Thomas A. Hickson¹, Ben Sheets¹, Jeff Marr¹
(1) University of Minnesota, Minneapolis, MN

Abstract: Filling of intraslope basins by turbidity currents: results from experimental simulations

Intraslope basins—such as those on the northern Gulf of Mexico slope—have become important deep-water petroleum plays in recent years. Sand principally is delivered to these basins via turbidity currents, yet no well-constrained mechanical or theoretical models exist to explain how sediment-gravity flows shape their architecture. In the first experiments of their kind, we have undertaken a series of two-dimensional, flume simulations to examine the effects of intraslope basin topography on turbidity current deposition, deposit architecture, and sand caliber. We used high resolution bathymetric data of the Gulf of Mexico to derive a ‘typical’ intraslope basin topographic profile which was, in turn, used to construct a scale basin model. Two model basins were submerged on the sloping floor of a flume and individual turbidity currents (comprised of kaolinite clay and silt) were allowed to flow over this topography for up to 35 minutes. Deposit thickness ranged between 0 and 15 cm, with the thickest accumulations near the inlet and in the upstream basin. Sediment trapping efficiencies were found to be highest in the upstream basin and declined rapidly in downdip basins. Surprisingly, plots of deposit thickness indicate that there is a weak stratigraphic signature of the antecedent topography within the deposit, and this signature is rapidly attenuated in a downdip direction, such that the same topography has a much reduced effect on stratal geometry in more distal intraslope basins.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana