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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 mixing length is the length over which mixing occurs, especially of momentum in turbulent flow [16].?

Checkout all 2699 terms in the KarstBase Glossary of Karst and Cave Terms


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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 ratios (Keyword) returned 116 results for the whole karstbase:
Showing 46 to 60 of 116
Stability charts for predicting sinkholes in weakly cemented sand over karst limestone, 2002,
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Goodings D. J. , Abdulla W. A. ,
Forty-nine physical models of sinkhole development were constructed and tested using a geotechnical centrifuge to replicate full scale sinkhole development in the small models. The soil profile studied was weakly cemented sand, overlying cavities in karst limestone with uncemented sand over the cemented sand layer in half the models. In configurations with no uncemented soil overburden, the parameters critical to predicting failure were: the unit weight of the cemented sand,,; the thickness of the cemented sand overlying the karst cavity, H-c; the true cohesion of the weakly cemented sand, c; and the diameter of the underlying karst cavity, D. Brittle collapse of the cemented soil into the underlying cavity took one of two forms depending on geometry: when H-c/D was less than or equal to 0.25, the plug of soil that fell into the cavity penetrated through the full thickness of the cemented layer leaving an open hole. When H-c/D was greater than or equal to 0.31, the plug of soil that fell into the cavity did not penetrate through the full thickness of the cemented layer, but left behind a stable arch. A dimensionless stability chart was developed based on model results relating (gamma(c)H(c)/c) and (H-c/D) at failure; that chart can be used to predict the onset of failure extrapolating to configurations and soil cementation strengths not specifically tested in this research. A study was also made of the influence of uncemented sand overburden on hastening sinkhole development for configurations with ratios of H-c/D less than or equal to 0.25; the thickness of the uncemented overburden was varied. At the brink of sinkhole development, there was significant arching within the uncemented sand, and the influence of the overburden on hastening sinkhole failure was much less than the full geostatic overburden. The maximum uncemented overburden pressure bearing down on the breakthrough plug never exceeded the weight of a cone of sand of diameter D', and height 1.25D', where D' equals the diameter of the top of that inclined plug. (C) 2002 Elsevier Science B.V All rights reserved

A decision-logic framework for investigating subsidence problems potentially attributable to gypsum karstification, 2002,
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Lamontblack J. , Younger P. L. , Forth R. A. , Cooper A. H. , Bonniface J. P. ,
Karst regions, especially gypsum ones, are prone to subsidence; this can cause severe problems in urban areas. However, this subsidence may have causes other than active karstification. A decision-logic framework designed to tackle this issue is presented. It comprises subsidence description identification of causal mechanisms; construction and evaluation of conceptual models; evaluation and parameterization of fundamental processes and development of a management strategy. This framework is applied to an area of active subsidence in the UK underlain by gypsiferous rocks. In this example, particular attention is paid to the evaluation of gypsum dissolution using four criteria: presence of evaporite; presence of undersaturated water; energy to drive water through the system; and an outlet for the water. Gypsum palaeokarst was identified from borehole evidence and contemporary karstification is indicated by groundwaters containing up to 1800 mg/l of dissolved sulphate. Strontium/sulphate ratios enabled the discrimination of gypsum and non-gypsum-derived sulphate ions and correlation with the hydrostratigrapby. Continuous measurement of groundwater levels showed differential potentiometric surfaces between stratigraphical horizons and indicated a complex pattern of groundwater movement. Integration of these data in a physically and chemically based groundwater model, incorporating a void evolution capability, is suggested. (C) 2002 Elsevier Science B.V. All rights reserved

