The Mesozoic succession of Dire Dawa, Harar Province, Ethiopia

Author : A. Bosellini, a, , A. Russob and G. Assefac

Year : 2001

The Mesozoic succession of Dire Dawa, Harar Province, Ethiopia, consists of a lower fluviatile sandstone (Adigrat Sandstone); an intermediate carbonate-marly unit, formerly called Antalo Limestone; and an upper fluviatile sandstone (Amba Aradam Formation). This study has shown that the intermediate unit consists of four different formations grouped into two depositional sequences. These sequences and their boundaries, Middle-Late Jurassic in age, are well correlated with sequences recognised throughout East Africa and a large part of Yemen. The base of the lower sequence (Antalo Supersequence) is time-transgressive (Pliensbachian to Oxfordian) and is the result of the first flooding of this sector of the Gondwana continent during the Mesozoic. The second major sequence boundary is also time-transgressive and corresponds to an abrupt deepening of East Africa and southern Arabia shallow water ramps and carbonate platforms, a collapse most probably related to the separation of Madagascar from Africa. A major tectonic event occurred in Early Cretaceous from northern Ethiopia to Yemen, and southern Ethiopia and Somalia. This vast uplift, testified by faults and angular uncomformities, was followed by deposition of fluviatile sediments over the entire region.