MWH Global

Enviroscan Ukrainian Institute of Speleology and Karstology


Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/template/toolbar_left.php on line 5
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 pisanite is a cave mineral - (fe,cu)so4.7h2o [11].?

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


Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/template/toolbar_right.php on line 7
What is Karstbase?

Search KARSTBASE:

keyword
author

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;
See all featured articles from other geoscience journals

Search in KarstBase

Your search for units (Keyword) returned 164 results for the whole karstbase:
Showing 151 to 164 of 164
Biodiversity and conservation of subterranean fauna of Portuguese karst. Ph.D. thesis, 2012,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Ana Sofia P. S. Reboleira

This research is a contribution to the study of subterranean biodiversity in karst areas of Portugal, towards its conservation.

The relative inaccessibility of the subterranean environment is a challenge for the study of its fauna, often accessible only in caves but more widely distributed. The subterranean animals are among the most rare, threatened and worldwide underprotected, often by the simple fact of being unknown.

Karst areas of Portugal occupy a considerable part of the territory and harbor more than 2000 caves. The complex biogeographical history of the Iberian Peninsula allowed the survival of several relict arthropod refugees in the subterranean environment.

Subterranean invertebrates have been ignored, as for as the protection of karst systems are concerned in Portugal, largely because knowledge was scarce and disorganized. Reviewing all the bibliographic sources about subterranean fauna from Portugal and listing troglobiont and stygobiont species and locations, was essential to understand the state of knowledge of species richness and the biogeography and conservation status for the studied areas.

In order to understand subterranean biodiversity patterns in karst areas from Portugal, one year of intense fieldwork was performed in more than 40 caves from 14 karst units. Several new species for science were discovered and 7 taxa comprising 2 new genera and 5 new species were described.

Bearing in mind that spatial distribution of subterranean species is crucial to ecological research and conservation, the distribution of hypogean species, from Portuguese karst areas, was mapped using geographic information systems. Also, its subterranean richness was compared with other areas of the world and missing species were estimated on a regional scale. The subterranean biodiversity patterns were analyzed, and several factors were tested to explain richness patterns. Evapotranspiration and the consequent high productivity on the surface may be determinant in the species richness in the different karst units of Portugal, but the depth of the caves and the unique geological features of every massif seemed to play a more important role.

In order to evaluate the tolerance of organisms to groundwater contamination, the acute toxicity of two substances were tested on stygobiont crustaceans with different degrees of troglomorphism. Our study showed that the high levels of endemism contribute to remarkably different toxicological responses within the same genus.

The major problems related to conservation of subterranean habitats were associated to direct destruction and their contamination. These ecosystems lack of specific protection, implying an adequate management of surface habitats and the establishment of priority areas. Integrating all the previous information, this study establishes a ranking of sites for conservation of subterranean fauna in karst areas of Portugal.This research is a contribution to the study of subterranean biodiversity in karst areas of Portugal, towards its conservation.

The relative inaccessibility of the subterranean environment is a challenge for the study of its fauna, often accessible only in caves but more widely distributed. The subterranean animals are among the most rare, threatened and worldwide underprotected, often by the simple fact of being unknown.

Karst areas of Portugal occupy a considerable part of the territory and harbor more than 2000 caves. The complex biogeographical history of the Iberian Peninsula allowed the survival of several relict arthropod refugees in the subterranean environment.

Subterranean invertebrates have been ignored, as for as the protection of karst systems are concerned in Portugal, largely because knowledge was scarce and disorganized. Reviewing all the bibliographic sources about subterranean fauna from Portugal and listing troglobiont and stygobiont species and locations, was essential to understand the state of knowledge of species richness and the biogeography and conservation status for the studied areas.

In order to understand subterranean biodiversity patterns in karst areas from Portugal, one year of intense fieldwork was performed in more than 40 caves from 14 karst units. Several new species for science were discovered and 7 taxa comprising 2 new genera and 5 new species were described.

