Encyclopedia of Caves || Hydrothermal Caves

aquifers. Different categories of contaminants havedifferent modes of transport within karst aquifers.Types of contaminants are listed below:

1. Water-soluble compounds. Inorganic salts and someorganic compounds are soluble in water. Thesemove with the water in the aquifer and appear atthe springs possibly in a somewhat diluted form.In the case of a spill, water-soluble compounds willreach the spring in about the same time as thetravel time of the water, often a matter of hours orat most a few days.

2. Light nonaqueous phase liquids (LNAPLs). Gasoline,fuel oil, home heating oil, and related hydrocarbonsare less dense than water and are only slightlysoluble. These compounds will float on the watertable and will float on free-surface undergroundstreams. However, they tend to pond behind sumpsand tend to be trapped in pockets in the ceilings ofwater-filled conduits. Rising water levels can forceLNAPLs upward along fractures where fumes canenter homes and other buildings.

3. Heavy nonaqueous phase liquids (DNAPLs). Chlorinatedhydrocarbons such as trichloroethylene (TCE) andperchloroethylene (PCE)—both used as solvents,degreasers, and dry cleaning agents—as well aspolychlorinated biphenyls (PCB) and many othercompounds are denser than water and are onlyslightly soluble. These materials are sometimestrapped in the epikarst but when they enter theaquifer, they tend to sink to the lowest water-filledpassages or become trapped in the clastic sedimentsthat occur in the conduits. As a result, spills ofDNAPLs often never reappear at springs and remaintrapped in the karst aquifer for long periods of time.

4. Metals. Metallic elements such as chromium, cadmium,lead, and mercury are highly toxic, while others suchas copper and zinc are less so, and these can be carriedinto karst aquifers either as ionic species in solution oras solid particles of various sorts. Because of thealkaline chemistry of karst waters, some metals areprecipitated, some are adsorbed on clay particles, andsome are incorporated into the manganese and ironoxides/hydroxides that form coatings on cave streamsediments. Metal transport in karst aquifers, therefore,involves a very complex chemistry that is not easilygeneralized.

5. Pathogens. Viruses, bacteria, protozoa, and largerorganisms are easily transported into karstaquifers because of the large solution openingsand the absence of filtering. Most common ofthese are the fecal coliform family of organismsand fecal streptococci. These organisms areindications of contamination by sewage or animalwaste. Giardia lamblia is of most concern among

protozoa. It is released in a cyst form in animalfeces and is present in many surface waters.Sinking streams carry the stable cysts into thesubsurface. Die-off is slow underground so thatkarst waters remain contaminated far fromsurface inputs.

See Also the Following Articles

Modeling of Karst AquifersSinking Streams and Losing StreamsSpringsWater Tracing in Karst Aquifers

Bibliography

Ford, D., & Williams, P. W. (2007). Karst hydrogeology and geomorphologyand hydrology. Chichester, U.K.: John Wiley.

Milanovic, P. T. (1981). Karst hydrogeology. Littleton, CO: WaterResources Publications.

Milanovic, P. T. (2004). Water resources engineering in karst. BocaRaton, FL: CRC Press.

Palmer, A. N. (1991). Origin and morphology of limestone caves.Geological Society of America Bulletin, 103(1), 1�21.

Palmer, A. N. (2007). Cave geology. Dayton, OH: Cave Books.United States Geological Survey (1992�1998). Ground water atlas of

the United States. Hydrologic investigations atlas, 730-B-M, 12 foliovolumes.

White, W. B. (1988). Geomorphology and hydrology of karst terrains.New York: Oxford University Press.

White, W. B. (2002). Karst hydrology: Recent developments and openquestions. Engineering Geology, 65(2), 85�105.

White, W. B. (2007). Groundwater flow in karst aquifers. In J. W. Delleur(Ed.), Handbook of groundwater engineering (2nd ed., pp. 21-1�21-47).Boca Raton, FL: CRC Press.

