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Caliche

(Redirected fromCalcrete)

Caliche(/kəˈliːtʃiː/) (unrelated to the street-slang "Caliche" spoken inEl Salvador) is a soil accumulation of solublecalcium carbonateat depth, where it precipitates and binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, inaridisolandmollisolsoil orders—generally inaridorsemiaridregions, including in central and westernAustralia,in theKalahari Desert,in theHigh Plainsof the westernUnited States,in theSonoran Desert,Chihuahuan DesertandMojave Desertof North America, and in eastern Saudi Arabia atAl-Hasa.Caliche is also known ascalcreteorkankar(in India). It belongs to theduricrusts.The termcalicheis borrowed from Spanish and is originally from the Latin wordcalx,meaninglime.[1]

Calichefossil forestonSan Miguel Island,California

Caliche is generally light-colored but can range from white to light pink to reddish-brown, depending on the minerals present. Caliche is a mark of older landscapes. It generally occurs on or very near the surface. Where caliche layers originate at some depth from the soil surface, intact landscapes and buried landscapes are more likely than eroded surfaces to have caliche well below the soil surface. Layers vary from a few inches to feet thick, and multiple layers can exist in a single location. The caliche layer in asoil profileis sometimes called a K horizon.[2][3]

In northernChileandPeru,calichealso refers to mineral deposits that includenitratesalts.[4][5]Caliche can also refer to various claylike deposits inMexicoandColombia.In addition, it has been used to describe some forms ofquartzite,bauxite,kaolinite,laterite,chalcedony,opal,andsoda niter.

A similar material, composed ofcalcium sulfaterather thancalcium carbonate,is calledgypcrust.

Formation

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Caliche forms where annual precipitation is less than 65 centimeters (26 in) per year and the mean annual temperature exceeds 5 °C (41 °F). Higher rainfall leaches excess calcium completely from the soil, while in very arid climates, rainfall is inadequate to leach calcium at all and only thin surface layers ofcalciteare formed. Plant roots play an important role in caliche formation, by releasing large amounts ofcarbon dioxideinto theA horizonof the soil. Carbon dioxide levels here can exceed 15 times normal atmospheric values. This allows calcium carbonate to dissolve asbicarbonate.Where rainfall is adequate but not excessive, the calcium bicarbonate is carried down into theB horizon.Here there is less biological activity, the carbon dioxide level is much lower, and the bicarbonate reverts to insoluble carbonate. A mixture of calcium carbonate and clay particles accumulates, first forming grains, then small clumps, then a discernible layer, and finally, a thicker, solid bed.[6]

However, caliche also forms in other ways. It can form when water rises throughcapillary action.In an arid region, rainwater sinks into the ground very quickly. Later, as the surface dries out, the water below the surface rises, carrying up dissolved minerals from lower layers. These precipitate as water evaporates and carbon dioxide is lost. This water movement forms a caliche that is close to the surface.[7]Caliche can also form on outcrops ofporousrocks or in rock fissures where water is trapped and evaporates.[8]In general, caliche deposition is a slow process, requiring several thousand years.[3]

The depth of the caliche layer is sensitive to mean annual rainfall. When rainfall is around 35 centimeters (14 in) per year, the caliche layer will be as shallow as 25 centimeters (9.8 in). When rainfall is around 75 centimeters (30 in) per year, the caliche layer will be at a depth of around 125 centimeters (49 in). The caliche layer disappears complete in temperate climates if annual rainfall exceeds 100 centimeters (39 in).[9]

The source of the calcium in caliche may be the underlying bedrock, but caliche can form even over bedrock that is not rich in calcium. This is attributed to calcium brought in asaeolian dust.[10][11]

Examples of natural occurrence

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Caliche — sedimentary rock, Ridgecrest, Kern County, California
Calcrete rubble was widely used for building construction inSouth Australiaduring the 19th century.

While the formation of other caliches is relatively well understood, the origin of Chilean caliche is not clearly known. One possibility is that the deposits were formed when aprehistoricinland sea evaporated. Another theory is that it was deposited due to weathering of theAndes.

One of the world's largest deposits of calcrete is in theMakgadikgadi PansinBotswana,where surface calcretes occur at the location of a now-desiccated prehistoric lake.[12]

Highly indurated (hardened) caliche is known as calcrete, and it gives rise to characteristiclandformsin arid environments. Calcrete is found throughout the geologic record, forming a record of past climate. Examples includeMississippiancalcretes inSouth WalesandPliocenetoPleistocenecaprock of theLlano EstacadoofTexas,US, andMormon Mesa,Nevada,US.[10]

Caliches can store significant amounts of carbon, making them of significance to the overall globalcarbon cycle.[13]

In Jurassic geological settings, the caliche is often indicator of warm climate with well marked wet-dry seasonality[14]that could indicate seasonal monsoons.