Bearing in mind that spatial distribution of subterranean species is crucial to ecological research and conservation, the distribution of hypogean species, from Portuguese karst areas, was mapped using geographic information systems. Also, its subterranean richness was compared with other areas of the world and missing species were estimated on a regional scale. The subterranean biodiversity patterns were analyzed, and several factors were tested to explain richness patterns. Evapotranspiration and the consequent high productivity on the surface may be determinant in the species richness in the different karst units of Portugal, but the depth of the caves and the unique geological features of every massif seemed to play a more important role.

In order to evaluate the tolerance of organisms to groundwater contamination, the acute toxicity of two substances were tested on stygobiont crustaceans with different degrees of troglomorphism. Our study showed that the high levels of endemism contribute to remarkably different toxicological responses within the same genus.

The major problems related to conservation of subterranean habitats were associated to direct destruction and their contamination. These ecosystems lack of specific protection, implying an adequate management of surface habitats and the establishment of priority areas. Integrating all the previous information, this study establishes a ranking of sites for conservation of subterranean fauna in karst areas of Portugal.


Hydrogeology of the Gokpinar karst springs, Sivas, Turkey , 2012,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Kaaroğ, Lu Fikret

Gökpınar karst springs are located 8 km to the south of the Gürün district centre, Sivas, Turkey. The springs have two main outlets (Gökpınar-1 and Gökpınar-2) and outflow from Jurassic-Cretaceous Yüceyurt formation (limestone). The total discharge of the springs ranges between 4.5 and 7.8 m3/s.The study area is formed of allocthonous and autocthonous lithological units whose ages range from Upper Devonian to Quaternary. These lithologies are mostly formed of limestones. Yüceyurt formation (limestone), from which Gökpınar karst springs outflow, constitute the main aquifer in the study area and is karstified. The unit has a well developed karst system comprising karren, dolines, ponors, underground channels and caves. The recession (discharge) analysis of the Gökpınar springs was carried out and the storage capacitiesand discharge (recession) coefficients of the Gökpınar-1 and Gökpınar-2 springs were calculated as 141×10^6 m3 and 98×10^6 m3, and 2.71×10^-3 day-1 and 2.98×10^-3 day-1, respectively. The storage capacities and discharge (recession) coefficients obtained suggest that the karst aquifer (Yüceyurt limestone) has large storage capacity, and drainage occurs very slow. The major cations in the study area waters are Ca2+ and Mg2+, and anion is HCO3-. The waters are calcium bicarbonate type. Some of the water chemistry parameters of the Gökpınar springs range as follows: T=10.8–11.1°C, pH=7.65–7.95,EC=270–310 μS/cm, TDS=170–200 mg/L, Ca2+=40.0–54.0 mg/L,Mg2+=4.5–10.0 mg/L, HCO3-=144.0–158.0 mg/L. Temperature, EC, TDS, and Ca2+ and HCO3- concentrations of the Gökpınar springs did not show significant variations during the study period.


Hypogene Speleogenesis, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Klimchouk, A. B.

Recognition of the wide occurrence, significance, and specific characteristics of hypogene speleogenesis during last twodecades signifies a major paradigm shift in karst science, previously overwhelmingly dominated by epigene concepts and models. Hypogene karst is one of the fundamental categories of karst, at least of equal importance with more familiar epigenic karst. Hypogene and epigenic karst systems are regularly associated with different types, patterns, and segments off low systems, which are characterized by distinct hydrokinetic, chemical, and thermal conditions. Hypogene speleogenesis is the formation of solution-enlarged permeability structures by water that recharges thecavernous zone from below, independent of recharge from the overlying or immediately adjacent surface. It develops mainly in leaky confined conditions, although it may continue through unconfined ones. Hydraulic communication along cross-formational flow paths, across lithological boundaries, different porosity systems, and flow regimes allows deeper ground waters in regional or intermediate flow systems to interact with shallower and more local systems, permittinga variety of dissolution mechanisms to operate. A specific hydrogeologic mechanism acting in hypogenic transverse speleogenesis (restricted input/output) suppresses the positive flow-dissolution feedback and speleogenetic competition seen in the epigenic development. Hypogenic caves occur in different soluble rocks in a wide range of geological and tectonic settings, basinal throughorogenic. Overall patterns of cave systems are strongly guided by the spatial distribution of the initial (prespeleogenetic) permeability features and hydrostratigraphic barriers and interfaces within the soluble and adjacent units, by the mode of water input to, and output from, cave-forming zones and by the overall recharge–discharge configuration in the multiple aquifer system. Because of their transverse nature, hypogene caves have a clustered distribution in plan view, althoughinitial clusters may merge laterally across considerable areas. Hypogene caves display remarkable similarity in their pattern sand mesomorphology, strongly suggesting that the type of flow system is the primary control. The rapidly evolving understanding of hypogene speleogenesis has broad implications for many applied fields such asprospecting and characterization of hydrocarbon reservoirs, groundwater management, geological engineering, and mineral resources industries


