What Term Refers to the Formations That Grow Downward From the Top of Mammoth Caves
Cave labeled with the half-dozen about common types of speleothems.
A speleothem (; from Greek: σπήλαιον , spḗlaion , 'cave' + θέμα , théma , 'eolith') is a geological formation past mineral deposits that accumulate over time in natural caves.[1] Speleothems most normally form in calcareous caves due to carbonate dissolution reactions. They tin take a variety of forms, depending on their depositional history and surroundings. Their chemical composition, gradual growth, and preservation in caves make them useful paleoclimatic proxies.
Chemic and physical characteristics [edit]
More than 300 variations of cave mineral deposits take been identified.[2] The vast majority of speleothems are calcareous, composed of calcium carbonate (CaCO3) minerals (calcite or aragonite). Less commonly, speleothems are fabricated of calcium sulfate (gypsum or mirabilite) or opal.[ii] Speleothems of pure calcium carbonate or calcium sulfate are translucent and colorless. The presence of atomic number 26 oxide or copper provides a blood-red brown color. The presence of manganese oxide tin create darker colors such equally black or dark brownish. Speleothems can also be chocolate-brown due to the presence of mud and silt.[two]
Many factors impact the shape and color of speleothems, including the chemical composition of the rock and h2o, water seepage rate, water period direction, cave temperature, cave humidity, air currents, aboveground climate, and aboveground plant embrace. Weaker flows and short travel distances form narrower stalagmites, while heavier period and a greater autumn distance tend to form broader ones.
Formation processes [edit]
Nearly cave chemistry involves calcium carbonate (CaCOiii) containing rocks such every bit limestone or dolomite, composed of calcite or aragonite minerals. Carbonate minerals are more soluble in the presence of higher carbon dioxide (COii) and lower temperatures. Calcareous speleothems class via carbonate dissolution reactions whereby rainwater reacts with soil COtwo to create weakly acidic water via the reaction:[three]
- H2O + CO2 → H2COiii
Equally the acidic water travels through the calcium carbonate boulder from the surface to the cave ceiling, it dissolves the bedrock via the reaction:
- CaCO3 + HiiCO3 → Ca2+ + 2 HCOthree −
When the solution reaches a cave, the lower pCO2 in the cavern drives the precipitation of CaCO3 via the reaction:
- Ca2+ + two HCOthree − → CaCOthree + H2O + CO2
Over time, the accumulation of these precipitates form dripstones (stalagmites, stalactites), and flowstones, 2 of the major types of speleothems.
Climate proxies [edit]
Speleothem transects can provide paleoclimate records similar to those from ice cores or tree rings.[four] Slow geometrical growth and incorporation of radioactive elements enables speleothems to exist accurately and precisely dated over much of the late Quaternary by radiocarbon dating and uranium-thorium dating, as long as the cavern is a airtight organisation and the speleothem has not undergone recrystallization.[v] Oxygen (δ18O) and carbon (δ13C) stable isotopes are used to track variation in rainfall temperature, atmospheric precipitation, and vegetation changes over the past ~500,000 years.[6] [7] Variations in precipitation alter the width of speleothem rings: closed rings indicates little rainfall, wider spacing indicates heavier rainfall, and denser rings indicate college wet. Drip charge per unit counting and trace element analysis of the h2o drops record short-term climate variations, such as El Niño–Southern Oscillation (ENSO) climate events.[viii] Exceptionally, climate proxy data from the early Permian menses accept been retrieved from speleothems dated to 289 million years agone sourced from infilled caves exposed by quarrying at the Richards Spur locality in Oklahoma.[9]
Types and categories [edit]
(A) Stalactite (B) Soda straws (C) Stalagmites (D) Coned stalagmite (Eastward) Stalagnate or cavalcade (F) Drapery (K) Drapery (H) Helictites (I) Moonmilk (J) Sinter puddle, rimstone (K) Calcite crystals (50) Sinter terrace (M) Karst (N) Body of water (O) Shield (P) Cavern clouds (Q) Cave pearls (R) Tower cones (S) Shelfstones (T) Baldacchino awning (U) Bottlebrush stalactite (V) Conulite (Due west) Flowstone (X) Trays (Y) Calcite rafts (Z) Cave popcorn or coralloids (AA) Frostworks (AB) Flowstone (Ac) Splattermite (Advertising) Speleoseismites (AE) Boxworks (AF) Oriented stalactite (AG) complanate rubble
Speleothems take diverse forms, depending on whether the water drips, seeps, condenses, flows, or ponds. Many speleothems are named for their resemblance to man-made or natural objects. Types of speleothems include:[ten]
- Dripstone is calcium carbonate in the form of stalactites or stalagmites
- Stalactites are pointed pendants hanging from the cavern ceiling, from which they abound
- Soda straws are very thin but long stalactites with an elongated cylindrical shape rather than the usual more conical shape of stalactites
- Helictites are stalactites that have a fundamental canal with twig-like or spiral projections that announced to defy gravity
- Include forms known equally ribbon helictites, saws, rods, butterflies, hands, curly-fries, and "clumps of worms"
- Chandeliers are complex clusters of ceiling decorations
- Ribbon stalactites, or just "ribbons", are shaped accordingly
- Stalagmites are the "ground-upwardly" counterparts of stalactites, often blunt mounds
- Broomstick stalagmites are very alpine and spindly
- Totem pole stalagmites are besides tall and shaped like their namesakes
- Fried egg stalagmites are small, typically wider than they are tall
- Stalagnate results when stalactites and stalagmites meet or when stalactites reach the floor of the cave
- Stalactites are pointed pendants hanging from the cavern ceiling, from which they abound
- Flowstone is sheet like and plant on cave floors and walls
- Draperies or defunction are thin, wavy sheets of calcite hanging downwards
- Salary is a drapery with variously colored bands within the sheet
- Rimstone dams, or gours, occur at stream ripples and form barriers that may comprise water
- Stone waterfall formations simulate frozen cascades
- Draperies or defunction are thin, wavy sheets of calcite hanging downwards
- Cave crystals
- Dogtooth spar are big calcite crystals often institute near seasonal pools
- Frostwork is needle-like growths of calcite or aragonite
- Moonmilk is white and cheese-similar
- Anthodites are flower-similar clusters of aragonite crystals
- Cryogenic calcite crystals are loose grains of calcite institute on the floors of caves formed by segregation of solutes during freezing of h2o.
