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Enviroscan Ukrainian Institute of Speleology and Karstology


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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 daylight hole is a hole in the roof of a cave, reaching the surface [10].?

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 regression (Keyword) returned 49 results for the whole karstbase:
Showing 16 to 30 of 49
Application and simplification of the SIMERO model for the Vozmediano Spring (Spain), 1996,
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Sanz E. ,
In order to explain the functioning of the Moncayo karst aquifer, the mathematical SIMERO model has been applied to the 21 years of information on the flow of the spring. The results yield the following mean values for the annual water balance: rainfall 714.2 mn; surface runoff 35.6 mm; actual evaporation 404.9 mn; recharge 273.7 mm. With the results of the recharge, the dependencies between it and the rainfall and temperature values have been calculated, obtaining a regression line. The SIMERO model has been simplified in such a way that the flow of the spring in a given month can be calculated by knowing only the precipitation and the temperature of that month and the flow of the previous month

Rillenkarren in the British Isles, 1996,
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Vincent P. ,
This paper presents the first descriptions of rillenkarren in the British Isles. Rillenkarren are widely developed at two 'classic' karst locations, namely: the Burren coast of Co. Clare, Ireland, and the Morecambe Bay area of north west England. Rillenkarren are also found on hard Cretaceous chalks of Northern Ireland and Carboniferous limestones on the Anglesey coast, north Wales. The limestones at all sires are very hard, extremely pure and dolomite poor. A logit regression model is developed, based on published rillenkarren data from the Napier Range, Western Australia. The model suggests that the two rock properties, % calcite in the rock fabric and % calcite in the micrite cement are key variables in explaining the presence of rillenkarren. Within the context of the model, these two explanatory variables define a feasible domain for the development of rillenkarren. British rillenkarren data satisfy the conditions of this model

The Lower Triassic Montney Formation, west-central Alberta, 1997,
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Davies Gr, Moslow Tf, Sherwin Md,
The Lower Triassic Montney Formation was deposited in a west-facing, arcuate extensional basin, designated the Peace River Basin, on the northwestern margin of the Supercontinent Pangea, centred at about 30 degrees N paleolatitude. At least seasonally arid climatic conditions, dominance of northeast trade winds, minimum fluvial influx, offshore coastal upwelling, and north to south longshore sediment transport affected Montney sedimentation. Paleostructure, particularly highs over underlying Upper Devonian Leduc reefs and lows associated with graben trends in the Peace River area, strongly influenced Montney depositional and downslope mass-wasting processes. A wide range of depositional environments in the Montney is recorded by facies ranging from mid to upper shoreface sandstones, to middle and lower shoreface HCS sandstones and coarse siltstones, to finely laminated lower shoreface sand and offshore siltstones. and to turbidites. Dolomitized coquinal facies occur at seven stratigraphic horizons in the Montney. Some coquinas are capped by karst breccias and coarse-grained aeolian deflation lag sand residues indicating subaerial exposure. The Montney has been divided into three informal members that have been dated by palynology and compared with global Early Triassic sequences. The subdivisions are: the Lower member, of Griesbachian to Dienerian age, correlated with a third-order cycle; the Coquinal Dolomite Middle member, of mixed Dienerian and Smithian ages; and the Upper member, of Smithian to Spathian age, correlative with two, shorter-duration third-order cycles. A forced regressive wedge systems tract model is adopted for deposition of the Coquinal Dolomite Middle member and for turbidites in the Valhalla-La Glace area of west-central Alberta. With this model, coquinas and turbidites accumulated during falling base level to lowstand, with a basal surface of forced regression at the base of the coquina and a sequence boundary at the top of the coquinal member. This is supported by the evidence for subaerial exposure and maximum lowstand at the top of the coquina. Very limited grain size distribution in the Montney, dominantly siltstone to very fine-grained sandstone, but often very well sorted, is interpreted to reflect an aeolian influence on sediment source and transport, High detrital feldspar and detrital dolomite in the Montney are consistent with (but not proof of) aeolian source from an arid interior, as is high detrital mica content in finer size grades. Extensive and often pervasive dolomitization, and early anhydrite cementation within the Montney, are also consistent with an arid climatic imprint. As new exploratory drilling continues to reveal the wide range of facies in the Montney, it adds to both the complexity and potential of this relatively unique formation in western Canada

