Accumulation of sediment

In the case of the turbidity currents, this redistribution usually occurs along the foot of the continental slope and is largely responsible for the accumulation of sediments in the continental rise. The resuspension of particles by contour currents can also maintain permanent nepheloid layers as shown in Figure 13.10. 

Baker, E.G. A h3q>othesis concerning the accumulation of sediment hydrocarbons to form crade oil, Geochim. Cosmochim. Acta, 19(4) 309-317, 1980. 

Delta A fan-shaped accumulation of sediments that forms when a river empties into a sea, large lake, or ocean. 

Sedimentation (geology) The accumulation of sediment in a natural environment, including rivers, lakes, seas, oceans, and deserts. 

The accumulation of sediments in estuaries appears to be so effective that Meade (1981) has estimated that, "Probably less than 5 percent of all river sediment discharged into the tidal waters of the Atlantic seaboard is deposited on the floor of the continental shelf or the deep sea". These sediments contain an often dramatic imprint of human activity and impact on the estuary and its watershed. But it is an imprint which results not only from the input of materials, but also from the interaction of a great variety of physical, chemical and biological processes in the estuary. We are only beginning to learn to read that record, but the early results suggest that we may learn more about what flows between rivers and the sea from the humble muds on the estuary floor than we can from the water above. 

As a result of particle settlement to the sediment-water interface, there is a mass accumulation of sediments which results in compaction of sediments and the physical upward transport or advection of solutes in porewaters to the overlying water. Similarly, solutes in porewaters can also move by diffusion as a result of concentration gradients. Thus, porewaters can be transported by advection from burials, molecular diffusion, and biological pumping or irrigation (Aller, 2001 Jprgensen and Boudreau, 2001). Diffusion in aqueous environments occurs according to Fick s laws of diffusion (Berner, 1980). Fick s first law, used for steady-state conditions, is as follows ... 

Asa result of particle settlement to the sediment-water interface there is a mass accumulation of sediments which results in compaction of sediments and the physical upward transport or advection of solutes in porewaters to the overlying water. Similarly, solutes in porewaters can also move by diffusion as a result of concentration gradients. 

McCaffrey, R.J., and Thomson, J. (1980) A record of the accumulation of sediments and trace metals in a Connecticut salt marsh. In Advances in Geophysics, Estuarine Physics and Chemistry Studies in Long Island Sound (Saltzman, B., ed.), pp. 165-236, Academic Press, New York. 

Due to accumulation of sediments in reservoirs, the sediment load of the majority of rivers decreased much more than their water runoff. A maximum decrease in sediment load has occurred in the Kuban, Don, Rioni, and Danube rivers (by a factor of 5.6,2.8, 2.4 and 1.5, respectively). 

Tectonic processes, by contrast, can be simplified to two parameters. These are vertical uplift, which creates crustal source areas for weathering and erosion, and subsidence, which together with eustasy acts to control the accommodation space availaltle for accumulation of sediments (e.g., Sloss, 1962). 

Deposition— Accumulation of sediments at the end of their transport by erosion. 

Sedimentary—Formed by accumulation of sediment, mostly commonly by deposition from water. 

Some of the features of beaches are created by wave action. An accumulation of sediment that is deposited parallel to shore forms a section called the berm. The berm marks the upper limit of sand deposition by waves. The top of the berm, the berm crest, is usually the highest place on the beach. The backshore, an area made up of sand that is deposited in... 

Wind-blown sand dunes are accumulations of sediment laid down by aeolian processes and fashioned into bedforms by deflation and deposition (Livingstone and Warren, 1996). A supply of sand grains, either marine carbonate material or terrigenous lithoclasts that can be entrained by the... 

In addition to appreciable amounts of water (ASTM D-4176, ASTM D-4860), sediment can also occur and will cause fouling of the fuel handling facilities and the fuel system. An accumulation of sediment in storage tanks and on filter screens can obstruct the flow of oil from the tank to the combustor. A test method is available to determine the water and sediment in fuels (ASTM D-2709). In this test, a sample of fuel is centrifuged at a ref of 800 for 10 min at 21-32°C in a centrifuge tube readable to 0.005 ml and measurable to 0.01 ml. After centrifugation, the volume of water and sediment that has settled into the tip of the centrifuge tube is read to the nearest 0.005 ml. 

The transport mechanisms include dispersal by diffusional processes, water flow (advection), settling of biological or detrital particles through the water column, and accumulation of sediment on the floor. In view of the primary significance of diffusion in the transport of dissolved matter in a water column, this mechanism and its bearing on a number of chemical processes will be discussed in detail in this paper. 

A RECORD OF THE ACCUMULATION OF SEDIMENT AND TRACE METALS IN A CONNECTICUT SALT MARSH... 

If the rate of accumulation of sediment and excess Pb have both been constant, as is often assumed, and the deposit is undisturbed, then the accumulation rate S can be estimated from the best-fit straight-line equation describing radioactive decay ... 

McCaffrey, R. J. (1977). A record of the accumulation of sediment and trace metals in a Connecticut, U.S.A., salt marsh. Ph.D. Thesis, Yale University, New Haven, Connecticut. 

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