Main observations on genesis and morphological evolution of submarine valleys

Submarine valleys, in some cases tightly linked to fluvial systems, represent one of the main source of sediment for deep oceanic basins. They are located along the main continental margins and show, depending on their subaerial or deep origin, different morphologies and evolutionary patterns. With the aim of highlighting the mechanisms involved in the genesis and evolution of submarine valleys, 50 of them, located in different parts of the world, have been classified and analyzed on the basis of their morphometric parameters, as well as of the morphological and tectonic parameters of the continental margins where they lie. Common structural and/or morphological features have been pointed out for canyons located along the same continental margin and similar evolutionary trends for those located on margins of the same kind. The analysis of these data helped to reconstruct the evolutionary trend of the submarine valley as a process tightly related to the local tectonic history, to the sedimentary processes acting on the shelf and on the continental scarp as well as to the shelf-scarp system morphology. Furthermore, it has been possible to recognise the subaerial or submarine origin of a canyon through its profile and cross section morphologies. Finally, this study has allowed the definition of the canyon morpho-evolutionary trends with respect to glacio-eustatic and subsidence phenomena.