HYDROTHERMAL CAVESYuri Dublyansky

Innsbruck University, Austria

DEFINITION

The term hydrothermal karst defines a process ofdissolution of cavities in the rocks under the action ofhot waters. This definition, though quite simple, is some-times difficult to apply, because it requires another defi-nition of which water should be called hot or thermal. Inhydrological studies any water that is appreciablywarmer (5�C or more) than the surrounding environ-ment is called thermal. This type of definition is fairlysatisfactory when it is applied to a still-active process inareas with a moderate climate. It is difficult to apply,however, to those settings where neither resurgence

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Encyclopedia of Caves. © 2012 Elsevier Inc. All rights reserved.

temperatures nor annual climatic averages are applicable(i.e., to deep-seated waters tapped by boreholes or to fos-sil karst process). Conventionally, the temperature of20�C is considered to be the lower limit of the hydrother-mal environment. Although some meteoric karst sys-tems in hot arid climates may exceed this limit withoutany thermal input, most hydrothermal cave systemsrelate to hypogenic sources of energy (i.e., internal heatof the Earth). Formed due to the action of rising waters,hydrothermal systems typically lack any geneticrelationships to recharge from overlying or directly adja-cent surfaces. Caves must be uplifted with the rock andintersected by surface erosion by common karst, or bydrilling, mining, or quarrying to be discovered and stud-ied. Hydrothermal karst is a special case of hypogenekarst.

The concept that some caves could have beenformed by ascending thermal waters rather than bycold descending, gravity-driven ones was first putforth as early as in the mid-nineteenth century. It hasbeen suggested that Pb-Zn ores in some of theEuropean deposits in carbonate rocks were emplacedin dissolution cavities and that these cavities owetheir existence to the same solutions from which, atlater stages, the ores were deposited. In his “A Treatiseon Metamorphism”, Charles Van-Hise (1904) providedexplanations for how and why hydrothermal solutionsmove advectively through the rocks, and what causestheir aggressiveness. He conjectured that most hydro-thermal solutions originate as common meteoricwaters that become heated during their circulationdeep in the Earth’s crust. These early works laid afoundation for the concept of hydrothermal karst.

SETTINGS OF HYDROTHERMAL KARST

It is convenient to subdivide hydrothermal karstsettings into the following three categories: endokarst,deep-seated hydrothermal karst, and shallow hydro-thermal karst.

Endokarst

It is a well-known fact that the rate of karst devel-opment decreases with increasing depth. However,deep drilling for oil and gas reveals that solutionalporosity of carbonate rocks at depths of 4�5 km maybe as great as 18�28%, and the porosity of aluminosil-icate rocks may be as great as 30�35%. The pressuresof fluids at these depths are typically greater than thehydrostatic ones and may approach lithostatic values.At those levels, where the pressure exceeds thestrength of the rock, pores and cavities may exist only

if they are filled with high-pressure fluid, which pre-vents them from failure. The process of formationof such cavities is termed endokarst (Andreychouket al., 2009). The size of endokarstic cavities does notnormally exceed several centimeters. Though thistype of karst apparently does not produce traversablecaves, it may play a significant role in creation ofdeep-seated reservoirs for hydrocarbons.

Deep-Seated Hydrothermal Karst

This covers a range of depths (approximately 0.3 to4.0 km) where the temperature gradients are relativelysmall, pressures are close to hydrostatic, and the influ-ence of the temperature changes at the Earth’s surfaceis practically absent. Processes of cave excavation andcave infilling occur in response to the change in physi-cochemical parameters of fluids moving toward theEarth’s surface, such as the decrease in temperatureand pressure. It is thought that dissolution related tothe elevated content of carbonic acid is the leading fac-tor in initiation and enlargement of caves in the deepsetting. Recent studies, however, revealed the impor-tant role of dissolution processes involving sulfuricacid. At certain specific combinations of bedrock solu-bility and frequency of fractures, dissolution is accom-panied by collapse. Characteristic collapse breccias areknown in many fossil hydrothermal systems related toPb-Zn ore deposits in dolomitic rocks (e.g., in Silezia,Poland).

