Neoproterozoic to lower paleozoic sequences of the Congo shield: Comparisons between the Congo and its peripheral basins

Abstract

The Congo Basin (CB) was initiated during a Neoproterozoic intracratonic rifting process across the Congo Shield, possibly related to the break-up of the Rodinia Supercontinent. The Neoproterozoic history of the CB remains poorly constrained because it is largely concealed by Phanerozoic sequences and is thus accessible only by drilling and geophysical investigations. Neoproterozoic basins peripheral to the CB, however, share first-order similarities in their stratigraphic successions: An initial coarse clastic sequence followed by a thick carbonate sequences and terminating by a dominantly siliciclastic sequence. The subsequent transition to the Lower Paleozoic is influenced by regional Pan-African deformation and molasses-like foreland basin sediment-fill. The Neoproterozoic stratigraphy and structure beneath the CB can be tested also using data from two fully cored stratigraphic wells (Samba: 2,038 m and Dekese: 1,836 m), and two exploration wells (Gilson-1: 4,563 m and Mbandaka-1: 4,350 m), seismic refraction and reflection profiles, gravimetric and magnetic data. Synthesizing this data, we show that the CB shares a similar early evolution as its flanking basins in that they all initiated in extensional tectonic environments and were subsequently affected by compressional deformation during late Neoproterozoic to Early Cambrian Pan-African orogenesis.