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Enviroscan Ukrainian Institute of Speleology and Karstology


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Community news

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 gravity drainage is the flow of water towards a well under its own weight [16].?

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.
See all featured articles
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 recharge (Keyword) returned 431 results for the whole karstbase:
Showing 421 to 431 of 431
Characteristics of channel networks in unconfi ned carbonate aquifers, 2014,
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Carbonate aquifers are some of most challenging to characterize because dissolution can greatly enhance permeability, but its effects are often difficult to determine. This study analyzes data from caves, wells, and tracer tests to explore the extent of solution channel networks and the factors that influence their development. The nonlinear dissolution kinetics of calcite, mixing of waters with different CO2 concentrations, and unstable dissolution fronts all promote the development of solution channels, which are widespread in unconfined carbonate aquifers. Fractures are important for guiding channels at a local scale, but hydraulic gradients are the dominant control at a regional scale. Channels provide continuous, large-aperture pathways that result in rapid groundwater flow. Small channels are much more abundant than large channels, and often account for most of the permeability measured in wells. Caves represent the largest channels; they are more common in limestone than in dolostone, and the development of caves rather than smaller channels is also favored where there is sparse fracturing, low matrix porosity, and the presence of sinking stream recharge rather than percolation recharge. Solution channel networks have fractal properties, and their presence explains why carbonate aquifers have higher permeability than aquifers in any other rock type.


Characteristics of channel networks in unconfined carbonate aquifers, 2014,
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Worthington, Stephen R. H.

Carbonate aquifers are some of most challenging to characterize because dissolution can greatly enhance permeability, but itseffects are often diffi cult to determine. This study analyzes data from caves, wells, and tracer tests to explore the extent of solution channel networks and the factors that infl uence their development. The nonlinear dissolution kinetics of calcite, mixing of waters with different CO2 concentrations, and unstable dissolution fronts all promote the development of solution channels, which are widespread in unconfi ned carbonate aquifers. Fractures are important for guiding channels at a local scale, but hydraulic gradients are the dominant control at a regional scale. Channels provide continuous, large-aperture pathways that result in rapid groundwater fl ow. Small channels are much more abundant than large channels, and often account for most of the permeability measured in wells. Caves represent the largest channels; they are more common in limestone than in dolostone, and the development of caves rather than smaller channels is also favored where there is sparse fracturing, low matrix porosity, and the presence of sinking stream recharge rather than percolation recharge. Solution channel networks have fractal properties, and their presence explains why carbonate aquifers have higher permeability than aquifers in any other rock type


Hydrogeological Characteristics of Carbonate Formations of the Cuddapah Basin, India, 2014,
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Farooq Ahmad Dar

Karst hydrogeology is an important field of earth sciences as the aquifers in carbonate formations represent vital resource of groundwater that feeds a large part of the world population particularly in semi-arid climates. These unique aquifers posses peculiar characteristics developed by dissolutional activities of water. Karst aquifers possess a typical hydrogeological setup from surface to subsurface. The aquifers are governed by slow groundwater flow in matrix porosity, a medium to fast flow in fractures and rapid flow in conduits and channels. This large variability in their properties makes the prediction and modeling of flow and transport very cumbersome and data demanding. The aquifers are vulnerable to contamination as the pollutants reach the aquifer very fast with little or no attenuation. The geomorphological and hydrogeological properties in these aquifers demand specific techniques for their study. The carbonate aquifers of the semi-arid Cuddapah basin were characterized based on geomorphological, hydrogeological and hydrochemical investigations. All the formations are highly karstified possessing one of the longest and deepest caves of India and few springs along with unique surface features. Karstification is still in progress but at deeper levels indicated by growing speleothems of different architectural size. Model of karstification indicates that lowering of base level of erosion resulted in the dissolution of deeper parts of the limestone as represented by paleo-phreatic conduits in the region. Moist conditions of the past were responsible for the karst development which has been minimized due to the onset of monsoon conditions. Karst has developed at various elevations representing the past base levels in the region.

