Anomalies altimetriques de la zone afro-arabe

The formation of the Afro-Arabian swell, including the Ethiopian and Yemeni plateau may be linked either to the flexural response due to the Red Sea-Gulf of Aden rifting or to the activity of the Afar plume. A Digital Elevation Model (DEM) of the whole region has been used, in an attempt to determine the role of either alternative. Once the boundaries of the blocks have been defined, the treatment applied to this DEM aims to lower the shoulders of the rifts, considering that they are similar to the co-seismic deformations linked to a normal fault system. Calculated altitudes provided by several topographic cross-sections have been taken into account in their computation. After reassembling of the three blocks, one notices the existence of numerous residual reliefs showing an asymmetrical repartition. The highest elevations are not centred on the triple junction zone, but are located on one hand in an ensemble including the Ethiopian and Yemeni plateau, and on the other hand, farther north on the western border of the Arabian block. According to the hypothesis of a mantellic plume linked to a hotspot, it can be assumed that these elevations correspond to the hotspot track. Using pre-existing data, the first hotspot impingement beneath the Arabian platform, would have occurred during the Cretaceous, and would then be responsible for the emplacement of the powerful paleogene volcanic traps covering onto the Ethiopian plateau. It appears that the whole hotspot track corresponds to the remnant relief.