Structural Modelling in the East African Rift

Alastair Beach
Exploration Outcomes, Glasgow, United Kingdom

The East African rift system shows a complex structural development through successive phases of rifting from Cretaceous until Recent. A lot of sub-surface data were collected during exploration in the 1980’s, and subsequently published, for example by Morley et al (AAPG). These data have been used to determine more precisely and systematically the structural history of the region. Various seismic lines have then be modelled using forward modelling to show the structural and tectonic development of successive rift phases superimposed on each other. Topographic expression of footwall uplift is normally one obvious consequence of Late Neogene rift development, and is preserved in the present day. Topography related to older rift phases has often been largely degraded and destroyed. Structural models for the Lake Albert, Turkana and Rukwu rifts are examined and discussed.
One way of evaluating basins without seismic data comes from modelling the development of topography related to the basin. The Lake Albert Basin is characterised by the development of strong footwall uplift topography along its western margin, whereas topography related to the Turkana rifts is more subdued, and may be the result of older Cretaceous to Paleogene rifting in this area, as seen in the development of for example the Muglad Basin and the Anza Rift. Such modelling can be used to inform the general exploration concepts of what sequences and petroleum systems might be present, to assist with the interpretation of any new seismic data, and to help understand the upfront geological model risks of unexplored basins.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery