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Speleology in Kazakhstan

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

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. ...

Speleology in Kazakhstan

Shakalov on 11 Jul, 2012
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 desorption is the reverse process of sorption [22]. see also sorption.?

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Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
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Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
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Your search for flow-through (Keyword) returned 33 results for the whole karstbase:
Showing 1 to 15 of 33
The Aggitis karst system, Eastern Macedonia, Greece: Hydrologic functioning and development of the karst structure, , Novel Jean Paul, Dimadi Agoro, Zervopoulou Anna, Bakalowicz Michel,
SummaryThe Aggitis karst system developed in the marbles of the Rhodope massif. The conditions of the development of its karst drainage network are determined from the geological and geomorphologic settings by means of a microstructural analysis, following Eraso's method. This analysis shows that the karst conduit network intensely developed in the western part of the mountain Falakro where the majority of the open fractures oriented in the same direction as the hydraulic gradient, while the two directions are perpendicular in its eastern part drained by the spring of Drama.The behaviour of the system was analysed by means of hydrodynamic and water geochemical techniques. Despite the extension of the cave system and of the favourable development conditions of conduits, the functioning appears complex, with a significant storage, and a slow infiltration as well as an easy drainage. On the contrary the Drama karst system, characterised by a low variability in its hydrological and geochemical characteristics does not show any karst functioning.In the Aggitis karst system the initial groundwater flow conditions in combination with the aperture planes of which the directions are in agreement with the hydraulic gradient, favoured the rapid development of a drainage network system. The recharge from a large surface catchment area on non-karstic rocks, through swallow holes in a wide polje contributed to increase the groundwater flow through the karst part of the system, facilitating the development of the conduits

IMPACT OF PAST SEDIMENT ECOLOGY ON ROCK FRACTURATION AND DISTRIBUTION OF CURRENT ECOSYSTEMS (JURA, FRANCE), 1991, Gaiffe M, Bruckert S,
Differences in the fracture type of limestone rocks have resulted in the formation of several main plant soil ecosystems in the montane and subalpine zones of the Jura (800-1 700 m). The sites were on stable landscape with slope < 5%. Locations were chosen to reflect the variation in physical properties of the bedrock and lithic contact. The rock fractures (densities and size), the shape and size of the fragments and the hydraulic conductivities were described and analyzed to characterize the 3 main bedrocks in the area studied (table 1): 1), lapiaz, ie, large rock fragments separated from each other by wide fractures (figs 1-2), 'broken' rocks traversed by numerous fine fractures (fig 2-3), paving-stones crossed by infrequent narrow fractures (fig 3). The effects of rock fracturing on vegetation (table II) and soil formation were significant in reference to porosity and permeability relationships (figs 6-7). Under similar precipitation, meteoric waters flow through the soil and porosity is relative to fracture systems (figs 4, 5). The weathering of cobbles in the soil profiles and along the lithic contacts maintains different soil solution Ca levels and is an important variable in soil and ecosystem formation (table III). Regarding the regional orogenic phases and the tectonic origin of the fractures, we postulate that the different types of fracturation originated from the different chemical and mineralogic composition of the rocks. Significant differences exist in both the calcite and dolomite content, in the insoluble residue content (table IV) and in the percentage of organic matter of the carbonate-free residues (table V, fig 8). The results indicate that the differences in rock composition arose early at about the period of sedimentation. The origin of the differentiation might be due to the sedimentation conditions and environment (fig 9). It is concluded that the present-day plant soil ecosystems may be related to the marine sediment environments of the Jurassic period (fig 10)

INFILTRATION MECHANISMS RELATED TO AGRICULTURAL WASTE TRANSPORT THROUGH THE SOIL MANTLE TO KARST AQUIFERS OF SOUTHERN INDIANA, USA, 1995, Iqbal M. Z. , Krothe N. C. ,
A hydrogeological study was conducted, during the 1991-1992 water year, in the clay-soil mantled portion of a limestone terrain in southern Indiana. The purpose of the study was to investigate the modes of soil-water infiltration contributing to rapid transport of nitrate to the saturated zone. The I-year-cycle profiles of nitrate concentration vs. time show a consistent increase of nitrate at various depths in the unsaturated zone during the period of investigation. The increase of nitrate in soil water is attributed to the rapid flushing of the inorganic fertilizers from the fields after the area received sufficient rainfall in late fall. The investigation also showed a major movement of nitrate in quick pulses through the unsaturated zone, rather than a slow uniform recharge, immediately after a major storm event. The asymmetric profiles of nitrate concentration vs. depth point to the existence of preferential flow through macropores in the clay-soil mantle above the bedrock. Soil-water transport between storm events is by matrix type flow. Nitrogen isotopes were analyzed for representative groundwater samples collected before and immediately after fertilization of fields in the summer, 1991. The delta(15)N values of the samples did not show any major shift in nitrate sources between the sampling periods. The summer of 1991 was extremely dry prohibiting vertical transport of nitrate from the fields to the groundwater system. Any change in nitrate concentration in groundwater during this time is attributed to the mixing through lateral flow within the aquifer