Temporal Variability of cave-Air CO2 in Central Texas, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Cowan B. D. , Osborne M. C. , Banner J. L.

 

The growth rate and composition of cave calcite deposits (speleothems) are often used as proxies for past environmental change. There is, however, the potential for bias in the speleothem record due to seasonal fluctuations in calcite growth and dripwater chemistry. It has been proposed that the growth rate of speleothem calcite in Texas caves varies seasonally in response to density-driven fluctuations in cave-air CO2, with lower growth rates in the warmer months when cave-air CO2 is highest. We monitored CO2 in three undeveloped caves and three tourist caves spread over 130 km in central Texas to determine whether seasonal CO2 fluctuations are confined to tourist caves, which have been modified from their natural states, and the extent to which cave-air CO2 is controlled by variations in cave geometry, host rocks, cave volume, and soils. Nearly 150 lateral transects into six caves over three years show that CO2 concentrations vary seasonally in five of the caves monitored, with peak concentrations in the warmer months and lower concentrations in the cooler months. The caves occur in six stratigraphic units of lower Cretaceous marine platform carbonate rocks and vary in volume (from 100 to .100,000 m3) and geometry. Seasonal CO2 fluctuations are regional in extent and unlikely due to human activity. Seasonal fluctuations are independent of cave geometry, volume, depth, soil thickness, and the hosting stratigraphic unit. Our findings indicate that seasonal variations in calcite deposition may introduce bias in the speleothem record, and should be considered when reconstructing paleoclimate using speleothem proxies.


Hydrogeology of gypsum Formations in Iran, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Raeisi E. , Zare M. , Aghdam J. A.

The gypsum formations in Iran are mainly Upper Red (URF), Gachsaran (GF), and Sachun. The GF is divided into salt (SGF) and its non-salt equivalents (NSGF). The conductivity of the spring’s water in Sachun, URF and NSGF is below 3500 mS cm21, but the conductivity of the SGF varies from 2400 to 400,000 mS cm21. Three different sites, Tangsorkh (NSGF), Ambal and Salbiz (SGF), were selected for further studies. The Tangsorkh area is composed of alternating units of marlstone and gypsum. The hydraulic connections between these units are broken by the marls and no sub-aquifer is developed in the gypsum units due to their small catchment area and lack of karst development. The Ambal area, adjacent to the large Karun River, consists of units of marl, anhydrite, and halite. Sinkholes cover all parts of the area. Contact of Karun River with the Amble ridge causes the chemistry of the river to evolve from bicarbonate type to chloride type. The presence of the Karun River inside this ridge formed a network of karstic conduits and sinkholes, which causes the marly layers to collapse such that the Ambal area cannot be considered to have several independent subaquifers. The Salbiz site is composed of alternating units of marl-marlstone and gypsum without any sinkholes or exposed salt layers. It consists of independent sub-aquifers with general flow directions parallel to the strike. The study indicates that the GF is mainly composed of small independent sub-aquifers due to its alternative marl or marlstone layers, resulting water flows parallel to the strike, except in the SGF under specific conditions.


