Print this pageThe Influence of Sea-Floor Topography on the Depositional Styles of a Deep-Water Sand-Rich System: The Paraíba do Sul Turbidite System Example, Campos Basin (BRazil Deep Seds - Deep-Water Sedimentation on the Southeast Brazilian Margin Project)
Adriano R. Viana1, L.C.R. Machado2, W.
Almeida1, R. O. Kowsmann1, and R. C. Gontijo1
1 Petrobras, Rio de Janeiro, Brazil
2 Petrobras, Macae, Brazil
Interaction between halokinesis and sedimentation processes is responsible for a complex sea-floor physiography all along the SE Brazilian margin. Sand transfer from shallow to deep is strongly influenced by the declivity, connectivity, size and degree of confinement of the resultant deep-sea conduits. The Paraíba do Sul Turbidite System is developed by the connection of a modern fluvial system to the submarine drainages.
A sinuous, 4.5° dip canyon carves the continental slope and is used as a by-pass zone, where very little coarse-grained sediment is trapped, mostly at its head, driven by surface contour currents. Basinward, the sea-floor expression of salt movements defines deep-water troughs that were occupied by sediment-rich gravity flows. Giant mass-movement deposits provoked modifications on such conduit by introducing chaotic heterolites laterally to the trough.
Despite the predominance of late lowstand coarser-grained deposits in the lower slope proximal area, transgressive and highstand sands are observed in the middle to distal lower slope. Erosive features and elongated, amalgamated depositional geometries predominate in steeper, confined areas whereas depositional, radial, finger-like channel-lobe features predominate in non-confined areas.
Due to its geometric and faciologic similarities with Campos Basin oil-bearing reservoirs, this system is being largely used as a local analogue for both exploratory and appraisal studies.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005