Depositional models in Cretaceous rift stage of Fula sag, Muglad Basin, Sudan

Abstract

Abstract According to the study of petrology, log-phase, seismic facies, and sandstone distribution, the distribution of the Cretaceous rift sedimentary system in Fula sag of the Muglad Basin have been predicted, and the sedimentary models in two rift periods have been established. There developed eight 3 rd -order sequences in the two rift periods in the Cretaceous of Fula sag, which have 5 types of sedimentary facies, namely, braided river delta, meandering river delta, fan delta, lacustrine, and turbidite fan. There mainly developed fan delta-meandering river delta facies in the west steep slope, braided river delta-meandering river delta in the east step-fault, and lacustrine and turbidite fan facies in the center of the sag respectively in the Fula sag. It is found from comparison of the depositional models in the two rift periods that, in the depositional stage of Abu Gabra Formation in early Cretaceous, the rifting activity was strong, the distribution of sedimentary system was mainly affected by syn-sedimentary faults, and there were preferential channels and areas of sediments transportation and accumulation; in the depositional stage of Darfur Group in late Cretaceous, the rifting activity weakened, the distribution of sedimentary system was less affected by syn-sedimentary faults, and the sediments were in wide distribution.