Because turbidite beds aggrade progressively beneath a moving current, the vertical grain-size profile of a bed is generally an indication of the longitudinal velocity structure of the flow, and longitudinal gradients in suspended sediment concentration ("density"). A current is more likely to show a simple waning flow history farther from its source; this is because faster-moving parts of the flow overtake slower moving parts, and the flow organizes itself over time so that the fastest parts are at the front. Thus distal (e.g., basin plain) turbidites commonly show simple, normally graded profiles, whereas more proximal turbidites often show complex vertical sequences within a bed, related to unsteadiness. A turbidity current may deposit a structureless, poorly sorted bed where the capacity of the current is exceeded, i.e., where there is insufficient turbulent kinetic energy to maintain the entire suspended mass. Capacity-driven deposition may occur where the flow decelerates. Where flow nonuniformity is the cause of capacity-driven deposition, a massive interval will form the lowest part of the bed, and will have a flat base. Where flow unsteadiness is the cause, a normally graded massive interval may overlie erosional features or traction structures at the base of the bed. Based on the assumption of longitudinal gradients in velocity, density, and grain-size distribution, the longitudinal density structure of a current may induce a switch, at any given point, from capacity-driven deposition to either (1) bypass and resuspension, (2) bypass with traction, or (3) competence-driven deposition, each resulting in a characteristic upward change in deposit character. The temporal evolution of the flow at a point varies systematically in a streamwise sense. Taking account of these longitudinal variations permits predictions of complex vertical sequences within beds, and of their downstream relations.

Mass-transport events are virtually ubiquitous on the modern continental slope and are also frequent in the stratigraphic record, but the potential they create for stratigraphic trapping within the sea-floor topography is not generally appreciated. Given the abundance of mass-transport deposits (MTDs), we should expect that many turbidite systems are so affected. The MTDs may be very large (volumes > 103 km3 [∼250 mi3], areas > 104 km2 [∼6250 mi2], thicknesses > 102 m [∼330 ft]), and they extensively remold sea-floor topography on the continental slope and rise. Turbidity currents are highly sensitive to topography; thus, turbidite reservoir distribution and geometry on the slope and rise are often significantly affected by subjacent MTDs or their slide scars. Turbidites may be captured within slide scars and on the trailing edges, margins, and rugose upper surfaces of MTDs; developed in accommodation when the mass movement comes to rest; or subsequently resulting from compaction or creep. The filling of such accommodation depends on the properties of the turbidity currents, their depositional gradient, and how they interact with basin floor topography. The scale of accommodation on top of MTDs is determined largely by the dynamics of the initial mass flow and internal structure of the final deposit, and it typically has a limited range of length scales. We present interpretations of a range of previously published and original case studies to illustrate the range of accommodation styles associated with MTD-related topography within the evacuated space of the slide scar, around and on top of the deposits themselves. In fact, several well-known deep-water outcrops probably represent examples of sedimentation influenced by MTDs. Hydrocarbon reservoirs in many slope settings may be controlled by the accommodation related to MTD topography. At the exploration scale, entire shelf margin and slope depositional systems may be contained within the scars evacuated on the upper slope by mass failure, whereas at the production scale, the rugosity on the top of MTDs creates widespread potential for stratigraphic trapping. The location, geometry, and property distribution of such reservoirs are closely controlled by the interaction of turbidity currents with the topography; thus, an understanding of these processes and their impact on slope stratigraphy is vital to reservoir prediction.