Circulation of hydraulically ponded turbidity currents in three-dimensional minibasins with implications for turbidite shape

Minibasins on continental margins trap turbidity currents transporting material downslope, but little is known about the inherently three-dimensional (3-D) mechanics of these confined flows. Utilizing new methodology, experimental results quantify flow dynamics in minibasins for the first time. It is shown that dynamics are dominated by 3-D circulation cell structures, across the fill-to-strip-to-spill transition that are controlled by flow discharge. Measurements of velocity throughout circulation cells indicate vorticity dominates strain rate with fluid rotating into the center of cells where it upwells: this influences minibasin sediment trapping potential and deposit heterogeneity. Flow properties link to depositional patterns on minibasin slopes. Specifically, higher input discharges are correlated with higher fluxes into the center of minibasins and reduced deposit tapering on minibasin slopes. This geometry is linked to the amount of sediment rich flow runup on the distal minibasin wall, where flow and sediment is delivered to circulation cells.