- Speleogens (technically distinct from speleothems) are formations inside caves that are created by the removal of bedrock, rather than as secondary deposits. These include:
- Pillars
- Scallops
- Boneyard
- Boxwork
- Others
- Cavern popcorn, likewise known equally "coralloids" or "cave coral", are small, knobby clusters of calcite
- Cave pearls are the upshot of water dripping from high above, causing small "seed" crystals to turn over so often that they form into near-perfect spheres of calcium carbonate
- Snottites are colonies of predominantly sulfur oxidizing bacteria and accept the consistency of "snot", or fungus
- Calcite rafts are thin accumulations of calcite that appear on the surface of cave pools
- Hells Bells, a item speleothem plant in the El Zapote cenote of Yucatan in the form of submerged, bong-like shapes
- Lava tubes contain speleothems composed of sulfates, mirabilite or opal. When the lava cools, precipitation occurs.
Calthemites [edit]
The usual definition of speleothem excludes secondary mineral deposits derived from concrete, lime, mortar, or other calcareous material (eastward.grand. limestone and dolomite) exterior the cave environment or in artificial caves (due east.m. mines, tunnels), which can have similar shapes and forms equally speleothems. Such secondary deposits in man-made structures are termed calthemites. Calthemites are often associated with concrete degradation, or due to leaching of lime, mortar, or other calcareous cloth.
Gallery [edit]
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Image of Cave Pearl germination
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Prototype of flowstone in Mammoth Cave, KY
Run across likewise [edit]
- Petrifying well
References [edit]
- ^ White, W. B. (2019). "Speleothems". Encyclopedia of Caves: 1006–17. doi:10.1016/B978-0-12-814124-3.00117-5. ISBN9780128141243.
- ^ a b c White, William (2016). "Chemistry and karst". Acta Carsologica. 44 (iii). doi:10.3986/air-conditioning.v44i3.1896. ISSN 0583-6050.
- ^ J., Fairchild, Ian (2012). Speleothem science: from procedure to past environments. Wiley-Blackwell. ISBN978-1-4051-9620-8. OCLC 813621194.
- ^ Bradley, Raymond S. (2015). Paleoclimatology: Reconstructing Climates of the 4th. Academic Printing. pp. 291–318. doi:10.1016/b978-0-12-386913-5.00008-nine. ISBN978-0-12-386913-v.
- ^ Richards, David A.; Dorale, Jeffrey A. (2003). "Uranium-series Chronology and Ecology Applications of Speleothems". Reviews in Mineralogy and Geochemistry. 52 (1): 407–460. Bibcode:2003RvMG...52..407R. doi:10.2113/0520407. ISSN 1529-6466.
- ^ Fairchild, Ian J.; Smith, Claire L.; Baker, Andy; Fuller, Lisa; Spötl, Christoph; Mattey, Dave; McDermott, Frank; E.I.M.F. (2006). "Modification and preservation of ecology signals in speleothems" (PDF). Earth-Scientific discipline Reviews. ISOtopes in PALaeoenvironmental reconstruction (ISOPAL). 75 (1–4): 105–153. Bibcode:2006ESRv...75..105F. doi:ten.1016/j.earscirev.2005.08.003.
- ^ Hendy, C. H (1971). "The isotopic geochemistry of speleothems–I. The calculation of the furnishings of dissimilar modes of formation on the isotopic composition of speleothems and their applicability equally palaeoclimatic indicators". Geochimica et Cosmochimica Acta. 35 (8): 801–824. Bibcode:1971GeCoA..35..801H. doi:10.1016/0016-7037(71)90127-X.
- ^ McDonald, Janece; Drysdale, Russell; Hill, David (2004). "The 2002–2003 El Niño recorded in Australian cave drip waters: Implications for reconstructing rainfall histories using stalagmites". Geophysical Research Letters. 31 (22): L22202. Bibcode:2004GeoRL..3122202M. doi:10.1029/2004gl020859. ISSN 1944-8007.
- ^ Woodhead, Jon; Reisz, Robert; Fox, David; Drysdale, Russell; Hellstrom, John; Maas, Roland; Cheng, Hai; Edwards, R. Lawrence (2010-05-01). "Speleothem climate records from deep time? Exploring the potential with an instance from the Permian". Geology. 38 (v): 455–458. doi:10.1130/G30354.1. hdl:1959.13/931960. ISSN 0091-7613.
- ^ Hill, C A, and Forti, P, (1997). Cavern Minerals of the World, (2nd edition). [Huntsville, Alabama: National Speleological Society Inc.] pp. 217, 225
External links [edit]
- The Virtual Cave: an online guide to speleothems
- Mineral aggregates from carst caves, formed in capillary film solutions
- Gallery of speleothems from NPS Cave and Karst Program (archived on 23 January 2013)
Source: https://en.wikipedia.org/wiki/Speleothem
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