Fault by combination of shallow seismic exploration of three profiles across the fault and a composite drilling cross-section data.The anti-interference and high resolution shallow seismic reflection exploration method based on Vibseis techniques was used in the seismic survey.The results show the existence of the main fault and its southern branch.It can be determined that the the Zhuyangguan-Xiaguan fault is a NWW-trending normal fracture.The composite drilling cross-section reveals that the buried depth of the fault s up-breakpoint is about 17.6 to 20.5 meters and the latest active time is the late Middle Pleistocene.As one of the major buried faults in the Nanyang Basin,the Zhuyangguan-Xiaguan fault has restricted the development of Nanyang City for a long time due to its unclear location and activity characteristics.The results of this study can provide geological and geophysical evidence for seismic risk assessment and site selection for the major lifeline projects in Nanyang City.