L'halloysite karstique; comparaison des gisements types de Wallonie (Belgique) et du Perigord (France), 1997,
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Perruchot A. , Dupuis C. , Brouard E. , Nicaise D. , Ertus R. ,
Two cryptokarstic (covered karsts) halloysitic deposits were compared: the Entre Sambre et Meuse in Belgium and the Perigord in France. Both belong to a continental margin subject to marine transgression and regression cycles which enhance the karstic activity. This geodynamic context appears to be very favourable to the formation of halloysite. The similarity of the geodynamic context of both sites leads to a genetic convergence linked to specific properties of the cryptokarstic system, especially, the ability to collect the percolating waters and to juxtapose the conditions of precipitation, accumulation and maturation of the halloysite silico-aluminous gel precursors. However, each site also displays pronounced specificities relevant to: the nature of the host rock of the halloysite (a partly silicified limestone in the first, a smectite-kaolinite argilite in the second); the aluminium source (allochthonous in the first, relatively autochthonous in the second); and the halloysite content of the deposits (of approximately 100% in the first, and 40% maximum in the second)

Rapport entre karst et glaciers durant les glaciations dans les valles pralpines du sud des Alpes, 1998,
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Bini Alfredo, Tognini Paola, Zuccoli Luisa
At least 13 glaciations occurred during the last 2.6Ma in the Southern pre_alpine valleys. The glaciers scouring alpine and pre-alpine valleys had all the same feature, being valley temperated glaciers. Their tracks and feeding areas were always the same, just like the petrological contents of their deposits. Contrary to previous assumptions until a few years ago, the origin of these valleys and of the lakes occupying the floor of some of them (Orta, Maggiore, Como, Iseo, Garda Lakes) is due to fluvial erosion related to Messinian marine regression. The valley slopes modelling is Messinian in age, too, while most caves are older. As a general rule, glaciers worked on valley slopes just as a re_modelling agent, while their effects were greater on valley floors. The karstic evolution began as soon as the area was lifted above sea level (upper Oligocene - lower Miocene), in a palaeogeographical environment quite different from the present one, although the main valley floors were already working as a base level. During Messinian age, the excavation of deep canyons along pre-existing valleys caused a dramatic lowering of the base level, followed by a complete re-arrangement of the karstic networks, which got deeper and deeper. The Pliocene marine transgression caused a new re-arrangement, the karst network getting mostly drowned under sea level. During these periods, the climate was hot-wet tropical, characterised by a great amount of water circulating during the wet season. At the same time tectonic upliftings were at work, causing breaking up of the karst networks and a continuous rearrangement of the underground drainage system. In any case, karstic networks were already well developed long before the beginning of Plio-Quaternary glaciations. During glaciations, karst systems in pre-alpine valleys could have been submitted to different drainage conditions, being: a) isolated, without any glacial water flowing; b) flooded, connected to the glacier water-filled zone; c) active, scoured by a stream sinking at glacier sides or in a sub glacial position. The stream could flow to the flooded zone (b), or scour all the unflooded system long down to the resurgence zone, the latter being generally located in a sub glacier position. The glacier/karst system is a very dynamic one: it could get active, flooded or isolated depending on endo- and sub-glacial drainage variations. Furthermore, glaciers show different influences on karstic networks, thus working with a different effect during their advance, fluctuations, covering and recession phases. Many authors believe, or believed, the development of most surface and underground karst in the Alps is due to glaciations, with the last one held to be mostly responsible for this. Whatever the role of glaciers on karstic systems, in pre-alpine valleys caves, we do not have evidence either of development of new caves or of remarkable changes in their features during glaciations. It is of course possible some pits or galleries could have developed during Plio-Quaternary glaciations, but as a general rule glaciers do not seem to have affected karstic systems in the Southern pre-alpine valleys with any remarkable speleogenetic effects: the glaciers effects on them is generally restricted to the transport of great amounts of debris and sediments into caves. The spotting of boulders and pebbles trapped between roof stalactites shows that several phases of in- and out-filling of galleries occurred with no remarkable changing in pre-dating features, including cave decorations. The presence of suspended karst systems does not prove a glacial origin of the valleys, since most of them pre-date any Plio-Quaternary glaciation, as shown by calcite cave deposits older than 1,5Ma. The sediments driven into caves might have caused a partial or total occlusion of most galleries, with a remarkable re-arrangement of the underground drainage system. In caves submitted to periglacial conditions all glaciations long, we can find deposits coming from weathered surface sediments, sharp-edged gelifraction debris and, more rarely, alluvial deposits whose origin is not related to the circulation of the glacial meltwater. In caves lower than or close to the glaciers limit we generally find large amounts of glacier-related deposits, often partly or totally occluding cave galleries. These sediments may be directly related to glaciers, i.e. carried into caves by glacial meltwaters, resulting from surface glacial deposit erosion. They generally show 3 dominant facies: A) lacustrine deposits; B) alluvial deposits and C) debris flow deposits facies. The only way of testing the soundness of the forementioned hypothesis is to study the main characters and spreading of cave sediments, since they are the only real data on connection of glaciers to endokarst networks.