The Grosmont: the worlds largest unconventional oil reservoir hosted in polyphase-polygenetic karst, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Machel Hans G. , Borrero Mary Luz, Dembicki Eugene, Huebscher Harald4

The Upper Devonian Grosmont platform in Alberta, Canada, is the world’s largest heavy oil reservoir hosted in carbonates, with 400-500 billion barrels of IOIP at an average depth of about 250 – 400 m. Advanced thermal recovery technologies, such as SAGD and electrical in-situ retorting, much higher world market prices for oil and certain political pressures have led to a flurry of activity in the Grosmont since 2006.
The sedimentary stratigraphy of the Grosmont reservoir consists of six stacked car-bonate units interbedded with marls and some evaporites. The latter two originally acted as aquitards during diagenesis but are breached or missing in parts of the area today. Dolomitization by density-driven reflux was the first pervasive diagenetic pro-cess. A dense fracture network was created in three or four phases. Most fractures probably originated from collapse following subsurface salt dissolution and/or from Laramide tectonics far to the west, whereby pulsed crustal loading in the fold-and-thrust belt created a dynamic forebulge in the Grosmont region via multiple pulses of basin-wide crustal flexing, each followed by relaxation. The fracture network probably was reactivated and/or expanded by glacial loading and post-glacial isostatic rebound in the Pleistocene and Holocene, respectively.
The region experienced three or four prolonged periods of epigene karstification, alt-hough there is tangible evidence for only two of them in the Grosmont platform. The first of these episodes was a ‘warm epigene karstification’ during the Jurassic - Creta-ceous, and the second was/is a ‘cold epigene karstification’ that started sometime in the Cenozoic and is continuing to this day. In addition, there is circumstantial evidence for hypogene ‘karstification’ (= dissolution) throughout much of the geologic history of the Grosmont since the Late Devonian. Karstification was accompanied and/or by fol-lowed by extensive hydrocarbon biodegradation.


Investigating Groundwater Flow Between Edwards and Trinity Aquifers in Central Texas, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Wong C. I. , Kromann J. S. , Hunt B. B. , Smith B. A. , Banner J. L.

Understanding the nature of communication between aquifers can be challenging when using traditional physical and geochemical groundwater sampling approaches. This study uses two multiport wells completed within Edwards and Trinity aquifers in central Texas to determine the degree of groundwater inter-flow between adjacent aquifers. Potentiometric surfaces, hydraulic conductivities, and groundwater major ion concentrations and Sr isotope values were measured from multiple zones within three hydrostratigraphic units (Edwards and Upper and Middle Trinity aquifers). Physical and geochemical data from the multiport wells were combined with historical measurements of groundwater levels and geochemical compositions from the region to characterize groundwater flow and identify controls on the geochemical compositions of the Edwards and Trinity aquifers. Our results suggest that vertical groundwater flow between Edwards and Middle Trinity aquifers is likely limited by low permeability, evaporite-rich units within the Upper and Middle Trinity. Potentiometric surface levels in both aquifers vary with changes in wet vs. dry conditions, indicating that recharge to both aquifers occurs through distinct recharge areas. Geochemical compositions in the Edwards, Upper, and Middle Trinity aquifers are distinct and likely reflect groundwater interaction with different lithologies (e.g., carbonates, evaporites, and siliceous sediments) as opposed to mixing of groundwater between the aquifers. These results have implications for the management of these aquifers as they indicate that, under current conditions, pumping of either aquifer will likely not induce vertical cross-formational flow between the aquifers. Inter-flow between the Trinity and the Edwards aquifers, however, should be reevaluated as pumping patterns and hydrogeologic conditions change.


Deep 3D thermal modelling for the city of Berlin (Germany), 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Sippel Judith, Fuchs Sven, Cacace Mauro, Braatz Anna, Kastner Oliver, Huenges Ernst, Scheckwenderoth Magdalena

This study predicts the subsurface temperature distribution of Germany’s capital Berlin. For this purpose, a data-based lithosphere-scale 3D structural model is developed incorporating 21 individual geological units. This model shows a horizontal grid resolution of (500 9 500) m and provides the geometric base for two different approaches of 3D thermal simulations: (1) calculations of the steadystate purely conductive thermal field and (2) simulations of coupled fluid flow and heat transport. The results point out fundamentally different structural and thermal configurations for potential geothermal target units. The top of the Triassic Middle Buntsandstein strongly varies in depth (159–2,470 m below sea level) and predicted temperatures (15–95 _C), mostly because of the complex geometry of the underlying Permian Zechstein salt. The top of the sub-salt Sedimentary Rotliegend is rather flat (2,890–3,785 m below sea level) and reveals temperatures of 85–139 _C. The predicted 70 _C-isotherm is located at depths of about 1,500–2,200 m, cutting the Middle Buntsandstein over large parts of Berlin. The 110 _C-isotherm at 2,900–3,700 m depth widely crosscuts the Sedimentary Rotliegend. Groundwater flow results in subsurface cooling the extent of which is strongly controlled by the geometry and the distribution of the Tertiary Rupelian Clay. The cooling effect is strongest where this clay-rich aquitard is thinnest or missing, thus facilitating deep-reaching forced convective flow. The differences between the purely conductive and coupled models highlight the need for investigations of the complex interrelation of flow- and thermal fields to properly predict temperatures in sedimentary systems.


