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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 Mischungskorrosion is (german.) dissolution of calcite (and hence of limestone) by ground water that is derived from the mixing of two different waters that were originally saturated with carbon dioxide but had reached saturation under differing carbon dioxide partial pressures. the resultant mixture is undersaturated and capable of further calcite dissolution, because the relationship between calcite solubility and carbon dioxide partial pressure is non-linear [9].?

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Chemistry and Karst, White, William B.
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Geochemical and mineralogical fingerprints to distinguish the exploited ferruginous mineralisations of Grotta della Monaca (Calabria, Italy), Dimuccio, L.A.; Rodrigues, N.; Larocca, F.; Pratas, J.; Amado, A.M.; Batista de Carvalho, L.A.
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
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Your search for saline (Keyword) returned 98 results for the whole karstbase:
Showing 1 to 15 of 98
Identification of the origin of oreforming solutions by the use of stable isotopes, 1977, Sheppard S. M. F. ,
SynopsisThe four major different types of water -- magmatic, metamorphic, sea water and/or connate, and meteoric water -- have characteristic hydrogen (D/H) and oxygen (18O/16O) isotope ratios. Applied to the analysis of isotopic data on hydrothermal minerals, fluid inclusions and waters from active geothermal systems, these ratios indicate that waters of several origins are involved with ore deposition in the volcanic and epizonal intrusive environment. Water of a single origin dominates main-stage mineralization in some deposits: magmatic -- Casapalca, Peru (Ag-Pb-Zn-Cu); meteoric -- Butte, Montana (Cu-Zn-Mn), epithermal deposits, e.g. Goldfield, Tonopah, Nevada (Ag-Au), Pachuca, Mexico (Ag-Au), San Juan Mountains District, Colorado (Ag-Au-Pb-Zn); sea water -- Troodos, Cyprus (Fe-Cu), Kuroko, Japan (Fe-Cu-Pb-Zn). Solutions of more than one origin are important in certain deposits (magmatic and meteoric -- porphyry copper and molybdenum deposits) and are present in many. In the porphyry Cu-Mo deposits the initial major ore transportation and alteration processes (K-feldspar-biotite alteration) are magmatic-hydrothermal events that occur at 750-500{degrees}C. These fluids are typically highly saline Na-K-Ca-Cl-rich brines (more than 15 wt % equivalent NaCl). The convecting meteoric-hydrothermal system that develops in the surrounding country rocks with relatively low integrated water/rock ratios (less than 0.5 atom % oxygen) subsequently collapses in on a waning magmatic-hydrothermal system at about 350-200{degrees}C. These fluids generally have moderate to low salinities (less than 15 wt % equivalent NaCl). Differences among these deposits are probably in part related to variations in the relative importance of the meteoric-hydrothermal versus the magmatic-hydrothermal events. The sulphur comes from the intrusion and possibly also from the country rocks. Deposits in which meteoric or sea water is the dominant constituent of the hydrothermal fluids come from epizonal intrusive and sub-oceanic environments where the volcanic country rocks are fractured or well jointed and highly permeable. Integrated water/rock ratios are typically high, with minimum values of 0.5 or higher (atom % oxygen) -- the magmatic water contribution is often drowned out'. Salinities are low to very low (less than 10 wt % equivalent NaCl), and temperatures are usually in the range 350-150{degrees}C. The intrusion supplies the energy to drive the large-scale convective circulation system. The sulphur comes from the intrusion, the country rocks and/or the sea water. Argillic alteration, which occurs to depths of several hundred metres, generated during supergene weathering in many of these deposits is isotopically distinguishable from hydrothermal clays

Saline Lakes, 1978, Eugster H. P. , Hardie L. A.

