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Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That goethite is a cave mineral - feo(oh) [11].?

Checkout all 2699 terms in the KarstBase Glossary of Karst and Cave Terms

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KarstBase a bibliography database in karst and cave science.

Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
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Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
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Your search for coating (Keyword) returned 30 results for the whole karstbase:
Showing 1 to 15 of 30
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Kendall C. G. S. , Sadd J. L. , Alsharhan A. ,
Marine carbonate cements, which are superficially like travertines from meteoric caves, are coating and binding some intertidal sedimentary rock surfaces occurring in coastal Abu Dhabi, the United Arab Emirates, (UAE). Near Jebel Dhana these surficial cements can be up to 3 cm thick and envelope beach rock surfaces and fossils. They are also present both as thin coats and a fracture-fill cement in the intertidal hard grounds associated with the Khor Al Bazam algal flats. The thickness, microscopic characteristics, and morphology of the marine cement coatings from Jebel Dhana indicates incremental deposition of aragonite in conjunction with traces of sulfate minerals. Most of these cement coatings are micritic, but the layers which encrust the hard grounds from the algae flat of the Khor al Bazam have a more radial and fibrous micro-structure and are composed solely of aragonite. The stable isotopic composition of coatings from Jebel Dhana (delta(18)O = .35, delta(13)C = .00) falls within the compositional range for modem marine non skeletal aragonite and suggests that the marine travertine-like cements precipitate from the agitated slightly hypersaline Arabian Gulf sea water during repeated cycles of exposure, evaporation and immersion. Similar cement coatings and microfabrics are present in the tepee structured and brecciated sediments of the Guadalupe Mountains (Permian) and the Italian Alps (Triassic), in Holocene algal head cements from the Great Salt Lace, and in similar Tertiary algal heads in the Green River Formation of the western US. The petrographic similarity of these ancient ''flow stone'' like cements with Recent hypersaline marine cement coatings suggests that high rates of carbonate cementation and hypersaline conditions contribute to tepee formation and cavity fill

Presence of Rare-Earth Elements in Black Ferromanganese Coatings from V?ntului Cave (Romania), 1997,
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Onac, B. P. , Pedersen, R. B. , Tysseland, M.
This study examines the rare-earth elements (REEs) found in ferromanganese coatings covering both sandy alluvium and submerged boulders in an underground stream from V?ntului Cave, Romania. The black ferromanganese sediments are mainly composed of birnessite and other poorly-crystallized manganese oxide and hydroxides (pyrolusite, romanechite, todorokite, rhodochrosite) as well as goethite and kaolinite. Scanning electron microscope and EDX analyses performed on the black ferromanganese sediments show the material to have concentrated considerable amounts of REEs (La, Ce, Sm, Nd) in iron-rich spheres that build up botryoidal-like aggregates. The correlation of 143Nd/144Nd ratio for 6 different samples indicates that the REEs were concentrated in the cave environment after being leached from bauxitic and red residual clays from above the cave. Based on our observations, we conclude that an increase in pH resulted in adsorption of REE onto the surface of ferromanganese minerals. This study demonstrates the potential of using Nd isotopes as a tool for paleochemistry studies of the cave environment.

Hydrobasaluminite and Aluminite in Caves of the Guadalupe Mountains, New Mexico, 1998,
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Polyak, V. J. , Provencio, P.
Hydrobasaluminite, like alunite and natroalunite, has formed as a by-product of the H2S-H2SO4 speleogenesis of Cottonwood Cave located in the Guadalupe Mountains of New Mexico. This mineral is found as the major component of white pockets in the dolostone bedrock where clay-rich seams containing kaolinite, dickite, and illite have altered during speleogenesis to hydrobasaluminite, amorphous silica, alunite, and hydrated halloysite (endellite). Gibbsite and amorphous silica are associated with the hydrobasaluminite in a small room of Cottonwood Cave. Opalline sediment on the floor of this room accumulated as the cave passage evolved. Jarosite, in trace amounts, occurs in association with the opalline sediment and most likely has the same origin as hydrobasaluminite and alunite. The hydrobasaluminite was found to be unstable at 25C and 50% RH, converting to basaluminite in a few hours. Basaluminite was not detected in the cave samples. Aluminite has precipitated as a secondary mineral in the same small room where hydrobasaluminite occurs. It comprises a white to bluish-white, pasty to powdery moonmilk coating on the cave walls. The bedrock pockets containing hydrobasaluminite provide the ingredients from which aluminite moonmilk has formed. It appears that recent cave waters have removed alumina and sulfate from the bedrock pocket minerals and have deposited aluminite and gypsum along the cave wall. Gypsum, amorphous silica and sulfate-containing alumina gels are associated with the aluminite moonmilk.

