# Dish structure > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Dish_structure > Markdown URL: https://mediated.wiki/source/Dish_structure.md > Source: https://en.wikipedia.org/wiki/Dish_structure > Source revision: 1311813643 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) A '''dish structure''' is a type of [sedimentary structure](/source/sedimentary_structure) formed by [liquefaction](/source/liquefaction) and [fluidization](/source/fluidization) of water-charged soft sediment either during or immediately following deposition. == Terminology == Due to the similarity in its shape to a [dish](/source/Plate_(dishware)), 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 1961K. A. W. Crook (1961). In: J. Proc. R. Soc. N.S.W., 94, p. 189 – 207 who still used the title ''discontinuous curved lamination''. The established term was used for the first time in 1967 by StaufferP. H. Stauffer (1967). Grain flow deposits and their implications, Santa Ynes Mountains, California. Journal of Sedimentary Petrology, '''32''', p. 487-508 and by Wentworth.C. M. Wentworth (1967). Dish structure, a primary sedimentary structure and coarse turbidites. Am. Assoc. Petrol. Geol. Bull., '''51''', p. 85 -96 Comprehensive studies are due to Lowe and LoPiccolo in 1974 and Lowe in 1975.D. R. Lowe (1975). Water escape structures in coarse-grained sediments. Sedimentology, '''22''', p. 157 – 204 == Description == thumb|Sketched dish structure from the Jack Fork Group. Nearly perfect dish in red, water escape indicated by yellow arrows. Upturned edge of a dish in blue. The subhorizontal dish structure consists of two parts, the dish itself and the [sediment] contained 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, to strongly concave up. The bounding surfaces are often thin and darker laminae that are richer in clay, silt or organic material than the surrounding sediment. The individual dishes are arranged ''[en echelon](/source/wiktionary%3Aen_echelon)''. Their width can vary from 2 centimeters to over 50 centimeters, the vertical spacing ranges usually from less than 1 centimeter to about 8 centimeters. Their plan shape grades from circular/polygonal to oval/elliptical. Their bases are sharp, but the tops are gradational. Commonly the dishes are separated by vertical streaks of massive sand called 'pillars'. These pillars can be small-scale structures (Type A pillars) or large and throughgoing high-discharge structures (Type B pillars). Within an individual bed an increase in concavity combined with a simultaneous decrease in width of the dishes can often be observed towards the top. == Occurrence == thumb|Giant dish structure near Talara, Peru Dish structure occurs in laterally extensive sheets. The medium in which the structure forms is usually coarse [silt](/source/silt), but it also appears in all grades of [sand](/source/sand). They are never found in [gravel](/source/gravel)s nor in [clay](/source/clay)s. The containing beds are normally graded. The [depositional environment](/source/depositional_environment) of the structure is mainly deep-water marine (i.e. [continental rise](/source/continental_rise)) comprising coarser grained [turbidity current](/source/turbidity_current)s and related high-concentration flows (grain flows, fluidized flows, liquefied flows). But dish structure can also be encountered in [shallow-marine](/source/shallow-marine) deposits and in [fluviatile](/source/fluviatile), [lacustrine](/source/lake) and [delta](/source/River_delta) environments.T. H. Nilsen et al. (1977). New occurrence of dish structure in the stratigraphic record. Journal of Sedimentary Petrology, '''47''', p. 1299–1304 It is occasionally found in [ash](/source/Volcanic_ash) layers within marine sediments. In turbidites dish structure usually forms within [Bouma C](/source/Bouma_sequence), occasionally also within Bouma B. Good examples of dish structure can be seen for instance in the [Jack Fork Group](/source/Jack_Fork_Group) in [Oklahoma](/source/Oklahoma), in [Ordovician](/source/Ordovician) turbidites at [Cardigan](/source/Cardigan%2C_Ceredigion) in [Wales](/source/Wales), in deep-sea fan deposits near [San Sebastián](/source/San_Sebasti%C3%A1n) in Spain and in the [Cerro Torro Formation](/source/Cerro_Torro_Formation) of southern [Chile](/source/Chile). Some of the largest dish structure is found near [Talara](/source/Talara) in northern [Peru](/source/Peru). == Formation == Up to 1974 dish structure was still regarded as a '''primary sedimentary structure'''. The formation of the structure was thought to be related either to the mechanics of sediment transport or to deposition in high-concentration [gravity-flows](/source/sediment_gravity_flow). Only since Lowe and LoPiccolos's study, the structure is recognized as penecontemporaneous or '''secondary''', formed during the dewatering of rapidly deposited quick or underconsolidated beds.D. R. Lowe & R. D. LoPiccolo (1974). The characteristics and origins of dish and pillar structures. Journal of Sedimentary Petrology, '''44''', p. 484 – 501 The '''postdepositional character''' of dish structure can sometimes clearly be seen in cut or displaced primary sedimentary structures (like [convolute-laminated beds](/source/convolute_bedding)). During the dewatering process less [permeable](/source/permeability_(earth_sciences)) horizons (richer in small grain sizes like dispersed mud) act as barriers to upward flow; the flow is consequently forced sideways until an upward escape is possible. The sideways directed fluid motion has the tendency to leave fines along the low-permeability barriers which eventually become the clay-enriched laminae of the dishes. When the fluid finally finds a possibility to escape vertically it turns up the edges of the dishes. More forceful upward flow creates pillars – which are essentially dewatering pipes. == Use == Dish structure is a powerful means to recognize the [younging direction](/source/Way_up_structure) in sediments. == References == == Literature == * J. R. L. Allen (1984). Sedimentary structures. Their character and physical basis. Elsevier. {{ISBN|0-444-42232-3}} * M. E. Leeder (1999). Sedimentology and Sedimentary Basins. Blackwell Science. {{ISBN|0-632-04976-6}} * H.-E. Reineck & I.B. Singh (1980). Depositional Sedimentary Environments. Springer-Verlag. {{ISBN|0-387-10189-6}} {{DEFAULTSORT:Dish Structure}} Category:Sedimentology Category:Sedimentary structures --- Adapted from the Wikipedia article [Dish structure](https://en.wikipedia.org/wiki/Dish_structure) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Dish_structure?action=history)). 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