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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 roof pocket is blind upward extension into the ceiling of a cave passage, commonly enlarged by dissolution along a transverse fracture, and less extensive than an aven or chimney [9].?

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 cave (Keyword) returned 5844 results for the whole karstbase:
Showing 5821 to 5835 of 5844
Microbial mediation of complex subterranean mineral structures, 2015,
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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

Helictites—an enigmatic type of mineral structure occurring in some caves—differ from classical speleothems as they develop with orientations that defy gravity. While theories for helictite formation have been forwarded, their genesis remains equivocal. Here, we show that a remarkable suite of helictites occurring in Asperge Cave (France) are formed by biologically-mediated processes, rather than abiotic processes as had hitherto been proposed. Morphological and petro-physical properties are inconsistent with mineral precipitation under purely physico-chemical control.

Instead, microanalysis and molecular-biological investigation reveals the presence of a prokaryotic biofilm intimately associated with the mineral structures. We propose that microbially-influenced mineralization proceeds within a gliding biofilm which serves as a nucleation site for CaCO3, and where chemotaxis influences the trajectory of mineral growth, determining the macroscopic morphology of the speleothems. The influence of biofilms may explain the occurrence of similar speleothems in other caves worldwide, and sheds light on novel biomineralization processes.


23rd International Karstological School "Classical Karst". Caves - exploration and studies combined with the 50th anniversary of the International Union of Speleology - UIS, 2015,
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Zupan Hajna Nadja, Mihevc Andrej, Gostinčar Petra (eds. )

23rd International Karstological School "Classical Karst", Postojna, June 15th to 21st 2015

Caves - exploration and studies combined with the 50th anniversary of the International Union of Speleology - UIS : program & excursions & UIS & abstracts

 

 


Depth and timing of calcite spar and “spar cave” genesis: Implications for landscape evolution studies, 2015,
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Calcite spar (crystals >1 cm in diameter) are common in limestone and dolostone terrains. In the Guadalupe Mountains, New Mexico and west Texas, calcite spar is abundant and lines small geode-like caves. Determining the depth and timing of formation of these large scalenohedral calcite crystals is critical in linking the growth of spar with landscape evolution. In this study, we show that large euhedral calcite crystals precipitate deep in the phreatic zone (400–800 m) in these small geode-like caves (spar caves), and we propose both are the result of properties of supercritical CO2 at that depth. U-Pb dating of spar crystals shows that they formed primarily between 36 and 28 Ma. The 87Sr/86Sr values of the euhedral calcite spar show that the spar has a signifi cantly higher 87Sr/86Sr (0.710–0.716) than the host Permian limestone (0.706–0.709). This indicates the spar formed from waters that are mixed with, or formed entirely from, a source other than the surrounding bedrock aquifer, and this is consistent with hypogene speleogenesis at signifi cant depth. In addition, we conducted highly precise measurements of the variation in nonradiogenic isotopes of strontium, 88Sr/86Sr, expressed as 88Sr, the variation of which has previously been shown to depend on temperature of precipitation. Our preliminary 88Sr results from the spar calcite are consistent with formation at 50–70 °C. Our fi rst U-Pb results show that the spar was precipitated during the beginning of Basin and Range tectonism in a late Eocene to early Oligocene episode, which was coeval with two major magmatic periods at 36–33 Ma and 32–28 Ma. A novel speleogenetic process that includes both the dissolution of the spar caves and precipitation of the spar by the same speleogenetic event is proposed and supports the formation of the spar at 400–800 m depth, where the transition from supercritical to subcritical CO2 drives both dissolution of limestone during the main speleogenetic event and precipitation of calcite at the terminal phase of speleogenesis. We suggest that CO2 is derived from contemporaneous igneous activity. This proposed model suggests that calcite spar can be used for reconstruction of landscape evolution


Basinscale conceptual groundwater flow model for an unconfined and confined thick carbonate region, 2015,
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Application of the gravitydriven regional groundwater flow (GDRGF) concept to the hydrogeologically complex thick carbonate system of the Transdanubian Range (TR), Hungary, is justified based on the principle of hydraulic continuity. The GDRGF concept informs about basin hydraulics and groundwater as a geologic agent. It became obvious that the effect of heterogeneity and anisotropy on the flow pattern could be derived from hydraulic reactions of the aquifer system. The topography and heat as driving forces were examined by numerical simulations of flow and heat transport. Evaluation of groups of springs, in terms of related discharge phenomena and regional chloride distribution, reveals the dominance of topographydriven flow when considering flow and related chemical and temperature patterns. Moreover, heat accumulation beneath the confined part of the system also influences these patterns. The presence of cold, lukewarm and thermal springs and related wetlands, creeks, mineral precipitates, and epigenic and hypogenic caves validates the existence of GDRGF in the system. Vice versa, groups of springs reflect rock–water interaction and advective heat transport and inform about basin hydraulics. Based on these findings, a generalized conceptual GDRGF model is proposed for an unconfined and confined carbonate region. An interface was revealed close to the margin of the unconfined and confined carbonates, determined by the GDRGF and freshwater and basinal fluids involved. The application of this model provides a background to interpret manifestations of flowing groundwater in thick carbonates generally, including porosity enlargement and hydrocarbon and heat accumulation.


