SHELF PROCESSES AND CANYON/CHANNEL EVOLUTION CONTROLLING TURBIDITE SYSTEMS: EXAMPLES FROM THE SERGIPE-ALAGOAS BASIN, BRAZIL

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Abstract
An industrial data set (seismic sections, well logs, and cores), extending to a water depth of 3,000 m, provided the opportunity to conduct an integrated stratigraphic analysis among shelf, slope, and basin depositional environments. The study focused on a 3,000-m seaward-thickening prograding wedge, subdivided into four sequences. The high energy shelf, dominated by waves and currents, produced mature sands mixed seaward with carbonates that border the shelf edge. Basinward, a thick section of shales was developed contemporaneously. Canyon systems on the sequence boundaries acted as routes through the shelf carbonate rims in the development of deep-water turbidite systems. The timing for down-slope transport of shelf sands was controlled by the evolution of few canyons from immature to mature. Mature canyons that entrenched deeply onshoreward tapped the sands dammed by shelf-edge carbonates. Sands funneled downcanyon were concentrated into isolated or migrating leveed channels as coarsegrained lags of turbidite systems distributed in time and space into the thick slope apron.