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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. ...

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 kaolin is a common clay mineral [16].?

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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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Within the Franco-Belgian segment of the Hercynian orogen, two thick Dinantian anhydritic formations are known, respectively in the Saint-Ghislain (765 m) and Epinoy 1 (904 m) wells. Nevertheless, occurrences of widespread extended breccias and of numerous pseudomorphs of gypsum/anhydrite in stratigraphically equivalent carbonate deposits (boreholes and outcrops), suggest a larger extent of the evaporitic conditions (fig. 1, 2). The present distribution of evaporites is controlled by palaeogeographical differentiation and post-depositional parameters such as tectonics and dissolution. These latter have dissected the deposits formerly present in all the structural units. By using depositional, diagenetic and deformational characters of these formations, the article provides a model for the reconstruction of a dislocated evaporitic basin. This segment of the Hercynian chain is schematically composed of two main units (fig. 1, 3) : (1) the autochthonous or parautochthonous deposits of the Namur synclinorium, (2) the Dinant nappe thrusted northward over the synclinorium of Namur. The major thrust surface is underlined by a complex fault bundle (faille du Midi) seismically recognized over more than 100 km. A complex system of thrust slices occurs at the Hercynian front. Except for local Cretaceous deposits, most of the studied area has been submitted to a long period of denudation since the Permian. Sedimentary, faunistic and geochemical data argue for a marine origin of the brines which have generated the evaporites interbedded with marine limestones. Sedimentary structures. - The thick evaporitic formations are composed of calcium-sulfates without any clear evidence of the former presence of more soluble salts (with the exception of a possible carbonate-sulfate breccia in the upper part of the Saint-Ghislain formation). As in all the deeply buried evaporitic formations, the anhydrite is the main sulfate component which displays all the usual facies : pseudomorphs after gypsum (fig. 4A, B), nodular and mosaic (fig. 4C), laminated. The gypsum was probably an important component during the depositional phase despite the predominant nodular pattern of the anhydrite. Early diagenetic nodular anhydrite may have grown during temporary emersion of the carbonates (sabkha environments), but this mechanism cannot explain the formation of the whole anhydrite. So, most of the anhydrite structures result from burial-controlled gypsum --> anhydrite conversion and from mechanical deformations. Moreover, a complex set of diagenetic processes leads to various authigenic minerals (celestite, fluorite, albite, native sulfur, quartz and fibrous silica) and to multistaged carbonate <> sulfate replacements (calcite and dolomite after sulfate, replacive anhydrite as idiomorphic poeciloblasts, veinlets, domino-like or stairstep monocrystals...). These mineral transformations observed ill boreholes and in outcrops have diversely been controlled during the complex evolution of the series as : depositional and diagenetic pore-fluid composition, pressure and temperature changes with burial, bacterial and thermochemical sulfate reduction, deep circulations favored by mechanical brecciation, mechanical stresses, role of groundwater during exhumation of the series. Deformational structures. - A great variety of deformational structures as rotational elongation, stretching, lamination, isoclinal microfolding, augen-like and mylonitic structures are generated by compressive tectonic stresses (fig. 4D to J). The similarities between tectonic-generated structures and sedimentary (lamination) or diagenetic (pseudo-nodules) features could lead lo misinterpretations. The calcareous interbeds have undergone brittle deformation the style and the importance of which depend of their relative thickness. Stretching, boudins, microfolds and augen structures F, H. I) affect the thin layers while thicker beds may be broken as large fractured blocks dragged within flown anhydrite leading to a mylonitic-like structure (fig, 4G). In such an inhomogeneous formation