Distribution and Habitat Diversity of Subterranean Amphipods in the Rocky Mountains of Colorado, U.S.A., 1981, Holsinger John R. , Ward James W.
Subterranean amphipods have been collected from 35 locations on the eastern and western slopes of the Continental Divide in Colorado. All belong to the exclusively subterranean genus Stygobromus. Five species have been identified, two of which are undescribed. Specimens have been collected from (a) the hyporheic zone of rivers, (b) interrupted streams, (c) springs, and (d) seeps at elevations from 1597-2134 m a.s.l. Stygobromus occurs in several habitat types in interrupted drainage basins including sources, seeps, and isolated pools containing leaf detritus. All habitats contained waters which were cool to cold with dissolved oxygen values ranging from 4.3 ppm to fully saturated. Most waters exhibited soft or medium hardness, although one spring containing an undescribed species of Stygobromus had very hard waters (203 ppm bound CO2) and was mildly saline (913 mg/l TDS). There is evidence that the subterranean amphipods are phreatobites which, only under special conditions, establish relatively permanent populations in epigean habitats. Although little is known regarding ecology, zoogeography, or even taxonomy of the subterranean fauna of this region, stygobromid amphipods from the Cordilleran of western North America are apparently represented by fewer well differentiated species per unit area than their congeners from the geobiologicably older Appalachian region of eastern North America where numerous species are found in caves.

Hydrogeological conditions in the Middle East, 1982, Burdon Dj,
The geology of Middle East is summarized under the subheadings: Precambrian basement, epicontinental sediments, geosynclinal and shelf deposits, Tertiary volcanics and Quaternary cover. The main tectonic episodes including epeirogenic movements, rifting and the Tertiary orogeny, are reviewed. The imposition of hydrometeorolocal and climatic conditions upon the regional geology provides the setting for the hydrogeological discussion. Five factors which influence infiltration to aquifers under conditions of low precipitation and high potential evaportranspiration are discussed. The predominance of fossil groundwater is the most striking hydrogeological phenomenon occurring on a regional scale in the Middle East. Its mode of formation during the pluvials is outlined and the isotopic evidence is reviewed. The main physical and chemical characteristics of fossil ground-waters are described. It is conservatively estimated that some 65 000 km3 of good- to medium-quality groundwater are stored in the great artesian basins of the Near East. These fossil ground-waters are a non-renewable natural resource. Current annual abstraction is, as yet, a small percentage of the total reserves but economic factors rather than the volume of reserves will determine the ultimate extent of their exploitation. The renewable groundwater resources of the Middle East tend, by comparison, to be of local rather than regional significance. Some originate outside the Middle East, coming in as surface flows in the Nile and Tigris-Euphrates and infiltrating into the sediments in and adjacent to the flood plains. Other renewable resources accumulate within the region where high precipitation and mountainous relief are associated. Such areas include the Djebel Akhdar of Cyrenacia, the Tertiary fold mountains from the Taurus through the Zagros to the Oman ranges, and the volcanic and basement highlands of Yemen, Asir and Ethiopa. Locally, in areas of lower precipitation, lenses of recent fresh groundwater float on regional more saline groundwater. In some areas subsurface flows towards and through wadi systems are also of importance

Palaeoenvironment of lateritic bauxites with vertical and lateral differentiation, 1983, Valeton Ida,
Formation of lateritic bauxites of the type described in this paper occurs world-wide in Cretaceous and Tertiary coastal plains. The bauxites form elongate belts, sometimes hundreds of kilometres long, parallel to Lower Tertiary shorelines in India and South America and their distribution is not related to a particular mineralogical composition of the parent rock. The lateral movement of the major elements Al, Si, Fe, Ti is dependent on a high level and flow of groundwater. Varying efficiency of subsurface drainage produces lateral facies variations. Interfingering of marine and continental facies indicate a sea-land transition zone where the type of sediments also varies with minor tectonic movements or sea-level changes. A typical sediment association is found in India, Africa, South and North America. It consists of (i) red beds rich in detrital and dissolved material of reworked laterites, (ii) lacustrine sediments and hypersaline precipitates, (iii) lignites intercalated with marine clays, layers of siderite, pyrite, marcasite and jarosite, and (iv) marine chemical sediments rich in oolitic iron ores or glauconite. A model is developed to account for element distributions in lateritic bauxites in terms of groundwater levels and flow. Finally it is shown that many high-level bauxites are formed in coastal plains and that they are subsequently uplifted to their present altitude

Climatostratigraphic scheme of the Black Sea pleistocene and its correlation with the oxygen-isotope scale and glacial events, 1988, Zubakov V. A. ,
New evidence from the Asov Sea-Black Sea region shows that after the Cobb Mountain magnetic event (1.1 myr) there were 8 saline water events, with Mediterranean molluscs penetrating into the Asov Sea (five times farther than the western Manych Strait), and 7 or 10 cold freshwater events. During the freshening phase, the Caspian Sea molluscan fauna penetrated into the Black Sea; each time the Caspian mollusc assemblage was characterized by a new species of Didacna. Thus, some 18-20 bioclimatostratigraphic units can be distinguished in the Asov Sea-Black Sea section for the last 1 myr. Their numerical age is estimated by some dozen thermoluminescence dates and 12 magnetic-polarity datum planes. The Karangatian s. lato corresponds to the interval 300,000-50,000 yr, the Uzunlarian to 580,000-300,000 yr, and the Chaudian to 1,100,000-600,000 yr. The Karangatian and Tyrrhenian marine terraces correspond to marine isotope stages 5 and 7, the Uzunlarian and Milazzian to stages 11-15, and the Chaudian and Sicilian to stages 16-28. The number and ages of glacial-interglacial cycles in continental Europe are identical to the climatic cycles in the Black Sea and Mediterranean

Glaciation and saline-freshwater mixing as a possible cause of cave formation in the eastern Midcontinent region of the United States; a conceptual model, 1990, Panno Samuel V. , Bourcier William L. ,

DIAGENESIS AND MINERALIZATION PROCESSES IN DEVONIAN CARBONATE ROCKS OF THE SIDING-GUDAN LEAD-ZINC MINERAL SUBDISTRICT, GUANGXI, SOUTHWEST CHINA, 1991, Schneider W. , Geng A. Q. , Liu X. Z. ,
The lead-zinc ore deposits of the Siding-Gudan mineral subdistrict Guangxi are part of the large Nanling district of South China, and hosted in Devonian carbonate rocks. The ore bodies occur significantly along main faults and fault zones, and concentrate up to 300 meters above the Cambrian/Devonian unconformity. Connected with hydrothermal karst, size and volume of the ore bodies increase in proximity to this unconformity. Moving from the unaffected host rocks to the center of the ore bodies, four zones can be discriminated by the mineral assemblage (pyrite, sphalerite, galena) as well as by the degree of ordering, Ca/Mg, and Fe/Mn ratios of different dolomites. Homogenization temperatures range from 80-100-degrees-C (Presqu'ile dolomite) to 230-260-degrees-C (massive sphalerite). The sulfides reveal delta-S-34 = -20 to parts per thousand, and fluid inclusions display a salinity of 5-12 wt % equivalent NaCl. The diagenetic and hydrothermal history is similar to that of classic Mississippi Valley Type (MVT) sulfide mineral deposits as, for example, Pine Point in Canada. Mineralization and remobilization of the sulfides took place during a wide time span from late Paleozoic through Mesozoic. Both processes are considered as an interaction of saline basinal brines ascended from the adjoining dewatering trough, and magmatic-hydrothermal fluids of several magmatic-tectonic events

