Deep pockmarks as natural sediment traps: a case study from southern Santos Basin (SW Atlantic upper slope)

Abstract

This study examines the role of deep pockmarks in acting as natural sediment traps. Multibeam bathymetry, single-channel seismic and sediment samples data were used for describing the morphology of pockmarks as well as the nature of sediments inside and outside these depressed features, in an area of Santos Basin (SW Atlantic upper slope), dominated by the strong flow of Brazil Current. Results show that the grain size and chemical composition of sediments inside pockmarks are distinct from the outside. Also, radiocarbon dating shows that Holocene ages are found only in samples located inside the pockmarks. Combination of sedimentological, geochemical and geochronological data allowed to recognise that deep pockmarks might present distinct sediment deposition processes when compared with those of shallow pockmarks, in which turbulence impedes sediment deposition, as reported in the literature.