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Enviroscan Ukrainian Institute of Speleology and Karstology

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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 reaction path modeling is a simulation approach to studying the chemical evolution of a (natural) system [22].?

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

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What is Karstbase?



Browse Speleogenesis Issues:

KarstBase a bibliography database in karst and cave science.

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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Search in KarstBase

Your search for correlation (Keyword) returned 209 results for the whole karstbase:
Showing 16 to 30 of 209
The role of the subcutaneous zone in karst hydrology, 1983,
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Williams Paul W. ,
The subcutaneous zone is the upper weathered layer of rock beneath the soil, but above the permanently saturated (phreatic) zone. It is of particular hydrological importance in karst because of its high secondary permeability, arising from the considerable chemical solution in this zone. However, corrosional enlargement of fissures diminishes with depth; thus permeability decreases in the same direction with the result that percolation is inhibited, except down widened master joints and faults. Storage of water consequently occurs in this zone, particularly after storms. The upper surface of this suspended saturated layer in the subcutaneous zone is defined by a perched water table, which slopes towards points of rapid vertical percolation. The potential induces lateral water movement converging on the most permeable areas such as beneath dolines. Leakage from the subcutaneous store sustains slow percolation in the vadose zone. Cross-correlation of rainfall with percolation rates in caves in New Mexico, U.S.A., and New Zealand reveal response lags of 2-14 weeks with no apparent relationship to depth below the surface. Other percolation sites show no correlation with rainfall; interpreted as being a consequence of considerable friction in tight fissure networks. The recognition of storage and rapid as well as very slow percolation from the subcutaneous zone requires re-interpretation of the components of hydrographs from karst springs and of some conceptual models of karst aquifers. The importance of subcutaneous storage in sustaining baseflow discharge at some sites must be recognised, as must the contribution of subcutaneous water to flood hydrographs. Methods of estimating the volumes of subcutaneous and phreatic components of karst-spring flood hydrographs are presented. The paper concludes with a discussion of the significance of subcutaneous hydrologic processes for an understanding of karst geomorphology. The desirability of explaining karst landform evolution in terms of hydrologic processes is stressed

Uranium-Series Ages of Speleothem from Northwest England: Correlation with Quaternary Climate, 1983,
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Gascoyne M, Schwarcz Hp, Ford Dc,
Over 180 $^{230}$Th/$^{234}$U ages have been obtained for 87 speleothems from caves in the Craven district of northwest England. Periods of abundant speleothem growth, 0-13, 90-135 and 170 to > 350 ka, are correlated with interglacial isotope stages 1, 5 and 7-9 respectively. Periods of zero growth, 14-35 and 140-165 ka, are correlated with glacial stages 2 and 6 respectively. A prominent break in growth of one speleothem, dated at about 260 ka, may be correlated with glacial stage 8. Lower-frequency growth from 35 to 90 ka is correlated with stages 3 and 4. The results may also be related to the British Quaternary sequence within the range of $^{14}$C determinations, as follows: 0-13 ka. Flandrian plus late Devensian deglaciation; 14-35 ka, late Devensian glaciation; 35-45 ka. Upton Warren interstadial. Low but finite speleothem abundance during the period 45-90 ka correlates with the early Devensian and is in good agreement with evidence indicating the non-glacial, but tundra-like, climate over this period. The Ipswichian interglacial is broadly related to the abundant growth period 90-135 ka, but is more closely defined by the interval 115-135 ka, from results of dating speleothems enclosing remains of Ipswichian fauna in one cave. By analogy with the zero speleothem abundance during the late Devensian glaciation, the period 140-165 ka may be tentatively correlated with the Wolstonian glaciation. Lack of direct stratigraphic relationships with, or absolute ages of, middle to early Pleistocene stages prevents further correlation of speleothem age data. From the frequency of abundance of speleothem basal ages for the period 0-13 ka, it appears that speleothem growth lags ice recession by up to 4 ka

