Multi-direction flow in a mass-transport deposit, Santos Basin, Offshore Brazil

Abstract

The complex Quaternary Rebelde Slide is located on the northeastern corner of the Sao Paulo Plateau at the base of the upper continental slope in water depths of 1, 600-1, 700 m. This mass-transport deposit (MTD) is up to 300 m thick, 10 km wide where confined, 36 km long, and is buried beneath 50-65 m of hemipelagic drape. The Rebelde Slide is unusual because it appears to have flowed parallel to the slope. The majority of the failure is confined to a contouritic moat that runs along the base of the upper continental slope. The sliding surface of the failure is undulating, and coincides with the top of an underlying sediment wave. The Rebelde Slide consists of three components. Each one is characterized by different structural characteristics and direction of movement, as if the entire interval collapsed under its own weight on a multi-directional sliding surface. The coincidence of the sliding surface of the Rebelde Slide with the source area of fluid-expulsion features observed near the moat suggests failure along a zone of overpressured, geotechnically weak layers. © Springer Science + Business Media B.V. 2010.