LATE TO POSTHERCYNIAN HYDROTHERMAL ACTIVITY AND MINERALIZATION IN SOUTHWEST SARDINIA (ITALY), 1992, Boni M, Iannace A, Koppel V, Fruhgreen G, Hansmann W,
Several kinds of base metal deposits occur in the lower Paleozoic of southwest Sardinia (Iglesiente-Sulcis mineral district). This paper deals with those deposits which are generally referred to as Permo-Triassic, because they accompany and postdate the Hercynian orogeny and are related to magmatic activity. A large number of previously published geochemical data, integrated with additional new data (Sr, Pb, O, C, and S isotopes), are reviewed and discussed in the frame of the late to post-Hercynian geologic evolution of southwest Sardinia. According to geological and mineralogical characteristics, three types of deposits can be distinguished: (1) skarn ores related to late Hercynian leucogranitic intrusions, (2) high-temperature veins, and (3) low-temperature veins and karst filling. Pervasive epigenetic dolomitization phenomena are geochemically related to the low-temperature deposits. Sr and Pb isotopes of the first and second types (0.7097-0.7140 Sr-87/Sr-86; 17.97-18.29 Pb-206/Pb-204; 38.11-38.45 Pb-208/Pb-204) are distinctly more radiogenic than those of the third type (0.7094-0.7115 Sr-87/Sr-86; 17.86-18.05 Pb-206/Pb-204; 37.95-38.19 Pb-208/Pb-204) which, in turn, are closer to Paleozoic ores and carbonates. Fluid inclusion data indicate that the fluids responsible for mineralization of the first and second types of deposits were hot and dilute (T(h)= 370-degrees-140-degrees-C; <5 wt % NaCl equiv). In contrast, relatively colder and very saline fluids (T(h)= 140-degrees-70-degrees-C; >20 wt % NaCl equiv) were responsible for the third type of mineralization, as well for epigenetic dolomitization of the Cambrian host rocks. O isotopes measured in minerals from the first two types (deltaO-18SMOW = 12.8-18.9 parts per thousand) are O-18 depleted with respect to the third type (deltaO-18SMOW = 15.9-22.1 parts per thousand). These data, coupled with fluid inclusion formation temperatures, indicate that the fluids responsible for the first two types of mineralization were O-18 enriched with respect to those of the third type and related hydrothermal phenomena. The deltaS-34CDT in sulfides of the first two types vary between 3.7 and 10.73 per mil, whereas the values of the third type range from 12.0 to 17.9 per mil. Late to post-Hercynian mineralization is thus explained as the result of three distinct, though partly superimposed, hydrothermal systems. System 1 developed closer to the late Hercynian leucogranitic intrusions and led to the formation of the first and subsequently the second type of mineralization. The relatively hot and diluted fluids had a heated meteoric, or even partly magmatic, origin. Metals were leached from an external, radiogenic source, represented either by Hercynian leucogranites or by Paleozoic metasediments. Sulfur had a partly magmatic signature. System 2 was characterized by very saline, colder fluids which promoted dolomitization, silicification, and vein and karst mineralization. These fluids share the typical characteristics of formation waters, even though their origins remain highly speculative. The hydrothermal system was mainly rock dominated, with only a minor participation of the external radiogenic source of metals. Sulfur was derived by recirculation of pre-Hercynian strata-bound ores. System 3 records the invasion of fresh and cold meteoric waters which precipitated only minor ore and calcite gangue. It may represent the further evolution of system 2, possibly spanning a time well after the Permo-Triassic. The timing of all these phenomena is still questionable, due to the poor geologic record of the Permo-Triassic in southwest Sardinia. Nevertheless, the hypothesized scenario bears many similarities with hydrothermal processes documented throughout the Hercynian in Europe and spanning the same time interval. A comparison with the latter mineralization and hydrothermal activities leads to the hypothesis that the first two types of mineralization are linked to late Hercynian magmatic activity, whereas the third type may be related to either strike-slip or tensional tectonics which, throughout Europe mark the transition from the Hercynian orogeny to the Alpine cycle

