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Gravity Processes and Deposits on Continental Slope, Rise and Abyssal Plains

2010; Elsevier BV; Linguagem: Inglês

10.1016/b978-0-444-53000-4.00002-0

2352-2844

Thierry Mulder,

Hydrocarbon exploration and reservoir analysis

This chapter discusses the gravity processes and deposits on continental slope, rise, and abyssal plains. The impact on human infrastructure helps in detecting the gravity processes. They are mainly interpreted from the nature of their deposits. Submarine gravity processes are classified according to the mechanical behavior of the process, the particle-support mechanism, the concentration or the longitudinal change in their deposits. The classification distinguishes four types of particle-support mechanism: matrix strength; grain-to-grain interactions; fluid support; and turbulence. The main types of flow processes are rock or consolidated material avalanching, creeping and failures, slides and slumps, flows, water-dominated flow, and turbulent flow. The characteristics of turbulent flows are determined by their morphology, velocity, and erosion. The terminology of turbulent-flow is turbulent surge, surge-like flow, and quasi-steady flow or turbidity current. The formation, plunging and persistence of a hyperpycnal flow are also discussed. Gravity-fall and gravity-flow deposits discussed are: rockfall- and slope-faliure deposits; gravity-flow deposits. Particle deposition by sediment gravity flow can occur by freezing, traction, and suspension fallout. Freezing or "en masse" deposition occurs when the flow resistance exceeds the driving shear force in a cohesive flow; the flow then stops abruptly.