accommodation

eustasy

parasequence

progradation

relative sea level

relative sea level fall

relative sea level rise

regression

retrogradation

Sediment accumulation represents the amount of sediment that gathers and is stored in the rock records sedimentary sections in outcrops, wells and seismic. Sediment accumulation is the result of both the cumulative records of both sediment supply and erosion and represents the sediment that fills accommodation. Sediment accumulation can be accurately measured as a thickness. Interestingly it is subject to rates of sediment supply and rates of erosion, but neither of these latter can be measured in the rock record but they can be inferred on the basis of nearby thicknesses, evidence in the form erosion surfaces and projected or expected rates. Sediment accumulation is responsible for the local variation in the geometric character of the sedimentary parasequence sequences sets and facies patterns of basin fill. As with supply and rates of erosion, its controls include climate, relief of fluvial drainage basin, lithology of substrate, and vegetative cover. Changes of sediment supply can be caused by tectonism and climate changes, often at a local level. The rate and nature of sediment supply may cause changes in accommodation.

Sediment accumulation for both clastics and carbonates vary as a function of sea level position. Clastic accumulation will tend to vary as a function of accommodation. It is higher offshore during relative sea level lows when higher rates of erosion of the more exposed inland interfluve areas occur and deposition is distal to this erosion. During the same lows carbonate accumulation will fill offshore basins if these are shallow enough, but will be non-existent on the exposed basin margin. The source of the clastic sediment is likely the updip unconformities associated with sequence boundaries. Clastic accumulation rates are lower during transgressions and highstands in sea level. carbonates tend to accumulate in the offshore with rapid rises in sea level, and can keep pace with the sea level rise in the inner shelf lagoons. During highs in sea level the carbonate accumulation fills the inner shelf and progrades seaward across shallow shelves. carbonate turbidites are associated with the increase in slope of the basin margins during sea level highs but will be their most prolific when the upper part of the margin is exposed during sea level lows while the down slope margin can become the main carbonate factory and the site of greatest carbonate

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