A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - Interpretation of satellite photographs of the Red Sea and Gulf of Aden

Abstract

Geological structures observed in Gemini and Apollo colour photographs suggest that large-scale translational movements could have taken place in the Red Sea and Gulf of Aden. In the northern Red Sea the apparent displacement of two pairs of shear zones and three pairs of serpentinite belts is consistent with a movement of Arabia towards the NNE of some 150 km. In the southern part of the Red Sea evidence of displacement is derived from correlation of Precambrian trend-lines, particularly at points where there is an abrupt change in the regional grain; at Ras Kasr-Al Lith (latitudes 18° N and 20° N) the total movement could be 225 km. Across the Gulf of Aden observations are in general agreement with the pre-Miocene fit proposed by Laughton (1965). Study of satellite photographs provide the following additional evidence: (1) The continuity of the Hadramawt folds (southern Arabia) in the Somali Plateau; the southern Hadramawt arch appears to be extended in the northern Somali arch. (2) Pre-drift correlation of several fault zones of WNW-ESE trend across the Gulf. The NE-SW faults, on the other hand, show poor correlation across the Gulf and appear to be related to fault lineaments within the Gulf of Aden. Across the Strait of Bab El Mandeb geological and morphological similarities in the distribution of Quaternary sediments, volcanic fields, intervening alluvial deposits, fault and drainage lineaments suggest a left-lateral displacement of Arabia some 40 km to the NNE since the Plio-Pleistocene. Such a movement could have resulted in the final opening of the Bab El Mandeb Strait.