高密度电阻率法在西藏日喀则地区隐伏断裂探测中的应用

Application of high density resistivity method to exploring buried faults in Xigazê region of Xizang

以跨谢通门—青都断裂的两条高密度电阻率法探测资料为基础,对高密度电阻率法在青藏高原日喀则地区隐伏断裂探测中的首次应用进行了详细介绍.所获取的高密度电法剖面显示,该断层的电阻率异常特征清晰,其上断点埋深可达20—30m,较浅层人工地震探测所揭示的断层上断点埋深(50m)更浅,结合地层年代资料推测该断裂的最新活动时期为早—中更新世.探测结果表明:高密度电法剖面清晰地显示了断层在浅部松散层的延伸,适用于日喀则地区的隐伏断层探测;相较于浅层人工地震探测,该方法对浅部松散层的探测具有明显优势,一定条件下能够更好地揭示断层上断点埋深,可与浅层人工地震探测形成互补.需要指出的是,在应用中需重视测区水文地质及地层发育情况对探测的影响.

This paper introduces the application of high density resistivity method in detail to the exploration of buried faults in Xigazêregion of Xizang for the first time.The resistivity imaging from the survey lines across the XietongmenQingdu fault show that the resistivity anomalies of the faults are clear and the fault up-breakpoint may reach 20--30 meters which is more shallow than the result that the up-break point reaches 50 meters from seismic reflection survey.Combined with the strata age data,the latest active time of the faults is deduced to be Early-Middle Pleistocene.In addition,the extension of the fault in shallow loose bed is displayed clearly in resistivity imaging,and thus the high density resistivity method is suitable for detecting of buried faults in Xigazêregion.Comparing with shallow seismic exploration,the high density resistivity method has an advantage in exploration of shallow loose deposits and displays more effectively fault up-breakpoint on some conditions.However,it is necessary to fully aware of influence of hydrogeololgy and stratigraphic development on exploration in surveyed area.