made of interlayered ductile (anhydrite) and brittle (carbonate) beds, the style and the intensity of the deformation vary with respect to the relative thickness of each of these components. Such deformational features of anhydrite may have an ubiquitous significance and can result either from compressive constraints or geostatic movements (halokinesis). Nevertheless, some data evidence a relation with regional tangential stresses: (1) increase of the deformation toward the bottom of the Saint-Ghislain Formation which is marked by a deep karst suggesting the presence of a mechanical discontinuity used as a drain for dissolving solutions (fig. 3, 4); (2) structural setting (reversed series, internal slidings) of the Epinoy 1 formation under the Midi thrust. However, tectonic stresses also induce flowing deformations which have contributed to cause their present discontinuity. It can be assumed that the evaporites played an active role for the buckling of the regional structure as detachment or gliding layers and more specifically for the genesis of duplex structures. Breccia genesis. - Great breccia horizons are widely distributed in outcrops as well as in the subsurface throughout the greater part of the Dinant and Namur units (fig. 2). The wide distribution of pseudomorphosed sulfates in outcrops and the stratigraphical correlation between breccia and Saint-Ghislain evaporitic masses (fig. 2) suggest that some breccia (although not all) have been originated from collapse after evaporites solution. Although some breccia may result from synsedimentary dissolution, studied occurrences show that most of dissolution processes started after the Hercynian deformation and, in some cases, were active until recently : elements made of lithified and fractured limestones (Llandelies quarries) (fig. 5A), preservation of pseudomorphs of late replacive anhydrite (Yves-Gomezee) (fig. 5B, C), deep karst associated with breccia (Douvrain, Saint Ghislain, Ghlin boreholes) (fig. 3, 4, 5D)). Locally, the final brecciation may have been favored by a mechanical fragmentation which controlled water circulations (fig. 5E). As postulated by De Magnee et al. [19861, the dissolution started mostly after the Permian denudation and continued until now in relation with deep circulations and surface weathering (fig. 6). So, the above-mentioned occurrences of the breccia are logically explained by collapse after dissolution of calcium-sulfates interbeds of significant thickness (the presence of salt is not yet demonstrated), but other Visean breccia may have a different origin (fig. 5F). So, these data prove the extension of thick evaporitic beds in all the structural units including the Dinant nappe, before dissolution and deformation. Implications. - Distribution of Visean evaporites in northern France and Belgium is inherited from a complicated paleogeographic, tectonic and post-tectonic history which has strongly modified their former facies, thicknesses and limits (fig. IA, 6). Diversified environments of deposition controlled by both a palaeogeographical differentiation and water level fluctuations led to the deposition of subaqueous (gypsum) or interstitial (gypsum, anhydrite) crystallization. Nevertheless, most of the anhydrite structures can be interpreted as resulting from burial conversion of gypsum to anhydrite rather than a generalized early diagenesis in sabkha-like conditions. Deformation of anhydrite caused by Hercynian tangential stresses and subsequent flow mechanisms, have completed the destruction of depositional and diagenetic features. The tectonic deformations allow us to consider the role of the evaporites in the Hercynian deformations. The evaporites supplied detachment and gliding planes as suggested for the base of the Saint-Ghislain Formation and demonstrated by the structural setting of Epinoy 1 evaporites in reverse position and in a multi-system of thrust-slices below the Midi overthrust (fig. 7). So, although the area in which evaporation and precipitation took place cannot be exactly delineated in geographic extent, all the data evidence that the isolated thick anhydritic deposits represent relics of more widespread evaporites extending more or less throughout the different structural units of this Hercynian segment (fig. 1B). Their present discontinuity results from the combination of a depositional differentiation, mechanical deformations and/or dissolution