Earliest evidence of pollution by heavy metals in archaeological sites, 2015,
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Guadalupe Monge, Francisco J. Jimenezespejo, Antonio Garcíaalix, Francisca Martínezruiz, Nadine Mattielli, Clive Finlayson, Naohiko Ohkouchi, Miguel Cortés Sánchez, Jose María Bermúdez De Castro, Ruth Blasco, Jordi Rosell, José Carrión, Joaquí

Homo species were exposed to a new biogeochemical environment when they began to occupy caves. Here we report the first evidence of palaeopollution through geochemical analyses of heavy metals in four renowned archaeological caves of the Iberian Peninsula spanning the last million years of human evolution. Heavy metal contents reached high values due to natural (guano deposition) and anthropogenic factors (e.g. combustion) in restricted cave environments. The earliest anthropogenic pollution evidence is related to Neanderthal hearths from Gorham's Cave (Gibraltar), being one of the first milestones in the so-called “Anthropocene”. According to its heavy metal concentration, these sediments meet the present-day standards of “contaminated soil”. Together with the former, the Gibraltar Vanguard Cave, shows Zn and Cu pollution ubiquitous across highly anthropic levels pointing to these elements as potential proxies for human activities. Pb concentrations in Magdalenian and Bronze age levels at El Pirulejo site can be similarly interpreted. Despite these high pollution levels, the contaminated soils might not have posed a major threat to Homo populations. Altogether, the data presented here indicate a long-term exposure of Homo to these elements, via fires, fumes and their ashes, which could have played certain role in environmental-pollution tolerance, a hitherto neglected influence.


Hydrothermal speleogenesis in carbonates and metasomatic silicites induced by subvolcanic intrusions: a case study from the Štiavnické vrchy Mountains, Slovakia, 2015,
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Several caves of hydrothermal origin in crystalline limestones and metasomatic silicites were investigated in the central zone of the Štiavnica stratovolcano, Štiavnické vrchy Mountains, central Slovakia. Evidence of hydrothermal origin includes irregular spherical cave morphology sculptured by ascending thermal water, occurrence of large calcite crystals and hydrothermal alteration of host rocks, including hydrothermal clays. The early phases of speleogenesis in the crystalline limestone near Sklené Teplice Spa were caused by post-magmatic dissolution linked either to the emplacement of subvolcanic granodiorite intrusions during Late Badenian time or to the spatially associated Late Sarmatian epithermal system. Speleogenesis in metasomatic silicites in the Šobov area is related to hydrothermal processes associated with the pre-caldera stage of the Štiavnica stratovolcano in Late Badenian. Both localities are remarkable examples of hydrothermal speleogenesis associated with Miocene volcanic and magmatic activity in the Western Carpathians


Superposed folding and associated fracturing influence hypogene karst development in Neoproterozoic carbonates, São Francisco Craton, Brazil, 2015,
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Porosity and permeability along fractured zones in carbonates could be significantly enhanced by ascending fluid flow, resulting in hypogene karst development. This work presents a detailed structural analysis of the longest cave system in South America to investigate the relationship between patterns of karst conduits and regional deformation. Our study area encompasses the Toca da Boa Vista (TBV) and Toca da Barriguda (TBR) caves, which are ca. 107 km and 34 km long, respectively. This cave system occurs in Neoproterozoic carbonates of the Salitre Formation in the northern part of the São Francisco Craton, Brazil. The fold belts that are around and at the craton edges were deformed in a compressive setting during the Brasiliano orogeny between 750 and 540 Ma. Based on the integrated analysis of the folds and brittle deformation in the caves and in outcrops of the surrounding region, we show the following: (1) The caves occur in a tectonic transpressive corridor along a regional thrust belt; (2) major cave passages, at the middle storey of the system, considering both length and frequency, developed laterally along mainly (a) NE–SW to E–W and (b) N to S oriented anticline hinges; (3) conduitswere formed by dissolutional enlargement of subvertical joints,which present a high concentration along anticline hinges due to folding of competent grainstone layers; (4) the first folding event F1was previously documented in the region and corresponds with NW–SE- to N–S-trending compression, whereas the second event F2, documented for the first time in the present study, is related to E–Wcompression; and (5) both folding  еvents occurred during the Brasiliano orogeny. We conclude that fluid flow and related dissolution pathways have a close relationship with regional deformation events, thus enhancing our ability to predict karst patterns in layered carbonates.


