Influence of Coriolis forces on turbidity currents and sediment deposition

Abstract

Using laboratory analogue experiments I show how the Earth’s rotation can influence the deposition patterns of large-scale turbidity currents. While it has been previously recognized that the EarthOs rotation can influence the trajectories of turbidity currents (Middleton 1993; Huppert 1998; Kneller & Buckee, 2000) the experiments discussed in this paper represent the first systematic laboratory study of the Coriolis forces acting upon turbidity currents. The scale at which Coriolis forces become important is best expressed using the Rossby number, defined as Ro = U/fL, where U is a depth averaged velocity, L the length scale and the Coriolis frequency, f, is defined by f = 2Ω sin θ, where Ω is the Earth’s rotation rate and θ is the latitude. Coriolis forces will dominate a current when Ro < 1 (Nof 1996). For example a large turbidity current with a velocity of U = 10m s−1 at a latitude of 45° North where f = 1 × 10− 4 s −1, has Ro < 1 for length scales greater than 100 km.