Controls on geometry and composition of a levee built by turbidity currents in a straight laboratory channel

摘要

Experimental results are presented that quantify properties of a channel levee built by depositional turbidity currents. Nine currents of constant initial thickness and composition were released into a pre-existing channel and levee growth on the channel bank was observed. Rates of sediment deposition on the proximal levee, grain size, and taper of levee deposits were all found to be inversely related to local channel depth. These relationships were controlled by 1) the thickness of the depositing current relative to the local channel depth and 2) the vertical profiles of concentration and size for grains suspended within the current. Change in local depth confined more or less current within the channel and determined the fraction of current present at and above the levee-crest elevation where it could act as a sediment source for bank construction. The results are used to develop a simple framework for interpreting submarine levees.