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.


Sulfuric acid speleogenesis (SAS) close to the water table: Examples from southern France, Austria, and Sicily, 2015,
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Caves formed by rising sulfuric waters have been described from all over the world in a wide variety of climate  settings, from arid regions to mid-latitude and alpine areas. H2S is generally formed at depth by reduction of  sulfates in the presence of hydrocarbons and is transported in solution through the deep aquifers. In tectonically  disturbed areas major fractures eventually allow these H2S-bearing fluids to rise to the surface where oxidation  processes can become active producing sulfuric acid. This extremely strong acid reacts with the carbonate  bedrock creating caves, some of which are among the largest and most spectacular in the world. Production of  sulfuric acid mostly occurs at or close to the water table but also in subaerial conditions in moisture films and  droplets in the cave environment. These caves are generated at or immediately above the water table, where  condensation–corrosion processes are dominant, creating a set of characteristic meso- and micromorphologies.  Due to their close connection to the base level, these caves can also precisely record past hydrological and  geomorphological settings. Certain authigenic cave minerals, produced during the sulfuric acid speleogenesis  (SAS) phase, allow determination of the exact timing of speleogenesis. This paper deals with the morphological,  geochemical and mineralogical description of four very typical sulfuric acid water table caves in Europe: the  Grotte du Chat in the southern French Alps, the Acqua Fitusa Cave in Sicily (Italy), and the Bad Deutsch Altenburg  and Kraushöhle caves in Austria


Hypogene speleogenesis in dolomite host rock by CO2-rich fluids, Kozak Cave (southern Austria), 2015,
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A growing number of studies suggest that cave formation by deep-seated groundwater  (hypogene) is a more common process of subsurface water-rock interaction than previously  thought. Fossil hypogene caves are identified by a characteristic suite of morphological  features on different spatial scales. In addition, mineral deposits (speleothems) may provide  clues about the chemical composition of the paleowater, which range from CO2-rich to  sulfuric acid-bearing waters. This is one of the first studies to examine hypogene cave  formation in dolomite. Kozak Cave is a fossil cave near the Periadriatic Lineament, an area  known for its abundance of CO2-rich springs. The cave displays a number of macro-, mesoand  micromorphological elements found also in other hypogene caves hosted in limestone,  marble or gypsum, including cupolas, cusps, Laughöhle-type chambers and notches. The  existance of cupolas and cusps suggests a thermal gradient capable of sustaining free  convection during a first phase of speleogenesis, while triangular cross sections (Laughöhle  morphology) indicate subsequent density-driven convection close to the paleowater table Notches mark the final emergence of the cave due to continued rock uplift and valley  incision. Very narrow shafts near the end of the cave may be part of the initial feeder system,  but an epigene (vadose) overprint cannot be ruled out. Vadose speleothems indicate that the  phreatic phase ended at least about half a million years ago. Drill cores show no evidence of  carbon or oxygen isotope alteration of the wall rock. This is in contrast to similar studies in  limestone caves, and highlights the need for further wall-rock studies of caves hosted in  limestone and dolomite


Hidden sinkholes and karst cavities in the travertine plateau of a highly-populated geothermal seismic territory (Tivoli, central Italy), 2015,
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Sinkholes and other karst structures in settled carbonate lands can be a significant source of hazard for humans and human works. Acque Albule, the study area of this work, is a Plio-Pleistocene basin near Rome, central Italy, superficially filled by a large and thick deposit of late Pleistocene thermogene travertine. Human activities blanket large portions of the flat territory covering most evidence from geological surface processes and potentially inducing scientists and public officials to underestimate some natural hazards including those connected with sinkholes. To contribute to the proper assessment of these hazards, a geomorphologic study of the basin was performed using digital elevation models (DEMs), recent aerial photographs, and field surveys. Historical material such as old aerial photographs and past geomorphologic studies both pre-dating the most part of quarrying and village building was also used together with memories of the elderly population. This preliminary study pointed out the presence of numerous potentially active sinkholes that are at present largely masked by either quarrying or overbuilding. Where this first study pointed out the apparent absence of sinkholes in areas characterized by high density of buildings, a detailed subsurface study was performed using properly-calibrated electrical resistivity tomography (ERT) and dynamic penetration measurements (DPSH), together with some borehole logs made available from the local municipality. This second study highlighted the presence of sinkholes and caves that are, this time, substantially hidden to the resolution of standard methods and materials such as aerial photographs, DEMs, and field surveys. Active sinkhole subsidence in the Acque Albule Basin may explain, at least in part, the frequent damages that affect numerous buildings in the area. The main conclusion from this study is that the mitigation of sinkhole hazard in highly populated areas has to pass through a thorough search of (hidden) sinkholes that can be masked by the Anthropocenic molding and blanketing of the territory. For these purposes, data from historical (pre-Anthropocene) documents as well as, where possible, subsurface investigations are fundamental.