Seasonal Effects on the Geochemical Evolution of the Logsdon River, Mammoth Cave, Kentucky., 1998,
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Anthony, Darlene M. , Ms

The following research describes the collection and evaluation of geochemical data from the Logsdon River, an open-flow conduit that drains a portion of the Turnhole Spring drainage basin within the Mammoth Cave karst aquifer of south-central Kentucky. This spatial survey of nearly 10 km of continuous base-level conduit included seasonal sampling of carbon dioxide partial pressures (PCO2), dissolved ions, and saturation indices for calcite (SIcal). The highest PCO2 are found at the upstream site closest to the Sinkhole Plain recharge area, which creates undersaturated conditions. Rapid outgassing of CO2 into the cave atmosphere creates oversaturated conditions for several thousand meters. This change in chemistry results in the accumulation of travertine in these areas. A boost in PCO2 roughly half-way through the flow path returns the water to slightly undersaturated conditions. The most likely source for additional CO2 is in-cave organic decay, as the boost also occurs during winter months when microbial activity in the soil is at a minimum. A general decline in Ca2+, Mg2+, and HCO3- concentrations occurred over the distance through the Logsdon River conduit. This decline may reflect a diluting of water by localized inputs from the Mammoth Cave Plateau and precipitation of travertine along the flow path. Although values for all parameters are greater in summer than winter, the trend in evolution is similar for both seasonal extremes.
The nature of the transition from summer to winter conditions in the aquifer was investigated by way of an intensive study of the geochemistry at the Logsdon River monitoring well. The relationship between conductivity (spC) and pH was evaluated during both seasons in an attempt to predict the activity of hydrogen for any given water sample, based on continuous spC measurements at the well. Data collected during the 1997-98 seasonal transitions supported a single, nonlinear regression equation that may represent two distinct seasonal regimes.


