Depositional Turbidity Currents in Diapiric Minibasins on the Continental Slope

The northern continental slope of the Gulf of Mexico is riddled with subsiding diapiric minibasins bounded by ridges, and often connected by channels created by turbidity currents. These minibasins constitute excellent focal points for the deposition of sand. These deposits are economically important because they serve as reservoirs for hydrocarbons. A better understanding of the “fill and spill” process by which minibasins fill with sediment as the intervening ridges are dissected by canyons may serve to aid in the location of such reservoirs. A theoretical analysis has revealed two key aspects of the “fill and spill” process; a) the formation of an internal hydraulic jump as a turbidity current spills into a confined basin, and b) the detrainment of water across a settling interface forming at the top of the ponded turbidity current downstream of the hydraulic jump. It is shown that sufficiently strong detrainment can consume the flow, so that there is no outflow of either water or sediment even with continuous inflow. As the basin fills with sediment, however, overspill is eventually realized. A numerical model of ponding of turbidity currents was developed. The analysis and the numerical model were confirmed with laboratory experiments.