Caliche

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Caliche fossil forest on San Miguel Island, California San-miguel-island-caliche.jpg
Caliche fossil forest on San Miguel Island, California

Caliche ( /kəˈliːtʃiː/ ) (unrelated to the street-slang "Caliche" spoken in El Salvador) is a soil accumulation of soluble calcium carbonate at depth, where it precipitates and binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or semiarid regions, including in central and western Australia, in the Kalahari Desert, in the High Plains of the western United States, in the Sonoran Desert, Chihuahuan Desert and Mojave Desert of North America, and in eastern Saudi Arabia at Al-Hasa. Caliche is also known as calcrete or kankar (in India). It belongs to the duricrusts. The term caliche is borrowed from Spanish and is originally from the Latin word calx , meaning lime. [1]

Contents

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

In northern Chile and Peru, caliche also refers to mineral deposits that include nitrate salts. [4] [5] Caliche can also refer to various claylike deposits in Mexico and Colombia. In addition, it has been used to describe some forms of quartzite, bauxite, kaolinite, laterite, chalcedony, opal, and 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 calcite are formed. Plant roots play an important role in caliche formation, by releasing large amounts of carbon dioxide into the A horizon of the soil. Carbon dioxide levels here can exceed 15 times normal atmospheric values. This allows calcium carbonate to dissolve as bicarbonate. Where rainfall is adequate but not excessive, the calcium bicarbonate is carried down into the 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 capillary 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 of 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 Caliche - Sedimentary Rock Ridgecrest Kern County California.jpg
Caliche — sedimentary rock, Ridgecrest, Kern County, California
Calcrete rubble was widely used for building construction in South Australia during the 19th century. Limestone rubble wall with brick quoins.jpg
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 Caliche-5731.jpg
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 sugar. 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 requires beneficiation to meet the requirements, its use can still be significantly cheaper than shipping in limestone. [20]

Chilean caliche

In the Atacama Desert in northern Chile, vast deposits of a mixture, also referred to as caliche, are composed of gypsum, sodium chloride and other salts, and sand, associated to salitre ("Chile saltpeter"). Salitre, in turn, is a composite of sodium nitrate (NaNO3) and potassium nitrate (KNO3). Salitre was an important source of export revenue for Chile until World War I, when Europe began to produce both nitrates 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 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 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

Related Research Articles

<span class="mw-page-title-main">Weathering</span> Deterioration of rocks and minerals through exposure to the elements

Weathering is the deterioration of rocks, soils and minerals through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs in situ, and so is distinct from erosion, which involves the transport of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity.

<span class="mw-page-title-main">Sodium carbonate</span> Chemical compound

Sodium carbonate is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water. Historically, it was extracted from the ashes of plants grown in sodium-rich soils, and because the ashes of these sodium-rich plants were noticeably different from ashes of wood, sodium carbonate became known as "soda ash". It is produced in large quantities from sodium chloride and limestone by the Solvay process, as well as by carbonating sodium hydroxide which is made using the chloralkali process.

<span class="mw-page-title-main">Sodium nitrate</span> Chemical compound

Sodium nitrate is the chemical compound with the formula NaNO
3. This alkali metal nitrate salt is also known as Chile saltpeter to distinguish it from ordinary saltpeter, potassium nitrate. The mineral form is also known as nitratine, nitratite or soda niter.

<span class="mw-page-title-main">Travertine</span> Form of limestone deposited by mineral springs

Travertine is a form of terrestrial limestone deposited around mineral springs, especially hot springs. It often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and rusty varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot spring or in a limestone cave. In the latter, it can form stalactites, stalagmites, and other speleothems. It is frequently used in Italy and elsewhere as a building material. Similar deposits formed from ambient-temperature water are known as tufa.

<span class="mw-page-title-main">Dry lake</span> Area that contained a standing surface water body

A dry lake bed, also known as a playa, is a basin or depression that formerly contained a standing surface water body, which disappears when evaporation processes exceed recharge. If the floor of a dry lake is covered by deposits of alkaline compounds, it is known as an alkali flat. If covered with salt, it is known as a salt flat.

<span class="mw-page-title-main">Niter</span> Mineral form of potassium nitrate

Niter or nitre is the mineral form of potassium nitrate, KNO3. It is a soft, white, highly soluble mineral found primarily in arid climates or cave deposits.

<span class="mw-page-title-main">Duricrust</span> Type of surface soil layer

Duricrust is a hard layer on or near the surface of soil. Duricrusts can range in thickness from a few millimeters or centimeters to several meters.

The pedosphere is the outermost layer of the Earth that is composed of soil and subject to soil formation processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. The pedosphere is the skin of the Earth and only develops when there is a dynamic interaction between the atmosphere, biosphere, lithosphere and the hydrosphere. The pedosphere is the foundation of terrestrial life on Earth.

In soil science, agriculture and gardening, hardpan or soil pan is a dense layer of soil, usually found below the uppermost topsoil layer. There are different types of hardpan, all sharing the general characteristic of being a distinct soil layer that is largely impervious to water. Some hardpans are formed by deposits in the soil that fuse and bind the soil particles. These deposits can range from dissolved silica to matrices formed from iron oxides and calcium carbonate. Others are man-made, such as hardpan formed by compaction from repeated plowing, particularly with moldboard plows, or by heavy traffic or pollution.

