Geothermal exploration using airborne gravity and magnetic data at Siwa Oasis, Western Desert, Egypt

Abstract

Siwa Oasis is a part of the greatest northern depression in the Egyptian Western Desert, located just 50km east of the Libyan border. It represents one of the most interesting potential candidates for the development of the Northern Western Desert of Egypt. Temperature data from deep wells in the Western Desert of Egypt indicate low geothermal resources. Here, we present the contribution of airborne gravity and magnetic geophysical data for the preliminary exploration of geothermal potential in Siwa Oasis. To achieve this objective, a 3D inversion of aerogravity data was used to delineate the depths to basement rocks, while spectral analysis of the aeromagnetic data was used to estimate the Curie Point Depth (CPD) and provide geothermal gradient and heat flow maps for the Siwa Oasis. The depth to the Precambrian basement rock is commonly greater than 2km, ranging from 2km to 5km, whereas the CPDs range from 21km to 28km. Our results imply an inverse relationship between these two depths, in which the deeper basement regions are associated with shallow Curie depths. The derived geothermal gradients range from 21 to 27°C/km and the heat-flow values range from 49 to 64mW/m2 for the study area.