The recharge processes in these aquifers are complex due to climatic and karst specificities. Point recharge is the major contributor which enters the aquifer as allogenic water. It replenishes the groundwater very rapidly. Diffuse recharge travels through soil and epikarst zone. Average annual recharge of semi-arid Narji limestone aquifer is 29% of the rainfall which occurs during 5-7 rain events in the year.

The hydrogeochemical characteristic of karst aquifers is quite varaible. A significant difference is observed in hydrochemistry. High concentrations of SO42-, Cl-, NO3- suggests the anthropogenic source particularly from agriculture. Local Meteoric Water Line of δ2H and δ18O isotopes of rain and groundwater shows a slope of 7.02. Groundwater isotope data shows more depletion in heavy isotopes -a result of high evaporation of the area. Groundwater samples show a trend with a slope of 4 and 3.1 for δ2H and δ18O respectively. Groundwater during dry months gets more fractionated due to higher temperature and little rainfall. The irrigated water becomes more enriched and then recharges the aquifer as depleted irrigation return flow. The isotopes show large variation in spring water. Few springs are diffuse or mixed type and not purely of conduit type in the area. Tracer results indicate that the tracer output at the sampling location depends on the hydrogeological setup and the nature of karstification.

The study has significantly dealt with in disclosing the typical characteristics of such aquifer systems and bringing out a reliable as well as detailed assessment of various recharges to the system. The groundwater chemistry has been elaborated to establish the nature of possible hydrochemical processes responsible for water chemistry variation in semi-arid karst aquifer. Such study has thrown light on the aquifers that are on one hand very important from social and strategic point of view and on the hand were left unattended from the detailed scientific studies.


Hydrogeology of northern Sierra de Chiapas, Mexico: A conceptual model based on a geochemical characterization of sulfide-rich karst brackish springs, 2014,
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Conspicuous sulfide-rich karst springs flow from Cretaceous carbonates in northern Sierra de Chiapas, Mexico. This is a geologically complex, tropical karst area. The physical, geologic, hydrologic and chemical attributes of these springs were determined and integrated into a conceptual hydrogeologic model. A meteoric source and a recharge elevation below 1500 m are estimated from the spring water isotopic signature regardless of their chemical composition. Brackish spring water flows at a maximum depth of 2000 m, as inferred from similar chemical attributes to the produced water from a nearby oil well. Oil reservoirs may be found at depths below 2000 m. Three subsurface environments or aquifers are identified based on the B, Li+, K+ and SiO2 concentrations, spring water temperatures, and CO2 pressures. There is mixing between these aquifers. The aquifer designated Local is shallow and contains potable water vulnerable to pollution. The aquifer named Northern receives some brackish produced water. The composition of the Southern aquifer is influenced by halite dissolution enhanced at fault detachment surfaces. Epigenic speleogenesis is associated with the Local springs. In contrast, hypogenic speleogenesis is associated with the brackish sulfidic springs from the Northern and the Southern environments.


Thermal damping and retardation in karst conduits, 2015,
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Luhmann A. J. , Covington M. D. , Myre J. M. , Perne M. , Jones S. W. , Alexander Jr. E. C. , Saar M. O

Water temperature is a non-conservative tracer in the environment. Variations in recharge temperature are damped and retarded as water moves through an aquifer due to heat exchange between water and rock. However,within karst aquifers, seasonal and short-term fluctuations in recharge temperature are often transmitted over long distances before they are fully damped. Using analytical solutions and numerical simulations, we develop relationshipsthat describe the effect of flow path properties, flow-through time, recharge characteristics, and water and rock physical properties on the damping and retardation of thermal peaks/troughs in karst conduits. Using these relationships, one can estimate the thermal retardation and damping that would occur under given conditions with a given conduit geometry. Ultimately, these relationships can be used with thermal damping and retardation field data to estimate parameters such as conduit diameter. We also examine sets of numerical simulations where we relax some of the assumptions used to develop these relationships, testing the effects of variable diameter, variable velocity, open channels, and recharge shape on thermal damping and retardation to provide some constraints on uncertainty. Finally, we discuss a multitracer experiment that provides some field confirmation of our relationships. High temporal resolution water temperature data are required to obtain sufficient constraints on the magnitude and timing of thermal peaks and troughs in order to take full advantage of water temperature as a tracer.

