瞬变电磁法在巨厚覆盖层地区勘查地下水源的应用

Application of Transient Electromagnetic Method in Groundwater Exploration in Areas under Thick Layer of Overburden

河南新郑市区东部覆盖层厚度达400m左右,其电阻率很低,对直流电法及瞬变电磁法勘探起着屏蔽作用,根据该区的地质条件在水源地勘察中,使用瞬变电磁法绘制TEM多测道剖面图,ρτ延时拟断面图,利用该区已知钻孔,求取得深度校正系数为1.8,得到深度拟断面成果图,最终查清巨厚覆盖层下的断层位置,圈定含水岩溶带,确定井位。

The overburden thickness can be up to about 400 meters in eastern part of Xinzheng City, Henan Province. Since the low resistivity, it has shielding effect on direct current and transient electromagnetic methods. According to the concrete geological condition in the area, during the water source exploration, we use transient electromagnetic method to plot TEM multichannel sections and ρ τ time-lapse pseudosection maps. By the use of drilling data in the area, evaluated 1.8 as the depth coefficient of correction, then acquired depth pseudosection maps. Finally ascertained fault location under the thick layer of overburden, blocked out water containing karst zone and located the well site.