Bacteria in the Castleton karst, Derbyshire, England, 1997, Tranter J. , Gunn J. , Hunter C. , Perkins J. ,
The Castleton area contains an extensive and complex karst drainage system. Recharge is provided by allogenic stream sinks and by infiltration into a soil covered autogenic catchment. Concentrations of the sanitary indicator bacteria faecal coliform (FC) were measured weekly over a 84-week period at three stream-sinks (P6, P7 and P8) and at two contrasting springs (Russet Well and Peak Cavern Rising). Russet Well drains the allogenic catchment, but also receives some autogenic recharge whereas Peak Cavern Rising receives only autogenic recharge except at high stage when it functions as an overflow spring for the Russet Well system. Over the year as a whole and during each three-month season, median FC concentrations at P6 were significantly higher than at Russet Well. The difference was greatest during summer/autumn and was lowest in winter/spring and it appears that FC concentrations at the rising are a complex function of faecal inputs and flow-through time. The relationship between FC concentrations at Russet Well and at Peak Cavern Rising proved to be complex. Over the sampling period as a whole and during the spring and autumn there was no significant difference between median FC concentrations at the two risings; during the winter, when discharge was highest, median FC concentrations at Russet Well were significantly higher than at Peak Cavern Rising; and during the summer FC concentrations at Peak Cavern Rising were significantly higher than at Russet Well. The high FC concentrations in the sinking streams and at the risings suggest that there could be a health risk to cavers, especially during storm events and the summer. Furthermore, the fact that the waters from both springs contain significant concentrations of FC bacteria indicates that even soil covered karat systems are unable to filter out potentially harmful micro-organisms

An inexpensive flow-through field fluorometer., 1997, Schnegg Pa. , Doerfliger N.
In order to simplify sampling dye tracers in water streams without having to invest money in expensive systems, we developed a highly sensitive flow-through field fluorometer. This apparatus was tested successfully in the field with fluorescein and sulforhodamine. A submersible probe is connected to a digital data logger and the data is written to a PCMCIA memory card allowing 2 weeks of unattended recording at 1 sample every 4 minutes. A sensitivity as low as 0.05 ppb has been achieved. Simultaneous concentration measurements of 2 tracers is possible, at the expense of reduced sensitivity, however.

Relationships between karst and tectonics: case-study of the cave system north of Lake Thun (Bern, Switzerland): Relations entre karst et tectonique : l'exemple du reseau speleologique du nord du lac, 1999, Hauselmann Philipp, Jeannin Pierre Yves, Bitterli Thomas,
The cave system is situated north of Lake Thun, in the Helvetic border chain. The overall geology is simple: the slightly dipping (15-25[deg] towards the southeast) strata are interrupted by a NE-SW trending normal fault with a throw of 150 m in the NE and about 500 m in the SW. Since a part of the region is covered by flysch, the caves are the only way to observe the geological setting of the underlying Cretaceous and Eocene series. We show that observations in caves may yield valuable information about the onset of the tectonic movements: in particular, observations in the Barenkluft region clearly demonstrate that the beginning of prealpine extension had already begun in the Upper Cretaceous, and that this normal fault has been inverted later during Alpine compression. We also illustrate the influence of tectonic stress and strain upon karstification. The Alpine tectonic phases, with alternating compression and extension, contributed to the development of different karstogenetic levels. Tectonic strains opened and possibly closed some fractures, allowing (or preventing) water to flow through parts of the karst massive. The structural setting, defining the overall geometry of the limestone bed, played an important role in the development of the various phases of the system. Most of the conduits appear to belong to old, deep phreatic systems. Tectonics is only one of a number of factors controlling karstification. Together with lithology, it represents the geological control. Geomorphological factors (mainly spring and catchment positions, but also erosion of the flysch cover), as well as bioclimatical factors (quantity and physico-chemical characteristics of water), and hydrodynamics and transport processes can play a significant role on the genesis of karst systems