Morphological clines in reduced areas. The case of Henrotius jordai (Reitter), cave-dwelling beetle from Majorca Island., 1985,
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Bells Xavier
The present paper shows a statistically significant correlation between the geographical latitude and the morphological variation of the pronotum of Henrotius jordai (Reitter) (Col. Caraboidea), cave-dwelling beetle from Majorca island, after studying the linear and curvilinear regression between these two variables. The existence of specimens situated at different heights of the regression lines leads to the conclusion that morphological variation is clinal. The phenomenon of "semi-isolation" to which the studied populations are subjected, because of their cavernicolous character, allows to explain the existence of a cline in such a restricted area as that occupied by this beetle (ca. 500 Km2). It is worth pointing out the interest in the study of these reduced clines of cavernicolous populations, because they can provide a restricted "observation field"; easier to deal with; to investigate these genetic phenomena and their evolutive implications.

Les cavits de la Sierra d'Aralar (Pays Basque espagnol), 1986,
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Ugarte, F. M.
CAVES OF THE SIERRA OF ARALAR (NAVARRA-GUIPUZCOA, SPAIN). CORRELATION BETWEEN UNDERGROUND FORMATIONS AND GEOLOGICAL STRUCTURES - The study of numerous cavities of the Sierra of Aralar permits to give importance to: 1/ the relations between the subterranean morphology and the structural network; 2/ the relations with the actual morphoclimatic conditions of the middle-mountain exokarst; 3/ the part of the heritages of the Quaternary cold-periods. Following important speleological research carried out by the Aranzadi Society of Science (San Sebastian) in the central mountains of the sierra d'Aralar the majority of the PKH (Karst phenomenons) have been located and mapped (PKH = 2,78 km2). As a result of this work, we have attempted to correlate endokarstic landscape with geological structure

Genetic analysis of evolutionary processes, 1987,
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Wilkens Horst
Epigean and cave populations of A. fasciatus (Characidae, Pisces) differ in a series of morphological physiological, and ethological features. The interfertility of these populations made possible a genetic analysis of organs characteristic of interspecific divergence. The study of the regressive organs "eye" and "melanophore system" on the one hand and that of the constructively improved "gustatory equipment and feeding behaviour" on the other yielded identical principles of genetic manifestation: (1) All features have a polygenic basis with an at least di- to hexahybrid inheritance. (2) All polygenes have the same amount of expressivity. (3) After recombination of a minimum number of genes, discontinuous distributions (threshold effects) develop. (4) All features are independently inherited. (5) The genes responsible for a feature are unspecific. In the case of the eye this means that no "lens-" or "retinagenes" are analyzed; due to developmentally physiological interdependence within complex structures, only so-called "eye-genes" have as yet been described. Because of the developmentally physiological interdependence of complex organs, the process of reduction proceeds as a diminution in size, that of constructive evolution as enlargement. In both cases different allometric correlations of the single structures can be found. The convergent reduction of eyes in cave animals is caused by the loss of stabilizing selection which normally keeps the eye in its appropriate adapted form. It is not directional selection pressure, like f. ex. energy economy, but mutation pressure that causes eye reduction. By this, random mutations, which are mostly of deleterious character, are accumulated. The principles of regressive evolution are not restricted to the development of cave species. The absence of stabilizing selection regularly occurs during transitional evolutionary phases. These are f. ex. initial stages of speciation which may be observed when biotopes with little or no interspecific competition are colonized by an invader. Genotypic and phenotypic variability now arise and equilibria become punctuated, because stabilizing selection for a specific ecological niche which has once been acquired by the invading species is no longer acting. Examples include the evolution of species flocks in geologically young lakes or oceanic islands. Rapidly increasing variability now secondarily provides the material for directional selection which radiates such species into vacant niches. Genetic threshold effects as described above may accelerate this process. Variability will finally become lower again under the influence of inter- and intraspecific competition. A new equilibrium is attained.

Climatostratigraphic scheme of the Black Sea pleistocene and its correlation with the oxygen-isotope scale and glacial events, 1988,
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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

The origin and development of Brucker Breakdown and the adjacent area, Mammoth Cave System, Kentucky. Masters Thesis, 1989,
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Blackeagle, Cory W.

