Oölites or cave pearls in the Carlsbad Caverns

Hess, Frank L.

doi:10.5479/si.00963801.76-2813.1

Cited by 15 publications

(10 citation statements)

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“…The surfaces of the large concretions are usually rugose like those of the larger pisoliths. Similar concretions from caves have been pictured by Hess (1930), Baker & Frostick (1947, 1951, Black (1952), Hahne etal. (1968 and Donahue (1969).…”

Section: Encrustations and Concretionssupporting

confidence: 75%

Holocene pisoliths and encrustations associated with spring‐fed surface pools, Pastos Grandes, Bolivia

Raffi

Eügster

1979

Sedimentology

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Calcite pisoliths, with diameters ranging from 1 to 200 mm, are forming now on the surface of a playa (salar) in the Andean Altiplano (4500 m above MSL) of Bolivia. They are associated with active or recently active hot springs (20‐75°C) which flow onto the playa surface. Encrustations of pieces of an older caliche‐type crust, of pisoliths, of indurated mud and of older concretions are also found as well as series of small (1‐3 cm high) sinter terraces (rimstone dams). Arborescent concretions and overgrowths are common and they are reminiscent of drip‐stone textures. Water analyses demonstrate that calcite supersaturation (about twenty times) occurs mainly through CO2 loss, with photosynthesis by algae and degassing the main removal mechanisms. The two available analyses indicate slight evaporation and a calcium loss between spring and pool of 2.3 mmol per litre of water. It is thought that the hot springs pick up much of their solute load from the playa sediments. The closest analogues to these deposits have been reported from caves (cave pearls and concretions). Although the depositional processes may be similar, the environment on an evaporitic playa surface is quite different. The geological implications for this newly observed pisolith environment may be considerable.

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Section: Encrustations and Concretionssupporting

confidence: 75%

Holocene pisoliths and encrustations associated with spring‐fed surface pools, Pastos Grandes, Bolivia

Raffi

Eügster

1979

Sedimentology

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“…Consequently, the composition and fabrics of the cortical laminae are usually consistent, even though there may be variations in the thickness of the laminae and disconformities in the cortex (e.g. Hess, 1930;Coleman, 1949;Donahue, 1969Donahue, , 1978Braithwaite, 1979;Jones & MacDonald, 1989). Variations in the composition and fabric of cortical laminae are a response to environmental changes during growth, most commonly related to water chemistry, temperature, depth or flow velocity.…”

Section: Discussionmentioning

confidence: 99%

Crystal fabrics and microbiota in large pisoliths from Laguna Pastos Grandes, Bolivia

Jones

Renaut

1994

Sedimentology

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Large pisoliths from the Laguna Pastos Grandes playa in the Bolivian Altiplano have a wide diversity of cortical fabrics and variable mineralogical composition. The cortical laminae are composed of radial calcite bundles, spar calcite, micrite, amorphous silica, mixed micrite-amorphous silica, quartz, gypsum and halite. Diatoms are common in the outer parts of some radial calcite laminae and amorphous silica laminae, but cyanobacterial filaments are rare. Although the organization of the cortical laminae is highly variable, some repetitive sequences of different laminae are present. Cavities in and between pisoliths contain micrite, detrital grains, calcite bundles and peloids morphologically similar to those found in marine reefs.The pisoliths grow in shallow ephemeral pools fed by hot springs. Radial bundles of calcite precipitate rapidly by degassing and photosynthetic removal of CO, following spring snowmelt. Conditions for micrite precipitation are unclear, but there is evidence to suggest formation in partially stagnant waters, some of elevated salinity. Amorphous silica laminae precipitate mainly by evaporative concentration; quartz may precipitate from warm silica-rich spring waters that remain below amorphous silica saturation. The evaporite minerals form during desiccation of the pools or from spray. The peloids in cavities are probably primary precipitates. Different types of laminae may form simultaneously in different pools because of the highly variable conditions across the playa.Lateral migration of spring locations through time has created a complex carbonate-silica pavement. Large spherical pisoliths form in outflow channels near spring orifices and across discharge aprons where waters are several decimetres deep. With mineral precipitation, channels are filled and become shallow, producing discoid pisoliths and crusts. In shallow waters and on distal aprons only small pisolith gravels form. As spring pools fill with deposits, their locations shift laterally; new pisoliths form elsewhere or precipitation may recommence on older abandoned pisoliths.