 


The hydrogeology of high-mountain carbonate areas: an example of some Alpine systems in southern Piedmont (Italy), 2015,
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The hydrogeological characteristics of some springs supplied by high-mountain carbonate rock aquifers, located in the south of Piedmont, in Italy, are presented in this work. The aquifers have different geological-structural conditions, including both deep and superficial karstification. Their catchment areas are located in a typical Alpine context at a high altitude of about 2000 m. These aquifers are ideal representations of the different hydrogeological situations that can be encountered in the high-altitude carbonate aquifers of the Mediterranean basin. It is first shown how the high-altitude zones present typical situations, in particular related to the climate, which control the infiltration processes to a great extent. Snowfall accumulates on the ground from November to April, often reaching remarkable thicknesses. The snow usually begins to melt in spring and continues to feed the aquifer for several months. This type of recharge is characterized by continuous daily variations caused by the typical thermal excursions. The hourly values are somewhat modest, but snowmelt lasts for a long time, beginning in the lower sectors and ending, after various months, in the higher areas. Abundant rainfall also occurs in the same period, and this contributes further to the aquifer supply. In the summer period, there is very little rainfall, but frequent storms. In autumn, abundant rainfall occurs and there are there fore short but relevant recharge events. It has been shown how the trend of the yearly flow of the high mountain springs is influenced to a great extent by the snowmelt processes and autumn rainfall. It has also been shown, by means of the annual hydrographs of the flow and the electric conductivity of the spring water, how the different examined aquifers are characterized by very different measured value trends, according to the characteristics of the aquifer.

 


Hypogenic origin, geologic controls and functional organization of a giant cave system in Precambrian carbonates, Brazil, 2015,
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This study is focused on speleogenesis of the Toca da Boa Vista (TBV) and Toca da Barriguda (TBR), the longest caves in South America occurring in the Neoproterozoic Salitre Formation in the São Francisco Craton, NE Brazil. We employ a multidisciplinary approach integrating detailed speleomorphogenetic, lithostratigraphic and geological structure studies in order to reveal the origin of the caves, their functional organization and geologic controls on their development. The caves developed in deep-seated confined conditions by rising flow. The overall fields of passages of TBV and TBR caves represent a speleogenetically exploited large NE–SW-trending fracture corridor associated with a major thrust. This corridor vertically extends across the Salitre Formation allowing the rise of deep fluids. In the overall ascending flow system, the formation of the cave pattern was controlled by a system of sub-parallel anticlines and troughs with NNE–SSWdominant orientation, and by vertical and lateral heterogeneities in fracture distribution. Three cave-stratigraphic stories reflect the actual hydrostratigraphy during the main phase of speleogenesis. Cavities at different stories are distinct inmorphology and functioning. The gross tree-dimensional pattern of the system is effectively organized to conduct rising flow in deep-seated confined conditions. Cavities in the lower story developed as recharge components to the system. A laterally extensive conduit network in the middle story formed because the vertical flow from numerous recharge points has been redirected laterally along the highly conductive unit, occurring below the major seal - a scarcely fractured unit. Rift-like and shaft-like conduits in the upper story developed along fracturecontrolled outflow paths, breaching the integrity of the major seal, and served as outlets for the cave system. The cave system represents a series of vertically organized, functionally largely independent clusters of cavities developed within individual ascending flow cells. Lateral integration of clusters occurred due to hydrodynamic interaction between the flow cells in course of speleogenetic evolution and change of boundary conditions. The main speleogenetic phase, during which the gross cave pattern has been established and the caves acquired most of their volume, was likely related to rise of deep fluids at about 520 Ma or associated with rifting and the Pangea break-up in Triassic–Cretaceous. This study highlights the importance of speleogenetic studies for interpreting porosity and permeability features in carbonate reservoirs.