Pre-Devonian landscape of the Baltic Oil-Shale Basin, NW of the Russian Platform, 1999,
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Puura Vaino, Vaher Rein, Tuuling Igor,
The erosional relief of Ordovician and Silurian deposits in Estonia was developed during the continental period in late Silurian and early-middle Devonian times. The uplift of the area and marine regression were induced by compressional tectonics in the continental interior related to the closure of the Iapetus and Tornqvist Oceans. In the northern part of the Baltic sedimentary basin (Estonia), on the gentle southerly dipping slope between the Fennoscandian Shield (Finland) and Baltic Syneclise (Latvia), a pre-Devonian, slightly rugged erosional relief with few cuesta was developed. The pre-Devonian erosional landforms -- hills, depressions and escarpments reaching 150 m in height -- were probably buried under the Devonian deposits and then partly re-exposed by pre-Quaternary erosion. These landforms are described in detail using data from several thousands of cores drilled in the course of oil-shale and phosphorite exploration and mining

Evaluation of terra rossa geochemical baselines from Croatian karst regions, 1999,
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Miko S. , Durn G. , Prohic E. ,
In karst regions of Croatia, regolith is the only favourable medium for geochemical mapping. Mediterranean climate and good drainage due to hard, fissured, permeable limestones and dolomites result in a spacious distribution of terra rossa (FAO-luvisols and cambisols) - a polygenetic type of soil. Samples of terra rossa from coastal and inland Croatian Dinaric karst terrains were collected during the initial studies for the Geochemical Map of Croatia at a density of 1 site/25 km(2). A total of 87 terra rossa soil samples taken from a depth of 5-25 cm together with 27 samples from deeper profiles (down to 850 cm) were analysed for total Al, Ba, Ca, Co, Cr, Cu, Fe, Ga, La, Mg, Mn, Ni, Pb, Na, Sr, Ti, V and Zn concentrations. A stoichiometric approach was applied by modeling of terra rossa baselines on the basis of Linear regressions of metals on Al and the calculation of enrichment factors (EF and CEFs) on the basis of soil standards. A noticeable enrichment of Pb was found in surface samples compared to the terra rossa deeper in the soil profile. Using these baseline relationships, an attempt is made to partition terra rossa metal concentrations into natural and anthropogenic fractions. Also, the models from both polluted and less polluted (uninhabited) karstic terrains improve the comparability of element contents through correction of variable background concentrations. A comparison of elemental concentrations revealed that due to contributions of bauxite debris, a number of studied samples is enriched in Cr and Ni (also with variable amounts of boehmite). The corrections will serve to reduce data variability and to increase the detection of spatial and temporal differences presented on the geochemical maps. (C) 1999 Elsevier Science B.V. All rights reserved

Infiltration measured by the drip of stalactites, 2000,
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Sanz E. , Lopez J. J. ,
The hydrodynamic processes and mechanisms involved in rain infiltration and recharge in local areas of karst terrain can be identified and quantified by using measurements of the seepage of cave stalactites, Detailed measurements of the seepage of stalactites in seven caves located in an area close to the land surface, or the subcutaneous area of the karst, show a diversity of complex factors involved in infiltration: type of precipitation (rain or snow), air temperature, soil type and thickness, etc., which give rise to larger or smaller variations of flow in the espeleothem hydrographs, In some cases, no explanation can be found for the response of stalactites to rainfall, while in others there is a relationship between outer atmospheric parameters and the recharge represented by the stalactite drip. Romperopas Cave (Spain) has both a rapid and a basic flow, with hydrograph recessions similar to those observed in other caves. Water seepage in this cave varies greatly both in space and in time. The infiltration in Altamira Cave (Spain) was calculated and a multiple regression was found between infiltration, rain and outside air temperature. In other cases, the balance of the water on the soil is responsible for the seepage, Thus, a precipitation runoff numerical model that simulated the stalactite hydrographs could be applied to the Baradla and Beke Caves (Hungary), The complex properties of the ground, which are required for other flow numerical models for the unsaturated zone, were not taken into consideration

