Tectonic and sedimentary evolution of the eastern Gulf of Aden continental margins: new structural and stratigraphic data from Somalia and Yemen

Abstract

The purpose of this work is to reconstruct the tectonic and stratigraphic evolution of the eastern sectors of these young margins. New structural and stratigraphic data were collected for the two continental margins facing the Gulf of Aden, in northern Somalia and southern Yemen, by integrating field work, aerial photo analysis and satellite multispectral data processing. A detailed stratigraphic correlation of pre-rift, Mesozoic to Eocene strata was constructed through north-eastern Somalia (Migiurtinia region), and selected sections were correlated between the two sides of the Gulf. The analysis of the deformation of these strata leads to the recognition of west-north-west-east-south-east trending half-graben and tectonic depressions, separated by structural highs interpreted as transfer zones. The transfer zones appear to be located on the landward extension of transform faults in the oceanic setting of the Gulf, and the tectonic depressions are approximately parallel to the oceanic ridge. Oligo-Miocene syn-tectonic basins developed within the depressions, and their patterns reflect their tectonic evolution of the eastern sector of the Gulf of Aden. The age of the deposits sealing the faults cutting Eocene strata confirm a early-middle Oligocene age for the beginning of rifting. The restoration of the pre-drift setting leads to a matching of the continental structures, such as basins and transfer zones, on the two sides of the Gulf. The comparison between the tectonic and stratigraphic features of both continental margins and the oceanic setting of the Gulf of Aden, indicates that a progressive crustal extension brought about the formation of oceanic spreading centres which correspond to the pre-existing syn-rift basins.