Morphodynamics and spatial distribution of regional slope failures in the Offshore Amazon Basin, Brazilian Equatorial Margin

Abstract

Slope instabilities occur in distinct geological contexts on the marginal basins worldwide and are known for constitute true risks to submarine infrastructure and even to coastal populations, thus representing potential submarine geohazards. In the Offshore Amazon basin, instabilities features and associated mass-transport deposits were already mapped in a series of previous works where (i) quaternary and near-surface remobilized deposits were identified on high-resolution data, occurring interbedded with channel-levee systems on subsurface; and (ii) remobilized masses were also identified as huge vertical stacked deposits on seismic scale, constituting megaslide complexes, throughout the basin. This paper presents an updated scenario for the distribution of slope instability features in the Offshore Amazon basin, based on the integration of newly geophysical data, with variable resolution. The analysis included the identification and detailing of morphological elements related to failure processes and the interpretation of main echofacies on high-resolution profiles, focusing on the seismic signatures indicative of remobilization processes. The recognition of potential geohazards in the Offshore Amazon basinconsidered a new frontier basin in terms of hydrocarbon potentialcan subside future projects concerning hazard and risk assessment and can aid the development of exploration and other activities on the basin.