A Mathematical Model of Air Temperature in Mammoth Cave, Kentucky, 2001,
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Jernigan, J. W. , Swift, R. J.
Alterations made to the Natural (Historic) Entrance into Mammoth Cave over the past two centuries have resulted in disrupted atmospheric conditions in the Historic Section of Mammoth Cave. In an effort to understand atmospheric phenomena in this section of the cave, Division of Science and Resources Management personnel at Mammoth Cave National Park collected atmospheric data from various sites throughout the Historic Section of Mammoth Cave. These data are used to construct a mathematical model that predicts air temperature at various sites within the cave system. First, an approximate mathematical model is constructed that could apply to any cave system with characteristics (such as cave geometry and the natural force driving airflow) similar to those in Mammoth Cave. Then, the regression analysis of atmospheric data and the use of the derived model allow the construction of a mathematical model that is specific to the Historic Section of Mammoth Cave.

Les travertins de Saint-Antonin : squence gobotanique et climato-anthropique holocne (Bouches-du-Rhne, France), 2003,
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Guendon Jeanlouis, Ali Adam A. , Roiron Paul, Terral Jeanfrdric, Danna Andr, Diazdelolmo Fernando, Baenaescudero Rafael
Travertine deposit of St-Antonin (Bouches-du-Rhne, France): lithostratigraphy, palaeobotany and Holocene palaeoenvironments - Travertines are carbonate deposits formed generally during temperate climatic periods. The travertine of Saint-Antonin was formed during the Holocene in accordance with this model. They usually present a succession of travertinous units and detrital sedimentary levels containing, respectively, leaf impressions and charcoal; snail shells and archaeological material have also been preserved, essentially in detritial levels. Two kinds of plant remains (leaf imprints and charred wood) have been sampled and analysed, allowing the reconstruction of vegetation dynamics based on a well-defined sedimentary sequence. Our results were compared with those of previous malacalogical, archaeological studies and climatic changes. The Preboreal and Boreal sequence, characterised by travertine unites with detritial deposits, is dominated by a riverside vegetation (Populus alba, Salix sp., Phragmites communis) associated with some pubescent oak growing in the plateau. After this first period, detritial levels and hygrophilous species decrease. Correlatively travertinous facies and leaf impressions of mesophilous forest species increase (Quercus pubescent, Acer monspessulanum). They suggest the existence of homeostatic conditions, such as regular river flow, dense vegetation and few disturbances during deposition. The Middle Atlantic period shows optimal travertinisation and maintenance of forest environment. But this period is characterised by the beginning of the Quercus pubescens regression and the dominance of Acer monspessulanum. From the Atlantic to the first part of Subboreal, important detrital sedimentary levels disturb the deposition of carbonate. They contain reworked archaeological material dating to the Neolithic. Vegetation seems to have been profoundly affected by intensive human exploitation. This process has broken up the forested area into different plant communities and favoured the dominance of heliophilous and thermophilous species (Pinus halepensis, Rubus ulmifolius and Juniperus sp.).

Vitesse de recul dun escarpement lapiaz (Ile Diego de Almagro, Patagonie, Chili),, 2003,
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Veress Mrton, Toth Gbor, Zentai Zoltn, Czpek Istvn
Backward rate of a marble side slope (Island Diego de Almagro, Chilean Patagonia) - Our research group measured the dissolution caused regressive velocity of the marbles side slope on one of the marble stripes on the island of Diego de Almagro. Using the time of ice melting and the width of rim bordering the edge of the sidewall the velocity of regression is 0,4-0,5 mm per year. This velocity of regression exceeds with an order of magnitude the velocity of denudation caused by dissolution on marble surface. Due to this fact, the marble stripes of the island become narrower to a bigger degree than they become shorter.