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“…Unattached spherical bodies formed of a nucleus encased by concentric cortical laminae are common in pools and depressions on the floors of many caves. Usually formed of calcite and rarely aragonite (Forti et al 2006), these coated grains have been called concretions (Stone 1932;White 1976, p. 298;Pentecost 2005, p. 71), cave pearls (Hess 1930;Kirchmayer 1969;de Swart 1972;Kirchmayer 1987;Woo et al 2008), or cave oolites/pisolites/pisoliths/pisoids (Pond 1945;Baker and Frostick 1947;Coleman 1949;Barczyk 1956;Donahue 1969;Roberge and Caron 1983). This plethora of names has arisen through casual labeling of these grains and debate over their mode of origin.…”

Section: Introductionmentioning

confidence: 95%

“…Any debate on the origin of ''cave pearls'' must assess their biogenicity even though this will engender semantic issues arising from the classification systems of coated grains (e.g., Peryt 1983, his Table 2) that are based on the role that microorganisms played in their formation. In most studies, however, the possibility that microbes played any role in the growth of coated grains in caves was ignored because the lightless cave environments were tacitly assumed unsuitable for microbe growth (e.g., Hess 1930;Keller 1937). With the ever-increasing knowledge of microbes in speleothems (e.g., Cañaveras et al 2001;Jones 2001;Northup and Lavoie 2001;Barton and Northup 2007) and the demonstrated presence of microbes in ''cave pearls'' (e.g., Jones and MacDonald 1989;Gradzinski 1999Gradzinski , 2001, there is a need to reassess the role that microbes play in their formation.…”

Section: Introductionmentioning

confidence: 99%

Cave Pearls--The Integrated Product of Abiogenic and Biogenic Processes

Jones

2009

Journal of Sedimentary Research

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Cave pearls, up to 8 cm long, collected from dried-out rimstone pools in Old Man Village cave on Grand Cayman, British West Indies, have nuclei (e.g., bone) that are encased by laminated cortices. These laminae are composed of trigonal prismatic calcite crystals, calcite crystal bushes, or particulate calcite that is formed of filamentous microbes (four morphotypes), spores (seven morphotypes), extracellular polymers (EPS), disorganized and organized calcite fiber crystals, and detrital calcite grains. Syntaxial overgrowths modified many of the fiber crystals and the trigonal calcite crystals. Thin, laterally discontinuous growth lines are formed of micrite that may have been precipitated in a microbial mat. Growth of the cave pearls involved abiogenic and biogenic processes. The trigonal calcite crystals and crystal bushes probably formed abiogenically whereas the particulate calcite laminae appear to have formed as microbes trapped and bound detrital grains to the surfaces of the cave pearls and indirectly mediated precipitation of the fiber crystals.Water flow into the rimstone pools, which was linked to local rainfall, controlled the influx of detrital grains, water chemistry, and microbe growth into the pools and hence, the growth of the cave pearls. Periods of low water influx led to stagnation of pool waters that seemed to trigger periods of rapid abiogenic calcite precipitation and curtail microbial colonization. High flow rates slowed abiogenic calcite precipitation, promoted microbe growth, and fed detrital materials into the pools. Despite the lightless environment of the cave, the evidence clearly shows that the microbes and their associated EPS played a critical role in the growth and development of the cave pearls.

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Oölites or cave pearls in the Carlsbad Caverns

Abstract: Forhandl., Stockholm, vol. 24, 1902, pp. 501-507, 5 pho. reps.) The illustrations show well the formation of irregular pisolites by dripping calcium carbonate (CaCOs) bearing water (HoO).

Cited by 15 publications

References 0 publications

Holocene pisoliths and encrustations associated with spring‐fed surface pools, Pastos Grandes, Bolivia

Holocene pisoliths and encrustations associated with spring‐fed surface pools, Pastos Grandes, Bolivia

Crystal fabrics and microbiota in large pisoliths from Laguna Pastos Grandes, Bolivia

Cave Pearls--The Integrated Product of Abiogenic and Biogenic Processes

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