Figure 8
 

The mapping of all available seismic and well data allowed a full overview of the structural development of offshore Suriname.
It allowed a better understanding of the initial graben configuration prior to the break-up of North-America and Africa (the Central Atlantic phase). These grabens were later only mildly affected/re-activated by the drifting apart of South America and Africa (the Equatorial Atlantic phase).
It is important to realise that offshore Suriname is not a classic passive margin setting, where an initial rift system preceded the break-up of the continents. The strike of the graben system related to the Central Atlantic phase was at an angle (approximately 60o) to the coast. This rift system was later cut, from (Albian)-Aptian onwards, by several major transcurrent faults along which South America and Africa drifted apart (Equatorial drift phase). No stretching preceded the later phase and thermal subsidence was less well expressed. The low thermal subsidence, combined with a large supply of clastics from the shield resulted in a sand rich outbuilding shelf.

Figure 9 illustrates the nature of the basement and the initial graben. It is an example of a section off the west coast of Suriname.
The clear change from a very hard Top Crystalline Basement reflection to an angular unconformity can be observed. One offshore well in the west of Suriname offshore (I/23-1X) has penetrated some 400 m of this dipping sequence, which proved to be of volcanic or volcano/clastic nature. The bulge in front of the boundary fault may be caused by some mild compression. Note as well the amplitude anomalies in the sequence above the syn-rift setting.
 

Figure 10 is a regional map of the Top-Cretaceous/Base Tertiary unconformity.
The continuing influence of the rift boundary faults can be seen in the contour spacing on the shelf. The flexure some 100 km north of the coast also affects this event. The nature of the basin and the major tectonic elements will be illustrated by three seismic sections (red lines).