Kinetics and mechanisms of precipitation of calcite as affected by P-CO2 and organic ligands at 25 degrees C, 1998,
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Lebron I. , Suarez D. L. ,
This study was conducted to develop a model for the precipitation rate of calcite under varying CO2 partial pressures and concentrations of dissolved organic carbon (DOG). Precipitation rates of calcite were measured in solutions with supersaturation values (Omega) between 1 and 20 and in the presence of 2 m(2)L(-1) of calcite. Experiments were run at partial pressures of CO2 (P-CO2) in the range of 0.035-10 kPa and DOC concentrations in the range of 0.02-3.50 mM. The effects of these two variables were quantified separately for the precipitation mechanisms of crystal growth and heterogeneous nucleation. We found an increase in precipitation rate (at constant Omega) when P-CO2 increased. For constant Omega, we also found a linear relationship between calcite precipitation rate and activity of CaHCO3, indicating that CaHCO3 species have an active role in the mechanism of calcite precipitation. These findings suggest that the increase in the precipitation rate with higher P-CO2 levels is likely caused by the increase in the negative charge on the calcite surface together with an increase in the activity of CaHCO3 species in solution. The mechanism of inhibition of calcite crystal growth by organic ligands has been shown to be surface coating of the crystals by DOG. The amount of DOC adsorbed on the surface of the calcite crystals follows a Langmuir isotherm for all the P-CO2 levels studied; however, the amount of DOC necessary to inhibit calcite precipitation increased. With increasing P-CO2, the negative charge on the crystal increases, which affects crystal growth, but also these increases in P-CO2 cause a decrease in the solution pH and increase in the ionic strength for constant Omega. Solution pH and ionic strength affect the structure and degree of dissociation of the organic functional groups, which in turn affects the and DOC concentration on the inhibition of crystal growth and heterogeneous nucleation. The effect of P-CO2 and DOC concentration on the precipitation rate of calcite is expressed in a precipitation rate model which reflects the contributions of crystal growth and heterogeneous nucleation. Copyright (C) 1998 Elsevier Science Ltd

Rock Coatings, 1998,
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Dorn Ronald I.
The arid, arctic and alpine regions of the earth expose +bare' rock surfaces that are, in reality, clothed by paper-thin coatings on rocks. Intellectual curiosity about the nature, origin, and application of these encrustations has spawned over 2000 scientific papers in over two dozen disciplines. Even as there has been a burgeoning interdisciplinary interest in rock coatings, the lack of a synthesis has seriously hindered advances in research. This book presents the first-ever synthesis on rock coatings.