Research frontiers in speleogenesis. Dominant processes, hydrogeological conditions and resulting cave patterns, 2015,
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Speleogenesis is the development of well-organized cave systems by fluids moving through fissures of a soluble rock. Epigenic caves induced by biogenic CO2 soil production are dominant, whereas hypogenic caves resulting from uprising deep flow not directly connected to adjacent recharge areas appear to be more frequent than previously considered. The conceptual models of epigenic cave development moved from early models, through the “four-states model” involving fracture influence to explain deep loops, to the digital models demonstrating the adjustment of the main flow to the water table. The relationships with base level are complex and cave levels must be determined from the elevation of the vadose-phreatic transitions. Since flooding in the epiphreatic zone may be important, the top of the loops in the epiphreatic zone can be found significantly high above the base level. The term Paragenesis is used to describe the upward development of conduits as their lower parts fill with sediments. This process often records a general baselevel rise. Sediment influx is responsible for the regulation of long profiles by paragenesis and contributes to the evolution of profiles from looping to water table caves. Dating methods allow identification of the timing of cave level evolution. The term Ghost-rock karstification is used to describe a 2-phase process of speleogenesis, with a first phase of partial solution of rock along fractures in low gradient conditions leaving a porous matrix, the ghost-rock, then a second phase of mechanical removing of the ghost-rock mainly by turbulent flow in high gradient conditions opening the passages and forming maze caves. The first weathering phase can be related either to epigenic infiltration or to hypogenic upflow, especially in marginal areas of sedimentary basins. The vertical pattern of epigenic caves is mainly controlled by timing, geological structure, types of flow and base-level changes. We define several cave types as (1) juvenile, where they are perched above underlying aquicludes; (2) looping, where recharge varies greatly with time, to produce epiphreatic loops; (3) water-table caves where flow is regulated by a semi-pervious cover; and (4) caves in the equilibrium stage where flow is transmitted without significant flooding. Successive base-level drops caused by valley entrenchment make cave levels, whereas baselevel rise is defined in the frame of the Per ascensum Model of Speleogenesis (PAMS), where deep passages are flooded and drain through vauclusian springs. The PAMS can be active after any type of baselevel rise (transgression, fluvial aggradation, tectonic subsidence) and explains most of the deep phreatic cave systems except for hypogenic.

The term Hypogenic speleogenesis is used to describe cave development by deep upflow independent of adjacent recharge areas. Due to its deep origin, water frequently has a high CO2-H2S concentration and a thermal anomaly, but not systemati­cally. Numerous dissolution processes can be involved in hypogenic speleogenesis, which often include deep-seated acidic sources of CO2 and H2S, “hydrothermal” cooling, mixing corrosion, Sulfuric Acid Speleogenesis (SAS), etc. SAS particularly involves the condensation-corrosion processes, resulting in the fast expansion of caves above the water table, i.e. in an atmo­spheric environment. The hydrogeological setting of hypogenic speleogenesis is based on the Regional Gravity Flow concept, which shows at the basin scales the sites of convergences and upflows where dissolution focuses. Each part of a basin (mar­ginal, internal, deep zone) has specific conditions. The coastal basin is a sub-type. In deformed strata, flow is more complex according to the geological structure. However, upflow and hypogenic speleogenesis concentrate in structural highs (buried anticlines) and zones of major disruption (faults, overthrusts). In disrupted basins, the geothermal gradient “pumps” the me­teoric water at depth, making loops of different depths and characteristics. Volcanism and magmatism also produce deep hypogenic loops with “hyperkarst” characteristics due to a combination of deep-seated CO2, H2S, thermalism, and microbial activity. In phreatic conditions, the resulting cave patterns

can include geodes, 2–3D caves, and giant ascending shafts. Along the water table, SAS with thermal air convection induces powerful condensation-corrosion and the development of upwardly dendritic caves, isolated chambers, water table sulfuricacid caves. In the vadose zone, “smoking” shafts evolve under the influence of geothermal gradients producing air convectionand condensation-corrosion.

Likely future directions for research will probably involve analytical and modeling methods, especially using isotopes, dating, chemical simulations, and field investigations focused on the relationships between processes and resulting morphologies.