Shallow Hydrothermal Karst

The shallow setting describes processes developingnear the free surface of the thermal water—bothbelow and above it. In this zone the pressures are low(down to atmospheric) and temperatures may rangefrom boiling to just slightly exceeding the ambientones. The temperature gradients may be significant,which leads to the appearance of some specific andpowerful processes, like thermal convection andcondensation corrosion. Also, this is a zone whereupwelling thermal waters meet colder oxidized mete-oric waters and atmosphere. This may induce specificreactions and processes such as H2S oxidation, mixingcorrosion, and cooling corrosion. The caves formed insuch a setting commonly exhibit extremely diversemorphologies. Characteristic dimensions of individ-ual caves are appreciably greater than those ofthe deep-seated hydrothermal caves. Also, shallowhydrothermal karst speleothem types are much morevaried than those of the deep-seated karst.

All enterable active hydrothermal caves (those contain-ing hot waters) are examples of shallow hydrothermal

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ENCYCLOPEDIA OF CAVES

karst. Examples of such caves are known in many placesincluding Turkmenistan (Bakharden Cave, with a lakewith temperature of 35�37�C), Italy (Grotta Giusti,32�34�C), Mexico (Sistema Zacaton, 29�32�C), andHungary (Molnar Janos Cave, 18�24�C).

CHEMISTRY OF FLUIDS AND PROCESSESOF CAVE EXCAVATION

Hydrothermal caves associated with the CO2 andcaves formed by waters containing H2S are consideredtwo major classes of hydrothermal (hypogene) caves.

Dissolution by Rising Thermal Water (CO2)

Thermal waters rising from significant depth arecommonly saturated with CO2, which may originatefrom metamorphism of carbonate rocks and igneousactivity. The solubility of CO2 in water depends onboth temperature and pressure. Water saturated withrespect to CO2 at deep levels (e.g., 2�4 km) becomessupersaturated as it rises toward the surface. Hence,CO2 must exsolve in the gaseous phase and leave thesystem. Rising carbonic thermal waters also cool down.Due to inverse relationships between carbonate solubil-ity and temperature, they may acquire and maintainaggressiveness, even at decreasing CO2 levels. The sol-ubility of CaCO3 increases evenly along the ascendingfluid path, but near the land surface (or water table) itdrops drastically. Such nonlinear behavior leads to theappearance of two geochemical zones: a zone of car-bonate dissolution at depth and a zone of carbonateprecipitation closer to the surface.

Oxidation of Sulfides (H2S)

Sulfuric waters become aggressive when their dis-solved H2S oxidizes on contact with oxygen-richwaters or air to form sulfuric acid. Conversion of H2Sto H2SO4 produces a sharp increase in dissolution. Theeffect is attenuated when CO2 generated by the H2SO4-CaCO3 reaction is degassed. In two settings, hydrogensulfide oxidation is an important speleogenetic pro-cess. The first is subaqueous dissolution of carbonatesnear the water table. Large rooms of the Carlsbad Cavernin New Mexico, U.S.A., are believed to be formed thisway. The second setting is dissolution of and subse-quent replacement of calcite by gypsum and its conse-quent removal above the water table. The mechanism,termed replacement corrosion, was suggested for cavesof the Big Horn Basin in Wyoming, U.S.A.

Dissolution Due to Mixing of Waters(CO2 and H2S)

Solutional aggressiveness can be renewed or enhancedby mixing of waters with contrasting chemistry, particu-larly those differing in CO2 and H2S content or salinity.Mixing of waters having different temperatures producesa similar effect, due to contrasts in CO2 contents. Thiseffect, known as mixing corrosion, is thought to be respon-sible for the development of network maze cave systemsin Budapest, Hungary, for example, Pal-volgy, Szemlo-hegy, and Ferenc-hegy.

Hydrothermal Karst in Noncarbonate Rocks

The mechanisms described above pertain to themost common variety of hydrothermal karst develop-ing in carbonate rocks. Besides, hydrothermal caveshave been reported from silicate rocks (quarzite, scarn,jasperoid, quartz veins), sulfate rocks (gypsum, anhy-drite), rock salt, and even from massive sulfide ores.