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

HALITE SALTERN IN THE CANNING BASIN, WESTERN-AUSTRALIA - A SEDIMENTOLOGICAL ANALYSIS OF DRILL CORE FROM THE ORDOVICIAN-SILURIAN MALLOWA SALT, 1992, Cathro Dl, Warren Jk, Williams Ge,
The Late Ordovician-Early Silurian Mallowa Salt of the Carribuddy Group, Canning Basin, north-west Australia, is the largest halite deposit known in Australia, attaining thicknesses of 800 m or more within an area of approximately 200 000 km2. Study of 675 m of drill core from BHP-Utah Minerals' Brooke No. 1 well in the Willara Sub-basin indicates that the Mallowa Salt accumulated within a saltern (dominantly subaqueous evaporite water body) that was subject to recurrent freshening, desiccation and exposure. Textures and bromine signatures imply a shallow water to ephemeral hypersaline environment typified by increasing salinity and shallowing into evaporitic mudflat conditions toward the top of halite-mudstone cycles (Type 2) and the less common dolomite/anhydrite-halite-mudstone cycles (Type 1). The borate mineral priceite occurs in the capping mudstones of some cycles, reinforcing the idea of an increasing continental influence toward the top of mudstone-capped halite cycles. The rock salt in both Type 1 and Type 2 cycles typically comprises a mosaic of large, randomly orientated, interlocking halite crystals that formed during early diagenesis. It only partially preserves a primary sedimentary fabric of vertically elongate crystals, some with remnant aligned chevrons. Intraformational hiati, halite karst tubes and solution pits attest to episodic dissolution. Stacked Type 2 cycles dominate; occasional major recharges of less saline, perhaps marine, waters in the same area produced Type 1 cycles. The envisaged saltern conditions were comparable in many ways to those prevailing during the deposition of halite cycles of the Permian Salado Formation in New Mexico and the Permian San Andres Formation of the Palo Duro Basin area in Texas. However, in the Canning Basin the cycles are characterized by a much lower proportion of anhydrite, implying perhaps a greater degree of continental restriction to the basin. The moderately high level of bromine in the Mallowa Salt (156.5 43.5 ppm Br for primary halite, 146.1 54.7 ppm Br for secondary halite) accords with evolved continental brines, although highly evaporative minerals such as polyhalite and magnesite are absent. The bromine levels suggest little or no dissolution/reprecipitation of primary halite and yet, paradoxically, there is little preservation of the primary depositional fabric. The preservation of early halite cements and replacement textures supports the idea of an early shutdown of brine flow paths, probably at burial depths of no more than a few metres, and the resultant preservation of primary bromine values in the secondary halite

HOLOCENE MARINE CEMENT COATINGS ON BEACH-ROCKS OF THE ABU-DHABI COASTLINE (UAE) - ANALOGS FOR CEMENT FABRICS IN ANCIENT LIMESTONES, 1994, Kendall C. G. S. , Sadd J. L. , Alsharhan A. ,
Marine carbonate cements, which are superficially like travertines from meteoric caves, are coating and binding some intertidal sedimentary rock surfaces occurring in coastal Abu Dhabi, the United Arab Emirates, (UAE). Near Jebel Dhana these surficial cements can be up to 3 cm thick and envelope beach rock surfaces and fossils. They are also present both as thin coats and a fracture-fill cement in the intertidal hard grounds associated with the Khor Al Bazam algal flats. The thickness, microscopic characteristics, and morphology of the marine cement coatings from Jebel Dhana indicates incremental deposition of aragonite in conjunction with traces of sulfate minerals. Most of these cement coatings are micritic, but the layers which encrust the hard grounds from the algae flat of the Khor al Bazam have a more radial and fibrous micro-structure and are composed solely of aragonite. The stable isotopic composition of coatings from Jebel Dhana (delta(18)O = .35, delta(13)C = .00) falls within the compositional range for modem marine non skeletal aragonite and suggests that the marine travertine-like cements precipitate from the agitated slightly hypersaline Arabian Gulf sea water during repeated cycles of exposure, evaporation and immersion. Similar cement coatings and microfabrics are present in the tepee structured and brecciated sediments of the Guadalupe Mountains (Permian) and the Italian Alps (Triassic), in Holocene algal head cements from the Great Salt Lace, and in similar Tertiary algal heads in the Green River Formation of the western US. The petrographic similarity of these ancient ''flow stone'' like cements with Recent hypersaline marine cement coatings suggests that high rates of carbonate cementation and hypersaline conditions contribute to tepee formation and cavity fill

