Delineation of sinkhole in evaporite deposits using electrical resistivity survey: a case study of southern Kohat Plateau, Pakistan

Abstract

Vertical electrical sounding (VES) is a non-destructive geophysical technique which provides fast subsurface lithological investigations and it is widely used in exploration of water, mineral resources, and its characterization. The present study work has been focused on subsurface imaging over evaporite deposits in Bahadarkhel area, Karak, Pakistan where multiple VES points along three profile lines have been acquired using Schlumberger electrode configuration to delineate subsurface lithology and structure of the area. The VES curves have been modeled and interpreted which resulted in true resistivities, depths, and thicknesses of layers. These VES points have been stacked along their respective profile lines for pseudosections and resistivity cross section preparation. Five distinct geoelectrical units have been identified depending upon their true resistivity values. Iso-resistivity 3D surfaces at 30 m and 60 m depths have been generated using the interpreted data which exhibits salt diapiric structure and dissolution of salt at depth by the action of infiltrating water from nearby ephemeral stream. Dar-zarrouk parameter calculations yield transverse resistance, longitudinal conductance, and anisotropy maps which infer that the area is mostly covered with rock salt and the presence of clay beds and calcareous sediments increases the resistivity values.