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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 grouting is the operation by which grout is placed between the casing and the sides of a well bore to a predetermined height above the bottom of the well. this secures the casing in place and excludes water and other fluids from the well bore [6].?

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Karst environment, Culver D.C.
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Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
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Your search for freshwater lens (Keyword) returned 17 results for the whole karstbase:
Showing 1 to 15 of 17
Hydrogeological investigations into discharge of salt-containing water from a stream into an aquifer., 1976, Neuss Matthias
An aquifer in a horseshoe bend of the Weser river was investigated regarding the processes of the river water infiltration. The geology and geometry of the aquifer was ascertained by means of numerous borings. The hydraulic situation before and after infiltration was determined by water table maps. The intrusion of a salt-freshwater lens could be reconstructed from the beginning of infiltration until ten years later by means of previous results of chemical analysis. By new chemical analysis it was proved that river water infiltrates into the aquifer. Additionally it was established that the relatively high concentration of chloride is reduced during the passage of the groundwater both by mixing with recharged groundwater and by adsorption of the ground. Furthermore temperature measurements in the groundwater at selected stations confirm qualitatively the river water infiltration into the polder.

HYDROGEOLOGY OF GRAND CAYMAN, BRITISH-WEST-INDIES - A KARSTIC DOLOSTONE AQUIFER, 1992, Ng K. C. , Jones B. , Beswick R. ,
On Grand Cayman, freshwater bodies present in the Bluff Formation are typically small and occur as thin lenses floating on top of dense saline water. Evaluation of the water resource potential of these freshwater lenses is difficult because of their variable hydrological conditions, complex paleohydrogeology and aquifer heterogeneity. Secondary porosity created by preferential dissolution of aragonitic fossil components is common. Open fissures and joints developed under tectonic stress and karst development associated with sea-level fluctuations are, however, the two most important causes of porosity and permeability in the aquifers on Grand Cayman. Fracture and karst porosity control the lens occurrence by: (1) acting as avenues for the intrusion of seawater or upward migration of saline water; (2) acting as recharge focal points; (3) enhancing hydrodynamic dispersion; (4) defining lens geometry; (5) facilitating carbonate dissolution along joints and fissures. A clear understanding of the hydrological and geological conditions is important in developing small lenses in a setting similar to that on Grand Cayman. This pragmatic approach can help identify the optimum location of the well field and avoid areas particularly susceptible to saline water intrusion

An Electromagnetic Geophysical Survey of the Freshwater Lens of Isla de Mona, Puerto Rico, 1998, Richards, R. T. , Troester, Jo. W. , Mart?nez, M. I.
An electromagnetic reconnaissance of the freshwater lens of Isla de Mona, Puerto Rico was conducted with both terrain conductivity (TC) and transient electromagnetic (TEM) surface geophysical techniques. These geophysical surveys were limited to the southern and western parts of the island because of problems with access and cultural metallic objects such as reinforced concrete roadways on the eastern part of the island. The geophysical data were supplemented with the location of a freshwater spring found by scuba divers at a depth of about 20 m below sea level along the northern coast of the island. The geophysical data suggest that the freshwater lens has a maximum thickness of 20 m in the southern half of the island. The freshwater lens is not thickest at the center of the island but nearer the southwestern edge in Quaternary deposits and the eastern edge of the island in the Tertiary carbonates. This finding indicates that the ground-water flow paths on Isla de Mona are not radially symmetrical from the center of the island to the ocean. The asymmetry of the freshwater lens indicates that the differences in hydraulic conductivity are a major factor in determining the shape of the freshwater lens. The porosity of the aquifer, as determined by the geophysical data is about 33%