The appearance and relationships of Brucker Breakdown and adjacent area, a portion ofthe Mammoth Cave System,implythatcomplex structural and hydrogeological factors affectected and/or controlled passage development. Detailed surveys include geographic, cartographic, lithologic, morphologic, stratigraphic, and paleoflow indicators. The five proposed scenarios were the following. Case 1: All (or most) of the passages were once continuous across the Brucker Breakdown void, which is a subsequent feature. Case Ia: The Brucker Breakdown void is a subsequentfeature whose development caused morphological changes in the pre-existing passages adjacent to it (traditional hypothesis). Case II: The passages converge toward or diverge from the Brucker Breakdown void, which acted as either a source or target of flow and is a primary feature. Case Ila: Several passages converge on the Brucker Breakdown void and fewer components depart from it, indicating that the Brucker Breakdown void is a primary feature and represented a local potentiometric low. Case lIb: Several passages diverge from the Brucker Breakdown void, and fewer components converge on it, indicating that the Brucker Breakdown void is a primary feature and represented a local potentiometric high. Of these, Case lib was found to most closely represent the situation presented by the data.

To perform this study, a detailed procedure was developed that, until this time, had not been established nor outlined in the literature. Once the area of study was chosen and defined, an extremely detailed cartographic and morphologic survey was performed that established both horizontal and vertical data points throughout the area. These data points were tied to existing transit surveys of the surface that linked the subsurface area to U.S. Geological Survey bench marks. The cartographic, geographic, and morphologic data were converted with computer aid to map form. The maps were then field-checked for accuracy. Comprehensive geological mapping surveys were executed. Multiple stratigraphic sections were described and measured in each passage segment, and these were tied to the vertical data points. Correlations were made between sections and were physically traced whenever conditions permitted. Speleothem dating information from prior research was obtained and correlated throughout the study area. Finally, important features and passage morphologies were documented photographically.

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Magnin F. , Guendon J. L. , Vaudour J. , Martin P. ,
In the valleys of southeastern France, below karst massifs, river deposits with travertines show vertical sedimentary sequences always similar, with, from bottom to top: gravels, silts, chalks, travertines s.s. (stromatolitic encrustations with laminated facies), travertinous sand, silts. The study of flora and fauna fossilized by these formations shows a good correlation between the maximum of carbonate deposition (travertinous facies s.s.) and the optimum of vegetation development (forest). And finally, behind calcareous dams edified by travertine, paludal and lacustrine fields are environments developed trapping diversified sediments (clays, peats, silts,...). Then, dam and lake are forming a unit that we can call a 'travertine system'

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Strohmenger C. , Deville Q. , Fookes E. ,
The Upper Jurassic stratigraphy and the facies development of the Dinaric carbonate platform of Slovenia (northwest Yugoslavia) are compared with the Jura carbonate platform of southern Jura (southeast France). The similar facies development between the two platforms during the Kimmeridgian and the Tithonian, as well as a pronounced discontinuity in the same stratigraphical position (controlled by dasycladacean algae and/or ammonites), made it reasonable to correlate the two regions. This discontinuity is marked by a bauxite horizon and a karst breccia in south Slovenia (inner platform), and by a black-pebble conglomerate (inner platform) and a reef breccia (outer platform) in the southern Jura. These features are interpreted as type 1 sequence boundaries related to a global fall of sea level. In southern Jura, biostratigraphical elements situate the sequence boundary between the Eudoxus and the <> ( = Elegans) zones, most probably at the end of the Beckeri ( = Autissiodorensis) zone. Integrating this discontinuity into the eustatic sea level curve proposed by the Exxon group (version 3.1) is difficult because the only suitable sequence boundaries, SB 139 and SB 142, are respectively too young (younger than the <> zone) or too old (older than the Eudoxus zone). We therefore suggest to introduce a new sequence boundary within the upper part of the Beckeri zone which would correspond to a <> sequence boundary SB 140. The investigations further show that Clypeina jurassica FAVRE and Campbelliella striata (CAROZZI) BERNIER most likely appear in the Beckeri zone in the realm of the Jura carbonate platform. The same dasycladacean algae assemblage defines a cenozone identified as <> in Slovenia. It therefore seems possible to correlate the stratigraphic limit between <> and <> of the Dinaric carbonate platform with the beginning of the Beckeri zone