Economic uses

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Building applications

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Caliche is used in construction worldwide. Its reserves in theLlano EstacadoinTexascan be used in the manufacture ofPortland cement;the caliche meets the chemical composition requirements and has been used as a principal raw material in Portland cement production.[15]

Calichebermsurrounding astock tankinCentral Texas

The Great House atCasa Grande Ruins National Monument,Arizona,US, was built with walls of caliche.[16]Caliche was also used in mortars used in of theMayanbuildings in theYucatán PeninsulainMexico.[17]A dormitory inIngram, Texas,and a demonstration building inCarrizo Springs, Texas,for theUnited States Department of Energywere also built using caliche as part of studies by theCenter for Maximum Potential Building Systems.[18]

In many areas, caliche is also used for road construction, either as a surfacing material, or more commonly, as base material. It is one of the most common road materials used inSouthern Africa.Caliche is widely used as a base material when it is locally available and cheap. However, it does not hold up to moisture (rain), and is never used if a hard-rock base material, such as limestone, is available.[19]

Sugar refining

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A nearly pure source of calcium carbonate is necessary to refinesugar.It must contain at least 95% calcium carbonate (CaCO3) and have a low magnesium content. In addition, the material must meet certain physical requirements so it does not break down when burned. Although caliche does not generally meet all of the requirements for sugar refining, it is used in areas where another source of calcium carbonate, such as limestone, is not present. While caliche requiresbeneficiationto meet the requirements, its use can still be significantly cheaper than shipping in limestone.[20]

Chilean caliche

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See also:Paradas method

In theAtacama Desertin northernChile,vast deposits of a mixture, also referred to ascaliche,are composed ofgypsum,sodium chlorideand other salts, and sand, associated tosalitre( "Chile saltpeter" ).Salitre,in turn, is a composite ofsodium nitrate(NaNO3) andpotassium nitrate(KNO3).Salitrewas an important source of export revenue for Chile until World War I, when Europe began to produce both nitratesindustriallyin large quantities.[21]

The deposits contain an average of 7.5% sodium nitrate, as well as sodium sulfate (18.87%), sodium chloride (4.8%), and smaller amounts of potassium, calcium, magnesium,borate,iodine, andperchlorate.About two-thirds of the deposits are insolublegangueminerals. The caliche beds are from 2 cm to several meters thick in alluvial deposits, where the soluble minerals form a cement in unconsolidatedregolith.Nitrate-bearing caliche is also found impregnating bedrock to form bedrock deposits.[21]

Caliche and agriculture

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Problems caused by caliche

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Caliche beds can cause problems for agriculture. First, an impermeable caliche layer prevents water from draining properly, which can keep roots from getting enough oxygen. Salts can also build up in the soil due to the lack of drainage. Both of these situations are detrimental to plant growth. Second, the impenetrable nature of caliche beds excludes plant roots, limiting plant access to nutrients, water, and anchorage. Third, caliche beds can also cause the surrounding soil to bebasic.The basic soil, along with calcium carbonate from the caliche, can prevent plants from getting enough nutrients, especiallyiron.Aniron deficiencymakes the youngest leaves turn yellow. Soilsaturationabove the caliche bed can make the condition worse.[22]Its hardness can also make digging for projects such as canals more difficult.