Variation of karstic permeability between unconfined and confined aquifers, Grand Canyon region, Arizona, 1999, Huntoon Pw. .
Most of the ground water in the Grand Canyon region circulates to springs in the canyon through the thick, deeply buried, karstified Cambrian through Mississippian carbonate sectionThese rocks are collectively called the lower Paleozoic carbonates and comprise the Redwall-Muav aquifer where saturatedThe morphologies of the caves are primarily a function of whether the carbonates are unconfined or confined, a distinction that has broad significance for groundwater exploration and which appears to be generally transferable to other carbonate regionsCaves in unconfined high-gradient environments tend to be highly localized, partially saturated, simple tubes, whereas those in confined low-gradient settings are saturated 2- or even 3-dimensional mazesThe highly heterogeneous distribution of the unconfined conduits makes for difficult drilling targets, whereas the more ubiquitously distributed confined mazes are far easier to targetThe distinctions between the storage characteristics within the two classes is probably even more importantThere is minimal groundwater storage in the unconfined systems because they are well drainedIn contrast, the saturated mazes exhibit maximal storageConsequently, system responses to major storm recharge events in the unconfined systems is often dominated by flow-through rather than the pulse-through hydraulics as found in the confined systemsSpring discharges from the unconfined systems tends to be both flashy and highly variable from season to season, but total dissolved solids are smallIn contrast, the pulse-through hydraulics in the artesian systems causes spring discharge responses to be highly moderated and, in the larger basins, remarkably steadyBoth total dissolved solids and temperatures in the waters from the confined aquifers tend to be elevated because most of the water is derived from storageKarst permeability is created by the flow system, consequently predicting where the permeability is best developed in a carbonate section involves determining how circulation should be ideally organized through an examination of the geometry of the flow systemThe areas where flow concentrates are the areas where karstification will maximize, provided enough time has elapsed to allow dissolution to adjust to the imposed boundary conditionsThe rate of adjustment in the Grand Canyon region appears to be related to the degree of saturationThe artesian systems are far better adjusted to hydraulic gradients than the unconfined systems, a finding that probably implies that there is greater contact between the solvent and rock in the saturated confined systems

Variability of karstic permeability between unconfined and confined aquifers, Grand Canyon region, Arizona, 2000, Huntoon P. W. ,
Most of the ground water in the Grand Canyon region circulates to springs in the canyon through the thick, deeply buried, karstified Cambrian-Mississippian carbonate section. These rocks are collectively called the lower Paleozoic carbonates and comprise the Redwall-Muav aquifer where saturated. The morphologies of the caves in the Grand Canyon are primarily a function of whether the carbonates are unconfined or confined, a distinction that has broad significance for ground-water exploration and which appears to be generally transferable to other carbonate regions. Caves in unconfined high-gradient environments tend to be highly localized, partially saturated, simple tubes, whereas those in confined low-gradient settings are saturated 2- or even 3-dimensional mazes. The highly heterogeneous, widely spaced conduits in the unconfined settings make for difficult drilling targets, whereas the more ubiquitously distributed mazes in confined settings are far easier to target. The distinctions between the storage characteristics within the two classes are more important. There is minimal ground-water storage in the unconfined systems because cave passages tend to be more widely spaced and are partially drained. In contrast, there is maximum storage in the saturated mazes in the confined systems. Consequently, system responses to major storm recharge events in the unconfined systems are characterized by flow-through hydraulics. Spring discharge from the unconfined systems tends to be both flashy and highly variable from season to season, but total dissolved solids are small. In contrast, the pulse-through hydraulics in the artesian systems cause fluctuations in spring discharge to be highly moderated and, in the larger basins, remarkably steady. Both total dissolved solids and temperatures in the waters from the confined aquifers tend to be elevated because most of the water is derived from storage. The large artesian systems that drain to the Grand Canyon derive water from areally extensive, deep basins where the water has been geothermally heated somewhat above mean ambient air temperatures. Karst permeability is created by the flow system, so dissolution permeability develops most rapidly in those volumes of carbonate aquifers where flow concentrates. Predicting where the permeability should be best developed in a carbonate section involves determining where flow has been concentrated in the geologic past by examining the geometry and hydraulic boundary conditions of the flow field. Karstification can be expected to maximize in those locations provided enough geologic time has elapsed to allow dissolution to adjust to the imposed boundary conditions. The rate of adjustment in the Grand Canyon region appears to be related to the degree of saturation. The artesian systems are far better adjusted to hydraulic gradients than the unconfined systems, a finding that probably implies that there is greater contact between the solvent and rock in the saturated systems. These findings are not arcane distinctions. Rather, successful exploration for ground water and management of the resource is materially improved by recognition of the differences between the types of karst present. For example, the unsaturated conduit karsts in the uplifts make for highly localized, high risk drilling targets and involve aquifers with very limited storage. The conduits have highly variable flow rates, but they carry good quality water largely derived from seasonal flow-through from the surface areas drained. In contrast, the saturated basin karsts, with more ubiquitous dissolutional permeability enhancement, provide areally extensive low risk drilling targets with large ground-water storage. The ground water in these settings is generally of lesser quality because it is derived mostly from long term storage