The hydrogeochemistry of the karst aquifer system of the northern Yucatan Peninsula, Mexico, 2002,
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Perry E. , Velazquezoliman G. , Marin L. ,
Based on groundwater geochemistry, stratigraphy, and surficial and tectonic characteristics, the northern Yucatan Peninsula, Mexico, a possible analog for ancient carbonate platforms, is divided into six hydrogeochemical/physiographic regions: (1) Chicxulub Sedimentary Basin, a Tertiary basin within the Chicxulub impact crater; (2) Cenote Ring, a semicircular region of sinkholes; (3) Pockmarked Terrain, a region of mature karst; (4) Ticul fault zone; (5) Holbox Fracture Zone-Xel-Ha Zone; and (6) Evaporite Region. Regional characteristics result from tectonics, rock type, and patterns of sedimentation, erosion, and rainfall. The Cenote Ring, characterized by high groundwater flow, outlines the Chicxulub Basin. Most groundwater approaches saturation in calcite and dolomite but is undersaturated in gypsum. Important groundwater parameters are: SO4/Cl ratios related to seawater mixing and sulfate dissolution; Sr correlation with SO4, and saturation of Lake Chichancanab water with celestite. indicating celestite as a major source of Sr; high Sr in deep water of cenotes, indicating deep circulation and contact of groundwater with evaporite; and correlation of Ca, Mg, and SO4, probably related to gypsum dissolution and dedolomitization. Based on geochemistry we propose: (1) a fault between Lake Chichancanab and Cenote Azul; (2) deep seaward movement of groundwater near Cenote Azul; and (3) contribution of evaporite dissolution to karst development in the Pockmarked Terrain. Chemical erosion by mixing-zone dissolution is important in formation of Estuario Celestun and other estuaries, but is perhaps inhibited at Lake Bacalar where groundwater dissolves gypsum, is high in Ca, low in CO3, and does not become undersaturated in calcite when mixed with seawater

Dachstein-Altflche, Augenstein-Formation und Hhlenentwicklung - die Geschichte der letzten 35 Millionen Jahre in den zentralen Nrdlichen Kalkalpen, 2002,
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Frisch W. , Kuhlemann J. , Dunkl I. , Szekely B. , Vennemann T. , Rettenbacher A.
The landscape of the central Northern Calcareous Alps (NCA) is largely determined by the celebrate elevated karst plateaus, which represent relics of the Dachstein paleosurface and can be followed as far as the eastern margin of the NCA. The Dachstein paleosurface formed in late Eocene to early Oligocene times as a karstic hilly landscape. It was modified by later erosional processes to a limited extent only and is preserved as such in the karst plateaus. In the Oligocene, the paleosurface subsided and was sealed by the Augenstein Formation, a terrestrial sequence of conglomerates and sandstones, which are only preserved in small remnants on the plateaus. The poorly and contradictingly defined terms Rax landscape" and Augenstein landscape" are not used any more. From the overall geological situation, the age of the Augenstein Formation can be inferred as Lower Oligocene to early Lower Miocene. Fission track dating on zircon support the Lower Oligocene age of the basal Augenstein sediments (only these are preserved). Their source area was situated in the south and mainly occupied by weakly metamorphosed Paleozoic sequences (Graywacke Zone and its equivalents) and the latest Carboniferous to Lower Triassic siliciclastic base of the NCA. To the west, the Augenstein Formation interfingered with the Tertiary sediments of the Lower Inn Valley. Thermal modeling of fission track data from apatite, which is contained in pebbles as an accessory phase, suggest that the Augenstein Formation attained thicknesses of locally 1.3 km, possibly even more than 2 km. Augenstein sedimentation probably ended in Early Miocene times with the onset of lateral tectonic extrusion in the Eastern Alps, which caused lowering of the relief in the source area and created a new, fault-bounded river network. In the following period, the Augenstein sediments were eroded and redeposited in the foreland molasse basin. From Pannonian times (ca. 10 Ma) on, the central and eastern NCA, and therefore also the Dachstein paleosurface, experienced uplift in pulses. The paleosurface remained preserved in those areas, where thick limestone sequences enabled subsurface erosion in cave systems and considerably reduced surface erosion. Augenstein sediments became washed into the widespread cave systems of the plateau-topped limestone massifs. The arrangement of the caves in three horizons shows that uplift of the NCA occurred in pulses separated from periods of tectonic quiescence. In our model of the evolution of the NCA since the late Eocene, the highest cave system, the surface-near ruin cave system, was probably formed during formation of the Dachstein paleosurface. The largest system, the giant cave system, formed in Upper Miocene times, i.e., in the early stage of the final uplift period of the NCA. The youngest and lowest system, the source cave system, formed in Pliocene to Quaternary times. We aimed to date material from the giant cave system by radiometric methods. U/Pb dating on speleothems from the Mammut cave (Dachstein) and the Eisriesenwelt (Tennengebirge) gave no formation age because of the low U contents; however, the isotope ratios allow to infer that the speleothems formed in pre-Pleistocene time. Quartz pebbles from the Augenstein Formation, washed into the caves before the formation of the speleothems, were analyzer for cosmogenic beryllium and aluminum isotopes in order to date the time of redeposition. The isotope contents, however, did no yield a sufficiently strong signal. Oxygen and carbon isotope ratios were determined on the Eisriesenwelt speleothem in order to receive information on climatic changes during speleothem growth. A 260 mm long core from the outer zone of the speleothem shower limited variation for the temperatures of the seeping rainwater, which caused the speleothems to form. This indicates moderate climate and thus, again, pre-Pleistocene formation of the speleothems. All these results are in accord with the supposed Upper Miocene formation age of the giant cave system. Displacement of a speleothem along a shear plane and normal faults visible on the plateaus by the offset of the actual surface testify young, partly Quaternary tectonics, which affected the NCA.

