Figure explanation: Location map showing the major tectonic and structural features along the Gabon-northern Angolan continental margin. The base map is a crustal Bouguer gravity anomaly of the offshore region. Scale is in mgals with values greater than +40 being shown in white. Our modeled geological section is located in the outlined box. Two tectonic hinge zones, the Eastern (thin red line) and Atlantic (bold red line), trend subparallel to the margin. The onshore Eastern hinge zone demarcates the eastern limit of Neocomian extension and separates continental margin sediments from Precambrian basement. The Atlantic hinge zone occurs beneath the outer shelf/ upper slope transition as a series of en-echelon high-standing blocks. A series of small but in general unconnected subbasins, identified as localized negative gravity anomalies, exist on either side of the Atlantic hinge zone. The position of known basins and highs is readily apparent in this rendition of the gravity. The ocean/ continent boundary, approximately delineated by the strong positive/negative gradient in the gravity anomaly, is shown as a bold-aqua line. The gravity amplitude across the boundary ranges from 20-30 mgals. The source of the gravity gradient is in part a consequence of the juxtaposition of relatively thick, old oceanic crust adjacent to thinned continental crust. The thickened oceanic crust is a function of the decompressive melting of relatively hot mantle, likely induced by the presence of the Tristan da Cunha, Saint Helena, and Ascension hotspots