Structural development and crustal stretching in the Muglad Basin, southern Sudan

Abstract

A simplified model cross-section has been established from integrated well data, reflection seismic and gravity data along a northeast-southwest profile in the Unity-Kaikang area in the Muglad Basin, southern Sudan. A multi-layer crustal model has been created to produce a better estimate of the crustal extension involved and assess some of the key factors in the basin's formation by comparison to a theoretical model. Within the sedimentary section, three reflection seismic horizons were picked and their depths were calculated: Top Bentiu (Cenomanian), Top Abu Gabra (Aptian-Albian) and Top Basement (Late Jurassic-Early Cretaceous). The integrated well and seismic data indicate a sedimentary section up to 11 km thick along the cross-section. Different densities were assigned to the three sedimentary layers according to well data, and upper and lower crustal layers were incorporated in the model. Isostatic compensation of the sedimentary fill and the resultant crustal thinning was estimated by gravity modelling. The stretching of the lithosphere is estimated at ≈56 km (≈61%), corresponding to a β factor of 1.61. The form of the basin agrees with the model of a rift basin developed over an extended period of time.