--> Abstract: Characteristics of Laterally Confined Sheet Sands; #90063 (2007)

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Characteristics of Laterally Confined Sheet Sands. Quebrada Las Lajas, Northwestern Argentina

 

Kertznus, Vanessa1, Ben Kneller1, Mason Dykstra2 (1) University of Aberdeen, Aberdeen, United Kingdom (2) University of California, Santa Barbara, CA

 

Deepwater submarine environments are commonly characterized by a complex seafloor morphology comprising a mosaic of small depositional basins (minibasins) several kilometers across. Turbidity currents that run into these areas can be sufficiently large to spread across the entire basin floor. The degree of confinement experienced by flows depends on the height and volume of the flow compared to the confining seafloor topography, which my completely trap flows or only partially confine them.

 

Variability in petroleum reservoirs is typically not sufficiently described in fine scale. Seismic data provides information over a large area, but with limited resolution, whereas log and core data provide detailed measurements, but only over a limited area. Given these limitations the objectives of this study are to 1) document the influence of lateral confining slopes on the sedimentary characteristics of individual turbidite beds, and 2) establish whether turbidite sheet sands present lateral and longitudinal changes in bed thickness, sedimentary structures, and grain-size, related to the depositional processes involved in their emplacement, and the interaction of turbidity currents with the confining topography.

 

The Quebrada Las Lajas outcrops provide a degree of three-dimensionality, which allows the spatial characterization of layered and amalgamated sheet-like turbidite deposits confined laterally within a paleofjord. The spatial variations of this ponded fill succession can be used as partial analogs to intraslope basins formed by growth faulting, shale-based detachment faults, salt-withdrawal mini-basins, or salt-based detachment faults, such as those in the Gulf of Mexico, Nigeria, Angola, and others.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California