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Pelechaty S. M. , James N. P. , Kerans C. , Grotzinger J. P. ,
A major palaeokarst erosion surface is developed within the middle Proterozoic Elu Basin, northwestern Canada. This palaeokarst is named the sub-Kanuyak unconformity and truncates the Parry Bay Formation, a sequence of shallow-marine dolostones that were deposited within a north-facing carbonate platform under a semi-arid climate. The sub-Kanuyak unconformity exhibits up to 90 m of local relief, and also formed under semi-arid conditions when Parry Bay dolostones were subaerially exposed during a relative sea-level drop of about 180 m. Caves and various karren developed within the meteoric vadose and phreatic zones. Their geometry, size and orientation were largely controlled by northwest- and northeast-trending antecedent joints, bedding, and lithology. Near-surface caves later collapsed forming valleys, and intervening towers or walls, and plains. Minor terra rossa formed on top of highs. Karstification was most pronounced in southern parts of Bathurst Inlet but decreased northward, probably reflecting varying lengths of exposure time along a north-dipping slope. The Kanuyak Formation is up to 65 m thick, and partially covers the underlying palaeokarst. It consists of six lithofacies: (i) breccia formed during collapse of caves, as reworked collapse breccia and regolith; (ii) conglomerate representing gravel-dominated braided-fluvial deposits; (iii) sandstone deposited as braided-fluvial and storm-dominated lacustrine deposits; (iv) interbedded sandstone, siltstone and mudstone of sheet flood origin; (v) dolostones formed from dolocretes and quiet-water lacustrine deposits; and (vi) red-beds representing intertidal-marine mudflat deposits. Rivers flowed toward the northwest and northeast within karst valleys and caves; lakes were also situated within valleys; marine mudflat sediments completely cover the palaeokarst to the north. A regional correlation of the sub-Kanuyak unconformity with the intra-Greenhorn Lakes disconformity within the Coppermine homocline suggests that similar styles of karstification occurred over an extensive region. The Elu Basin palaeokarst, however, was developed more landward, and was exposed for a longer period of time than the Coppermine homocline palaeokarst

Carbonate chemistry of surface waters in a temperate karst region: the southern Yorkshire Dales, UK, 1992,
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Pentecost Allan,
A detailed study of surface water chemistry is described from an important limestone region in northern England. Major ions and pH were determined for 485 sites (springs, seeps, streams, rivers and lakes) during summertime. The saturation state of the waters with respect to calcite was determined as the calcite saturation ratio ([Omega]). An unexpectedly large number of samples were found to be supersaturated (65.5% of the 268 km of watercourses surveyed). As a consequence, several streams entering major cave systems were incapable of further limestone solution, at least during periods of low flow. Many waters were supersaturated from their source and some deposited travertine. A significant negative correlation was found between spring discharge and both ([Omega]) and pH. Supersaturation was caused primarily by atmospheric degassing, with some contribution from aquatic plant photosynthesis.The median total dissolved inorganic carbon and Ca concentrations were 2.49 and 1.35 millimoles 1-1 respectively. Calcium originated exclusively from limestone, and carbon dioxide mainly from the soil and dissolved limestone. South facing catchments provided springwaters with significantly higher levels of TDIC and Ca when compared with north facing catchments. The study suggests that acid rain made a measurable contribution to limestone dissolution.Carboniferous limestone denudation rates were estimated as 54 to 63 m3 km-2 a-1 (54 to 63 mm 1000 years-1). About 50% of the Mg came from limestone and the remainder, together with most K, Na, SO4 and Cl from precipitation.Concentrations of dissolved nutrients were low, medians for NO3, NH4, total PO4 and SiO3 were 24 [mu]mol, 1.4 [mu]mol, 0.64 [mu]mol and 15.5 [mu]mol 1-1 respectively. The concentration of a further 23 trace elements was determined

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Rouchy J. M. , Groessens E. , Laumondais A. ,
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