THE EFFECT OF ZONES OF HIGH-POROSITY AND PERMEABILITY ON THE CONFIGURATION OF THE SALINE FRESH-WATER MIXING ZONE, 1995, Wicks C. M. , Herman J. S. ,
Coastal karst aquifers have highly variable distributions of porosity and permeability. The ability to assess the volume of aquifer occupied by freshwater in coastal karst aquifers is limited by both the lack of understanding of the effect that regions of cavernous porosity and permeability have on the configuration of the saline-freshwater mixing zone and by the limited knowledge of the location of the cavernous regions. A dual-density ground-water flow and solute transport model was used to explore the effect that the depth, lateral extent, and proximity to the coast of zones of high porosity and permeability has on the configuration of the saline-freshwater mixing zone. These aquifer heterogeneities tend to shift the mixing zone upward relative to the position it would have in aquifers with homogeneous porosity and permeability, Zones of high porosity and permeability located at positions shallow in the aquifer or nearer to the coast had the greatest effect. In fact, for the conditions modeled, position was more important in modifying the configuration of the mixing zone than was changing the ratio of the intrinsic permeability of the cavernous zone to the aquifer matrix from 100 to 1000. Modeling results show that ground-water flow is concentrated into the zones of high porosity and permeability and that flow configuration results in steep salinity gradients with depth, Field observations of the location of the halocline and of step changes in ground-water composition coincident with regions of cavernous porosity in coastal karst aquifers corroborate the model results, In a coastal setting with saline water intruding into an aquifer, the effect of cavernous porosity and associated high permeability is to decrease the volume of aquifer in which freshwater occurs by a greater degree than would occur in an aquifer with homogeneous porosity and permeability

HYDROGEOCHEMISTRY OF GRAND-CAYMAN, BRITISH-WEST-INDIES - IMPLICATIONS FOR CARBONATE DIAGENETIC STUDIES, 1995, Ng K. C. , Jones B. ,
Groundwater in the dolostone aquifers of the Bluff Group (Oligocene-Miocene) on Grand Cayman is divided into fresh, lightly and highly brackish, and saline (Type I and II) zones according to chemical characteristics that were determined during a 3 year (1985-1988) monitoring program. Brackish and Type I saline waters display the greatest variation in chemical properties whereas the Type II saline water has the most stable chemical characteristics. Most groundwaters from these dolostone aquifers are thermodynamically capable of precipitating calcite and/or dolomite. The saturation indices for these minerals, however, vary through time and space even in the context of small water lens. Simple mixing of fresh and sea water cannot explain the chemistry of the water found in the joint and karst controlled dolostone aquifers of Grand Cayman. Deviation from a simple mixing model is due to variations caused by tidal fluctuation, the rate of rain water recharge, influx of Ca-rich groundwater from the surrounding limestone aquifers, influx of CO2-rich surface water from sinkholes and swamps, and water-rock interactions (dissolution and precipitation of calcite and dolomite). Sustained groundwater abstraction from a lens can significantly alter the hydrochemistry of the water lens. This suggests that hydrochemical characterization of small fresh water lenses, like those on Grand Cayman, cannot be based on spot or short-term sampling. Interpretation of such fluids in terms of calcite-dolomite precipitation and/or dissolution must be treated with caution if the data base has not been derived from long-term monitoring

Some examples of Gypsum karsts and the more important gypsum caves in Spain., 1996, Calaforra Jos Maria, Pulidobosch Antonio
Spain possesses some of the most important examples of gypsum karst in Europe, in terms of the extent and variety of the gypsiferous outcrops. These are divided into gypsum belonging to the Triassic, Palaeogene and Neogene epochs, each of which displays different lithological and structural aspects. Some of Spain's most significant gypsum karsts, from the speleological standpoint, are described, and these share a common characteristic of all supporting the development of large caves. Reference is made to the geomorphology, hydrogeology and hydrochemistry of the gypsum karsts of Sorbas, Vallada and Gobantes-Meliones, which provide significant examples of intrastratal karst, speleogenesis by saline groundwater mixing and the influence of carbonate strata, respectively. Finally, brief geomorphological and speleogenetic descriptions of the more significant gypsum caves in Spain are given, together with a list of the longest and deepest gypsum caves in Spain.

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