Upper Sinking Cove, dissecting the eastern escarpment of the Cumberland Plateau, is characterized by a multiple aquifer, predominantly vadose hydrologic system with minor surface components. There is a central trunk channel along the axis of the cove and a network of independent tributaries. Aquitards within the limestones, particularly Hartselle Formation shales, have influenced both cave and surface landform development by perching ground waters and slowing the vertical growth of closed depressions. Long-term solutional denudation in the portion of the cove underlain by limestones (40 per cent) is an estimated 56 mm per 1000 years, suggesting that karst development began 15-16 million years ago. Despite lower soil CO2 and spring water hardness, 61 per cent of annual denudation occurs in the six winter months when 76 per cent of yearly runoff occurs. Landform development in Upper Sinking Cove appears to have begun as stream erosion carved a valley first in the sandstone caprock of the escarpment and later in the underlying Pennington Formation limestones containing numerous shale layers which promoted surface stream flow. Eventually stream erosion exposed the massive Bangor limestones which allowed deep ground water flow. Surface streams were pirated underground with the eventual formation of the chain of three closed depressions which constitute Upper Sinking Cove

The Lower Mississippian Mission Canyon Formation of central to southwestern Montana was deposited under dominantly semiarid to arid climatic conditions during Osagean to early Meramecian times. Following deposition, a pronounced climatic shift to more humid conditions occurred during middle Meramecian times. This climatic change is indicated by extensive, post-depositional karst fabrics and in the stable isotopic composition of early, meteoric calcite cements and diagenetically altered sediments. Early meteoric calcite cement in Mission Canyon limestones is generally nonluminescent and fills intergranular and fenestral porosity. Petrographic data indicate that this cement formed during intermittent subaerial exposure of the Mission Canyon platform during Osagean times. This initial generation of meteoric calcite cement has deltaO-18 values from -8.1 to -2.6 parts per thousand PDB. These data, and the oxygen isotopic values from nonluminescent skeletal grains and micrite in host limestone indicate that Osagean meteoric water may have had deltaO-18 values as low as -6.0 parts per thousand SMOW. A second generation of petrographically similar, but isotopically distinct, calcite cement fills biomolds and porosity within solution-collapse breccias in the Mission Canyon Formation. This cement generation postdates earlier nonluminescent Osagean calcite cement and is volumetrically most abundant near the top of the Mission Canyon Formation. DeltaO-18 values from these cements and from nonluminescent lime mudstone clasts and matrix in solution collapse breccias range from -13.8 to -8.2 parts per thousand PDB. These data indicate that Meramecian meteoric water may have had deltaO-18 values as low as - 12.0 parts per thousand. However, a higher-temperature burial overprint on the deltaO-18 values of the calcite cement cannot be ruled out. The more positive deltaO-18 values of the Osagean calcite components probably indicate warm and arid conditions during short-term [10(4)(?) yr) subaerial exposure along intraformational sequence and parasequence boundaries. The more negative deltaO-18 values from Meramecian calcite components and the extensive karst associated with the post-Mission Canyon unconformity may have developed because of cooler and more humid climatic conditions and possible rain-out effects during middle Meramecian times. A dramatic shift towards cooler and more humid climatic conditions may be coincident with the onset of major continental glaciation in the Early Carboniferous. The post-Mission Canyon unconformity has been attributed to a major fall in sea level that may have glacio-eustatic origins. Growth of continental glaciers during a time of global cooling would have caused migration of polar fronts further toward the paleoequator. These polar fronts in turn, would have pushed moist, mid-latitude weather systems toward the paleoequator, resulting in cooler, more humid conditions in low-latitude settings during ''icehouse'' times

Rauhwackes (cornieules or cargneules) are breccias with a caicareous matrix and mainly dolomitic components that weather to form cavernous rocks. They are very often associated with tectonic contacts, e.g. detachment horizons. The origin of rauhwackes is still controversial, but has been attributed to the weathering and alteration of dolomite-bearing evaporites, the tectonisation of dolomites or other processes. New data based on field investigations show that the karstification of evaporites leads to the formation of rauhwackes. Two end member evaporitic protoliths can be distinguished: dolomite-bearing gypsum and gypsum-bearing dolomite. The karstification of the different protoliths leads to the formation of structurally distinct rauhwackes. Dolomite-bearing gypsum is associated with unstructured, often polymictic rauhwackes which reflect the shape of the karst cavities and which are interpreted as karst sediments. Gypsum-bearing dolomite occurs with stratiformal rauhwackes with fitting dolomite fragments that are arranged in layers. These rauhwackes can be regarded as collapse breccias. All investigated rauhwackes seem to have been formed after the alpine deformations and are probably of Quaternary age. In certain cases, the karstification of the evaporites and the formation of rauhwackes may have been favoured by fluvial or fluvioglacial processes at the surface. Therefore, these rauhwackes have nothing to do with alpine tectonics. Rather, it was the evaporitic protoliths of the rauhwackes that acted as detachment horizons and incompetent layers during folding