Sinkholes, collapse structures and large landslides in an active salt dome submerged by a reservoir: The unique case of the Ambal ridge in the Karun River, Zagros Mountains, Iran, 2015,
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Ambal ridge, covering 4 km2, is a salt pillowof Gachsaran Formationwith significant salt exposures in direct contact  with the Karun River, Zagros Mountains. The highly cavernous salt dome is currently being flooded by the  Gotvand Reservoir, second largest in Iran. Geomorphic evidence, including the sharp deflection of the Karun  River and defeated streams indicate that Ambal is an active halokinetic structure, probably driven by erosional  unloading. Around 30% of the salt dome is affected by large landslides up to ca. 50 × 106 m3 in volume. Slope  oversteepening related to fluvial erosion and halokinetic rise seems to be the main controlling factor. A total of  693 sinkholes have been inventoried (170 sinkholes/km2), for which a scaling relationship has been produced.  The depressions occur preferentially along a belt with a high degree of clustering. This spatial distribution is  controlled by the proximity to the river, slope gradient and halite content in the bedrock. A large compound  depression whose bottom lies below the normal maximum level of the reservoir will likely be flooded by  water table rise forming a lake. The impoundment of the reservoir has induced peculiar collapse structures  220–280 m across, expressed by systems of arcuate fissures and scarps. Rapid subsurface salt dissolution is  expected to generate and reactivate a large number of sinkholes and may reactivate landslideswith a significant  vertical component due to lack of basal support.


Basin-scale conceptual groundwater flow model for an unconfined and confined thick carbonate region, 2015,
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Application of the gravity-driven regional  groundwater flow (GDRGF) concept to the  hydrogeologically complex thick carbonate system of the  Transdanubian Range (TR), Hungary, is justified based on  the principle of hydraulic continuity. The GDRGF concept  informs about basin hydraulics and groundwater as a  geologic agent. It became obvious that the effect of  heterogeneity and anisotropy on the flow pattern could be  derived from hydraulic reactions of the aquifer system.  The topography and heat as driving forces were examined  by numerical simulations of flow and heat transport.  Evaluation of groups of springs, in terms of related  discharge phenomena and regional chloride distribution,  reveals the dominance of topography-driven flow when  considering flow and related chemical and temperature  patterns. Moreover, heat accumulation beneath the confined  part of the system also influences these patterns. The  presence of cold, lukewarm and thermal springs and  related wetlands, creeks, mineral precipitates, and epigenic  and hypogenic caves validates the existence of GDRGF in  the system. Vice versa, groups of springs reflect rock–  water interaction and advective heat transport and inform  about basin hydraulics. Based on these findings, a  generalized conceptual GDRGF model is proposed for  an unconfined and confined carbonate region. An interface  was revealed close to the margin of the unconfined and  confined carbonates, determined by the GDRGF and  freshwater and basinal fluids involved. The application  of this model provides a background to interpret manifestations  of flowing groundwater in thick carbonates  generally, including porosity enlargement and hydrocarbon  and heat accumulation.


Karst pocket valleys and their implications on Pliocene–Quaternary hydrology and climate: Examples from the Nullarbor Plain, southern Australia, 2015,
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Karst on the Nullarbor Plain has been studied and described in detail in the past, but it lacked the determination of the karst discharge and palaeo-watertable levels that would explain the palaeohydrological regime in this area. This study explores the existence of previously unrecognised features in this area – karst pocket valleys – and gives a review on pocket valleys worldwide. Initial GIS analyses were followed up by detailed field work, sampling, mapping and measuring of morphological, geological, and hydrological characteristics of representative
valleys on the Wylie and Hampton scarps of the Nullarbor Plain. Rock and sand samples were examined for mineralogy, texture and grain size, and a U–Pb dating of a speleothem froma cave within a pocket valley enabled the establishment of a time frame of the pocket valleys formation and its palaeoenvironmental implications. The pocket valleys document the hydrological evolution of the Nullarbor karst system and the Neogene–Pleistocene palaeoclimatic evolution of the southern hemisphere. A review of pocket valleys in different climatic and geological settings suggests that their basic characteristics remain the same, and their often overlooked utility as environmental indicators can be used for further palaeoenvironmental studies. The main period of intensive karstification and widening of hydrologically active underground conduits is placed into the wetter climates of the Pliocene epoch. Subsequent drier climates and lowering of the watertable that followed sea-level retreat in the Quaternary resulted in formation of the pocket valleys (gravitational undermining, slumping, exudation and collapse), which, combined with periodic heavy rainfall events and discharge due to impeded drainage, caused the retreat of the pocket valleys from the edge of escarpments.


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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