Neocomian to early Aptian syn-rift evolution of the normal to oblique-rifted North Gabon Margin (Interior and N'Komi Basins)

摘要

The North Gabon coastal rift basins consist of a set of 130-150 long-segment asymmetrically tilted half grabens (Interior Basin) and 000-020 short-segment en echelon half grabens (N'Komi Basin) separated by 040-060 major transverse faults. Tectono-sedimentary analysis of field and subsurface data reveals the control exerted by extensional tectonism over continental sedimentation. During Berriasian to early Barremian times, uniform uniaxial 040-060 extension was responsible for the stretching of the brittle upper crust over a 100-km wide domain. During late Barremian-early Aptian times, the main locus of extension stepped westward resulting in severe end-rift uplift and erosion of the failed Interior and N'Komi rift basins. Early Cretaceous coastal rifts in North Gabon display a wide range of styles from oblique rifting (N'Komi Basin), normal rifting (Interior Basin) to transform rifting. The pre-existing Precambrian tectonic fabric exerts a strong control over the mode and over the 100-300 km-scale segmentation of the rifting.