Hydrothermal Karst Related to Oxidationof Sulfide Ores

A substantial amount of heat can be released wheninfiltrating oxygen-rich waters react with sulfide ores.This may lead to both increased temperatures andenhanced carbonate aggressiveness of waters passingthrough ore bodies. Those thermally and chemicallymodified waters may then attack carbonate rocks toproduce a specific type of hydrothermal karst. Thistype of hydrothermal karst is commonly triggered bymining activities that may facilitate access of waters tothe ore bodies.

Dissolution in Subaqueous andSubaerial Settings

Many large hydrothermal caves and cave systemshave formed in subaqueous conditions, that is, belowthe water table. In addition, significant developmentof caves can also occur in a subaerial setting, abovethe open surfaces of underground thermal lakes by amechanism of condensation corrosion. Moisture evapo-rating from the lake surface moves upward and con-densed on cooler bedrock. The resulting water filmbecomes aggressive by dissolving gaseous CO2; thecondensate attacks the bedrock and creates cavitieswith characteristic cupola-like morphology (Fig. 1).This speleogenetic mechanism can be very efficient,but requires a number of prerequisites, such as ele-vated temperature of water (promoting evaporation)and sustained gradient of temperatures between the



vapor phase and cave wall (promoting condensation).Importantly, by this mechanism, cavities can developabove the underground lake water in which it issaturated with respect to bedrock and is not capable ofdissolving it.

MORPHOLOGY OF HYDROTHERMALCAVES

Hydrothermal karst produces a large variety of cavemorphologies with cave sizes ranging from solutionenlarged pores to extensive cave systems with totalmapped passage length exceeding 100 km. The mostcommon morphologic types of hydrothermal caves arediscussed below.

Solution Porosity

Solution enlarged pores are commonly observedin borehole cores from depths up to 4�5 km in geother-mal areas and oil fields. They may form extensive layersof rock in which solution voids account for as much as5�15% of the entire rock volume. In these places suchhorizons become parts of oil and gas reservoirs. Layersof solution-enhanced transmissivity appear where themovement of the fluids is slow, of the order of a fewmillimeters per year or less, and where hydraulic struc-tures which could concentrate the flow (faults andfissures) are absent. Such zones of enhanced porositymay become the inception horizons for future caves.

Isometric Rooms

Roughly spherical pockets or rooms with diametersranging from 0.5 to 8.0 m were reported from Khod

Koniom Cave in the Crimea. The cavities, lined withcrystals of hydrothermal calcite (temperature of forma-tion 40�85�C) and filled with red clay are truncatedby a later vertical vadose cave at a depth of 80�200 m.Similar caves occur in Kighizstan, where medievalexcavations in the Birksu mercury mine (TurkestanRange) uncovered a series of near-spherical rooms3�8 m in diameter. The rooms coalesce in two- andthree-dimensional clusters following the beddingplanes and minor faults. Originally, the rooms wereentirely filled by massive hydrothermal calcite contain-ing veinlets of cinnabar, but the ore was removed bymedieval miners.

Individual Chambers

Individual chambers are distinguished from iso-metric rooms discussed above by their larger dimen-sions, ranging from tens to hundreds of meters. Cavesof this type are composed of one or several large indi-vidual chambers. The latter commonly have a lengthof 100�200 m, a width of 30�60 m, and a height of80 m. Examples of caves belonging to this type areBakharden Cave in Turkmenistan (Kopet-Dag Range),Novoafonskaya Cave in Abkhazia (Caucasus), KaraniCave in the Crimea, Ukraine, and Champignons Cavein Provence, France. Another spectacular example ofindividual chambers are cenotes Caracol and La Pilita(Mexico), which have nearly spherical shapes and di-ameters of 80 to 100 m and are filled with moderatelythermal water (29.6 and 31.6�C).