Research frontiers in speleogenesis. Dominant processes, hydrogeological conditions and resulting cave patterns, 2015,
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Speleogenesis is the development of well-organized cave systems by fluids moving through fissures of a soluble rock. Epigenic caves induced by biogenic CO2 soil production are dominant, whereas hypogenic caves resulting from uprising deep flow not directly connected to adjacent recharge areas appear to be more frequent than previously considered. The conceptual models of epigenic cave development moved from early models, through the “four-states model” involving fracture influence to explain deep loops, to the digital models demonstrating the adjustment of the main flow to the water table. The relationships with base level are complex and cave levels must be determined from the elevation of the vadose-phreatic transitions. Since flooding in the epiphreatic zone may be important, the top of the loops in the epiphreatic zone can be found significantly high above the base level. The term Paragenesis is used to describe the upward development of conduits as their lower parts fill with sediments. This process often records a general baselevel rise. Sediment influx is responsible for the regulation of long profiles by paragenesis and contributes to the evolution of profiles from looping to water table caves. Dating methods allow identification of the timing of cave level evolution. The term Ghost-rock karstification is used to describe a 2-phase process of speleogenesis, with a first phase of partial solution of rock along fractures in low gradient conditions leaving a porous matrix, the ghost-rock, then a second phase of mechanical removing of the ghost-rock mainly by turbulent flow in high gradient conditions opening the passages and forming maze caves. The first weathering phase can be related either to epigenic infiltration or to hypogenic upflow, especially in marginal areas of sedimentary basins. The vertical pattern of epigenic caves is mainly controlled by timing, geological structure, types of flow and base-level changes. We define several cave types as (1) juvenile, where they are perched above underlying aquicludes; (2) looping, where recharge varies greatly with time, to produce epiphreatic loops; (3) water-table caves where flow is regulated by a semi-pervious cover; and (4) caves in the equilibrium stage where flow is transmitted without significant flooding. Successive base-level drops caused by valley entrenchment make cave levels, whereas baselevel rise is defined in the frame of the Per ascensum Model of Speleogenesis (PAMS), where deep passages are flooded and drain through vauclusian springs. The PAMS can be active after any type of baselevel rise (transgression, fluvial aggradation, tectonic subsidence) and explains most of the deep phreatic cave systems except for hypogenic.

The term Hypogenic speleogenesis is used to describe cave development by deep upflow independent of adjacent recharge areas. Due to its deep origin, water frequently has a high CO2-H2S concentration and a thermal anomaly, but not systemati­cally. Numerous dissolution processes can be involved in hypogenic speleogenesis, which often include deep-seated acidic sources of CO2 and H2S, “hydrothermal” cooling, mixing corrosion, Sulfuric Acid Speleogenesis (SAS), etc. SAS particularly involves the condensation-corrosion processes, resulting in the fast expansion of caves above the water table, i.e. in an atmo­spheric environment. The hydrogeological setting of hypogenic speleogenesis is based on the Regional Gravity Flow concept, which shows at the basin scales the sites of convergences and upflows where dissolution focuses. Each part of a basin (mar­ginal, internal, deep zone) has specific conditions. The coastal basin is a sub-type. In deformed strata, flow is more complex according to the geological structure. However, upflow and hypogenic speleogenesis concentrate in structural highs (buried anticlines) and zones of major disruption (faults, overthrusts). In disrupted basins, the geothermal gradient “pumps” the me­teoric water at depth, making loops of different depths and characteristics. Volcanism and magmatism also produce deep hypogenic loops with “hyperkarst” characteristics due to a combination of deep-seated CO2, H2S, thermalism, and microbial activity. In phreatic conditions, the resulting cave patterns

can include geodes, 2–3D caves, and giant ascending shafts. Along the water table, SAS with thermal air convection induces powerful condensation-corrosion and the development of upwardly dendritic caves, isolated chambers, water table sulfuricacid caves. In the vadose zone, “smoking” shafts evolve under the influence of geothermal gradients producing air convectionand condensation-corrosion.

Likely future directions for research will probably involve analytical and modeling methods, especially using isotopes, dating, chemical simulations, and field investigations focused on the relationships between processes and resulting morphologies.


