Abstract
The topography and sediments of the northern Guiana Basin, including the northern section of the Demerara Abyssal Plain and the Barracuda Fault are discussed. A seismic profile from the Amazon Cone to the eastern end of the sediment-filled Barracuda Fault trough (the Barracuda Abyssal Plain) reveals a series of three ponded turbidite levels, the deepest being the Barracuda Abyssal Plain. The main source of the turbidites appears to be the Amazon region. A JOIDES hole in the turbidites of the Vema Fracture Zone has revealed very high sedimentation rates but as yet it is unclear what their relationship is to the Demerara Abyssal Plain sediments. A major deep-sea channel (the Vidal Channel) runs across the two levels of the northern Demerara Abyssal Plain and ends in the eastern Barracuda Abyssal Plain. It is the principle access for turbidites to the latter. The main channel has a length of at least 800 km and an average gradient of 1:1100. Several tributaries are also present. In its northern end there is an abrupt gradient change, and reflection records indicate this to be due to differential erosion. Backcutting has apparently been a major factor in the formation of the channel.
Published Version
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