Delineating the karstic flow system in the upper Lost River drainage basin, south central Indiana: using sulphate and delta S-34(SO4) as tracers, 2003,
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Lee E. S. , Krothe N. C. ,
A karstic flow system in the upper Lost River drainage basin in south central Indiana, USA, was investigated using SO4 concentration and delta(34)S(SO4) as tracers. The flow system was characterized as vadose flow and phreatic diffuse flow. Vadose-flow samples were collected from 7 epikarstic outlets after storm events. Phreatic diffuse flow samples were collected from the Orangeville Rise, the major emergence point for the drainage basin, during the base flow periods. Discharge from the Orangeville Rise was constant during the base flow periods but showed large variations in flow rate (0.3-11.7 m(3)/S), SO4 concentration (11-220 mg/l), and delta(34)S(SO4), ( 5.2 to 15.0parts per thousand) after storm events, due to the mixing of rain, vadose flow, and phreatic diffuse flow in the conduits that feed the Orangeville Rise. Sulphate concentrations and delta(34)S(SO4), were unique in vadose flow (S-SO4: 13-24 mg/l; delta(34)S(SO4),: 1.9 to 3.8parts per thousand) and phreatic diffuse flow (SO4: 220 mg/l; delta(34)S(SO4),: 15.0parts per thousand). Mean SO4 concentration of rainwater in the study area was measured as 1.8 mg/l. Using a 3-component mixing model for water in the karstic conduits, the mixing ratios of rain (16.5%), vadose flow (58.5%), and phreatic diffuse flow (25.0%) components were calculated in the Orangeville Rise discharge. These mixing ratios attained using SO4 concentration as a tracer indicated the important role of the vadose zone as a water storage area in karst aquifers. (C) 2002 Published by Elsevier Science Ltd

