Miocene isolated platform and shallow-shelf carbonates in the Red Sea coastal plain, north-east Sudan

Abstract

Detailed sedimentologic, pétrographic and micropalaeontologic studies of surface outcrops north of Port Sudan revealed:

• 1. Miocene carbonates of the Red Sea coastal plain of the Sudan occur in two different depositional settings: (a) isolated platforms characterized by massive margins and concave, closely crenulate talus slopes and (b) shallow shelf deposits characterized by horizontally and conformably deposited bioclastic sediments which, due to structural movement, now form tilt-blocks.

• 2. Both outcrop types are characterized by respective lateral patterns of facies and microfacies distribution; both were deposited in shallow water, at slightly elevated temperatures, in normal marine to hypersaline conditions.

• 3. Biostratigraphically these carbonates range from the Oligocene-Miocene boundary to at least late Serravallian, i.e. N4 to N13 planktonic foraminiferal zones. Deposition on the oldest isolated platform carbonates began in latest Oligocene; others followed. The shallow-shelf carbonates are younger than all platforms dated. These findings suggest considerable local differentiation during Miocene sedimentation.