Factors controlling asymmetry in submarine channels and submarine canyons: Insights from global morphological analysis

The formation of asymmetric submarine channels and canyons is the result of multiple processes, including bottom currents, Coriolis forcing, and centrifugal forces, acting on turbidity flows. Despite increasing studies of asymmetric submarine canyons and channels and recognition of the influence of bottom currents on turbidity flows, the relative contributions of these factors remain poorly constrained, often resulting in contradictory interpretations. In this study, we investigate whether morphometric characteristics of submarine canyons and channels – specifically relief and width asymmetries, and cross-sectional slope angles – can indicate the most likely processes responsible for their asymmetry, such as Coriolis effect versus bottom currents. We systematically analysed 24 asymmetric canyons and channels from diverse settings, integrating their morphometric data with environmental parameters including latitude, water depth, slope angle, and bottom current intensity and direction.
Our results reveal substantial variability in channel asymmetry along their lengths: the positions of the higher margin, thalweg, steeper margin, and the degree of asymmetry often change within a system, so that a single channel cannot be consistently described with one asymmetry value. Depth-dependent variations in slope, water-mass structure, turbidity current dynamics, and bottom-current intensity, combined with temporal variability in both turbidity-current characteristics and bottom-current velocities, create locally coherent, but non-predictive asymmetry. Thus, our observations suggest that morphological characteristics alone are insufficient to identify the main forces controlling channel asymmetry. We propose a classification scheme to aid interpretation of channel asymmetry and potential bottom current interactions, emphasizing the complexity of channel formation.