Sedimentologic, diagenetic and tectonic evolution of the Saint-Flavien gas reservoir at the structural front of the Quebec Appalachians, 2003,
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Bertrand R, Chagnon A, Malo M, Duchaine Y, Lavoie D, Savard Mm,
The Beekmantown Group (Lower Ordovician) of the Saint-Flavien reservoir has produced 162x106 m3 (5.7 bcf) of natural gas between 1980 and 1994. The conversion of the field into gas storage was initiated in 1992 and the pool became operational in 1998. Integration of structural and sedimentologic features, carbonate and organic matter petrography and geochemistry for 13 drill holes is used to define a tectonic-sedimentologic-diagenetic model for porosity evolution in these reservoir dolostones. The Beekmantown Group consists of numerous fifth-order shallowing-upward cycles 1.0 to 7.0 m thick (average of 2.4 m). Each cycle consists of a basal shale deposited during the initial flooding of the platform which was subsequently covered by a shoaling succession of subtidal and intertidal limestones to intertidal dolostones. Early dolomitization has produced intercrystalline porosity and preserved some moldic pores in the intertidal facies. Near surface, post-dolomite karstification has created vugs that were subsequently filled by early marine calcite fibrous cement based on the {delta}18O and {delta}13C ratios of calcite. Early burial elements consist of horizontal stylolites, pyrite and sphalerite. Late migrated bitumen was thermally altered or vaporized as native coke under deep burial conditions exceeding 240{degrees}C, partly due to overthrusting of Appalachian nappes. Under these conditions, breccias and fractures were generated and subsequently filled with K-feldspar, quartz, illite, and xenomorphic and poikilotopic calcite. The {delta}18O of the poikilotopic calcite and homogenization temperature of coeval fluid inclusions indicate formation under high temperatures (Th about 260{degrees}C). Horizontal shear zones and marcasite-rich vertical stylolites were produced during folding and thrusting. Dissolution has preferentially affected late fracture-filling calcite and generated most of the actual porosity during or soon after the Taconian Orogeny. The relationship between the occurrence of smectite and this type of porosity indicates the low temperature condition of this dissolution (T <100{degrees}C). Porosity in the Saint-Flavien reservoir has been mostly produced by fracture-controlled, late to post-Taconian dissolution of early to late calcite in the intertidal dolomitic slightly porous facies at the top of rhythmic cycles that compose the Beekmantown Group

Carbonate-Hosted Zn-Pb Deposits in Upper Silesia, Poland: Origin and Evolution of Mineralizing Fluids and Constraints on Genetic Models, 2003,
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Heijlen Wouter, Muchez Philippe, Banks David A. , Schneider Jens, Kucha Henryk, Keppens Eddy,
Microthermometric and crush-leach analyses of fluid inclusions in ore and gangue minerals of the Upper Silesian Zn-Pb deposits, Poland, along with first results of Rb-Sr geochronology on sulfides, provide important constraints on the paleohydrogeologic and metallogenetic models for the origin of these ores. The analyzed samples comprise two generations of dolomite, two generations of sphalerite, galena, and late calcite. The two dolomite generations and the late calcite were also analyzed for their oxygen and carbon isotope compositions, allowing a characterization of the mineralizing fluids. The ore-forming fluids represent highly saline (20-23 wt % CaCl2 equiv) Na-Ca-Cl brines, episodically introduced into the Triassic host carbonates. They had an oxygen isotope composition of ~0 per mil V-SMOW. Their Na-Cl-Br content (molar Na/Br and Cl/Br ratios between 99 and 337 and between 248 and 560, respectively) suggests that they originated by evaporation of seawater, which most likely occurred in the Permian-Triassic. The relative concentrations of potassium (molar K/Cl between 0.0147 and 0.0746) and lithium (molar Li/Cl between 0.0004 and 0.0031) further indicate that the fluids significantly interacted with siliciclastic rocks. The ionic and calculated oxygen isotope compositions of the fluids indicate that they were more evolved than present-day brines in the Upper Silesian coal basin, and the present-day brines show more extensive mixing with low-salinity fluids. The first results of direct Rb-Sr dating of ore-stage sulfides yield an isochron model age of 135 {} 4 Ma for the mineralizing event. This is consistent with hydrothermal activity and ore formation in Upper Silesia occurring in response to Early Cretaceous crustal extension preceding the opening of the northern Atlantic Ocean. The data presented support a model in which bittern brines migrated down into the deep subsurface and evolved into mineralizing fluids owing to extensive water-rock interaction. They were episodically expelled along deeply penetrating faults during the Early Cretaceous to form Zn-Pb deposits in the overlying Mesozoic carbonate rocks

Soil and karst aquifer hydrological controls on the geochemical evolution of speleothem-forming drip waters, Crag Cave, southwest Ireland, 2003,
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Tooth Anna F. , Fairchild Ian J. ,
In recent years there has been increased interest in cave speleothems as archives of palaeoclimate. Monitoring of rainfall and soil and karst water chemistries was performed at Crag Cave, Castleisland, Co. Kerry, southwest Ireland, in August 1997 and January 1998 in order to understand temporal and spatial variations in karst water hydrology and chemistry and their implications for interpreting the potential palaeohydrological signal preserved by speleothems at this site. Temporal variations in karst water drip rates and geochemistry allow drips to be classified by hydrological response to rainfall and the associated processes of dilution, piston flow, source change and prior calcite precipitation during aquifer throughflow. Evolution from soil matrix and preferential flow solutions has also been determined to exert an important control on karst water chemistries. As a result of these findings we present hydrogeochemical models and plumbing diagrams that delineate the controls on karst water evolution at a number of sampling locations within the cave at this site. We propose that a palaeohydrological signal may be recorded by Crag Cave speleothems that may be interpreted via the study of Mg/Ca ratios in speleothems linked to monitoring of modern drip water chemistry