Single-Conduit Caves

As implied by the name, the single-conduit caves arecomposed of a single long, typically tube-shaped pas-sage, which can be aligned horizontally, parallel to thewater table, or at a steep angle to it. Horizontal singleconduit caves are exemplified by the hydrothermalHellespont, Spence, and Kane Caves (Wyoming, U.S.A.),which represent nearly horizontal, tube-shaped con-duits 60�600 m long. They have developed in a vadosesetting, where ascending H2S-bearing fluid comes incontact with the air, resulting in replacement corrosion.Thermal springs discharge through the three above-mentioned caves, and several inactive caves havingsimilar morphology are known in the region. Steeplydipping single-conduit caves develop in a phreatic set-ting. Examples of such caves are Grotte de Chat(France), Pozzo del Merro (Italy; the deepest exploredunderwater cave of the world), and cenote Zacaton(Mexico).

FIGURE 1 Solutional cupolas in an ascending channel presum-ably formed in a subaerial setting by condensation corrosion. Krauscave, Austria. Photo by L. Plan. Used with permission.

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Bush-Like Caves or Caves with Cupolas

Such caves typically consist of a basal chamber fromwhich a branching pattern of rising passages develops.The branches are composed of coalesced spherical cupo-las whose typical size is 0.5�1.5 m, and cupolas termi-nate most of the branches. Such caves are known inHungary (e.g., Satorko-puszta and Batori caves; Fig. 2)and in the Azerous Mountains in northern Algeria.These types of caves are thought to be due to the deliv-ery of hot water to a single input point at the base of car-bonate rock having low fissure density. Bush-like cavesare an example of monogenetic hydrothermal karst,although the exact mode of formation for such caves isnot yet understood. One hypothesis ascribes their forma-tion to the convective movement of water in the phreaticzone, whereas another model (preferred) invokes theconvective movement of moist air above the hot-watertable coupled with condensation corrosion.

Phreatic Maze Caves

Maze caves are the most common types of hydro-thermal cave systems. Among them network caves,

anastomotic caves, spongework caves, and ramiformcaves are distinguished.

Network caves are angular grids of intersectingpassages formed by widening of nearly all majorfractures within favorable areas of soluble rocks.Two-dimensional rectilinear maze systems are createdwhere rising water is trapped in densely jointedcarbonate rock below a relatively impervious bed.Examples of such a pattern are Cserszegtomaji-kut andAcheron-kut caves in Hungary, developed in Triassicdolomite under the cover of Miocene sandstone.

Multistory rectilinear network caves are more com-mon. Examples of these are caves of the Buda Hills,Hungary (Pal-volgy, Szemlo-hegy, Ferenc-hegy) andcaves of the Black Hills in South Dakota (Wind andJewel caves). Many of the carbonate-hosted lead-zincore deposits (the so-called Mississippi Valley type)exhibit a network pattern of solutionally widened frac-tures later filled—partly or entirely—with sulfides(Jefferson City Mine in Tennessee and Devil’s HoleMine in the United Kingdom).

Anastomotic caves consist of curvilinear tubes thatintersect in a braided pattern. They usually form a

FIGURE 2 Examples of the presumably mono-genic hydrothermal bush-like caves with cupo-las: Satorko-puszta Cave in the Pilis Mountainsand Batori Cave in Buda Hills, Hungary. Mapsby M. Juhasz, P. Borke, and L. Karpat.



two-dimensional array along a single favorable parting oflow-angle fracture. Less common three-dimensional var-iants follow more than one geologic structure. An exampleof a supposedly hydrothermal three-dimensional anasto-motic cave is the Pobednaya Cave in Kirhgizstan, with its1.5 km of very narrow, tube-shaped crawlways.

Spongework caves consist of interconnected cavities ofvaried size in a seemingly random three-dimensionalpattern. Such caves appear to form by the coalescingof intergranular pores and minor interstices. Ramiformcaves consist of irregular rooms and galleries wander-ing three-dimensionally with branches extending out-ward from the main areas of development. Passageinterconnections are common, producing a continuousgradation with spongework and network caves. Josef-hegy Cave in the Buda Hills, Hungary, is a good exam-ple of the ramiform pattern.

