Rift Linkage Modelling in East Africa
The Turkana depression in the Kenya/Ethiopia borderland holds a rich geological history of continental separation. The Turkana region is a low-land located between the East African and Ethiopian domes because its crust and mantle have been stretched in a continent-wide rift event during Cretaceous times about 140-120 million years ago. This thin lithosphere exerted paramount control on the dynamics of East African rifting in this area, which commenced around 15 million years ago and persists until today.
Combining analog "sandbox" experiments with numerical geodynamic modeling we find that inherited rift structures explain the dramatic change in rift style from deep, narrow rift basins north and south of the Turkana area to wide, distributed deformation within the Turkana depression. The failed Cretaceous rift is also responsible for the eastward bend of the Ethiopian rift and the westward bend of the Kenyan rift when entering the Turkana depression, which generated the characteristic hook-shaped form of present-day Lake Turkana.
Brune, S., Corti, G., and Ranalli, G. Controls of inherited lithospheric heterogeneity on rift linkage: Numerical and analogue models of interaction between the Kenyan and Ethiopian rifts across the Turkana depression: Tectonics, p. 2017TC004739, doi: 10.1002/2017TC004739.
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Animation A1 (Reference Model): The animation depicts a numerical model that reproduces the along-axis transition from narrow rifting in Ethiopia and Kenya to a distributed deformation within the Turkana depression. Note the left-bending rift tips (and thus right-stepping rift segments) where the northern and southern rifts interact with the central domain.