Ring of cenotes (sinkholes), Northwest Yucatan, Mexico; its hydrogeologic characteristics and possible association with the Chicxulub impact crater, 1995, Perry Eugene, Marin Luis E. , Mcclain Jana, Velazquez Guadalupe,
A 180-km-diameter semicircular band of abundant karst sinkholes (Ring of Cenotes) in Northwest Yucatan, Mexico, coincides approximately with a concentric ring of the buried Chicxulub structure, a circular feature manifested in Cretaceous and older rocks, that has been identified as the product of the impact of a bolide. The ring, expressed in Tertiary rocks, marks a zone of high permeability as shown by (1) the sinkholes themselves, (2) breaks in the coastal dune system and high density of springs where the ring intersects the coast, and (3) water-level transects characterized by a decline in water level toward the ring. Any direct relation that exists between the Ring of Cenotes and the Chicxulub structure bears on regional hydrogeology. If the layer or zone responsible for the ring is deeply buried, it may act as a barrier to the movement of ground water across the main flow direction. Shallower zones of horizontal permeability could result in less complete diversion of ground water. Through its influence on Yucatan aquifer characteristics, the ring may provide a link between modern environmental problems and astrogeology. Possible origins for the Ring of Cenotes are (1) faulting, perhaps reactivated by post-Eocene-mid-Miocene basin loading, (2) permeability in a buried reef complex developed in the shallow Paleocene sea around the crater rim, or (3) breccia collapse occasioned by consolidation or by solution of evaporite components. If the ring developed on ancient faults, it may outline hydrothermal systems and mineral deposits produced during Paleocene cooling of the Chicxulub melt sheet

Excavations in Buried Cave Deposits: Implications for Interpretation, 1996, Brady, J. E. , Scott, A.
Karst areas in Belize are coming under increasing pressure from agriculture and other commerce. Opportunely protected karst areas are incorporated within forest reserves, national parks, wildlife sanctuaries, nature reserves, archaeological reserves, private conservation and management areas, and special development areas. The total area of karst afforded nominal protection is about 3400 km, or about 68% of the total. Incorporating special development areas, the protected karst area is about 4300 km, or 86% of the total. Even the more conservative percentage is unparalleled in Central America and the Caribbean, and perhaps the world. Significant protected karst areas include the Chiquibul, Blue Hole and Five Blues Lake national parks, the Bladen, Aquas Turbias and Tapir Mountain nature reserves, the Monkey Bay Wildlife Sanctuary, the Rio Bravo Conservation and Management Area, and the Caracol, Xunantunich, Cahal Pech and El Pilar archaeological reserves. Extensive karst areas are located within the Vaca, Columbia River, Sibun, and Manatee forest reserves. The Manatee and Cayo West special development areas have considerable karstic components.

Conservation of Karst in Belize, 1996, Day, M.
Karst areas in Belize are coming under increasing pressure from agriculture and other commerce. Opportunely protected karst areas are incorporated within forest reserves, national parks, wildlife sanctuaries, nature reserves, archaeological reserves, private conservation and management areas, and special development areas. The total area of karst afforded nominal protection is about 3400 km, or about 68% of the total. Incorporating special development areas, the protected karst area is about 4300 km, or 86% of the total. Even the more conservative percentage is unparalleled in Central America and the Caribbean, and perhaps the world. Significant protected karst areas include the Chiquibul, Blue Hole and Five Blues Lake national parks, the Bladen, Aquas Turbias and Tapir Mountain nature reserves, the Monkey Bay Wildlife Sanctuary, the Rio Bravo Conservation and Management Area, and the Caracol, Xunantunich, Cahal Pech and El Pilar archaeological reserves. Extensive karst areas are located within the Vaca, Columbia River, Sibun, and Manatee forest reserves. The Manatee and Cayo West special development areas have considerable karstic components.

