Subsidence History and Crustal Structure of the Somaliland-Yemen Conjugate Margin

In order to quantify the tectonic evolution of the Gulf of Aden region, we have carried out a backstripping study of bio-stratigraphic data from deep exploration wells in the Somaliland-Yemen conjugate margin. By backstripping the data, we have determined the tectonic subsidence history and used it to constrain the rifting history of the margin. The total tectonic subsidence has been used together with isostatic considerations to constrain the crustal thickness and, hence, the gravity anomaly associated with rifting and sedimentation at the margin. We focus here on the central segment of the margin where there have been no previous crustal studies. We show that the central segment of the Gulf of Aden has been subject to at least two, possibly three, rifting events and that the margin has a high degree of asymmetry with a steeper Moho beneath Somaliland than beneath Yemen. All three rifting episodes must be considered when assessing the thermal and maturation history of the margin.