Many deep-sea fan and sheet systems include deposits of rheologically complex sediment gravity currents (“hybrid flows”) with suggestions of turbulent, transitional and laminar flow character, most commonly interpreted to represent deposition in more distal regions. In this paper, Patacci et al. describe a succession deposited as strata that onlap a confining slope. The sedimentology and geometry of these strata illustrate that hybrid flow-associated deposits can occur in proximal settings, and on scales of just 100s of meters, given a confining topography (e.g., onlap) that transforms the flows. This flow hybridization mechanism provides an alternative explanation for the occurrence of clay-rich facies development at the foot of flow-confining seafloor slopes, and may be important for predicting trends in reservoir quality in subsurface analogs.
Rheological complexity insediment gravity flows forced to decelerate against a confining slope, Braux, SE France by Marco Patacci, Peter D.W. Haughton, and William D. McCaffrey