Deep 3D thermal modelling for the city of Berlin (Germany), 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Sippel Judith, Fuchs Sven, Cacace Mauro, Braatz Anna, Kastner Oliver, Huenges Ernst, Scheckwenderoth Magdalena

This study predicts the subsurface temperature distribution of Germany’s capital Berlin. For this purpose, a data-based lithosphere-scale 3D structural model is developed incorporating 21 individual geological units. This model shows a horizontal grid resolution of (500 9 500) m and provides the geometric base for two different approaches of 3D thermal simulations: (1) calculations of the steady state purely conductive thermal field and (2) simulations of coupled fluid flow and heat transport. The results point out fundamentally different structural and thermal configurations for potential geothermal target units. The top of the Triassic Middle Buntsandstein strongly varies in depth (159–2,470 m below sea level) and predicted temperatures (15–95 _C), mostly because of the complex geometry of the underlying Permian Zechstein salt. The top of the sub-salt Sedimentary Rotliegend is rather flat (2,890–3,785 m below sea level) and reveals temperatures of 85–139 _C. The predicted 70 _C-isotherm is located at depths of about 1,500–2,200 m, cutting the Middle Buntsandstein over large parts of Berlin. The 110 _C-isotherm at 2,900–3,700 m depth widely crosscuts the Sedimentary Rotliegend. Groundwater flow results in subsurface cooling the extent of which is strongly controlled by the geometry and the distribution of the Tertiary Rupelian Clay. The cooling effect is strongest where this clay-rich aquitard is thinnest or missing, thus facilitating deep-reaching forced convective flow. The differences between the purely conductive and coupled models highlight the need for investigations of the complex interrelation of flow- and thermal fields to properly predict temperatures in sedimentary systems.


SALT KARST AND COLLAPSE STRUCTURES IN THE ANADARKO BASIN OF OKLAHOMA AND TEXAS, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Johnson, K. S.

Permian bedded salt is widespread in the Anadarko Basin of western Oklahoma and the Texas Panhandle, where partial or total dissolution of the shallowest salt in some areas has resulted in subsidence and/or collapse of overlying strata. Groundwater has locally dissolved these salts at depths of 10–250 m. The distribution (presence or absence) of salt-bearing units, typically 80–150 m thick, is confirmed by interpretation of geophysical logs of many petroleum tests and a few scattered cores. Salt dissolution by ground water is referred to as “salt karst.”Chaotic structures, collapse features, breccia pipes, and other evidence of disturbed bedding are present in Permian, Cretaceous, and Tertiary strata that overly areas of salt karst. The dip of Permian and post-Permian strata in the region normally is less than one degree, mainly towards the axis of the Anadarko Basin. Where strata locally dip in various directions at angles of 5–25 degrees or more, and underlying salt units show clear evidence of dissolution, these chaotic dips must result (mostly, if not totally) from subsidence and collapse into underlying salt-dissolution cavities.Gypsum karst and resultant collapse of overlying strata have been proposed in many parts of the Anadarko Basin. However, the gypsum beds typically are only 1–6 m thick and more than 100 m deep, and cannot contribute to disruption of outcropping strata—except where they are within 10–20 m of the surface.Typical areas of disturbed bedding comprise several hectares, or more, with outcrops of moderately dipping strata—as though large blocks of rock have foundered and subsided into large underground cavities. Other examples of disturbed bedding are small-diameter breccia pipes, or chimneys, that extend vertically up from salt-karst cavities, through several hundred meters of overlying strata. The best evidence of these chimneys are collapsed blocks of Cretaceous strata, chaotically dropped some 50 m, or more, that are now juxtaposed against various Permian formations on the north flank of the Anadarko Basin. Any study of surface or shallow-subsurface geology in the Anadarko Basin must consider the influence of subsurface salt karst on the structure and distribution of overlying rocks


GYPSUM KARST CAUSES RELOCATION OF PROPOSED CEDAR RIDGE DAM, THROCKMORTON COUNTY, TEXAS, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Johnson K. S. , Wilkerson J. M.

