The influence of deep marine circulation on gas-related seafloor morphologies over a salt tectonic domain: Case studies on the continental slope of Santos Basin, southern Brazilian margin

The Santos Basin slope is a physiographic feature whose seafloor morphology is influenced by both geological and oceanographic processes. Regarding geological processes, halokinesis has been one of the main forces driving the geological evolution of this margin and influencing the present-day seafloor morphology. Salt dynamics is considered to be responsible for the development of faults and fractures, which behave as fluid conduits toward the seafloor surface. The supply of fluids added to the nature of the sediments provide favourable conditions for the formation of gas-escape seafloor morphologies, such as pockmarks, carbonate mounds and ridges. Additionally, the observation of exhumed salt diapirs in the south-western part of the Santos Basin seafloor is suggestive of active halokinesis. Besides, oceanographic processes leave a conspicuous fingerprint in the formation of an extensive array of morphological and sedimentary seafloor features. The interaction of bottom currents with pockmarks, carbonate structures and exhumed salt diapirs erodes the seafloor relief and contributes to the formation of moats, comet marks and scours. Associated with the prevailing erosive features, bottom currents-related deposits are formed along the slope structures constituting contourite systems.