Equatorial Atlantic (EA) Rift Phase

While there is still much debate ongoing among international researchers it is believed that the onset of equatorial Atlantic rifting occurred during early Barremian to Aptian. Different researchers interpret that oceanic crust first formed between the Guinea and Demerara Plateaus at 100-112 Ma. Recent internal evaluations and detailed seismic observations support thick skinned deformation due to Aptian aged compressional events. Observed structures are related to strike-slip faulting and support the findings from Edge, 2014, Basile et al., 2013 & Reuber et al., 2016. They specifically note that the formation of the Demerara-Guinea transform between the once-continuous Demerara Rise and Guinea Plateau resulted in a sheared margin to the north of the rise during the opening of east-west trending Equatorial Ocean. The transform faults were locally transpressional and/or transtensional as plate motion proceeded. Along the northern border of the Demerara Rise, these early Cretaceous sediments were deformed by south-west to north-east trending en echelon folds associated to strike-slip faulting (flower structures), compatible with right-lateral transpression.
On the contrary Yang et al., 2011 noted that during the early Cretaceous the rifting event happened in the South Atlantic because of the counterclockwise rotation of Africa relative to South America (Pindell, 1991; Mann et al., 1995) resulting in concomitant compression in the equatorial zone of the margin.
The folds, at least partly in a sub-aerial environment, were peneplained by a regional unconformity and covered by late Albian detrital sediments.
Aptian-Albian sediment loading from the east and south-east, complimented with the Equatorial Atlantic tectonics resulted in a gravity driven extensional front with listric and growth faults on the western edge of the Demerara Rise (a shelf collapse) and a gravity driven compressional front (toe-thrust belt) in the deep basin using the early Cretaceous shales as decollement and eroding as deep as the late Jurassic.

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