A conceptual view of carbonate island karst, 1999, Mylroie J. E. , Vacher H. L.
Conceptually, the karst of carbonate islands can be modeled as the result of eogenetic diagenesis, freshwater/ saltwater mixing, and glacioeustasyThe resulting eogenetic karst occurs in small, youthful limestone islands where the evolution of the karst is concurrent with meteoric diagenesis of the host rock, which has never been out of the active circulation of meteoric waterThe rearrangement of the material of high porosity / low permeability sediments into moderate porosity / high permeability rock feeds back to the nature of the diagenetic environment as the flow volume of the lens is reduced by increasing flow efficiencyLimestone islands are a constrained and simple environment, defined as carbonate islands (no noncarbonate rock) and composite islands (mixture of carbonate and non carbonate rock)Simple carbonate islands lack noncarbonate rocks within the active hydrological zone; carbonate-cover islands contain a noncarbonate contact that limits the freshwater lens and deflects vadose flowThe type of island greatly influences the subsequent karst hydrologyIncreasing island size appears to cross a threshold favoring conduit flowThe karst features resulting from these island types, combined with mixing geochemistry and glacioeustasy, differ from those in continental settings and require a unique conceptual approach to modeling

Speleogenesis in coastal and oceanic settings, 2000, Mylroie J. E. , Carew J. L.
Carbonate islands and coasts are directly influenced by the chemistry of mixing marine and fresh water, and by the migration of sea level in response to Quaternary glacio-eustasy. Carbonate islands are unique in particular because they are limited in recharge to their own areal extent, whereas carbonate coasts can obtain recharge from adjacent, non-carbonate areas. Carbonate islands fall into three categories: Simple carbonate islands which are entirely carbonate from the land surface to a depth exceeding the lowest Quaternary glacio-eustatic sea-level lowstand (approximately -125 m); carbonate-cover islands which are entirely carbonate, but a carbonate/non-carbonate contact exists within the range of Quaternary glacio-eustasy; and carbonate-rimmed islands where non-carbonate rocks are present at the surface. Simple carbonate islands have only autogenic recharge and develop pit caves in the epikarst, banana holes at the top of the fresh-water lens, and flank margin caves at the margin of the freshwater lens. Carbonate-cover islands develop additional caves at the carbonate/non-carbonate contact, and carbonate-rimmed islands form stream caves from non-carbonate allogenic recharge. Blue holes and large conduit caves exist on carbonate islands and coasts. They are overprinted by Quaternary glacio-eustasy, and their development is linked to processes not operating at their locations today.

The Carbonate Island Karst Model applied to Guam., 2001, Mylroie J. , Jenson J.
The karst of tropical carbonate islands is unique because: 1) fresh water-salt water mixing occurs at the base and margin of the fresh-water lens; 2) glacioeustasy has moved the freshwater lens up The karst of tropical carbonate islands is unique because: 1) fresh water-salt water mixing occurs at the base and margin of the fresh-water lens; 2) glacioeustasy has moved the freshwater lens up and down through a vertical range of over 100m; and 3) the karst is eogenetic, i.e., it has developed in young carbonate rocks that have never been buried beyond the range of meteoric diagenesis. Carbonate islands can be divided into three categories based on basement-sea level relationships: simple carbonate islands (no non-carbonate rocks), carbonate cover islands (non-carbonate rocks beneath a carbonate veneer), and composite islands (carbonate and non-carbonate rocks exposed on the surface). These ideas form the Carbonate Island Karst Model (CIKM) which can be visualized in terms of a three-dimensional framework, with island size on the x-axis, sea-level change on the y-axis, and bedrock relationships on the z-axis. On Guam, tectonic uplift and glacio-eustatic sea level change have produced a complex history on this composite island. The aquifer is partitioned in the subsurface by the .intecedent topography of the volcanic core of the island, and lens discharge is both diffuse and conduit controlled.

