Hydraulic controls on turbidity channel and slope gullies lateral migration induced by contour currents

Abstract

Recent observations derived from modern sea floor bathymetry, oceanographic data (flows), and shallow seismic data, suggest a strong link between a biased (one-sided) lateral migration tendency of submarine turbiditic channels and slope gullies, and the flow of along-slope contour currents (e.g. Gong et al., 2016; Miramontes et al., 2016; and references therein). Data coming from the subsurface also suggest in some cases similar unidirectional channel migration tendency, in associattion with asymmetrical levee building often (but not always) restricted to mid-to-lower continetnal slope, where contour current flows might have been presumably most active (Fonnesu et al., 2019). Here we present a set of hydraulic-based hypotheses that predict both up or downflow turbiditic channel migration (in relation to the contour current flow direction), depending primarily on the relative sizes of the bottom boundary layer (BBL) of the contour current and the turbiditic channel depth. These hydraulic hypotheses consider only the action of the contour currents alone, i.e. are applicable only during time periods of quiescent turbiditic flow activity. Prelimianry experimental results that in principle support these ideas are also