Mn-Fe deposits in shallow cryptic marine environment: examples in northwestern Mediterranean submarine caves, 2001,
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Allouc J, Harmelin Jg,
Black coating of hard substrates by Mn and Fe oxides has long been reported from shallow, dark, submarine caves. However, these littoral metallic deposits have never been studied in detail, despite expected analogies with deep-sea polymetallic crusts. Submarine caves are characterized by darkness and low rates of exchanges with the open sea. Lack of primary production and confinement of inner water bodies result in marked oligotrophy and extremely reduced biomass, i.e. conditions close to those prevailing in deep-sea habitats. Field evidences suggested that the formation of Mn-Fe coatings was closely tied to these particular environmental conditions. The goal of this study was to examine the detailed features of Mn-Fe coatings from dark caves with different local conditions, and to try to identify the processes responsible for their deposition. Study sites and methods Three sublittoral, single-entrance, caves were sampled by scuba diving along the coasts of Provence (France, Mediterranean Sea) (fig. 1). The first site is a large karstic cave (Tremies Cave, 16 m depth at entrance floor, 60 m long; Marseille-Cassis area) with an ascending profile which results in a buffered thermal regime and markedly oligotrophic conditions due to warm water trapping in its upper part (fig. 1 and 2). Wall fragments were sampled at 30 m (medium confinement : zone B) and 60 in (strong confinement : zone C) from the cave entrance. The second site is a large tubular cavity open in conglomerate formations (3PP Cave, 15 m depth at entrance floor, 120 m long; La Ciotat) with a descending profile which results in relative permanence of winter temperatures within the inner parts, complex water circulation and presumed greater input of sedimented particles than in the preceding cave (fig.1 and 2). Wall samples were taken at 25 m, 70 in and 100 m from entrance. The third site is a small, horizontal, cave open in quartzite formations (Bagaud Cave, 7 in depth at entrance floor, about 10 m long; WNW of Port-Cros Island, bay of Hyeres). Sampling was performed on walls of a narrow corridor between an anterior room and a smaller inner room. A sporadic outflow of continental waters is located in the inner room. The samples were preserved in 50% ethylic alcohol or studied soon after their sampling. Before carbon coating and SEM examination, or microanalyses with SEM-associated spectrometers, they were treated in a 33% Chlorox solution and thereafter washed in demineralized water and dried. Micromorphology At low-medium magnification (<20,000), the aspect of coatings varies between caves and, especially, between inner-cave locations. All the described structures are made up of Mn and Fe oxides. In Tremies Cave, coatings of walls from zone B are composed of irregular erected constructions (height : 10s to 100s μm) formed by the aggregation of roughly ovoid primary concretions of about 10 μm (fig. 3). The surface of those primary concretions displays numerous lacunose to reticulate films (pores, about 0.5 μm in diameter, are often subrounded). Remnants of these films and organomorphic corpuscles occur also within the primary concretions (fig. 4). On younger substrates (broken wall exposed since 1970), primary concretions are poorly developed and no prominent construction is visible (fig. 5). In more confined conditions (zone C), the erected constructions of ancient coatings are smaller and less numerous than in zone B but are well individualized (fig. 6). In this zone: C, besides some remnants of lacunose to reticulate films (fig. 7), there is an appearance of filaments and ovoid corpuscles (height/width : 10-30/5-15 μm), which seem to be linked to filaments by a short stalk (fig. 8). In 3 PP Cave, at 25-70 m from entrance, wall coatings present porous heaps of primary concretions (fig. 9). The surface and the inside of the latter comprise remnants of lacunose to reticulate films that evoke those observed in Tremies Cave (fig. 10 and 11). On younger substrates (hard parts of sessile invertebrates), coatings are restricted to micrometric organomorphic corpuscles with some remnants of lacunose or fibrous films (fig. 12). At 100 in from the entrance, coatings are shaped by numerous erected constructions, more or less coalescing (fig. 13). Besides remnants of lacunose films, the primary concretions contain interlacing filaments (diameter : 0.2-0.3 μm) forming cords or veils (fig. 14). In Bagaud Cave, the primary concretions are aggregated in irregular heaps (fig. 15). Lacunose films are particularly frequent and tend to form three-dimensional mamillated structures that were not observed in the other caves (fig. 16). In particular, there is an appearance of tubular structures (fig. 17) and of numerous hemispheroidal structures (diameter : 4-5 μm) with an upper orifice (fig. 18 and 19). At higher magnification (20,000), whatever the cave and inner-cave location, the aspect of oxide deposits is rather smooth or, especially, microgranular (fig. 20). Mineral composition The composition of coatings is different between caves and according to their inner-cave location. In both large caves (Tremies and 3 PP), the Mn/Fe ratio increases with the distance from the cave entrance, i.e. when exchanges with the open sea diminish (fig. 21a). This trend is particularly clear in Tremies Cave, where the confinement gradient is strongly marked. Besides, the Mn/Fe ratio also seems to increase when films are present in the analysed volume (some cubic micrometers) (fig. 21b). In Bagaud Cave, the Mn/Fe ratio reaches high values despite the small size of this cave and its low confinement level. Discussion and conclusions SEM observations suggest that in each studied cave, the Mn-Fe coatings are biosedimentary deposits. Genesis of these deposits is assumed to result mainly from the replacement of biofilms (composed of cells and slime, i.e, of extracellular polymeric substance produced by microorganisms) generated by microbial populations colonizing the cave walls. Considering the darkness of the cave-locations, microbes consist mainly in bacteria, but fungi are probably responsible for the filaments and ovoids corpuscules (evoking sporocysts) occurring in innermost parts. Observations at different scales of the morphological features of oxide deposits reveal a structured organisation which varies along the strong environmental gradients (particularly the confinement level) that occur from the entrance to the innermost parts : erected constructions made up of primary concretions become more and more defined and acquire a pseudo-columnar shape. The aspect of biofilms appears to be controlled by the same environmental parameters. In open or relatively open environments, they frequently show a three-dimensional development (with frequent skullcape-like shapes), while in more confined conditions they exhibit a planar layout. These changes reflect either the adaptation of the slime-producing bacteria to the local trophic resources (correlated to the rate of exchange with the open sea) and water movements, or spatial replacement of taxa. It is assumed that slime (mainly composed of water and exopolysaccharides) induces a local increase of the concentration in dissolved Mn and acts as an ion exchange resin that allows the retention of Mn on the functional groups of EPS. These conditions promote the nucleation of Mn oxide crystallites in the slime. Then. the anionic character of Mn oxides in seawater, and their capacity to catalyse the oxydation of Mn2 to Mn4, allow the process to go on without any other biological intervention; thus, the process of crystal growth becomes possible. In caves where Mn is only supplied by seawater (Tremies and 3 PP), the average value of the Mn/Fe ratio of coatings is negatively correlated to the local availability of nutrients. This trend is probably linked to changes in the selectivity of slimes towards the processes of retention of cations, because this ratio is clearly influenced by the occurrence of biofilms. However, independently from trophic resources, the Mn/Fe ratio can be notably increased when additional Mn is provided by the seeping or flowing of continental waters (Bagaud Cave)

