Events & Courses

Time and location

18:55 hrs for 19:00 hrs start. This event will be held online via Zoom

Event details

We are compiling an online atlas showing the development of the African plate and its conjugate margins through time. At this stage, 19 maps have been compiled for key periods of geological history from Permian to Recent, which are still being actively amended with new data and interpretations. The current maps can be viewed on www.macgeology.co.uk, a selection of which will be illustrated in this talk. The plate reconstructions on which the maps are based are available at www.reeves.nl.

Africa has a wide variety of continental margins ranging in age from Triassic (at least part of Eastern Mediterranean) to Pliocene in their initiation. A large number of these margins are volcanic, i.e. characterised by seaward dipping reflectors (e.g. Mozambique, Namibia, northern Gabon, at least parts of the NW African margin). Significant proportions of the margins are bounded by major transform faults (Tanzania, South African part of Indian Ocean, parts of Gulf of Guinea, much of Equatorial margin, most of north African margin) . Only a minority of African plate margins therefore tie to the classic hyperextended margin model for continental splitting (Levantine Basin, small part of Ghana, Angola/southern Gabon and Somalia). Also included in that category is the new margin now being formed in the Red Sea, which forms an important analogue for the past history of many aspects of extinct hyperextended margins , e.g. thermal history.

A large number of African margins seem to be initiated during the early Jurassic (Eastern Mediterranean, NW Africa, East Africa). Thereafter, the remaining margins from Mozambique round to Guinea seem to ‘unzip’ in a steady fashion from the Kimmeridgian in southern Africa through to the final last contact between Africa and South America in the latest Albian on the Equatorial Margin, thereby connecting the various segments of the Atlantic ocean. Many aspects of the geology, particularly the influx of marine waters, follow this clockwise unzipping. There are numerous phases of rifting within the continent, with peaks of rifting within the middle Permian, early Cretaceous and Plio-Pleistocene.

A further aspect of these maps is the interpretation of paleo-rivers, particularly those delivering the Cretaceous turbidites that are the main frontier play across most African deepwater basins. These are interpreted from a combination of different lines of evidence such as paleotopography based on AFTA derived cooling profiles and variations in sedimentation rates around the margins.

Speakers

Duncan Macgregor (MacGeology Ltd) 

Duncan Macgregor is a geologist specializing in regional African research, publishing, oil and gas exploration and training. He was employed by BP for over 20 years, working largely in the Far East and thereafter worked and consulted for a number of independent companies and consultancies, mainly on new ventures and play fairway scale studies in Africa. He has extensive research interests on the evolution and petroleum systems of the African continent, and has written over 20 papers on African and SE Asian petroleum systems. Duncan has also edited three books on African petroleum geology.

Registration

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