Cedar Ridge Dam and Reservoir will be built to supply water for the city of Abilene, Texas. The original damsite (CR) was to be located on Clear Fork of Brazos River in Throckmorton County, but initial coring of the damsite encountered unsuspected gypsum beds in the Permian-age Jagger Bend/Valera Formation. Gypsum is a highly soluble rock that typically contains karst features, and its presence in a dam foundation or impoundment area could allow water to escape from the reservoir. A decision was made to look at potential sites farther upstream (to the southwest), where west-dipping gypsum beds would be deeper underground and karst problems would be minimized or eliminated.The first phase of the relocation was a comprehensive field study of Clear Fork Valley, upstream of the original damsite, to identify gypsum outcrops; gypsum was exposed at only one location, just above damsite CR. The second phase of the study was examination of nearly 100 petroleum-test geophysical logs to identify, correlate, and map the subsurface gypsum and associated rock layers upstream of the original damsite. The gypsiferous sequence is 30–45 m thick, and consists of 8 gypsum beds, mostly 1–3 m thick, interbedded with red-brown and gray shale units 1–10 m thick. Gypsum beds comprise 25–30% of the gypsiferous sequence. Gypsum beds dip uniformly to the west at about 7 m/km (about 0.4 degrees), and thus the uppermost gypsum is at least 23 m beneath the newly proposed damsite (A), about 8 km to the southwest.Subsequent coring and other studies of the new damsite A confirm that gypsum beds are 23 m beneath the newly proposed dam. There is no evidence of solution channels or other karst features beneath this site, and thus there is little likelihood of water loss from the reservoir at the new site due to gypsum karst.


LANDFORMS OF MOUNTAINOUS KARST IN THE MIDDLE LATITUDES: REFLECTIONS, TRENDSAND RESEARCH PROBLEMS, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Sauro Ugo

Karstification of Dolomitic Hills at south of Coimbra (western-central Portugal) - Depositional facies and stratigraphic controls of the (palaeo)karst affecting the Coimbra Group (Lower Jurassic), 2014,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Dimuccio, Luca Antonio

An evolutionary model is proposed to explain the spatio-temporal distribution of karstification affecting the Lower Jurassic shallow-marine carbonate succession (Coimbra Group) of the Lusitanian Basin, cropping out in the Coimbra-Penela region (western-central Portugal), in a specific morphostructural setting (Dolomitic Hills). Indeed, in the Coimbra Group, despite the local lateral and vertical distributions of dolomitic character and the presence of few thick sandy-argillaceous/shale and marly interbeds, some (meso)karstification was identified, including several microkarstification features. All types of karst forms are commonly filled by autochthonous and/or allochthonous post-Jurassic siliciclastics, implying a palaeokarstic nature.

The main aim of this work is to infer the interplay between depositional facies, diagenesis, syn- and postdepositional discontinuities and the spatio-temporal distribution of palaeokarst. Here, the palaeokarst concept is not limited to the definition of a landform and/or possibly to an associated deposit (both resulting from one or more processes/mechanisms), but is considered as part of the local and regional geological record.

Detailed field information from 21 stratigraphic sections (among several dozens of other observations) and from structural-geology and geomorphological surveys, was mapped and recorded on graphic logs showing the lithological succession, including sedimentological, palaeontological and structural data. Facies determination was based on field observations of textures and sedimentary structures and laboratory petrographic analysis of thin-sections. The karst and palaeokarst forms (both superficial and underground) were classified and judged on the basis of present-day geographic location, morphology, associated discontinuities, stratigraphic position and degree of burial by post-Jurassic siliciclastics that allowed to distinguish a exposed karst (denuded or completely exhumed) than a palaeokarst (covered or partially buried).