Geochemistry of the Springfield Plateau aquifer of the Ozark Plateaus Province in Arkansas, Kansas, Missouri and Oklahoma, USA, 2000, Adamski Jc,
Geochemical data indicate that the Springfield Plateau aquifer, a carbonate aquifer of the Ozark Plateaus Province in central USA, has two distinct hydrochemical zones. Within each hydrochemical zone, water from springs is geochemically and isotopically different than water from wells. Geochemical data indicate that spring water generally interacts less with the surrounding rock and has a shorter residence time, probably as a result of flowing along discrete fractures and solution openings, than water from wells. Water type throughout most of the aquifer was calcium bicarbonate, indicating that carbonate-rock dissolution is the primary geochemical process occurring in the aquifer. Concentrations of calcium, bicarbonate, dissolved oxygen and tritium indicate that most ground water in the aquifer recharged rapidly and is relatively young (less than 40 years). In general, field-measured properties, concentrations of many chemical constituents, and calcite saturation indices were greater in samples from the northern part of the aquifer (hydrochemical zone A) than in samples from the southern part of the aquifer (hydrochemical zone B). Factors affecting differences in the geochemical composition of ground water between the two zones are difficult to identify, but could be related to differences in chert content and possibly primary porosity, solubility of the limestone, and amount and type of cementation between zone A than in zone B. In addition, specific conductance, pH, alkalinity, concentrations of many chemical constituents and calcite saturation indices were greater in samples from wells than in samples from springs in each hydrochemical zone. In contrast, concentrations of dissolved oxygen, nitrite plus nitrate, and chloride generally were greater in samples from springs than in samples from wells. Water from springs generally flows rapidly through large conduits with minimum water-rock interactions. Water from wells flow through small fractures, which restrict how and increase water-rock interactions. As a result, springs tend to be more susceptible to surface contamination than wells. The results of this study have important implications for the geochemical and hydrogeological processes of similar carbonate aquifers in other geographical locations. Copyright (C) 2000 John Wiley & Sons, Ltd

Simulated effect of vadose infiltration on water levels in the Northern Guam Lens Aquifer, 2000, Contractor Dn, Jenson Jw,
Regional-scale hydrology of the fresh water lens in the Northern Guam Lens Aquifer has been simulated in the past using a finite element, sharp interface computer model, SWIG2D. Systematic differences exist between observed and computed water levels. Computed seasonal peak water levels are higher, and the computed seasonal lows are lower than the respective observed levels. It is hypothesized that vadose storage must store a substantial amount of water during the wet season and release it gradually into the lens during the dry season. Flow through the vadose zone was simulated with a one-dimensional finite element, unsaturated flow program UNSATID, in which the van Genuchten model is used to characterize unsaturated diffuse flow through the matrix of the vadose zone. An additional parameter (SINK) was added to the van Genuchten set to account for rapid infiltration down open pathways (fractures) associated with the closed depressions of the karst terrain. A global-optimization technique (Shuffled Complex Evolution or SCE-UA Method) was used to obtain the parameters that minimized the difference between simulated and observed water levels. Simulations incorporating the van Genuchten model were accomplished by combining the two programs, UNSATID and SWIG2D, into a single program. The sum-of-squared-errors (SSE) between computed and observed water levels in four observation wells was minimized using SCE-UA, reducing the arithmetically averaged SSE of the four wells by 30% compared with the SSE obtained when the vadose zone was not modeled. These results suggest that vadose storage is significant. On the other hand, the fact that the best fit obtained with an optimum parameter set was able to reduce the SSE by no more than 30% suggests that additional phenomena have yet to be accounted for to mon fully explain differences between simulated and observed well water levels. (C) 2000 Elsevier Science B.V. All rights reserved