Depositional environment for metatyuyamunite and related minerals from Caverns of Sonora, TX (USA), 2001,
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Onac Bogdan P. , Veni George, White William B. ,
A new mineral association composed of metatyuyamunite, celestite, opal and several minor crystalline phases has been identified in the Caverns of Sonora (Texas). The minerals were identified by means of X-ray diffractometry and optical and scanning electron microscopy. The main component of this association is metatyuyamunite, a uranyl vanadate mineral that appears as aggregates of sub-millimeter platy-like crystals that are often covered by botryoidal opal coatings. The orthorhombic unit cell of the Sonora metatyuyamunite had parameters a = 10.418, b = 8.508, and c = 17.173 A. Opal and celestite formed either directly over the yellow crust or along the cracks that traverse the limy mud on which metatyuyamunite was precipitated. The secondary uranium-vanadium minerals described herein were precipitated in the final stages of cave development

On the genetic conditions of black manganese deposits from two caves of Eastern Serbia., 2001,
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Ljubojevic V. , Pafevski A. , Calicljubojevic J.
Portions of cave passages often have a black colour due to manganese deposits that occur as coatings on cave walls and ceilings, on clastic sediments, as well as on speleothems. On samples from the cave Buronov Ponor chemical analysis, infrared spectroscopy. X-ray diffraction and DTA analysis confirmed the presence of birnessite. In cave Cerjanska Pecina, the presence of manganese compounds in the black coating has been confirmed by chemical tests. In both caves it has been noted that cave passages with black coating have a distinct morphology. They are highly weathered showing an abundance of sharp prolusions, potholes in the streambed and scallops. The paper studies these occurrences and the possible link between the manganese deposition, hydrology and morphology of the passages and petrologic composition. Although this link was not identified, some interesting questions regarding manganese deposition arose. It remains unclear why manganese deposition is limited only to a certain part of cave Cerjanska Pecina, and what caused the cyclicity in manganese deposition in the cave Buronov ponor. manganese deposits, chemical analysis, speleomorphology