<span class="mw-page-title-main">Water softening</span> Removing positive ions from hard water

Water softening is the removal of calcium, magnesium, and certain other metal cations in hard water. The resulting soft water requires less soap for the same cleaning effort, as soap is not wasted bonding with calcium ions. Soft water also extends the lifetime of plumbing by reducing or eliminating scale build-up in pipes and fittings. Water softening is usually achieved using lime softening or ion-exchange resins, but is increasingly being accomplished using nanofiltration or reverse osmosis membranes.

A soil horizon is a layer parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture. These may be described both in absolute terms and in terms relative to the surrounding material, i.e. 'coarser' or 'sandier' than the horizons above and below.

<span class="mw-page-title-main">The Pinnacles (Western Australia)</span> Iimestone formation in Western Australia

The Pinnacles are limestone formations within Nambung National Park, near the town of Cervantes, Western Australia.

Gypcrete or gypcrust is a hardened layer of soil, consisting of around 95% gypsum. Gypcrust is an arid zone duricrust. It can also occur in a semiarid climate in a basin with internal drainage, and is initially developed in a playa as an evaporate. Gypcrete is the arid climate's equivalent to calcrete, which is a duricrust that is unable to generate in very arid climates.

<span class="mw-page-title-main">Calcareous</span> Adjective meaning mostly or partly composed of calcium carbonate

Calcareous is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.

<span class="mw-page-title-main">Sabkha</span> Salt lake above the tide line, where evaporite deposits accumulate

A sabkha is a coastal, supratidal mudflat or sandflat in which evaporite-saline minerals accumulate as the result of semiarid to arid climate. Sabkhas are gradational between land and intertidal zone within restricted coastal plains just above normal high-tide level. Within a sabkha, evaporite-saline minerals sediments typically accumulate below the surface of mudflats or sandflats. Evaporite-saline minerals, tidal-flood, and aeolian deposits characterize many sabkhas found along modern coastlines. The accepted type locality for a sabkha is at the southern coast of the Persian Gulf, in the United Arab Emirates. Evidence of clastic sabkhas are found in the geological record of many areas, including the UK and Ireland. Sabkha is a phonetic transliteration of the Arabic word used to describe any form of salt flat. A sabkha is also known as a sabkhah,sebkha, or coastal sabkha.

<span class="mw-page-title-main">Alkaline precipitation</span>

Alkaline precipitation occurs due to natural and anthropogenic causes. It happens when minerals, such as calcium, aluminum, or magnesium combine with other minerals to form alkaline residues that are emitted into the atmosphere, absorbed by water droplets in clouds, and eventually fall as rain. Aquatic environments are especially impacted by alkaline precipitation. Because alkaline precipitation can be harmful to the environment, it is important to utilize various methods such as air pollution control, solidification and stabilization, and remediation to manage it.

<span class="mw-page-title-main">Alkali soil</span> Soil type with pH > 8.5

Alkali, or Alkaline, soils are clay soils with high pH, a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 metre depth. Alkali soils owe their unfavorable physico-chemical properties mainly to the dominating presence of sodium carbonate, which causes the soil to swell and difficult to clarify/settle. They derive their name from the alkali metal group of elements, to which sodium belongs, and which can induce basicity. Sometimes these soils are also referred to as alkaline sodic soils. Alkaline soils are basic, but not all basic soils are alkaline.

Kankar or (kunkur) is a sedimentological term derived from Hindi which is occasionally applied in both India and the United States to detrital or residual rolled, often nodular calcium carbonate formed in soils of semi-arid regions. It is used in the making of lime and of roads. It forms sheets across alluvial plains, and can occur as discontinuous lines of nodular kankar or as indurated layers in stratigraphic profiles. Such are more generally referred to as calcrete, hardpan or duricrust.

Microspherulites are microscopic spherical particles with diameter less than two mm, usually in the 100 micrometre range, mainly consisting of mineral material. Only bodies created by natural physico-chemical processes, with no contribution of either biological or human activity, are considered to be microspherulites. Generally speaking, the common feature (sphericity) indicates that each sphere represents an internal equilibrium of forces within a fluid medium.

<span class="mw-page-title-main">Blanco Formation</span>

The Blanco Formation, originally named the Blanco Canyon Beds, is an early Pleistocene geologic formation of clay, sand, and gravel whitened by calcium carbonate cementation and is recognized in Texas and Kansas.

References

  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. S2CID   129247211.
  3. 1 2 Allaby, Michael, ed. (2013). "Caliche". A dictionary of geology and earth sciences (Fourth ed.). Oxford: Oxford University Press. ISBN   9780199653065.
  4. ↑ Chong et al. 2007, p. 211.
  5. ↑ A Most Damnable Invention: Dynamite, Nitrates, and the Making of the Modern World, Stephen R. Bown, Macmillan, 2005, ISBN   0-312-32913-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. 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. 1 2 Schlesinger, 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. S2CID   233857091.
  12. ↑ C. Michael Hogan (2008) Makgadikgadi, The Megalithic Portal, ed. A. Burnham
  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. S2CID   97632160 . Retrieved 25 March 2022.
  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 . ISSN   2183-4431.
  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 . Retrieved 25 March 2022.
  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. ISBN   9781000366549.{{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. ISBN   9780803107878 . Retrieved 26 March 2022.
  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. S2CID   195225634.
  21. 1 2 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.

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