Speleogenesis in Gypsum., 1996, Klimchouk Alexander
Satisfactory explanation of the origin and development of caves (speleogenesis) is a core problem of karst studies. Karst evolves as a circulation system, organised and interconnected through a conduit structure. Such a system may include superficial inputs and outputs, expressed as or related to karst landforms. However, there may be no such components if the system is represented entirely by conduits as in the case with deep-seated intrastratal karst. The main differences between speleogenesis in gypsum and in carbonate rocks lie in the chemistry and kinetics of their dissolution, in some of the lithological or structural peculiarities of the respective rocks and formations, and in their hydrogeological characteristics. The present chapter considers how these factors influence cave origin and development.

Geochemistry of submarine warm springs in the limestone cavern of Grotta Azzurra, Capo Palinuro, Italy: evidence for mixing-zone dolomitisation, 1996, Stuben Doris, Sedwick Peter, Colantoni Paolo,
Subtidal springs in and around the submarine limestone cavern of Grotta Azzurra, at Capo Palinuro, Italy, discharge fluids which are warm (-, Na and Mg2, and enriched in Si, alkalinity, Ca2, Sr2, Mn, NH4, PO43- and H2S, relative to surrounding seawater. The compositions of the warm fluid samples collected in and around the cave define mixing lines which suggest dilution of a single thermal fluid (T >= 23[deg]C) by cool overlying seawater (T= 17-17.6[deg]C). The chemical data suggest that the proposed thermal fluid contains two components, one derived from seawater ( 10%). Excess Si, alkalinity, Ca2, Sr2 and Mn relative to seawater are likely derived from the groundwater component or dissolution/hydrothermal alteration of the host rocks. Magnesium has been removed from the seawater component in exchange for Ca2, due to dolomitisation of the limestone and/or hydrothermal alteration reactions. Saturation-state calculations suggest that the vented fluids are near saturation with respect to calcite and supersaturated with respect to dolomite. This and the presence of dolomite in the host rocks and cave-floor sediments suggest that 'mixing-zone' dolomitisation of the limestones is occurring, perhaps kinetically assisted by elevated temperature and/or bacterial mediation in the reducing subseafloor zone. One possible 'end-member' condition is considered for the thermal fluid -- zero-Mg -- which suggests an end-member temperature of 50.5[deg]C and a fluid composition derived from ~ 38% seawater and ~ 62% groundwater. The heat source for the circulating fluids is uncertain, but may involve warm underlying igneous rocks or heating via the geothermal gradient. A continuous in-situ record of vent-fluid temperature, salinity, pH and O2 concentration collected within the cavern is consistent with our interpretation of the fluid origin, and suggests that tidal forcing affects circulation and venting of the warm fluids

Long term stability of a terrestrial cave community, 1997, Carchini Gianmaria, Di Russo Claudio, Luccarelli Marco, Rampini Mauro, Sbordoni Valerio
We report data on the spatial structure and seasonal variation of the community of Valmarino cave, a medium sized sandstone cave, located a few kilometres from the coast line, in Central Italy. Due to both its habitat features and its relatively recent geological history, Valmarino cave is only inhabited by terrestrial, troglophilic elements, i.e facultative cave dwellers. By means of monthly censuses and density plot estimates we have investigated species abundance, diversity and their spatial organization, by considering separately samples from different cave sectors. Homogeneous sampling design allowed to compare series of samplings performed in 1974 and 1994. On the whole 21 arthropods and one snail species constitute the cave community. Ordination plots resulting from correspondence analyses of monthly samples outline a distinct spatial and temporal structure. Two main sub-communities can be identified: a inner subcommunity, mainly represented by eu-troglophilic species, showing a remarkable stability throughout the year and an outer sub-community, mainly represented by sub-troglophilic species, showing strong seasonal variation. Both spatial and temporal vectors show similar importance in shaping the community structure. An interesting result of this study is the long term stability of both spatial and seasonal components of the community structure which remained almost identical after 20 years, as shown by the comparison of ordination plots obtained from 1974 and 1994 sampling series. Therefore this study provides empirical evidence of a frequently hypothesised, albeit never demonstrated feature of the cave ecosystem.