Effects of nearshore recharge on groundwater interactions with a lake in mantled karst terrain, 2000, Lee T. M. ,
The recharge and discharge of groundwater were investigated for a lake basin in the mantled karst terrain of central Florida to determine the relative importance of transient groundwater inflow to the lake water budget. Variably saturated groundwater flow modeling simulated water table responses observed beneath two hillsides radiating outward from the groundwater flow-through lake. Modeling results indicated that transient water table mounding and groundwater flow reversals in the nearshore region following large daily rainfall events generated most of the net groundwater inflow to the lake. Simulated daily groundwater inflow was greatest following water table mounding near the lake, not following subsequent peaks in the water level of upper basin wells. Transient mounding generated net groundwater inflow to the lake, that is, groundwater inflow in excess of the outflow occurring through the deeper lake bottom. The timing of the modeled net groundwater inflow agreed with an independent lake water budget; however, the quantity was considerably less than the budget-derived value

Exchange of water between conduits and matrix in the Floridan aquifer, 2001, Martin J. B. , Dean R. W. ,
Flow through carbonate aquifers may be dominated by conduits where they are present, by intergranular or fracture porosity where conduits are missing, or may occur in conduits and matrix porosity where both are well developed. In the latter case, the exchange of water between conduits and matrix could have important implications for water management and hydrodynamic modeling. An extensive conduit system has been mapped by dye trace studies and cave diving exploration at the Santa Fe Sink/Rise system located in largely unaltered rocks of the Floridan aquifer of north-central Florida. In this area, the Santa Fe River flows underground at the River Sink and returns to the surface similar to 5 km to the south at a first magnitude spring called the River Rise. Limited data show that discharge is greater by 27-96% at the River Rise than at the Sink and that the downstream increase in discharge is inversely related to discharge of the river. Natural SO42- concentrations indicate that similar to 25% of the water discharging from the Rise originates from the Sink during low flow. Conversely, SO42- and other solute concentrations indicate that most of the water discharging from the Rise originates from the Sink during floods. Ar similar to 40% decrease in Na () and Cl (-) concentrations over a 5 1/2-month period at a down-gradient water supply well may reflect flow of dilute flood water from the conduits into and through the matrix at rates estimated to be between 9 and 65 m/day, Calcium concentrations remain constant through time at the well, although flood waters have similar to 90% lower Ca (2) concentrations than ground water, perhaps reflecting dissolution of the matrix rocks. This apparent exchange of water between matrix and conduits is important for regional ground water quality and dissolution reactions, (C) 2001 Published by Elsevier Science B.V

A model of the early evolution of karst aquifers in limestone in the dimensions of length and depth, 2001, Gabrovsek F, Dreybrodt W,
A new model of the early evolution of limestone karst aquifers in the dimensions of length and depth is presented. In its initial state the aquifer consists of a rock massive with evenly spaced fractures of about 50 [mu]m aperture widths with an hydraulic conductivity of 10-7 ms-1. In addition to this a coarser network of prominent fractures with aperture widths of several 100 [mu]m is also present. Boundary conditions of constant recharge 450 mm/year, or constant head from the input of allogenic streams are imposed. First the position of the water table in the aquifer is calculated, then dissolutional widening during a time step in all the fractures below the water table is found by use of the well-known nonlinear dissolution kinetics of limestone. This is iterated and the position of the water table as well as the fracture widths are found as a function of time. In the case of constant recharge to a karst plateau, the water table in any case drops to base level and conduits there propagate from the spring headwards. If constant head conditions are valid the position of the water table remains almost stable and conduits propagate along the water table from the input towards the spring. There is competition between conduit evolution along prominent fractures and along tight fissures close to the water table. In any case under constant head conditions one of these pathways wins, and early karst evolution is terminated by a breakthrough event with an explosive increase of the flow through the aquifer until constant head conditions break down. Depending on the boundary conditions of constant head or constant recharge or a combination of both it is possible to describe models of cave genesis, which have been derived from field evidence, such as the water table models of Swinnerton and Rhoades as well as the four-state model by Ford and Ewers (Can. J. Earth Sci., 15 (1978) 1783)

