Mapping Quaternary deposits in the el-Jufr playa (Southeastern Jordan Plateau) using geoelectrical techniques: Implications for geology and hydrogeology

Abstract

Geoelectrical measurements using the vertical electrical sounding method were conducted on the elJufr playa, Southeastern Jordan Plateau. The objectives of the study were (i) to observe, map and describe the range of difference in Quaternary deposits, and (ii) to identify formations that may present fresh aquifer waters, and subsequently to understand the relationship between possible groundwater resources and structural elements. Data collected at 20 locations were interpreted first with curvematching techniques, using theoretically calculated master curves. The initial earth models were double-checked and reinterpreted using a one-dimensional inversion program in order to obtain the final subsurface electrical stratigraphy units, including the water-bearing aquifer. The results of interpretation are used to construct litho-resistivity cross sections across the study area in light of the surface and subsurface geologic information. The inspection of litho-resistivity cross sections reveals the presence of two main alluvial sequences. The upper sequence that attains resistivities ranging from 5 to 120 ohm-m and thickness ranging from 6 to 18 m are a mixture of reworked aeolian and alluvial sediments. The resistivity of this unit generally decreases south- and central-wards, indicating more homogeneous fine silty sand nature of the Pleistocene sediments. The lower stratigraphic sequence is the shallow sand and gravel layer saturated with fresh water. This layer is characterized by its relatively high resistivity (60 to 400 ohm-m) and varying thickness (8 to 23 m) in the northern and eastern sides and by its relatively low resistivity (20 to 90 ohm-m) and varying thickness (10 to 40 m) in the southern side.