The Brazilian Equatorial Margin (BEM) is a transform passive margin formed by the Gondwana break-up during the Early Cretaceous (Aptian-Albian) (Matos, 1999). Rifting created a series of rift sedimentary basins including the Potiguar Basin (POT) (Fig.1a)-NE Brazil. Despite the continental shelf of the POT had been extensively investigated, studies on the continental slope are still scarce, while they are essential to identify instabilities and their related mechanisms. These investigations can also provide information necessary to map possible geological risk areas and prevent accidents regarding submarine installations.
The dataset, conceded by the Brazilian National Agency of Petroleum, Natural Gas and Biofuels (ANP) is composed of a 3D high-resolution seismic cube of ~1850 Km2 and a velocity analysis cube. The software used to conduct seismic interpretation was Petrel EandP, licensed by Schlumberger. Here we report the very first results of this research which is the seabed mapping and morphological descriptions. The seabed horizon (SBH) was mapped by picking the first reflector with positive amplitude using a combination of manual tracking with 3D automatic tracking. Then, the SBH was used to create a surface (Fig.1b) by the convergent interpolation method. Finally, a velocity model was created using the velocity cube to provide a time-depth converted dataset.
Our results (Fig.1b) show that the slope is characterized by canyons/channels, landslides, sediment wave marks, and depressions organized in trails. The presence of these elements indicates that different processes may be shaping the slope. The slope is generally steep and characterized by erosional and depositional features indicating processes that can be related to slope instabilities (e.g., landslides). In addition, we observed trails of elliptical depressions similar to those observed at the Ceara basin (also a BEM basin) by Maestrelli et al., 2020 described as the result of upslope migration of sediment waves supplied by turbiditic flow. These features indicate how gravity-driven processes shape the slope’s morphology. Submarine channels formed between the two walls of some of the canyons (Fig.1b) have different morphologies: some are sinuous (C;J;K;P), other meanderings (D;E), and others rectilinear (F;O). Factors that influence the different shapes of the course of the channels will be fully understood during the next step of this research, which will be supported by sub-bottom seismic interpretation