Karst in evaporite rocks of the United States, 2002, Johnson K. S. ,
Evaporites are the most soluble of common rocks; they are dissolved readily to form the same range of karst features that typically are found in limestones and dolomites. Evaporites, including gypsum (or anhydrite) and salt, are present in 32 of the 48 contiguous United States, and they underlie about 35-40% of the land area. Evaporite outcrops typically contain sinkholes, caves, disappearing streams, and springs. Other evidence of active karst in evaporites includes surface-collapse features and saline springs or saline plumes that result from dissolution of salt. Many evaporites, including some in the deeper subsurface, also contain evidence of paleokarst that is no longer active; this evidence includes dissolution breccias, breccia pipes, slumped beds, and collapse structures. Evaporites occur in 24 separate structural basins or geographic districts in the United States, and either local or extensive evaporite karst is known in almost all of these basins or districts. Human activities also have caused development of evaporite karst, primarily in salt deposits. Boreholes or underground mines may enable (either intentionally or inadvertently) unsaturated water to flow through or against salt deposits, thus allowing development of small to large dissolution cavities. If the dissolution cavity is large enough and shallow enough, successive roof failures can cause land subsidence or catastrophic collapse. Evaporite karst, both natural and human-induced, is far more prevalent than commonly believed

Deep karst conduits, flooding, and sinkholes: lessons for the aggregates industry, 2002, Lolcama J. L. , Cohen H. A. , Tonkin M. J. ,
Limestone aggregate quarries in deeply penetrating karst terrain are often at considerable risk of artesian inflow from groundwater or surface water channeled through the karstic aquifer. The inflow occurs through what are likely to be complex conduits that penetrate hundreds of feet into bedrock. Rates of inflow can exceed the operation's pumping capabilities proving to be uneconomic to manage over the long term. Over time, inflow rates can increase dramatically as turbulent flow through the conduit erodes its soft residual clay-rich fill. One recent investigation observed an inflow rate of more than 40,000 gpm from a surface water source. Floodwater persistently laden with sediment is an indicator of conduit washout and implies increasing inflow rates over time. Conduits carrying floodwater can exist in a variety of forms: along deeply penetrating geologic faults, joints, or following the path of preferentially eroded bedding. Preferential structural deformation along faults or bedding can enhance dissolution during subsequent interaction with groundwater. The resulting conduit may be a complex combination of many geological features, making the exploration and remediation of the pathway difficult. Sinkholes at the site can occur within several contexts. Pre-existing subsidence structures can reactivate and subside further, forming new collapse sinkholes within soil directly overlying the conduit. Cover-collapse sinkhole development can be a direct result of increasing downward groundwater velocities and subsurface erosion associated with the enlargement of a conduit. Normal operation events such as a quarry blast can also provide a significant new linkage between the groundwater and the quarry, allowing rapid drainage of the groundwater reservoir. With such drainage and erosion of karst-fill, sinkholes will develop over localized water table depressions, most significantly over enhanced permeability zones associated with fractures. Paradoxically, although the rise in quarry water level will lead to regional reduction in the hydraulic gradients, on local scales, drainage of the groundwater reservoir increases gradients and leads to the development of cover-collapse sinkholes. Recommended methods for preliminary site investigation can include a detailed review of geological literature and drilling logs to compile a conceptual model of the site. A fracture trace analysis with EM geophysics can confirm the locations of major faults and fractures. Fingerprinting of the various water sources to the quarry and the water in the quarry is an inexpensive and effective means of identifying the source and likely direction of the groundwater and surface water flow. Automated geophysical equipment on the market for performing rapid resistivity and microgravity surveys speeds up the site screening process during reconnaissance exploration for deep structure. It is recommended that mine planning fully incorporate this information so that quarry operators can take proactive measures to avoid catastrophic and costly flooding events. (C) 2002 Elsevier Science B.V. All rights reserved

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