Geochemistry and water dynamics: Application to short time-scale flood phenomena in a small Mediterranean catchment .1. Alkalis, alkali-earths and Sr isotopes, 1997, Benothman D, Luck Jm, Tournoud Mg,
We report major, trace elements and Sr isotope data for water samples taken regularly during a four-day-long September flood of a Mediterranean river, the Vene (Herault, S. France). The objective is to combine all these data into a dynamic model that describes the origin(s) and movements of waters and their loads. This river drains the runoff from a small, mainly carbonate, partly karstified watershed with Miocene and Jurassic lithologies. The watershed is also impacted by both agricultural and urban activities. Both the dissolved and the particulate loads were analyzed. Concentrations of the dissolved components show major remobilization of almost all elements during the first few hours of the flood (water treatment plants and aerosol scavenging), followed by a sharp concentration decrease. Some major species return to their previous summer values (Ca, HCO3) while others reach low 'background' levels (Na, K, Cl, SO4). Some trace elements (Rb, Sr, Cs) show similar behaviour but (Ba) appears somewhat unaffected. Trace element concentrations and ratios define two main periods (three in the suspended particulate matter). Ratios do not allow distinguishing between the three main sources for the dissolved load in the first period (Miocene, Jurassic, water treatment plants), but clearly show the Jurassic karst influence later on. The Sr-87/Sr-86 Of the suspended particulate matter is more variable and more radiogenic than in the dissolved phase. Variations in concentration ratios and Sr isotope composition in particulates indicate the large and variable contribution of Miocene silicates with some carbonate. However, there is a need for another component with [Rb]/[Sr] higher than bedrocks, internal or external to the watershed, possibly due to differential erosion. Dissolved Ca and Mg fluxes during the flood were calculated at 0.26 ton and 0.029 ton/km(2), respectively. Even though the carbonate nature of the watershed restricts variability in Sr isotope composition in the dissolved load, we distinguish several endmembers: seawater(approximate to marine rain), Miocene marls, Jurassic limestones, water treatment plants (and possibly another attributable to fertilizers). Combined with major and trace element variational Sr isotope fluctuations indicate time-varying proportions of different water endmembers at the outflow and suggest a general dynamic model. Based on PCA (principal component analysis), a 3D representation allows to visualize the geochemical evolution of the Vene waters. In particular, Sr isotopes clearly indicate that the inflow of karstic waters during the flood was not continuous but occurred as a series of marked oscillations between flowing waters with chemical signature of Miocene lithologies and increasing flushes of deeper waters that interacted with Jurassic lithologies. (C) 1997 Elsevier Science B.V

Ce-anomalies in the textural components of upper Cretaceous karst bauxites from the Apulian carbonate platform (southern Italy), 1997, Mongelli G. ,
The chemical and mineralogical composition of Upper Cretaceous Apulian karat bauxites (southern Italy) and their textural components, i.e. ooids and matrix, has been studied. The bulk samples are composed of boehmite, hematite, anatase and kaolinite. The samples collected along a vertical profile show a downward enrichment for the elements Rb, Sr, Ba, Ni and Cr. A similar distribution is observed in deposits bauxitized in situ at the expense of matrix-like material collected in the karst zone. The ooids consist mainly of hematite with minor boehmite and anatase, whereas in the matrix boehmite prevails on hematite, kaolinite and anatase. In the void fillings in the matrix there is a Ca-fluorocarbonate having a Ce/Ce* of 5.8. The ooids, with the exception of Ce, are enriched in REE and show a higher (La/Yb)(ch) ratio relative to the matrix. The matrix exhibits a large positive Ce-anomaly whereas the ooids have negative Ce-anomaly. The Ce fractionation between the textural components can be explained assuming: (1) Ce oxidation and cerianite precipitation in the uppermost part of the deposits; (2) scavenging of REE from Ce-depleted percolating solutions by the iron oxide, inducing both REE-enrichment and Ce-negative anomalies in ooids; (3) remobilization of cerium as fluoride complex, as a consequence of more acidic conditions in the uppermost part of the deposit, and precipitation of Ce3 as fluorocarbonate mineral toward the carbonate bedrock barrier, at alkaline pH. Alternatively, the cerium remobilization, possibly as a carbonate-fluoride complex, could be due to an Eh decrease, favoured by a rise of the groundwater level. (C) 1997 Elsevier Science B.V

