Abstract The study focuses on the offshore Guyana–Suriname–French Guiana region. It draws from seismic, well, gravimetric and magnetic data. They indicate that the continental break-up along the western margin of the Demerara Plateau took place during the Callovian–Oxfordian, associated with the Central Atlantic opening, and accommodated by normal faults. The continental break-up in the SE offshore Guyana accommodated by strike-slip faults was coeval. The continental break-up along the NE and eastern margins of the Demerara Plateau took place during the late Aptian–Albian, associated with the opening of the Equatorial Atlantic, and accommodated by dextral strike-slip and normal faults, respectively. Different spreading vectors of the Central and Equatorial Atlantic required development of the Accommodation Block during the late Aptian/Albian–Paleocene in their contact region, and in the region between the Central Atlantic and its southernmost portion represented by the Offshore Guyana Block, which were separated from each other by the opening Equatorial Atlantic. Its role was to accommodate for about 20° mismatch between the Central and Equatorial Atlantic spreading vectors, which has decreased from the late Aptian/Albian to Paleocene down to 0°. Differential movements between the Central and Equatorial Atlantic oceans were also accommodated by strike-slip faults of the Guyana continental margin, some active until the Paleocene.

Abstract The study focuses on the Guyana–Suriname transform margin, utilizing well and reflection seismic data. Both datasets allow the permeability stratigraphy to be interpreted. It consists of areally extensive reservoir horizons separated by intraformational shale horizons and erosional unconformities. The youngest strata are deformed by the two generations of gravity glides, which took place fairly late in post-break-up history. Hydrocarbon shows from wells indicate that strata deformed by gravity glides are the only sedimentary packages where the vertical hydrocarbon migration dominates. Clusters of oil and gas shows have random spatial distribution in respective reservoir horizons within gravity glides. The base of the rock volume with dominating vertical migration is determined by the detachment horizon of the gravity-glide system. However, the areas unaffected by gravity glides are dominated by lateral migration, causing zonal distribution of oil and gas shows. Oil shows occur in wells penetrating the proximal margin and gas shows are found in wells penetrating the distal margin in respective reservoir horizons. Both sets are fed by the source rock occurring in the oceanic basin and the adjacent distal margin. The best example of this situation is provided by the Paleocene–Eocene reservoirs.

A ground penetrating radar (GPR) survey was used to image the fluvial architecture within a buried paleovalley at Maple Creek, Guyana. The survey was part of a larger study of the stratigraphy and organization of fluvial elements within the valley fill. The survey consisted of 44 km of 50 and 100 MHz GPR profiles collected in a grid pattern. The 100 MHz antennae were used where depth to bedrock was less than 20 m, and the 50 MHz antennae were used where depth to bedrock exceeded 20 m. The survey grid consisted of 28 east-west–trending transects and 6 north-south–trending transects. East-west transects in the southern part of the study area were spaced 100 m apart. Those in the northern part of the study area were spaced 400 m apart, and north-south cross-transects were spaced at 500 m intervals. The survey imaged two strong reflectors interpreted to represent major bounding surfaces. The lower surface was confirmed to be the bedrock-sediment interface defining the valley boundary. The second major surface is the boundary between the fluvial valley fill and overlying bleached sand correlative with the White Sand Formation. In addition to the major surfaces, several minor surfaces were also imaged, resulting in the identification of 21 radar elements. Sixteen of the elements were interpreted to represent fluvial architectural elements. Four distinct morphological zones were recognized and were differentiated by variation in the geometry of the bedrock-sediment interface and by distinctive assemblages of architectural elements.