The role of Internal Solitary Waves on deep-water sedimentary processes: the case of up-slope migrating sediment waves off the Messina Strait

摘要

Subaqueous, asymmetric sand waves are typically observed in marine channel/canyon systems, tidal\udenvironments, and continental slopes exposed to strong currents, where they are formed by current\udshear resulting from a dominant unidirectional flow. However, sand-wave fields may be readily\udobserved in marine environments where no such current exists; the physical processes driving their\udformation are enigmatic or not well understood. We propose that internal solitary waves (ISWs) induced\udby tides can produce an effective, unidirectional boundary “current” that forms asymmetric sand waves.\udWe test this idea by examining a sand-wave field off the Messina Strait, where we hypothesize that\udISWs formed at the interface between intermediate and surface waters are refracted by topography.\udHence, we argue that the deflected pattern (i.e., the depth-dependent orientation) of the sand-wave\udfield is due to refraction of such ISWs. Combining field observations and numerical modelling, we\udshow that ISWs can account for three key features: ISWs produce fluid velocities capable of mobilizing\udbottom sediments; the predicted refraction pattern resulting from the interaction of ISWs with bottom\udtopography matches the observed deflection of the sand waves; and predicted migration rates of sand\udwaves match empirical estimates. This work shows how ISWs may contribute to sculpting the structure\udof continental margins and it represents a promising link between the geological and oceanographic\udcommunities.