干旱区生态环境知识资源中心

The distribution, structural relations and ages of ophiolites and ophiolitic melanges in the Eastern Deserts of Egypt and north-east Sudan, and their relation to arc and post-arc magmatism, are used to infer the probable positions of sutures and the directions of obduction and subduction. The ages of the successive tectonic stages in the terranes decrease northwards, by about 100 Ma in the region discussed. Obduction was north-westwards. The obducted sheets of ophiolite and ophiolitic melange, extending about 500 km north from the Onib-Sol Hamed suture, may all represent a single back-arc basin. The direction of subduction is still not clearly proved: more geochemical evidence of arc-magmatic polarity is needed. The late tectonic north-westward thrusting, the NW - SE stretching lineation, the transpressional north - south Hamisama Shear Zone and the NW - SE sinistral Najd faults are all attributed to north-westward movement (present coordinates) of terranes towards the older craton west of the Nile. The Najd faults are interpreted as intracontinental transform faults.