The Pelusium Megashear System across Africa and associated lineament swarms

Publisher Website
Google Scholar
Abstract
The Pelusium megashear system (Neev, 1977) extends from the ‘border zone’ of Anatolia, along the eastern Mediterranean and across Africa from the Nile Delta to the delta of the Niger in the Gulf of Guinea. It appears to continue beyond Africa, via the Atlantic equatorial fracture zones, into the Amazon Basin. It has functioned as a system of en echelon left‐lateral megashears since Precambrian times. At least four other geosutures also cross Africa, paralleling the Pelusium system and similarly continuing into the Atlantic as fracture zones. Swarms of lineaments observed in LANDSAT image mosaics of central and northeast Africa are associated with the Pelusium megashear system. They are interpreted to be of tectonic origin. Linear dunes and yardangs oriented parallel to the lineaments appear to have been formed by winds deviated and channeled by the tectonic lineaments. These eolian features should not be considered therefore as reliable indicators for higher‐altitude atmospheric circulation. Whereas the patterns of the swarms are affiliated to that of the Pelusium megashear system, they are not related to most of the other nearby geologic features. Both the Pelusium megashear system and its associated lineament swarms exhibit northeastward convergence patterns, which suggest counterclockwise rotation of the crust. These probably result from left‐lateral shear movements within the asthenosphere which have continued since the Precambrian.