A formal lithostratigrafic framework was proposed for the local ca. 110-m-thick combined successions of Coimbra Group, ranging in age from the early Sinemurian to the early Pliensbachian and recorded in two distinct subunits: the Coimbra formation, essentially dolomitic; and the overlying S. Miguel formation, essentially dolomitic-limestone and marly-limestone.

The 15 identified facies were subsequently grouped into 4 genetically related facies associations indicative of sedimentation within supra/intertidal, shallow partially restricted subtidal-lagoonal, shoal and more open-marine (sub)environments - in the context of depositional systems of a tidal flat and a very shallow, inner part of a low-gradient, carbonate ramp. In some cases, thick bedded breccia bodies (tempestites/sismites) are associated to synsedimentary deformation structures (slumps, sliding to the W to NW), showing the important activity of N–S and NNE–SSW faults, during the Sinemurian. All these deposits are arranged into metre-scale, mostly shallowing-upward cycles, in some cases truncated by subaerial exposure events. However, no evidence of mature pedogenetic alteration, or the development of distinct soil horizons, was observed. These facts reflect very short-term subaerial exposure intervals (intermittent/ephemeral), in a semiarid palaeoclimatic setting but with an increase in the humidity conditions during the eogenetic stage of the Coimbra Group, which may have promoted the development of micropalaeokarstic dissolution (eogenetic karst).

Two types of dolomitization are recognized: one (a) syndepositional (or early diagenetic), massive-stratiform, of “penesaline type”, possibly resulting from refluxing brines (shallow-subtidal), with a primary dolomite related to the evaporation of seawater, under semiarid conditions (supra/intertidal) and the concurrent action of microbial activity; another (b) later, localized, common during diagenesis (sometimes with dedolomitization), particularly where fluids followed discontinuities such as joints, faults, bedding planes and, in some cases, pre-existing palaeokarstic features.

The very specific stratigraphic position of the (palaeo)karst features is understood as a consequence of high facies/microfacies heterogeneities and contrasts in porosity (both depositional and its early diagenetic modifications), providing efficient hydraulic circulation through the development of meso- and macropermeability contributed by syn- and postdepositional discontinuities such as bedding planes, joints and faults. These hydraulic connections significantly influenced and controlled the earliest karst-forming processes (inception), as well as the degree of subsequent karstification during the mesogenetic/telogenetic stages of the Coimbra Group. Multiple and complex karstification (polyphase and polygenic) were recognized, including 8 main phases, to local scale, integrated in 4 periods, to regional scale: Jurassic, Lower Cretaceous, pre-Pliocene and Pliocene-Quaternary. Each phase of karstification comprise a specific type of (palaeo)karst (eogenetic, subjacent, denuded, mantled-buried and exhumed).

Finally, geological, geomorphological and hydrogeological characteristics allowed to describe the local aquifer. The elaborated map of intrinsic vulnerability shows a karst/fissured and partially buried aquifer (palaeokarst) with high to very high susceptibility to the contamination.


Turkish karst aquifers, 2015,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Gunay G. , Guner N. , Tork K.

One third of Turkey’s surface is underlain by carbonate rocks that have been subdivided into four karst regions. The carbonate rock units are about 200 km wide along the Taurus Mountains that attain elevations of 2500 m. Karst features of western Turkey bordering the Aegean and Mediterranean seas demonstrate the tectonic, lithological and climatic controls on the occurrence, movement, and chemical characteristics of groundwater. In Turkey all karstic feature, such as lapies, caves, sinkholes, uvalas, poljes, ground river valleys developed in all karstic areas. Karstification is related not only to the thickness and to purity of limestone, climate and height but also to tectonic movements. Water resources of karst terrains of Turkey are relatively rich and as such are very important for the economic development of the country. High mountain chains, very often associated with the karst terrains, are responsible for some important and beneficial characteristics of these water resources. Four karst regions are: (1) Taurus karst region, (2) southeast Anatolia karst region, (3) central Anatolia karst region, and (4) northwest Anatolia and Thrace karst regions.


Results 151 to 164 of 164
You probably didn't submit anything to search for