Research frontiers in speleogenesis. Dominant processes, hydrogeological conditions and resulting cave patterns, 2015,
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Speleogenesis is the development of well-organized cave systems by fluids moving through fissures of a soluble rock. Epigenic caves induced by biogenic CO2 soil production are dominant, whereas hypogenic caves resulting from uprising deep flow not directly connected to adjacent recharge areas appear to be more frequent than previously considered. The conceptual models of epigenic cave development moved from early models, through the “four-states model” involving fracture influence to explain deep loops, to the digital models demonstrating the adjustment of the main flow to the water table. The relationships with base level are complex and cave levels must be determined from the elevation of the vadose-phreatic transitions. Since flooding in the epiphreatic zone may be important, the top of the loops in the epiphreatic zone can be found significantly high above the base level. The term Paragenesis is used to describe the upward development of conduits as their lower parts fill with sediments. This process often records a general baselevel rise. Sediment influx is responsible for the regulation of long profiles by paragenesis and contributes to the evolution of profiles from looping to water table caves. Dating methods allow identification of the timing of cave level evolution. The term Ghost-rock karstification is used to describe a 2-phase process of speleogenesis, with a first phase of partial solution of rock along fractures in low gradient conditions leaving a porous matrix, the ghost-rock, then a second phase of mechanical removing of the ghost-rock mainly by turbulent flow in high gradient conditions opening the passages and forming maze caves. The first weathering phase can be related either to epigenic infiltration or to hypogenic upflow, especially in marginal areas of sedimentary basins. The vertical pattern of epigenic caves is mainly controlled by timing, geological structure, types of flow and base-level changes. We define several cave types as (1) juvenile, where they are perched above underlying aquicludes; (2) looping, where recharge varies greatly with time, to produce epiphreatic loops; (3) water-table caves where flow is regulated by a semi-pervious cover; and (4) caves in the equilibrium stage where flow is transmitted without significant flooding. Successive base-level drops caused by valley entrenchment make cave levels, whereas baselevel rise is defined in the frame of the Per ascensum Model of Speleogenesis (PAMS), where deep passages are flooded and drain through vauclusian springs. The PAMS can be active after any type of baselevel rise (transgression, fluvial aggradation, tectonic subsidence) and explains most of the deep phreatic cave systems except for hypogenic.

The term Hypogenic speleogenesis is used to describe cave development by deep upflow independent of adjacent recharge areas. Due to its deep origin, water frequently has a high CO2-H2S concentration and a thermal anomaly, but not systemati­cally. Numerous dissolution processes can be involved in hypogenic speleogenesis, which often include deep-seated acidic sources of CO2 and H2S, “hydrothermal” cooling, mixing corrosion, Sulfuric Acid Speleogenesis (SAS), etc. SAS particularly involves the condensation-corrosion processes, resulting in the fast expansion of caves above the water table, i.e. in an atmo­spheric environment. The hydrogeological setting of hypogenic speleogenesis is based on the Regional Gravity Flow concept, which shows at the basin scales the sites of convergences and upflows where dissolution focuses. Each part of a basin (mar­ginal, internal, deep zone) has specific conditions. The coastal basin is a sub-type. In deformed strata, flow is more complex according to the geological structure. However, upflow and hypogenic speleogenesis concentrate in structural highs (buried anticlines) and zones of major disruption (faults, overthrusts). In disrupted basins, the geothermal gradient “pumps” the me­teoric water at depth, making loops of different depths and characteristics. Volcanism and magmatism also produce deep hypogenic loops with “hyperkarst” characteristics due to a combination of deep-seated CO2, H2S, thermalism, and microbial activity. In phreatic conditions, the resulting cave patterns

can include geodes, 2–3D caves, and giant ascending shafts. Along the water table, SAS with thermal air convection induces powerful condensation-corrosion and the development of upwardly dendritic caves, isolated chambers, water table sulfuricacid caves. In the vadose zone, “smoking” shafts evolve under the influence of geothermal gradients producing air convectionand condensation-corrosion.

Likely future directions for research will probably involve analytical and modeling methods, especially using isotopes, dating, chemical simulations, and field investigations focused on the relationships between processes and resulting morphologies.


