Influence of Lateral Channels of the Afar Plume on the Evolution of the Southern and Central Red Sea and the Gulf of Aden: Constraints from Gravity and Shear Wave Velocity Model

Abstract:

The Red Sea and the Gulf of Aden represent mature rift arms of the Afar triple junction, a site of plume-lithosphere interaction. In this study, a detailed analysis of satellite-derived gravity data along with shear wave velocity structure is carried out to interpret in terms of mass anomalies and crustal thickness below the Red Sea and the Gulf of Aden regions. The anomalous signatures in residual gravity anomalies in the southern Red Sea are attributed to the channeled flow of melt from Afar plume. Further, analysis of shear wave velocity at different upper mantle depths reveals prominent anomalies on the Arabian margin of the Red Sea and Gulf of Aden (near Alula Fartak Fracture zone-AFFZ). Both the velocity and gravity anomalies near the southern Red Sea margin are interpreted as zones of melt flow disruption by the continental lithosphere and are the locations of accumulated melt material. This interpretation is consistent with the up warping of the lithosphere-asthenosphere boundary at this location and the asymmetric flank uplift topography of conjugate margins of the southern Red Sea. To the south of this area of anomalous shear wave velocity, seafloor spreading has not initiated along the Red Sea and the rift margins are characterized by symmetric geometry. We interpret this basin geometry and evolution to be related to the lateral flow of melt from Afar plume. North of this area, mantle flow has dissipated and the continental margins are characterized by an i-symmetric geometry influenced by tectonic inheritance of pre-existing shear zones. The low-velocity anomaly near AFFZ of Gulf of Aden is not related to the eastward channel from Afar plume but is more related to the westward migration of Sheba ridge.