Temporal evolution of tertiary dolostones on Grand Cayman as determined by Sr-87/Sr-86, 2003,
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Jones B. , Luth R. W. ,
On the Cayman Islands, the Tertiary Bluff Group (Brac Formation, Cayman Formation, Pedro Castle Formation) is onlapped and overlain by the Pleistocene Ironshore Formation. On Grand Cayman, the Brac Formation and Cayman Formation are formed of finely crystalline dolostones; whereas the Pedro Castle Formation is formed of finely crystalline dolostones, dolomitized limestones, and limestones. No dolomite has been found in the Ironshore Formation. Dolostones in the Bluff Group, which retained their original depositional textures and lack evidence of any recrystallization, are formed of small (typically 5-15 mum long) interlocking, euhedral dolomite crystals. Dolomite cement is present in the Brac Formation and Cayman Formation but is very rare in the Pedro Castle Formation. Most of the dolomite crystals are characterized by oscillatory zoning with alternating zones of low-Ca calcian dolomite and high-Ca calcian dolomite. Grand Cayman is ideal for assessing the temporal evolution of Tertiary dolostones because the dolostones are young, have not been recrystallized, and are geographically isolated by the deep oceanic waters around the island. Interpretation of 158 new Sr-87/Sr-86 ratios from the dolostones in the Bluff Group indicate that the succession underwent three time-transgressive phases of dolomitization during the Late Miocene, the Late Pliocene, and Pleistocene. Petrographically similar dolomite was produced during each phase of dolomitization that was mediated by the same type of fluid and the same general conditions. Dolomitization was part of a dynamic cycle of processes that followed major lowstands. Karst development during the lowstands preconditioned the limestones for dolomitization by increasing their porosity and permeability. Thus, vast quantities of the dolomitizing fluids could freely circulate through the strata during the subsequent transgression. Dolomitization ceased once a stable highstand had been attained

Temporal Evolution of Tertiary Dolostones on Grand Cayman as Determined by 87Sr/86Sr, 2003,
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Jones Brian, Luth Robert W. ,
On the Cayman Islands, the Tertiary Bluff Group (Brac Formation, Cayman Formation, Pedro Castle Formation) is onlapped and overlain by the Pleistocene Ironshore Formation. On Grand Cayman, the Brac Formation and Cayman Formation are formed of finely crystalline dolostones whereas the Pedro Castle Formation is formed of finely crystalline dolostones, dolomitized limestones, and limestones. No dolomite has been found in the Ironshore Formation. Dolostones in the Bluff Group, which retained their original depositional textures and lack evidence of any recrystallization, are formed of small (typically 5-15 {micro}m long) interlocking, euhedral dolomite crystals. Dolomite cement is present in the Brac Formation and Cayman Formation but is very rare in the Pedro Castle Formation. Most of the dolomite crystals are characterized by oscillatory zoning with alternating zones of low-Ca calcian dolomite and high-Ca calcian dolomite. Grand Cayman is ideal for assessing the temporal evolution of Tertiary dolostones because the dolostones are young, have not been recrystallized, and are geographically isolated by the deep oceanic waters around the island. Interpretation of 158 new 87Sr/86Sr ratios from the dolostones in the Bluff Group indicate that the succession underwent three time-transgressive phases of dolomitization during the Late Miocene, the Late Pliocene, and Pleistocene. Petrographically similar dolomite was produced during each phase of dolomitization that was mediated by the same type of fluid and the same general conditions. Dolomitization was part of a dynamic cycle of processes that followed major lowstands. Karst development during the lowstands preconditioned the limestones for dolomitization by increasing their porosity and permeability. Thus, vast quantities of the dolomitizing fluids could freely circulate through the strata during the subsequent transgression. Dolomitization ceased once a stable highstand had been attained

Paleoclimate reconstruction based on the timing of speleothem growth, oxygen and carbon isotope composition from a cave located in the 'rain shadow', Israel, 2003,
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Vaks, A. , Barmatthews, M. , Ayalon, A. , Schilman, B. , Gilmour, M. , Hawkesworth, C. J. , Frumkin, A. , Kaufman, A. , And Matthews, A.

