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Liquefied Flow
Liquefied flows (also known as liquified flows and fluidized flows) are types of sediment-gravity flows in which grains within the flow are kept in suspension by the upward movement of fluid. They form in granular substances where the concentration of suspended mud is too low to develop cohesive forces within the flow. As grains at the base of the suspension settle out, fluid that is displaced upward by the settling generates pore fluid pressures that can help suspend grains in the upper part of the flow. Application of an external pressure to the suspension will initiate flow. This external pressure can be applied by a seismic shock, which may turn transform loose sand into a highly viscous suspension as in quicksand. Generally as soon as the flow begins to move, fluid turbulence results and the flow rapidly evolves into a turbidity current A turbidity current is most typically an underwater current of usually rapidly moving, sediment-laden water moving down a slope; although ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sediment-gravity Flows
upright=1.25, This Devonian.html" ;"title="turbidite from the Devonian">turbidite from the Devonian Becke-Oese Sandstone of Germany is an example of a deposit from a sediment gravity flow. Note the complete Bouma sequence. A sediment gravity flow is one of several types of sediment transport mechanisms, of which most geologists recognize four principal processes. These flows are differentiated by their dominant sediment support mechanisms, which can be difficult to distinguish as flows can be in transition from one type to the next as they evolve downslope. Sediment support mechanisms Sediment gravity flows are represented by four different mechanisms of keeping grains within the flow in suspension. *Grain flow – Grains in the flow are kept in suspension by grain-to-grain interactions, with the fluid acting only as a lubricant. As such, the grain-to-grain collisions generate a dispersive pressure that helps prevent grains from settling out of suspension. Although common in ter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbidity Current
A turbidity current is most typically an underwater current of usually rapidly moving, sediment-laden water moving down a slope; although current research (2018) indicates that water-saturated sediment may be the primary actor in the process. Turbidity currents can also occur in other fluids besides water. Researchers from the Monterey Bay Aquarium Research Institute found that a layer of water-saturated sediment moved rapidly over the seafloor and mobilized the upper few meters of the preexisting seafloor. Plumes of sediment-laden water were observed during turbidity current events but they believe that these were secondary to the pulse of the seafloor sediment moving during the events. The belief of the researchers is that the water flow is the tail-end of the process that starts at the seafloor. In the most typical case of oceanic turbidity currents, sediment laden waters situated over sloping ground will flow down-hill because they have a higher density than the adjacent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dish Structures
A dish structure is a type of sedimentary structure formed by liquefaction and fluidization of water-charged soft sediment either during or immediately following deposition. Terminology Due to the similarity in its shape to a dish, the structure, sometimes also referred to as dish-and-pillar or dish-and-pipe , was named after the common kitchen item. History Dish structure was described scientifically for the first time by Crook in 1961 who still used the title ''discontinuous curved lamination''. The established term was used for the first time in 1967 by Stauffer and by Wentworth. Comprehensive studies are due to Lowe and LoPiccolo in 1974 and Lowe in 1975. Description The subhorizontal dish structure consists of two parts, the dish itself and the edimentcontained within the dish plus the region stretching up to the bounding surface of the overlying dish(or dishes) above. The bounding surface of the dish can take on variable shapes, from substantially flat to bowl-like a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