Research frontiers in speleogenesis. Dominant processes, hydrogeological conditions and resulting cave patterns, 2015,
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Speleogenesis is the development of well-organized cave systems by fluids moving through fissures of a soluble rock. Epigenic caves induced by biogenic CO2 soil production are dominant, whereas hypogenic caves resulting from uprising deep flow not directly connected to adjacent recharge areas appear to be more frequent than previously considered. The conceptual models of epigenic cave development moved from early models, through the “four-states model” involving fracture influence to explain deep loops, to the digital models demonstrating the adjustment of the main flow to the water table. The relationships with base level are complex and cave levels must be determined from the elevation of the vadose-phreatic transitions. Since flooding in the epiphreatic zone may be important, the top of the loops in the epiphreatic zone can be found significantly high above the base level. The term Paragenesis is used to describe the upward development of conduits as their lower parts fill with sediments. This process often records a general baselevel rise. Sediment influx is responsible for the regulation of long profiles by paragenesis and contributes to the evolution of profiles from looping to water table caves. Dating methods allow identification of the timing of cave level evolution. The term Ghost-rock karstification is used to describe a 2-phase process of speleogenesis, with a first phase of partial solution of rock along fractures in low gradient conditions leaving a porous matrix, the ghost-rock, then a second phase of mechanical removing of the ghost-rock mainly by turbulent flow in high gradient conditions opening the passages and forming maze caves. The first weathering phase can be related either to epigenic infiltration or to hypogenic upflow, especially in marginal areas of sedimentary basins. The vertical pattern of epigenic caves is mainly controlled by timing, geological structure, types of flow and base-level changes. We define several cave types as (1) juvenile, where they are perched above underlying aquicludes; (2) looping, where recharge varies greatly with time, to produce epiphreatic loops; (3) water-table caves where flow is regulated by a semi-pervious cover; and (4) caves in the equilibrium stage where flow is transmitted without significant flooding. Successive base-level drops caused by valley entrenchment make cave levels, whereas baselevel rise is defined in the frame of the Per ascensum Model of Speleogenesis (PAMS), where deep passages are flooded and drain through vauclusian springs. The PAMS can be active after any type of baselevel rise (transgression, fluvial aggradation, tectonic subsidence) and explains most of the deep phreatic cave systems except for hypogenic.

The term Hypogenic speleogenesis is used to describe cave development by deep upflow independent of adjacent recharge areas. Due to its deep origin, water frequently has a high CO2-H2S concentration and a thermal anomaly, but not systemati­cally. Numerous dissolution processes can be involved in hypogenic speleogenesis, which often include deep-seated acidic sources of CO2 and H2S, “hydrothermal” cooling, mixing corrosion, Sulfuric Acid Speleogenesis (SAS), etc. SAS particularly involves the condensation-corrosion processes, resulting in the fast expansion of caves above the water table, i.e. in an atmo­spheric environment. The hydrogeological setting of hypogenic speleogenesis is based on the Regional Gravity Flow concept, which shows at the basin scales the sites of convergences and upflows where dissolution focuses. Each part of a basin (mar­ginal, internal, deep zone) has specific conditions. The coastal basin is a sub-type. In deformed strata, flow is more complex according to the geological structure. However, upflow and hypogenic speleogenesis concentrate in structural highs (buried anticlines) and zones of major disruption (faults, overthrusts). In disrupted basins, the geothermal gradient “pumps” the me­teoric water at depth, making loops of different depths and characteristics. Volcanism and magmatism also produce deep hypogenic loops with “hyperkarst” characteristics due to a combination of deep-seated CO2, H2S, thermalism, and microbial activity. In phreatic conditions, the resulting cave patterns

can include geodes, 2–3D caves, and giant ascending shafts. Along the water table, SAS with thermal air convection induces powerful condensation-corrosion and the development of upwardly dendritic caves, isolated chambers, water table sulfuricacid caves. In the vadose zone, “smoking” shafts evolve under the influence of geothermal gradients producing air convectionand condensation-corrosion.

Likely future directions for research will probably involve analytical and modeling methods, especially using isotopes, dating, chemical simulations, and field investigations focused on the relationships between processes and resulting morphologies.


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