NEW DEVELOPMENTS IN THE PRE-RIFT PROSPECTIVITY OF THE ERITREAN RED-SEA

Northern, central and southern Africa is covered by great thicknesses of Upper Palaeozoic and Mesozoic fluvio-deltaic and marine siliciclast ics, which include important source rocks, reservoirs and seals. In th e Eritrean Red Sea, the importance of these rocks has not yet been pro perly recognised. The Red Sea initially formed by rifting of the Afro- Arabian continent in Oligo-Miocene times. Palaeozoic and Mesozoic rock s were downthrown into the resultant Gulf of Suez/ Red Sea Graben and were rapidly buried by syn- and post-rift sediments. In the Eritrean R ed Sea area, pre-rift rocks are now only exposed in the Danakil Alps a t the Straits of Bab el Mandab, on the Eritrean Plateau, in the coasta l lowlands north of Massawa, and in isolated outcrops in Ethiopia.The authors believe that an as-yet untested pre-rift ''play'' is to be fou nd in the Eritrean Red Sea contiguous with the Danakil Alps. In additi on, syn- and post-rift ''plays'' cannot be ruled out in this area. The combination of newly-mapped pre-salt structures, containing Jurassic source rocks and Jurassic and Cretaceous reservoir sandstones and carb onates overlain by Tertiary clastics and/or salt, embodies the primary hydrocarbon entrapment model in the area. Secondary hydrocarbon ''pla ys'' centre on deformed Miocene siliciclastic sequences in proximity t o salt diapirs.