Symposium Abstract: Passage wall coatings in active phreatic conduits in the Yorkshire Dales, 2002,
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Murphy P. J.

Gypsum deposits in the Frasassi Caves, central Italy, 2003,
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Galdenzi, S. , Maruoka, T.
The Frasassi Caves are hypogenic caves in central Italy, where H2S-rich groundwater flows in the lowest cave level. Near the water table, the H2S is converted to sulfuric acid by biotic and abiotic processes, which have enhanced cave development. The sulfate generally deposits above the water table as a replacement gypsum crust coating limestone walls or as large gypsum crystals. Although the oxidation of sulfide also occurs below the water table, sulfate saturation is not achieved, therefore, sulfate does not precipitate below the water table. In the upper dry levels of the cave, three main types of ancient gypsum deposits occurs: (1) replacement crusts, similar to the presently forming deposits of the active zone, (2) microcrystalline large and thick floor deposits, and (3) euhedral crystals inside mud. The study of the depositional setting and the analysis of sulfur isotopes in the gypsum and groundwater clearly demonstrate that all the sampled gypsum in the cave formed by H2S oxidation above the water table. Some fraction of small sulfur isotopic differences between H2S in the water and gypsum can be explained by isotopic fractionation during abiotic and/or biotic oxidation of H2S.

Dissertation Abstract: Passage wall coatings in Joint Hole, a flooded cave system in Chapel-le-Dale, Yorkshire, 2004,
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Heneghan John

Stalactites extrieures dans les karsts tropicaux humides. Dpts stalagmitiques de tufs calcaires, 2004,
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Taborosi Danko, Hirakawa Kazuomi
Outside Stalactites in humid tropical karst Stalactitic deposits of calcareous tufa - Friable and porous stalactitic deposits composed of calcareous tufa rather than sparry calcite characteristic of normal cave stalactites are often encountered in the entrances of caves and plastered to cliffs in the humid tropics. Tufaceous stalactitic outside deposits are frequently mentioned in literature but are typically dismissed in a few sentences, even in review articles dedicated to calcareous tufa. Mostly based on fieldwork in the Mariana Island, we have identified a variety of depositional settings where stalactitic tufa occurs. These settings can be grouped into spelean, transitional, epigean, and littoral realms. Centimetre to tens of meters in scale, their overall shapes can be quite irregular, with crooked, bulbous, pendant-like, light-oriented and other deflected forms exceedingly common. The outside surfaces of these stalactites invariably lack the crystalline luster of cave speleothems and feel wet and pasty, or powdery and earthy when dry. They are often covered with organic coatings. Stalactitic tufas are generally lightweight, porous, and friable, and many small specimens are weak enough to be plucked by hand. Composed of layered microcrystalline material, sometimes reminiscent of chalk, these stalactites exhibit a bewildering variety of fabrics, which can be classified as encrusted, amorphous, and laminated. In addition, they contain much organic material, microbial structures, and detrital grains. A wide array of biota is associated with these features, and they are thought to form by biogenic mechanisms superimposed on abiotic physico-chemical precipitation from karst water. Biologic processes involved in the formation of stalactitic tufa are numerous and appear to involve hundreds of species. While it is now clear that stalactitic tufas are a result of abiotic and biogenic deposition, an additional possibility remains to be considered. It is not improbable that tufa-like stalactites could form by decay and diagenesis of true cave speleothems, if the latter are exposed at the land surface conditions. Stalactitic tufas represent a unique, subaerial variety of calcareous tufa rarely deliberated in karst literature.