Recharge and aquifer response: Northern Guam Lens Aquifer, Guam, Mariana Islands, 2002, Jocson J. M. U. , Jenson J. W. , Contractor D. N. ,
The Northern Guam Lens Aquifer is an island karst aquifer in uplifted young, highly conductive limestone. Calculations of recharge based on differences between daily rainfall and daily pan evaporation suggest that the maximum annual mass of water delivered to the freshwater lens is about 67% of mean annual rainfall. Hydrographs of daily well-level responses plotted against daily rainfall indicate that the rate at which water is delivered to the lens is a function of rainfall intensity and the relative saturation of the vadose zone. Together, these variables determine the degree to which stormwater is shunted into fast flow through preferred pathways that bypass the bedrock matrix, rather than percolating slowly through the bedrock matrix. Data from the 40-year interval from 1956 to 1995 show that some 17% of rainfall on northern Guam arrives in small amounts (<0.6 cm/day). Most of this light rainfall is probably lost to evapotranspiration. At least another 20% of total rainfall on Guam arrives at very high intensities (>5.0 cm/day), which tend to promote fast flow at the expense of percolation. Rapid recovery of the water table from rapid recharge suggests that the lens either takes such recharge into storage very rapidly, discharges it rapidly without taking it into storage, or some combination of both. Significant vadose buffering of recharge to the lens is indicated by the fact that simulations assuming that the recharge from precipitation received in any given month is transmitted to the lens during the same month consistently over-predict observed peak mean monthly water levels and under-predict the minima. (C) 2002 Elsevier Science B.V. All rights reserved

Blow Hole Cave: An unroofed cave on San Salvador Island, the Bahamas, and its importance for detection of paleokarst caves on fossil carbonate platforms, 2002, Bosá, K Pavel, Mylroie John E. , Hladil Jindrich, Carew James L. , Slaví, K Ladislav

The comparative study of a Quaternary carbonate platform (San Salvador Island, the Bahamas) and a Devonian Carbonate Platform (Krásná Elevation, Moravia) indicates a great similarity in karst evolution. Caves on both sites are interpreted as flank margin caves associated with a freshwater lens and halocline stabilised during sea-level highstands. The sedimentary fill of both caves is genetically comparable - beach and aeolian sediments with bodies of breccias.


Karst development on carbonate islands, 2003, Mylroie J. E. , Carew J. L.

Karst development on carbonate platforms occurs continuously on emergent portions of the platform. Surficial karst processes produce an irregular pitted and etched surface, or epikarst. The karst surface becomes mantled with soil, which may eventually result in the production of a resistant micritic paleosol. The epikarst transmits surface water into vadose pit caves, which in turn deliver their water to a diffuse-flow aquifer. These pit caves form within a 100,000 yr time frame. On islands with a relatively thin carbonate cover over insoluble rock, vadose flow perched at the contact of carbonate rock with insoluble rock results in the lateral growth of vadose voids along the contact, creating large collapse chambers that may later stope to the surface.
Carbonate islands record successive sequences of paleosols (platform emergence) and carbonate sedimentation (platform submergence). The appropriate interpretation of paleosols as past exposure surfaces is difficult, because carbonate deposition is not distributed uniformly, paleosol material is commonly transported into vadose and phreatic voids at depth, and micritized horizons similar in appearance to paleosols can develop within existing carbonates.
On carbonate islands, large dissolution voids called flank margin caves form preferentially in the discharging margin of the freshwater lens from the effects that result from fresh-water/salt-water mixing. Similarly, smaller dissolution voids also develop at the top of the lens where vadose and phreatic fresh-waters mix. Independent of fluid mixing, oxidation of organic carbon and oxidation/reduction reactions involving sulfur can produce acids that play an important role in phreatic dissolution. This enhanced dissolution can produce caves in fresh-water lenses of very small size in less than 15,000 yr. Because dissolution voids develop at discrete horizons, they provide evidence of past sea-level positions. The glacio-eustatic sea-level changes of the Quaternary have overprinted the dissolutional record of many carbonate islands with multiple episodes of vadose, fresh-water phreatic, mixing zone, and marine phreatic conditions. This record is further complicated by collapse of caves, which produces upwardly prograding voids whose current position does not correlate with past sea level positions.
The location and type of porosity development on emergent carbonate platforms depends on the degree of platform exposure, climate, carbonate lithology, and rate of sea-level change. Slow, steady, partial transgression or regression will result in migration of the site of phreatic void production as the fresh-water lens changes elevation and moves laterally in response to sea-level change. The result can be a continuum of voids that may later lead to development solution-collapse breccias over an extended area.


