Crustal structure of the Khartoum Basin, Sudan

The crustal structure of the northern part of the Khartoum Basin has been investigated using data from 3 permanent seismic stations within 40. km of Khartoum and two modeling methods, H-k stacking of receiver functions and a joint inversion of receiver functions and Rayleigh wave group velocities. The Khartoum Basin is one of several Mesozoic rift basins in Sudan associated with the Central African Rift System. Results from the H-k-stacking indicate that crustal thickness beneath the Khartoum Basin ranges between 33 and 37. km, with an average of 35. km, and that the crustal Vp/Vs ratio ranges from 1.74 to 1.81, with an average of 1.78. From the joint inversion of receiver functions and Rayleigh wave group velocities, we obtained similar results for Moho depth, as well as an average shear wave velocity of 3.7. km/s for the crust. These results provide the first seismic estimates of Moho depth for a basin in Sudan. When compared to average crustal thickness for unrifted Proterozoic crust in eastern Africa, our results indicate that at most only a few km of crustal thinning may have occurred beneath the Khartoum Basin. This finding is consistent with estimates of effective elastic plate thickness, which indicate little modification of the Proterozoic lithosphere beneath the basin, and suggests that there may be insufficient topography on the lithosphere-asthenosphere boundary beneath the Sudanese basins to channel plume material westward from Ethiopia.