See also

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References

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  1. ^Breazeale, J.F.; Smith, H.V. (15 April 1930). "Caliche in Arizona".Agricultural Experiment Station Bulletin.131.University of Arizona: 419.
  2. ^Gile, L. H.; Peterson, F. F.; Grossman, R. B. (February 1965). "The K Horizon".Soil Science.99(2): 74–82.Bibcode:1965SoilS..99...74G.doi:10.1097/00010694-196502000-00002.S2CID129247211.
  3. ^abAllaby, Michael, ed. (2013). "Caliche".A dictionary of geology and earth sciences(Fourth ed.). Oxford: Oxford University Press.ISBN9780199653065.
  4. ^Chonget al.2007, p. 211.
  5. ^A Most Damnable Invention: Dynamite, Nitrates, and the Making of the Modern World, Stephen R. Bown, Macmillan, 2005,ISBN0-312-32913-X,p. 157.
  6. ^Blatt, Harvey; Middleton, Gerard; Murray, Raymond (1980).Origin of sedimentary rocks(2d ed.). Englewood Cliffs, N.J.: Prentice-Hall. pp. 273–275.ISBN0136427103.
  7. ^Blatt, Middleton & Murray 1980,pp. 274–275.
  8. ^Breazeale & Smith 1930,pp. 420, 428–429.
  9. ^Blatt, Middleton & Murray 1980,p. 274.
  10. ^abSchlesinger, William H. (January 1985). "The formation of caliche in soils of the Mojave Desert, California".Geochimica et Cosmochimica Acta.49(1): 57–66.Bibcode:1985GeCoA..49...57S.doi:10.1016/0016-7037(85)90191-7.
  11. ^Valera Fernández, Daisy; Solleiro Rebolledo, Elizabeth; Sedov, Sergey; Pustovoitov, Konstantin (April 2022). "Provenance, and environment context of pedogenic carbonates formation from MIS 3 to MIS 1 in the Teotihuacan Valley, Mexico".Quaternary International.618:52–69.Bibcode:2022QuInt.618...52V.doi:10.1016/j.quaint.2021.03.019.S2CID233857091.
  12. ^C. Michael Hogan (2008)Makgadikgadi,The Megalithic Portal, ed. A. Burnham[1]
  13. ^Schlesinger, William H. (April 1982)."Carbon storage in the caliche of arid soils".Soil Science.133(4): 247–255.Bibcode:1982SoilS.133..247S.doi:10.1097/00010694-198204000-00008.S2CID97632160.Retrieved25 March2022.
  14. ^Mateus, O.; Dinis, J.; Cunha, P. P. (2017-09-28)."The Lourinhã Formation: the Upper Jurassic to lower most Cretaceous of the Lusitanian Basin, Portugal – landscapes where dinosaurs walked".Ciências da Terra / Earth Sciences Journal.19(1): 75–97.doi:10.21695/cterra/esj.v19i1.355.hdl:10316/79879.ISSN2183-4431.
  15. ^Reeves, C.C. Jr.; Suggs, J.D. (1964)."Caliche of central and southern Llano Estacado, Texas".Journal of Sedimentary Research.34(3): 669–672.Bibcode:1964JSedR..34..669R.doi:10.1306/74D71131-2B21-11D7-8648000102C1865D.Retrieved25 March2022.
  16. ^Matero, Frank (January 1999)."Lessons from the Great House: Condition and treatment history as prologue to site conservation and management at Casa Grande Ruins National Monument".Conservation and Management of Archaeological Sites.3(4): 203–224.doi:10.1179/135050399793138482.
  17. ^Straulino Mainou, Luisa; Sedov, Sergey; Soler Arechalde, Ana; Pi Puig, Teresa; Villa, Gerardo; Balanzario Granados, Sandra; Doménech-Carbó, María-Teresa; Osete-Cortina, Laura; Leonard, Daniel (4 November 2016)."Maya Lime Mortars—Relationship between Archaeomagnetic Dating, Manufacturing Technique, and Architectural Function—The Dzibanché Case".Geosciences.6(4): 49.Bibcode:2016Geosc...6...49S.doi:10.3390/geosciences6040049.hdl:10251/99948.
  18. ^Fisk, Pliny (2021). "Bioregional design: The design science of the future". In Neuman, M.; Zonneveld, W. (eds.).The Routledge handbook of regional design.Abingdon.ISBN9781000366549.{{cite book}}:CS1 maint: location missing publisher (link)
  19. ^Netterberg, F. (January 1982)."Geotechnical properties and behavior of calcretes in South and South West Africa".In Demars, K.R. (ed.).Geotechnical Properties, Behavior, and Performance of Calcareous Soils.West Conshohocken: American Society for Testing & Materials.ISBN9780803107878.Retrieved26 March2022.
  20. ^Velmayil, Perumal; Venu, Udayanapillai Alagaiah (June 2019). "Micromorphology and major element geochemistry of calcretes in the Thoppukulam mine section, Sathankulam region, Southern Tamil Nadu, India: implications on depositional environment".Arabian Journal of Geosciences.12(12): 385.doi:10.1007/s12517-019-4544-4.S2CID195225634.
  21. ^abWisniak, Jaime; Garces, Ingrid (September 2001)."The rise and fall of the salitre (sodium nitrate) industry"(PDF).Indian Journal of Chemical Technology.8:427–438.Retrieved26 March2022.
  22. ^Kelly, Jack; Walworth, Jim (March 2002)."Managing caliche in the home yard"(PDF).Cooperative Extension, The University of Arizona.College of Agriculture and Life Sciences, University of Arizona.Retrieved26 March2022.

Further reading

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  • Price, William Armstrong.Reynosa Problem of Southern Texas, and Origin of Caliche.Bulletin of the American Association of Petroleum Geologists 17.5 (1933): 488–522.
  • Reeves, C.C., Jr.Caliche: Origin, Classification, Morphology and Uses.Lubbock, Texas: Estacado Books, 1976.
  • Reeves, C.C., Jr. and J.D. Suggs.Caliche of Central and Southern Llano Estacado, Texas: Notes.Journal of Sedimentary Petrology 34.3 (1964): 669–672.
  • Chong Diaz, Guillermo;Gajardo Cubillos, Aníbal; Hartley, Adrian J.; Moreno, Teresa (2006). "7. Industrial minerals and rocks". In Moreno, Teresa; Gibbons, Wes (eds.).Geology of Chile.Geological Society of London. pp. 21–114.ISBN9781862392199.
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