High-resolution 230Th/234U ages and d18O and d13C compositions of speleothems in Ma?ale Efrayim Cave located to the east of the central mountain ridge of Israel enable us to examine the nature of the rain shadow aridity during glacial and interglacial intervals. Speleothem growth occurred during marine glacial isotopic periods, with no growth during the two last marine isotope interglacial intervals and during the peak of the Last Glacial Maximum. This contrasts with speleothem growth in caves located on the western flank of the central mountain ridge, in the Eastern Mediterranean semiarid climatic zone, which continued throughout the last 240,000 yr. Thus, during glacial periods water reached both sides of the central mountain ridge. A comparison of the present-day rain and cave water isotopic compositions and amounts at the Ma?ale Efrayim Cave site with those on the western flank shows that evaporation and higher temperatures on the eastern flank are major influences on isotopic composition and the lack of rainfall. The d18O and d13C profiles of the speleothems deposited between 67,000 and 25,000 yr B.P. match the general trends of the isotopic profiles of Soreq Cave speleothems, suggesting a similar source (eastern Mediterranean Sea) and similar climatic conditions. Thus, during glacial periods the desert boundary effectively migrated further south or east from its present-day location on the eastern flank, whereas interglacial periods appear to have been similar to the present, with the desert boundary at the same position. The decrease in overall temperature and a consequent reduction in the evaporation to precipitation ratios on the eastern flank are viewed as the major factors controlling the decay of the rain shadow effect during glacial periods.


Evolution of hydraulic conductivity by precipitation and dissolution in carbonate rock, 2003,
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The evolution of hydraulic conductivity and flow patterns, controlled by simultaneous  precipitation and dissolution in porous rocks, was examined in a series of laboratory  experiments. Linear flow experiments were performed in columns of crushed calcareous  sandstone by injecting different concentrations of HCl/H2SO4 mixtures at various flow  rates. The effect of simultaneous calcium carbonate dissolution and gypsum precipitation  was analyzed. Changes in head gradient, recorded at specific time intervals during the  experiments, were used to calculate overall hydraulic conductivity of each column. The  effluent acid was analyzed for Ca2+ and SO4  2_ concentrations in order to calculate porosity  changes during the experiments. After each experiment, the rock sample was retrieved and  sectioned in order to study the pore space geometry, micromorphology, and mineral  concentrations. Arange of injected H+/SO4  2_ ratios and flow rates was identified which leads  to oscillations in the effective hydraulic conductivity of the evolving carbonate rock  samples. Because the dissolution of calcium carbonate is a mass transfer limited process,  higher flow rates cause a more rapid dissolution of the porous medium; in such cases, with  dissolution dominating, highly conductive flow wormholes were observed to develop.  At slower flow rates, no wormhole formation was observed, but the porosity varied in  different parts of the columns. Analysis of the sectioned parts of the column, after each  experiment, showed that total porosity increased significantly by dissolution of carbonate  mineral near the inlet of the column and decreased along the interior length of the column by  gypsum precipitation. These findings are in qualitative accordance with conceptual  understanding of such phenomena


