Regional architecture of the
Nogal rift basin, Somalia
Summary
The Nogal basin study consisted of
two phases. Phase 1 used high resolution (3" x 3") topographic data and a
knowledge of the surface geology to determine: 1) The degree of
lithospheric extension responsible for the formation of the Nogal basin, 2)
The regional geometry of the Nogal basin, and 3) the spatial and temporal
variability of the basal heat flow engendered by the extension process. We
addressed these objectives by modeling the development of the Nogal
basin using a simple kinematic and isostatic model for the three-
dimensional thermal and mechanical response of the lithosphere to
extension. This approach uses the flanking topography of a rift basin to
estimate the regional geometry of the basin, the cumulative fault heave
responsible for the formation of the basin, and the thermal history of the
basin. Following the completion of Phase 1, Phase II of the Nogal study
examined the tectonic and stratigraphic evolution of the basin by using a
sequence stratigraphic approach to interpret the late Tertiary section.
Application of this approach has allowed us to address the following
questions: 1) Is the Nogal basin a pull-apart or a wrench basin? 2) Did
inversion of structures take place and if so, what was the magnitude of the
inversion? 3) Can the timing of late Tertiary structural development be
associated with opening of the Gulf of Aden or some other tectonic event.
And 4) compare and contrast the results of Phase II with the predictions
determined from the three-dimensional kinematic and isostatic modeling
of the region.