Zones of enhanced dissolution and associated cave morphology in an uplifted carbonate island karst aquifer, northern Guam, Mariana Island, 2003, Taboroi D. , Jenson J. W, Mylroie J. E.

n contrast to Paleozoic limestones where drainage is based on classical cave systems (secondary porosity), young limestones of uplifted carbonate islands retain substantial distributed primary porosity. Consequently, speleogenesis on such islands is restricted to environments where dissolution is sufficiently focused to produce caves. Thus, on Guam and similar islands, solution voids large enough for human traverse occur only in settings where dissolution has been focused by hydrologic or geologic boundaries. In the vadose zone, these boundaries are lithologic contacts or structural discontinuities that channel the flow of aggressive water. In the phreatic zone, the boundaries are hydrologic contacts, where aggressive water is produced through the mixing of saturated waters. These geologic and hydrologic settings are sites of significant speleogenesis, each characterized by morphologically and hydrologically distinct types of caves.


Hoga island, Sulawesi, Indonesia: geomorphology and groundwater resources of a small tropical carbonate island, 2006, Dykes A. P. , Gunn J.
This paper provides the first report of the geomorphology and hydrogeology of Hoga island, a small tropical carbonate island in southeast Sulawesi, Indonesia, based on reconnaissance field explorations and surveys. Hoga is being developed as a specialist ecotourism destination, and a sustainable water supply is one of the important development issues. The island comprises 3.42km2 of low-lying hard, but highly karstified, coral limestone covered with dense scrub forest and coconut plantations. It displays dissolution features typical of similar tropical islands, including pit caves and flank margin caves. A freshwater aquifer exists with a water table 1.57m above MSL near the centre of the less karstified western two-thirds of the island, where surface elevations locally exceed 6m above MSL. All occurrences of potable freshwater, i.e. having electrical conductivity < 1500 mS cm-1, are also within this main part of the island. Complex hydrogeological conditions are indicated by the patterns of tidal influences on water levels in existing wells and natural dissolution holes. Using published studies and empirical relationships, it is estimated that Hoga contains a potable freshwater lens at least 2m thick (total volume c.300,000m3) and that annual recharge may exceed 500,000m3. As actual annual demand for freshwater since 2001 was < 2800m3, it is concluded that Hoga contains an aquifer that could sustain the present and likely future freshwater demands of residents and seasonal ecotourist populations, subject to satisfactory water quality assessment and management.

Syngenetic Karst in Australia: a review, 2006, Grimes Ken G.
In syngenetic karst speleogenesis and lithogenesis are concurrent: caves and karst features are forming at the same time as the loose sediment is being cemented into a soft, porous rock. Eogenetic karst and soft-rock karst are closely related terms for features developed in soft, poorly-consolidated limestones. The distinctive features of syngenetic karst are: shallow horizontal cave systems; a general lack of directed conduits (low irregular chambers occur instead); clustering of caves at the margins of topographic highs or along the coast; paleosoil horizons; vertical solution pipes which locally form dense fields; extensive breakdown and subsidence to form collapse-dominated cave systems; a variety of surface and subsurface breccias and locally large collapse dolines and cenotes; and limited surface sculpturing (karren). These features are best developed in host sediments that have well developed primary matrix permeability and limited secondary cementation (and hence limited mechanical strength), for example dune calcarenites. Certain hydrological environments also assist: invading swamp waters or mixing at a well-developed watertable; or, near the coast, mixing at the top and bottom of a freshwater lens floating on salt water. Where these factors are absent the karst forms tend to be more akin to those of classical hard-rock or telogenetic karst.