Seasonal isotopic imprint in moonmilk from Caverne de l'Ours (Quebec, Canada): implications for climatic reconstruction, 2004,
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Lacelle D. , Lauriol B. , Clark I. D. ,
Moonmilk, which is often seen coating walls in temperate caves, is a porous secondary calcite deposit composed of an aggregate of microcrystalline calcite and water. This study, based on moonmilk deposits found in Caverne de l'Ours, Ottawa Valley region, proposes a model for its formation based on the calcite and water isotope chemistry and evaluates its use as a climatic proxy. In Caverne de l'Ours, non-calcitic mineral inclusions protrude from the bedrock (Grenville marble) into the moonmilk, while others are entirely enclosed within the moonmilk. This observation suggests a mechanism of bedrock dissolution and reprecipitation for the formation of moonmilk, which is controlled by the changing seasonal climate in the cave. The delta(18)O of the moonmilk interstial water indicates that the condensation of water vapour occurs mostly in winter and spring. The condensation of water vapour on the surface of the walls allows for the dissolution of the Grenville marble and releases ions necessary for the precipitation of moonmilk. The delta(18)O and delta(13)C of calcite and delta(18)O of the moonmilk interstitial water indicate that precipitation of moonmilk occurs during summer and fall. During these seasons, the relative humidity in the cave decreases resulting in moonmilk growth through the slow evaporation of calcite-saturated water. A comparison of the delta(18)O record of moonmilk from caves in Gaspesie (Canada) and from Aven d'Orgnac (France) shows that this material retains temperature information valuable for paleoclimatic reconstructions

The antiquity of Aillwee Cave calcite deposits, Burren District, Ireland, 2006,
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Lundberg J. , Drew D. P.
A layered calcite coating over ancient cave fill in Aillwee Cave, Co. Clare, Ireland, yielded a suite of four U-Th dates ranging in stratigraphical order from 441 (-44+79) ka to infinity. These mid-Pleistocene dates are the oldest finite dates from a cave in Ireland, and are clearly distinct from the (few) previously published dates, which are generally Holocene. They suggest that this cave had already been formed and partly re-filled by the mid-Pleistocene. Passage morphology and orientation indicate that topographical and hydrological conditions during cave formation were markedly different from those operating today.

Dominant Microbial Populations in Limestone-Corroding Stream Biofilms, Frasassi Cave System, Italy, 2006,
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Macalady Jennifer L. , Lyon Ezra H. , Koffman Bess, Albertson Lindsey K. , Meyer Katja, Galdenzi Sandro, Mariani Sandro,
Waters from an extensive sulfide-rich aquifer emerge in the Frasassi cave system, where they mix with oxygen-rich percolating water and cave air over a large surface area. The actively forming cave complex hosts a microbial community, including conspicuous white biofilms coating surfaces in cave streams, that is isolated from surface sources of C and N. Two distinct biofilm morphologies were observed in the streams over a 4-year period. Bacterial 16S rDNA libraries were constructed from samples of each biofilm type collected from Grotta Sulfurea in 2002. {beta}-, {gamma}-, {delta}-, and {varepsilon}-proteobacteria in sulfur-cycling clades accounted for [≥]75% of clones in both biofilms. Sulfate-reducing and sulfur-disproportionating {delta}-proteobacterial sequences in the clone libraries were abundant and diverse (34% of phylotypes). Biofilm samples of both types were later collected at the same location and at an additional sample site in Ramo Sulfureo and examined, using fluorescence in situ hybridization (FISH). The biomass of all six stream biofilms was dominated by filamentous {gamma}-proteobacteria with Beggiatoa-like and/or Thiothrix-like cells containing abundant sulfur inclusions. The biomass of {varepsilon}-proteobacteria detected using FISH was consistently small, ranging from 0 to less than 15% of the total biomass. Our results suggest that S cycling within the stream biofilms is an important feature of the cave biogeochemistry. Such cycling represents positive biological feedback to sulfuric acid speleogenesis and related processes that create subsurface porosity in carbonate rocks

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