A new turbidite facies-tract scheme including supercritical and hydraulic jump facies: interactions between basin morphology and criticality

Abstract

Studies of tectonically confined turbidite systems in Mediterranean-type foreland basins have shown that these deposits can be dominated by supercritical flows, which can transform into subcritical and/or transitional (mud–sand) flows. In these confined turbidite systems, supercritical flows tend to be favored by lateral confinements parallel to the paleocurrents. In contrast, flow decelerations are favored by morphologies transversal to paleocurrents, e.g., slope breaks or adverse slopes that can vary in scale from regional tectonic structures to depositional features such as thick mass-transport complexes and lobes. This evidence, together with the growing knowledge of supercritical flow processes and structures that has occurred over the last fifteen years, has led to the formulation of a new facies scheme that takes into account the relationship between basin geometry and criticality. This has also prompted a revisiting of the concept of efficiency, where the type of facies tract does not only depend on the flow behavior but also on the basin size and morphology.