Heterogeneity of parent rocks and its constraints on geochemical criteria in weathering crusts of carbonate rocks, 2004,
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Wang S. J. , Feng Z. G. ,
Owing to the low contents of their acid-insoluble components, carbonate rocks tend to decrease sharply in volume in association with the formation of weathering crust. The formation of a 1 m-thick weathering crust would usually consume more than ten meters to several tens of meters of thickness of parent rocks. The knowledge of how to identify the homogeneity of parent rocks is essential to understand the formation mechanism of weathering crust in karst regions. especially that of thick-layered red weathering crust. In this work the grain-size analyses have demonstrated that the three profiles studied are the residual weathering crust of carbonate rocks and further showed that there objectively exists the, heterogeneity of parent rocks in the three studied weathering crusts. The heterogeneity of parent rocks can also be. reflected in geochemical parameters of major elements, just as the characteristics of frequency plot of pain-size distribution. Conservative trace element ratios Zr/Hf and Nb/Ta are proven to be unsuitable for tracing the heterogeneity of parent rocks of weathering crust, but its geochemical mechanism is unclear. The authors strongly suggest in this paper that the identification of the homogeneity of parent rocks of weathering crust in karst regions is of prime necessity

Isotopic and geochemical evolution of ground and surface waters in a karst dominated geological setting: A case study from Belize, Central America, 2004,
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Marfia A. M. , Krishnamurthy R. V. , Atekwana E. A. , Panton W. F. ,
Analysis of stable isotopes and major ions in groundwater and surface waters in Belize, Central America was carried out to identify processes that may affect drinking water quality. Belize has a subtropical rainforest/savannah climate with a varied landscape composed predominantly of carbonate rocks and clastic sediments. Stable oxygen (delta(18)O) and hydrogen (deltaD) isotope ratios for surface and groundwater have a similar range and show high d-excess (10-40.8parts per thousand). The high d-excess in water samples suggest secondary continental vapor flux mixing with incoming vapor from the Caribbean Sea. Model calculations indicate that moisture derived from continental evaporation contributes 13% to overhead vapor load. In surface and groundwater, concentrations of dissolved inorganic carbon (DIC) ranged from 5.4 to 112.9 mg C/l and delta(13)C(DIC) ranged from -7.4 to -17.4parts per thousand. SO42, Ca2 and Mg2 in the water samples ranged from 2-163, 2-6593 and 2-90 mg/l, respectively. The DIC and delta(13)C(DIC) indicate both open and closed system carbonate evolution. Combined delta(13)C(DIC) and Ca2, Mg2 SO42- suggest additional groundwater evolution by gypsum dissolution and calcite precipitation. The high SO42- content of some water samples indicates regional geologic control on water quality. Similarity in the range of delta(18)O, deltaD and delta(13)C(DIC) for surface waters and groundwater used for drinking water supply is probably due to high hydraulic conductivities of the karstic aquifers. The results of this study indicate rapid recharge of groundwater aquifers, groundwater influence on surface water chemistry and the potential of surface water to impact groundwater quality and vise versa. (C) 2003 Elsevier Ltd. All rights reserved

Seasonal changes of fulvic acid, Ca and Mg concentrations of water samples collected above and in the Beke Cave of the Aggtelek karst system (Hungary), 2004,
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Tatar Eniko, Mihucz Victor G. , Zambo Laszlo, Gasparics Tibor, Zaray Gyula,
Magnesium and Ca concentration ratios, fulvic acid content, total dissolved inorganic carbon (DIC) and pH were determined in seepage water and drip water samples collected during one seasonal cycle between June 2000 and May 2001 above and in the Beke Cave of Aggtelek (Hungary). Seepage water samples were collected at 0.5 and 7 m below ground level from an observation point situated above the cave. Drip water was collected 40 m underground from a group of stalactites. The fulvic acid concentrations were determined by fluorescence spectrometry after pre-concentration on a XAD-8 chromatographic column. Calcium and Mg concentrations were measured by inductively coupled plasma atomic-emission spectrometry. DIC was determined with a CO2 - selective electrode. DIC values increased and the fulvic acid concentrations and Mg and Ca concentration ratios, generally, decreased with depth. The highest flux of fulvic acid was observed in spring. The fulvic acid flux increased by a factor of 2.6-3.6 and 1.4 for groundwater and drip water, respectively, compared with those registered in the winter samples. The variations in the Ca, Mg and fulvic acid concentrations of the seepage and drip water samples relate to the variable drip rate. The results revealed that there is a strong correlation between the daily average surface temperature, daily amount of precipitation and drip water rate registered in the cave

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