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

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


Comparison of immunofluorescence assay and immunomagnetic electrochemiluminescence in detection of Cryptosporidium parvum oocysts in karst water samples, 2003,
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Kuczynska E. , Boyer D. G. , Shelton D. R. ,
Immunofluorescence assay (IFA) and immunomagneticelectrochemiluminescence (IM-ECL) were used for comparison of the percent recovery of Cryptosporidium parvum in environmental water samples obtained from a spring draining a karst basin. The monoclonal antibodies to C. parvum, isotype IgG3 were used for optimization of the IM-ECL protocol. The combination of biotinylated and TAG-labeled anti-C. parvum antibodies with the streptavidin beads gave a linear regression slope for log ECL vs. log fresh oocysts of 0.79 (from 5 to 5000 oocysts), which indicates a constant ECL signal per oocyst. Standard curves gave a dynamic range of 5 to 5000 oocysts/ml (fresh) and 10 to 100,000 cells/ml (4-month-old oocysts) with the maximum limit of linear detection higher than 100,000. The linear slope of 4-month-old oocysts decreased to 0.62, which indicates that ECL signal is a function of oocyst age. The experiment associated with bead storage time shows that even after 4 months of storage of the biotinylated antibodies, the complex retains the ability for binding the oocysts and generating the ECL signal. Based on the IFA results in the experiment evaluating different protocols for oocysts recovery from karst water samples, the most efficient protocol involved dispersion, followed by flotation and immunomagnetic separation (IMS) (24% recovery). The ECL results obtained in that experiment were very similar to the results obtained in the IFA method, which indicates that the IM-ECL method is accurate. Results of the IFA in the study of the prevalence of C. parvum in the groundwater showed that oocysts were present in 78% of 1 L water samples with average number of oocysts of 6.4 5.5 and ranged from 0 (13 samples) to 23.3 (2 samples). The ECL signal generated from these water samples ranged from 3771 to 622 (average 1620 465). However, the background value estimated in groundwater samples with low number of oocysts detected by IFA was highly variable and elevated (from 3702 to 272, average 1503 475). The background value as a result of nonspecific binding to beads by unidentified organic components in the water can inhibit or even completely mask the signal generated by oocysts. Our investigations showed that the IM-ECL method appears to be promising for the qualitative and quantitative detection of C parvum from the environmental water; however, the method requires further development to improve sensitivity and account for background signals. Published by Elsevier Science B.V

Post-Miocene stratigraphy and depositional environments of valley-fill sequences at the mouth of Tampa Bay, Florida, 2003,
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Ferguson Tw, Davis Ra,
Post-Miocene sea-level low stands allowed rivers and karst processes to incise the exposed carbonate platform along the Gulf Coast of Florida. Few Miocene to mid-Pleistocene deposits survived erosion along the present coast except within incised valleys. Since their formation, these valleys have been filled and incised multiple times in response to sea-level changes. The thick sedimentary sequences underlying the mouth of Tampa Bay have been recorded as a range of depositional environments and multiple sea-level incursions and excursions during pre-Holocene time and subsequent to the accumulation of the Miocene carbonate sequences. Sediment analysis of cores collected from a north-south transect across the mouth of Tampa Bay has enabled the identification of lithofacies, ranging from well-sorted, quartz sand to dense, fossiliferous, phosphatic grainstone. These facies were deposited in freshwater, estuarine, and shallow, open marine environments. As a result of channel development and migration within the paleovalley, and cut-and-fill associated with individual transgressions and regressions, correlation of the lithofacies does not extend across the entire transect. Fining-upward sequences truncated by tidal ravinement surfaces that extend throughout the paleovalley can, however, be identified. Age determinations based on 14-C analysis, amino-acid racemization, and strontium isotope analysis dating of numerous samples yield ages of Miocene, Pliocene, early Pleistocene, and late Pleistocene, as well as Holocene for sequences that accumulated and were preserved in this valley-fill complex. Numerous inconsistencies in the stratigraphic organization of the age determinations indicate that there are bad dates, considerable reworking of shells that were dated, or both. For this reason as well as the lack of detailed correlation among the three relatively complete cores, it is not possible to place these strata in a sequence stratigraphic framework. (C) 2003 Elsevier B.V. All rights reserved

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