Lithospheric and asthenospheric properties of the saharan platform inferred from potential field, geoid and heat flow data

Abstract

In this paper, we construct a geophysical-based model of the crust and uppermost mantle to provide an understanding of the architecture of the intricate deep structures, and determine the origin of geothermal reservoirs within the Saharan platform. These structures influence the distribution of the geothermal resources in the eastern Algerian Sahara. This study illustrate the deep structures of the lithosphere and asthenosphere, extending to depths of ∼350 km. Heat flow values were measured from petroleum wells and calculated from the magnetic data. The estimation of lithospheric mantle density was at standard pressure-temperature (P-T) conditions. However, the layer thickness estimate was, based on coupled analysis of elevation-geoid anomaly information. Hence, thermal models were generated with respect to crustal, crystalline basement and lithospheric-asthenospheric boundaries. Analyses of gravity, geoid and topographic dataset, shows that the Moho depth is deeper towards the southeastern limits, and shallower across the M'zab dorsal and the Hassi R'mel basin. The Moho temperature estimates were between 415 and 498 °C, typical of a cold stable cratonic crust. Results of lithospheric thickness were between 177 and 222 km, with maximum depth occurring within the northwestern limits of the Saharan platform. Hence, this paper provides an initial comprehensive geodynamic model, and gives insight to the origin of the geothermal potential of the Eastern Sahara.