ABSTRACT

The influence of sea-floor topography on the deposits and flow paths of high-density, coarse-grained turbidity currents was investigated in experiments that concentrated on simple, wedge-shaped obstacles, representing tilted fault blocks, with heights of the same order as the thickness of the flows on a flat tank floor. Particle size, initial particle concentration, and tank floor configuration were varied independently, and the flow paths, sediment distribution, and surface features were recorded. These small topographic features significantly alter sediment distribution. Stationary mixing vortices (standing billows) formed near the obstacles, and the variations in flow thickness and velocity around the obstacle caused local, rapid deposition and resulted in very abrupt thickness var ations across the tank floor. Although the amplitude of thickness variations around obstacles is dependent on grain size and concentration (because of differences in settling velocity), the position of thickness variations is controlled strongly by the obstacle and flow characteristics and is largely independent of grain size.