Small-Scale Morphology

Hydrothermal caves commonly exhibit characteris-tic morphology of cave elements (e.g., cave passages,rooms, as well as yet smaller morphological features,such as rock relief of cave walls). Among thosefeatures Klimchouk (2007) has defined the morphologicsuite of rising flow. The suite comprises three majorcomponents: (1) feeders (inlets); (2) transitional walland ceiling features; and (3) outlet features. Feederscorrespond to sites of input of rising water into hypo-genic caves. Typical feeders are vertical or subverticalconduits, either individual or forming small networks.Transitional wall and ceiling features form with aconsiderable role of buoyant effects (upward-focuseddissolution associated with rising limbs of freeconvection cells). They include such small morphologi-cal forms as rising wall channels, ceiling channels(half-tubes), and ceiling cupolas. Outlet features representchannels of varying morphology, connecting the caveto the next upper story or discharging water out of thecave-development zone. Typically they are representedby cupolas and domepits (vertical tubes) that rise fromthe ceilings of cave passages and rooms. The suitecomprises morphological features created by risingwater, which may or may not be thermal.Nevertheless, identification of these morphologicalelements may be an important first step in determiningthe hydrothermal origin of a cave.

CAVE DEPOSITS

Mineralogy

Calcite is the most common mineral of hydrother-mal caves developed in carbonate rocks. In addition,

such minerals as quartz, barite, fluorite, and sulfidesare commonly reported from the deep-seated hydro-thermal caves. (Ore-related hydrothermal karst, wherethe list of minerals can be quite large, is not consideredhere.) Shallow hydrothermal karst caves rarely containany “exotic” minerals.

Character of Cave Deposits

Large euhedral (that is, having perfect crystallo-graphic shape) calcite crystals, aggregates, thick crusts,and sediments reflecting stable hydrodynamic condi-tions are common in deep-seated hydrothermal caves.Individual calcite crystals can be as large as 10�30 cmand even 100 cm; gypsum crystals can be even larger,reaching in some cases the length of several meters(the most striking example is the 11-m-long gypsumcrystals in Naica cave, Mexico; these largest-ever-found natural crystals were formed at 52�C).

The morphology of calcite crystals in deep-seatedhydrothermal caves is normally simple, dominated bya scalenohedron (dogtooth spar) sometimes combinedwith an obtuse rhombohedron. In contrast, the depos-its of shallow caves commonly reflect a more dynamicenvironment. Crusts are typically less thick (exceptin the immediate vicinity of the water table, wheremassive mammillary crusts called cave clouds mayform) and euhedral crystals are rare. The size of crys-tals in aggregates ranges from several millimeters to afew centimeters. The dominant crystal morphology isa combination of a scalenohedron and a prism withthe crystal tip blunted by obtuse rhombohedron (nail-head spar). Minerals might be contaminated by clay,which indicates that the paleowaters were dynamicenough to carry the particulate matter. In addition tosubaqueous deposits, two more types of speleothemsoccur in shallow hydrothermal karst: waterline depos-its (rafts, folia, cave cones), and subaerial deposits (e.g.,cave popcorn). These two types are also common incold karst.

HYDROTHERMAL CAVE LIFE

A peculiar cave life is known to exist in some activehydrothermal caves, the most striking example beingMovile cave (Romania). The cave hosts slightly ther-mal (20.9�C) water rich in dissolved hydrogen sulfide.The hydrogen sulfide is used as an energy sourceby bacteria to fix inorganic carbon, thus producing afood base for a highly evolved chemoautotrophic (i.e.,based on chemosynthesis rather than photosynthesis)ecosystem. As many as 48 species of cave-adaptedterrestrial and aquatic invertebrates, 33 of which are

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endemic to this ecosystem, have been identified inMovile. The cave did not have a natural entrance:it was intercepted by an artificial shaft at 18 m belowthe surface. It is thought that life in the cave has beenseparated from the outside environment for the past5.5 million years.