Risk assessment methodology for karst aquifers .2. Solute-transport modeling, 1997, Field Ms,
Ground-water flow and solute-transport simulation modeling are major components of most exposure and risk assessments of contaminated aquifers. Model simulations provide information on the spatial and temporal distributions of contaminants in subsurface media but are difficult to apply to karst aquifers in which conduit flow is important. Ground-water flow and solute transport in karst conduits typically display rapid-flow velocities, turbulent-flow regimes, concentrated pollutant-mass discharge, and exhibit open-channel or closed-conduit how Conventional groundwater models, dependent on the applicability of Darcy's law, are inappropriate when applied to karst aquifers because of the (1) nonapplicability of Darcian-flow parameters, (2) typically nonlaminar flow regime, and (3) inability to locate the karst conduits through which most flow and contaminant transport occurs. Surface-water flow and solute-transport models conditioned on a set of parameters determined empirically from quantitative ground-water tracing studies may be effectively used to render fate-and-transport values of contaminants in karst conduits. Hydraulic-flow and geometric parameters developed in a companion paper were used in the surface-water model, TOXI5, to simulate hypothetical slug and continuous-source releases of ethylbenzene in a karst conduit. TOXI5 simulation results showed considerable improvement for predicted ethylbenzene-transport rates and concentrations over qualitative tracing and analytical ground-water model results. Ethylbenzene concentrations predicted by TOXI5 simulations were evaluated in exposure and risk assessment models

Numerical simulation as a tool for checking the interpretation of karst spring hydrographs, 1997, Eisenlohr L, Kiraly L, Bouzelboudjen M, Rossier Y,
A schematic representation of karst aquifers may be that of a high hydraulic conductivity channel network with kilometre-wide intervals, surrounded by a low hydraulic conductivity fractured limestone volume and connected to a local discharge area, the karst spring, The behaviour of the karst spring (hydrographs, chemical or isotopic composition, etc.) represents the global response of the karst aquifer to input events. The available data an karst aquifer hydraulic parameters are limited, Global response is therefore more easily obtained and is commonly used to make inferences on the recharge and groundwater How processes, as well as on the hydraulic parameter fields. Direct verification of these interpretations is, obviously, very difficult. We have used an indirect method of verification, consisting of introducing well-defined theoretical karst structures into a finite element model and then analysing the simulated global response according to presently accepted interpretation schemes. As we know what we put into the numerical model, the validity of any interpretation may be checked. The first results indicate that some of the generally accepted interpretations are not necessarily true. In particular: (i) separation of simulated recession hydrographs into several components shows that different exponential components do not necessarily correspond to aquifer volumes with different hydraulic conductivities: (ii) non-exponential parts of recession hydrographs do not always give information about the infiltration process: and (iii) the recession coefficient of the baseflow (i.e. the last, nearly exponential part of the recession hydrograph) depends on the global configuration of the whole karst aquifer, not just on the hydraulic properties of the low hydraulic conductivity volumes. (C) 1997 Elsevier Science B.V

Differentiation of flow components in a karst aquifer using the ?I80 signature, 1997, Sauter M.

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