Evolution of submarine channel and lobe systems above dynamic stepped slopes

Submarine slopes with stepped profiles record sandy channel and lobe systems across depocentres and muddy bypass-prone ramps. The widely applied fill-and-spill model predicts the depositional architecture of stepped slope successions. However, this model implies a constant topographic configuration over the lifespan of a turbidite system. In contrast, the impact of dynamic slopes, with spatially variable topographic configurations, on patterns of erosion and deposition remains poorly investigated. This thesis aims to document deep-water sedimentation patterns above stepped slopes subject to active extensional salt tectonics using comprehensive subsurface datasets from the Campos Basin, offshore Brazil.
Extensive seismic mapping and well correlation of two Oligocene-Miocene deep-water successions support the interpretation of large-scale structural controls on the configuration of depocentres, and relationships between seismic geomorphology, depositional architecture, thicknesses and stacking patterns, and lithology/facies distribution above a dynamic slope topography. In the Marlim Unit area, high-resolution stratigraphic models capture the impact of subtle lateral and basinward tilting, and fluctuations in the sediment supply, which result in complex stratigraphic patterns with multiple phases, and multiple entry and exit points. Furthermore, extreme variations in the thickness of buried channel-fills are documented for the first time, which are interpreted to record a transient uplift related to salt tectonics in an otherwise subsiding depocentre. In the Albacora depocentre area, salt structures reactivated by extension and contraction formed subtle seabed topography that defined the edges of the depocentre. An elongate depression, later filled by sand-prone turbidites, developed immediately after the emplacement of a regional-scale mass transport complex. This contrasts with the role of mass wasting processes in active salt basins, which are a product of slope deformation and not a cause.
In summary, models of dynamic topographic deformation on the stratigraphic evolution of intraslope depocentres are developed, which can be applied to the extensional domains of salt basins globally.