IDENTIFICATION OFHYDROTHERMAL CAVES

Unequivocal evidence of the hydrothermal origin ofa cave can be provided by (1) the presence of thermalwaters in a cave (obviously, this indicator is only rele-vant in presently active hydrothermal-karst caves);(2) the presence of hydrothermal minerals depositedon the cave walls (hydrothermal character of minerali-zation is inferred from mineralogical and/or geochem-ical evidence; it is also necessary to demonstrate thatthe two speleogenetic stages, cave development andmineralization, are related to the same process); and(3) the presence of isotopic alteration of the cave walls(character and degree of alteration must correspond tothe water/rock interaction at elevated temperature,which is inferred on the basis of isotopic calculations).

Evidence suggesting the hydrothermal origin of acave includes characteristic morphological features,indicating very slow water movement, free convectionof water, and active enlargement of caves in a subaer-ial setting (air convection and condensation corrosionmechanism). Additional suggestive evidence includesa lack of morphological features and deposits indicat-ing running water environment; a lack of associationwith the surface features of “conventional” karst; andspatial association with hydrothermal activity (includ-ing extinct one).

REGIONAL EXTENT

Hydrothermal origins have been established formany large cave systems of the world: for example,caves in the United States (South Dakota, Wyoming,Montana), Austria, England, France, Italy, Poland, CzechRepublic, Slovak Republic, Hungary, Romania, Ukraine

(Crimea), Caucasus, Kyrgyzstan, Israel, Iran, Algeria,Namibia, Mexico, Mauritania, and South Africa.

See Also the Following Article

Speleogenesis, Hypogenetic

Bibliography

Andreychouk, V., Dublyansky, Y., Ezhov, Y., & Lysenin, G. (2009).Karst in the Earth’s Crust: its distribution and principal types.Sosnowiec (Poland) � Symferopol (Ukraine): University of Silesia �Ukrainian Institute of Speleology and Karstology.

Audra, P., Hoblea, F., Bigot, J.-Y., & Nobecourt, J.-C. (2007) The roleof condensation-corrosion in thermal speleogenesis: Study of ahypogenic sulfidic cave in Aix-Les-Bains, France. Acta Carsologica,36/2, 185–194.

Collignon, B. (1983). Speleogenese hydrothermale dans les Bibans(Atlas Tellien—Nord de l’Algerie). Karstologia, 2, 45�54 (in French).

Dublyansky, Y. (1997). Hydrothermal cave minerals. In C. Hill &P. Forti (Eds.), Cave minerals of the world (2nd ed., pp. 252�255).Huntsville, AL: National Speleological Society.

Dublyansky, Y. (2000). Hydrothermal speleogenesis: Its settingsand peculiar features. In A. Klimchouk, A. Palmer, D. Ford &W. Dreybrodt (Eds.), Speleogenesis: Evolution of karst aquifers(pp. 292�297). Huntsville, AL: National Speleological Society.

Dzulynsky, S., & Sass-Gustkiewicz, M. (1985). Hydrothermal karstphenomena as a factor in the formation of the Mississippi Valley-type deposits. Handbook of strata-bound and stratiform ore deposits,Vol. 13 (Pt. 4), 391�439.

Egemeier, S. J. (1981). Cavern development by thermal waters.National Speleological Society Bulletin, 43, 31�51.

Ford, D. C., & Williams, P. W. (1989). Karst geomorphology and hydrology.London: Unwin Hyman.

Ford, T. D. (1995). Some thoughts on hydrothermal caves. Cave andKarst Science, 22, 107�118.

Klimchouk, A. (2007). Hypogene speleogenesis: Hydrogeological andmorphogenetic perspective (Special Paper 1). Carlsbad, NM: NationalCave and Karst Research Institute.

Palmer, A. N. (1991). Origin and morphology of limestone caves.Geological Society of America Bulletin, 103, 1�21.

Sarbu, S. M., Kane, T. C., & Kinkle, B. K. (1996). A chemoautotrophi-cally based cave ecosystem. Science, 272(5270), 1953�1955.

Takacz-Bolner, K., & Kraus, S. (1989). The results of research intocaves of thermal water origin. Karszt es Barlang (Hungary) (SpecialIssue), 31�38.

Van-Hise, C.R. (1904). A Treatise on Metamorphism. Monographs ofthe United States Geological Survey, v. 47, Washington: Govt.Print. Off.



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