Reappraisal of the crustal configuration of three African hotspots from global gravity models constrained by seismic studies

Abstract

The Moho roviciÊ discontinuity (orMoho) is the boundary between the Earth’ scrust and mantle.The Moho dep this primarily detected from seismic data. Unfortunately, seismic data coverage in large parts of Africa islow.Gravity data isused to determine the Moho depth where seismic surveys are insufficient.The progressing gravity data acquisition from multiple sources(terrestrial,air borne,ship borne and satellite) in compiling new promising generation of global gravitational model as EIGEN≠6C4 and XGM2016 gravity data have been used in this work.In this regard,we compile a new Moho model of the Atlas Mountains,Cameroon Volcanic line and Tanzanian Craton,base done gravimetric inversionc on strained on seismic data respectively. The Bouguer gravity anomalies used for a gravimetric Moho recovery are obtained from the free-air gravity anomalies after subtracting the gravitationalc ontributions of topography,bathymetry and sediments.The regional gravimetric Moho inversion constrained on seismic data have been carried out by applying a regularized inversion technique based on Gauss-Newton’s formulation of improved Bott’smethod,while adopting aspherical approximation for the Earth.Along the Atlas mountains, our findings indicate a limited tectonic shortening of the High Atlas with the crustal thickness mostly within 36 ≠ 42 km.The Topographic discrepancies between the Rif Cordillera and the Atlas Mountains suggest that the hypothesis of isostaticcompen- sation can not be fully established.In Cameroon we found that theYaoundé domain likely represents the crustal manifestation of the suture zone between the Adamawa- Yadé domain,acting as a micro-continent and th eCongo Craton.Finally along the EARS, our result deciphersathick lower crustben eath theRwenzoriBelt which seems to be associated with a crustal modification occurring during rifting episodes that in duced the delamination of the lithospheric mantle and consequently resulted in crustal up lift.These findings supportanon-collisional origin of the central Rwenzori Mountains.