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Laurila T. , Lattila H. ,
The occurrence of ozone concentrations and exposure indices related to the adverse effects of ozone upon vegetation are reported for four Finnish background stations. In Finland, ozone concentrations are often near the background tropospheric values of cn. 30 ppb. Very high concentrations are not observed. The maximum 1-h average in this data set was 79 ppb. The exposure parameter, which accumulates growing season 1-h average concentrations above a 40 ppb base-line in daylight hours, gave clearly different exposure sums for the stations. These values varied between 4000 and 8500 ppb-h in the southern archipelago, 3000-6500 ppb-h in the southern coastal region, 2000-4000 ppb-h in central parts of the country, and 400-1000 ppb-h in the northern parts of the country. The date of the start of the vegetative season is important in high northern latitudes, because the spring maximum of ozone concentrations is relatively intense compared to the summer maximum. In northern Scandinavia, ozone exposures are particularly sensitive to the date of the start of the growing season. The long daylight period in northern Scandinavia is less important in this respect, since during the growing season ozone concentrations are usually below 40 ppb during the morning and evening hours. A good correlation was found between growing season average concentrations of the sum of gaseous HNO3 and particulate NO3-, and on ozone exposure index which accumulates concentrations above a 40 ppb base-line, confirming the anthropogenic origin of the elevated ozone exposures

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Haynes F. M. , Keslr S. E. ,
This study was undertaken to assess the relation of Mississippi Valley-type mineralization to wall-rock alteration and brecciation in the Mascot-Jefferson City district, the largest part of the East Tennessee Mississippi Valley-type ore field. The main question of interest was whether the Mississippi Valley-type-forming brines created or greatly enlarged the breccia system that hosts the ore or whether the breccia system was a preexisting paleoaquifer that simply controlled movement of the mineralizing brines. A secondary, and closely related, question was whether brine-wall rock interaction deposited Mississippi Valley-type ore. The breccia system that hosts the East Tennessee ore field began as karst breccias which formed in the upper part of the Late Cambrian-Early Ordovician Knox Group during Middle Ordovician emergence. Brecciation, which was most common at the paleosurface and in a limestone-rich zone about 200 m below the surface, took place when limestone solution caused collapse of primary dolostone layers. Mississippi Valley-type mineralization, consisting of sphalerite and sparry dolomite, fills interstices in the breccias that formed in the limestone-rich part of the Knox Group. Ore is associated with ''recrystalline dolomite'' that replaced limestone and there is an inverse correlation between the original limestone and sphalerite abundance suggesting that the ore-forming fluids reacted strongly with limestone wall rock, possibly dissolving it where alteration was most intense. The assessment of a relation between alteration and Mississippi Valley-type mineralization was based on 3,533 surface drill holes covering the 110-km2 Mascot-Jefferson City district, each of which provided stratigraphic data and quantified estimates of mineralization intensity and alteration intensity. These data show clearly that as much as 50 percent of the limestone in the mineralized breccia section was lost over enormous areas that extend far beyond significant mineralization. The intensity of this effect clearly decreases downdip (toward the east), away from the probable source of meteoric karst-forming waters. These relations, combined with isotopic analyses and reaction path calculations, suggest that breccia formation and limestone dissolution took place during the original karst breccia formation. In contrast, later Mississippi Valley-type mineralization was associated with replacement of limestone by recrystalline dolomite. The main effect of dolomitization on the chemistry of the Mississippi Valley-type brines, an increase in their Ca/Mg ratio, would not cause sulfide precipitation. Thus, it appears unlikely that Mississippi Valley-type-forming brines created much of their ore-hosting breccias or that water-rock interaction was a major cause of Mississippi Valley-type ore deposition

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Rovey C. W. ,
Counter to intuition, small-scale measurements of hydraulic conductivity do not average to regional values. Instead, mean hydraulic conductivity increases with measurement scale up to a critical distance termed the range, beyond which a constant regional value prevails. Likewise, variance in log hydraulic conductivity increases with separation distance between measurement points as the spatial correlation decreases. As dissolution proceeds in carbonate aquifers, heterogeneity and the volume necessary for an equivalent homogeneous medium (EHM) both increase. As these variables increase, the range of scale increase in both mean hydraulic conductivity and variance increases proportionately. Consequently, the range in scale effects is a reliable measure of the degree of secondary dissolution. By correlating the numeric value of range with independently measured hydraulic properties, the prevalent type of flow system, diffuse, mixed or conduit can be determined

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