Caliche

Source: Wikipedia, the free encyclopedia.
(Redirected from
Calcrete
)
Caliche fossil forest on San Miguel Island, California

Caliche (

lime.[1]

Caliche is generally light-colored, but can range from white to light pink to reddish-brown, depending on the impurities present. It generally occurs on or near the surface, but can be found in deeper subsoil deposits, as well. Layers vary from a few inches to feet thick, and multiple layers can exist in a single location. A caliche layer in a

soil profile is sometimes called a K horizon.[2][3]

In northern

soda niter
.

A similar material, composed of calcium sulfate rather than calcium carbonate, is called gypcrust.

Formation

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 of

B 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 through

porous rocks 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 as

aeolian dust.[10][11]

Examples of natural occurrence

Caliche — sedimentary rock, Ridgecrest, Kern County, California
Calcrete rubble was widely used for building construction in South Australia during 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 a

prehistoric inland sea evaporated. Another theory is that it was deposited due to weathering of the Andes
.

One of the world's largest deposits of calcrete is in the

Makgadikgadi Pans in Botswana, 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 characteristic

landforms in arid environments. Calcrete is found throughout the geologic record, forming a record of past climate. Examples include Mississippian calcretes in South Wales and Pliocene to Pleistocene caprock of the Llano Estacado of Texas, US, and Mormon Mesa, Nevada, US.[10]

Caliches can store significant amounts of carbon, making them of significance to the overall global carbon 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

Building applications

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

Caliche berm surrounding a stock tank in Central Texas

The Great House at Casa Grande Ruins National Monument, Arizona, US, was built with walls of caliche.[16] Caliche was also used in mortars used in of the Mayan buildings in the Yucatán Peninsula in Mexico.[17] A dormitory in Ingram, Texas, and a demonstration building in Carrizo Springs, Texas, for the United States Department of Energy were also built using caliche as part of studies by the Center 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 in Southern 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

A nearly pure source of calcium carbonate is necessary to refine

beneficiation to meet the requirements, its use can still be significantly cheaper than shipping in limestone.[20]

Chilean caliche

See also: Paradas method

In the

industrially in 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, and perchlorate. About two-thirds of the deposits are insoluble gangue minerals. The caliche beds are from 2 cm to several meters thick in alluvial deposits, where the soluble minerals form a cement in unconsolidated regolith. Nitrate-bearing caliche is also found impregnating bedrock to form bedrock deposits.[21]

Caliche and agriculture

Problems caused by caliche

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 impermeable nature of caliche beds prevents plant roots from penetrating the bed, which limits the supply of nutrients, water, and space so they cannot develop normally. Third, caliche beds can also cause the surrounding soil to be

basic. The basic soil, along with calcium carbonate from the caliche, can prevent plants from getting enough nutrients, especially iron. An iron deficiency makes the youngest leaves turn yellow. Soil saturation above the caliche bed can make the condition worse.[22]
Its hardness can also make digging for projects such as canals more difficult.

See also

References

  1. ^ Breazeale, J.F.; Smith, H.V. (15 April 1930). "Caliche in Arizona". Agricultural Experiment Station Bulletin. 131. University of Arizona: 419.
  2. S2CID 129247211
    .
  3. ^
    ISBN 9780199653065
    .
  4. ^ Chong et al. 2007, p. 211.
  5. ISBN 0-312-32913-X
    , p. 157.
  6. ISBN 0136427103
    .
  7. ^ Blatt, Middleton & Murray 1980, pp. 274–275.
  8. ^ Breazeale & Smith 1930, pp. 420, 428–429.
  9. ^ Blatt, Middleton & Murray 1980, p. 274.
  10. ^
    doi:10.1016/0016-7037(85)90191-7
    .
  11. S2CID 233857091
    .
  12. ^ C. Michael Hogan (2008) Makgadikgadi, The Megalithic Portal, ed. A. Burnham [1]
  13. S2CID 97632160
    . Retrieved 25 March 2022.
  14. ISSN 2183-4431
    .
  15. doi:10.1306/74D71131-2B21-11D7-8648000102C1865D
    . Retrieved 25 March 2022.
  16. doi:10.1179/135050399793138482
    .
  17. hdl:10251/99948
    .
  18. ISBN 9781000366549.{{cite book}}: CS1 maint: location missing publisher (link
    )
  19. ISBN 9780803107878
    . Retrieved 26 March 2022.
  20. S2CID 195225634
    .
  21. ^ a b Wisniak, Jaime; Garces, Ingrid (September 2001). "The rise and fall of the salitre (sodium nitrate) industry" (PDF). Indian Journal of Chemical Technology. 8: 427–438. Retrieved 26 March 2022.
  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. Retrieved 26 March 2022.

Further reading

  • 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.
  • ISBN 9781862392199
    .

External links

Look up caliche in Wiktionary, the free dictionary.
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