Paleokarst in Middle Devonian Winnipegosis mud mounds, subsurface of south-central Saskatchewan, Canada, 2006, Fu Q, Qing H, Bergman Km,

Paleokarst of the Winnipegosis mud mounds is mainly characterized by extensive solution features and cavity deposits. Solution features vary from millimetre-size vugs/channels to metre-scale caverns. Most solution voids are filled with anhydrite and/or carbonate deposits. 'Swiss-cheese' type porosities appear as oval to irregular pore networks and most of them remain open. Erosional surfaces are observed in several cores. Fractures and breccia fragments are small-scale and commonly associated with solution features or calcretes. Cavity sediments are dominantly detrital dolomite, interpreted as a product of weathering of the host rocks. Speleothems occur in vugs and channels but are not abundant. Caverns and large vugs likely formed at or just below the water table in the phreatic zone or in a freshwater-saltwater mixing zone during subaerial exposure of the mounds. Porous 'Swiss-cheese' fabrics resemble sponge-like pores that form in mixing zones of modern carbonate platforms and islands. Porosity in the Winnipegosis mounds was extensively modified by karstification and subsequent anhydrite cementation. Paleokarst occurs only in the middle and upper parts of relatively high Winnipegosis mounds with respect to the basin floor. Multiple levels of caverns and vugs are probably related to various positions of freshwater lenses corresponding to recurrent subaerial exposure and water level changes in the Elk Point Basin. Occurrence of caverns and large vugs at 55 m below the top of the mounds indicates that the mixing zone or freshwater has extended downward to this depth


Syngenetic Karst in Australia: a review, 2006, Grimes, Ken G.

In syngenetic karst speleogenesis and lithogenesis are concurrent: caves and karst features are forming at the same time as the loose sediment is being cemented into a soft, porous rock. "Eogenetic karst" and "soft-rock karst" are closely related terms for features developed in soft, poorly-consolidated limestones. The distinctive features of syngenetic karst are: shallow horizontal cave systems; a general lack of directed conduits (low irregular chambers occur instead); clustering of caves at the margins of topographic highs or along the coast; paleosoil horizons; vertical solution pipes which locally form dense fields; extensive breakdown and subsidence to form collapse-dominated cave systems; a variety of surface and subsurface breccias and locally large collapse dolines and cenotes; and limited surface sculpturing (karren). These features are best developed in host sediments that have well developed primary matrix permeability and limited secondary cementation (and hence limited mechanical strength), for example dune calcarenites. Certain hydrological environments also assist: invading swamp waters or mixing at a well-developed watertable; or, near the coast, mixing at the top and bottom of a freshwater lens floating on salt water. Where these factors are absent the karst forms tend to be more akin to those of classical hard-rock or telogenetic karst.


Time scales in the evolution of solution porosity in porous coastal carbonate aquifers by mixing corrosion in the saltwater-freshwater transition zone, 2007, Dreybrodt W. , Romanov D.

Dissolution of calcium carbonate in the saltwater-freshwater mixing zone of coastal carbonate aquifers up to now has been treated by coupling geochemical equilibrium codes to a reactive- transport model. The result is a complex nonlinear coupled set of differential transport-advection equations, which need high computational efforts. However, if dissolution rates of calcite are sufficiently fast, such that one can assume the solution to be in equilibrium with respect to calcite a highly simplified modelling approach can be used. To calculate initial changes of porosity in the rock matrix one only needs to solve the advection-transport equation for salinity s in the freshwater lens and its transition zone below the island. Current codes on density driven flow such as SEAWAT can be used. To obtain the dissolution capacity of the mixed saltwater-freshwater solutions the calcium equilibrium concentration ceq(s) is obtained as a function of salinity by PHREEQC-2. Initial porosity changes can then be calculated by a simple analytical expression of the gradient of the spatial distribution s(x, y) of salinity, the distribution of flow fluxes q(x,y) and the second derivative of the calcium equilibrium concentration ceq(s) with respect to salinity s. This modelling approach is employed to porosity evolution in homogeneous and heterogeneous carbonate islands and coastal aquifers. The geometrical patterns of porosity changes and the reasons of their origin will be discussed in detail. The results reveal initial changes of porosity in the order of several 10-6 per year. This places the time scale of cavern evolution to orders from several tens of thousands to a hundred thousand years.


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