Geophysical contribution to evaluate the subsurface structural setting using magnetic and geothermal data in El-Bahariya Oasis, Western Desert, Egypt

Abstract

The future development of agriculture, industry, and civil activity is planned to be in the Western Desert, Egypt. El-Bahariya Oasis is located in the heart of the Western Desert at a distance of about 370km to the southwest of Cairo. The area under investigation is located between latitudes 28°06′N & 28°16′N and longitudes 28°54′E & 29°04. The Bahariya depression comprises a total area of approximately 2250km2. The main target of the present study is to delineate the shallow and deep subsurface structures of the study area. To achieve this, two geophysical methods (magnetic and geothermal) have been used. A detailed land magnetic survey has been acquired. Fifty three land magnetic stations have been measured in a mesh like area with 500m spacing interval. The necessary corrections concerning daily variation, the regional gradient and time variations have been applied. Then, the total magnetic intensity anomaly map (TMI) has been constructed and reduced to the pole magnetic map (RTP). The Euler deconvolution has been applied to the TMI anomaly data as well as the analytical signal technique. Also, the magnetic interpretation has been carried out using the high-pass filtering technique and spectral frequency analysis. The analysis of the magnetic data shows that the dominant tectonic trends are NW–SE and E–W. The results show that, the average calculated depth ranges between 0.1km and 0.32km, while the depth to the basement intrusion is 0.4km, below the measuring level.The geothermal studies in EL Bahariya-Oasis comprise subsurface temperature contour map which illustrates that the study area has geothermal groundwater reservoirs. The measurements of the geothermal properties for measured rock samples show that the rocks of the study area have moderate values of geothermal properties. This may be due to the seasonal variation in soil temperatures. These soil thermal properties depend on soil porosity and moisture content.