MWH Global

Enviroscan Ukrainian Institute of Speleology and Karstology

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 sandstone caves is most natural sandstone caves are surface river-cut notches at the foot of rock cliffs, or left part way up the cliff due to later downcutting. this origin accounts for most of the caves once inhabited by the pueblo indians in the sandstone cliffs of the western usa. true caves do occur in sandstone and some of these appear to be at least partially of dissolutional origin. their existence probably reflects matrix leaching by ground water moving through zones of especially high primary porosity and permeability. though sandstones with a calcite matrix cement are more prone to such development, even siliceous cement, which has a very low solubility in water, may be removed during a sufficiently long time span. the sandstone caves of the sarisarinama plateau, venezuela may be a special case of this type of development. these include shafts 300m in diameter and 200m deep, and passages up to 500m long. they were probably cut in the quartz sandstone by underground streams, after early leaching of the cement by hydrothermal solutions, and the shafts have been modified by later collapse [9].?

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

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 semiarid (Keyword) returned 26 results for the whole karstbase:
Showing 16 to 26 of 26
Paleoclimate reconstruction based on the timing of speleothem growth, oxygen and carbon isotope composition from a cave located in the 'rain shadow', Israel, 2003, Vaks, A. , Barmatthews, M. , Ayalon, A. , Schilman, B. , Gilmour, M. , Hawkesworth, C. J. , Frumkin, A. , Kaufman, A. , And Matthews, A.

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


Contrle structural et tectonique sur lhydrogologie karstique du plateau Mahafaly (domaine littoral semi-aride, sud-ouest de Madagascar), 2005, Andr Grgoire, Bergeron Gilles, Guyot Luc
Structural and tectonic control on karstic hydrogeology of the plateau Mahafaly (semiarid coastal area, South-West of Madagascar) - The southwestern coast of Madagascar is characterized by a semiarid climate and low fresh water resources, which slow down the economic development. The studied area, located south of Toliara, is separated into a western coast of aeolian dunes and sandstones, where most of the people live, and the eastern, almost unoccupied, calcareous Mahafaly plateau. The coastal aquifer is dominated by salty water. The conductivity, close to 6000S/cm in the north, decreases to 3000S/cm in the south. The coastal plain is bordered to the East by highly karstified Cenozoic limestone, separated by a north-south cliff corresponding to the Toliara fault scarp. Surveys in coastal wells and in karstic aquifers clearly point out tidal influence on piezometric level and conductivity. In the north, the limestone cliff is directly in contact with the sea, whose water contaminates the karstic aquifer according to tidal variations. In the south, fresh water flows out on the beach by resurgences in the Quaternary sandstones, probably connected to the Eocene limestones, 5 km to the east. Drillings and exploration of some shafts on the plateau permitted access to the ground water table. It displays various conductivities ranging between 1500S/cm and 5000S/cm, unusually high for a karstic aquifer far away from the coast. The mapping of such conductivities suggests more complex phenomena than only marine intrusions into the different aquifer systems. Chemical and isotopic analyses show an obvious seawater intrusion and evaporation influence for the coastal aquifer. Iin the karstic aquifer, however, trace element analyses evoke contamination by upwelling of deep mineralized water. Salty water is frequent eastward on the basement and in the Mesozic formations. Today, fracture zones in both the coastal sandstones and in the Cenozoic limestone units control ground water circulations. Such fractures result from extensional phases in the past. The surface joint directions N-S, NE-SW and NW-SE reflect the deep-seated horst and graben structures. Microtectonic analyses give evidence of a post-Eocene WNW-ESE extension, and recent seismic data define an E-W extensional regime. The underground flowpaths are mostly on fractures oriented along the present stress field. The tectonic history in the area and the chemical composition of the waters suggest a connection of the karst aquifer with circulations from deep formations through deep-seated faults belonging to the Toliara fault system. This could explain abnormal salinities in the karstic system, far away from the coast.

Do woody plants affect streamflow on semiarid karst rangelands?, 2005, Wilcox B. P. , Owens M. K. , Knight R. W. , Lyons R. K. ,
There is considerable public and political pressure to reduce woody plant cover on rangelands as a means of increasing water yield, despite the lack of studies documenting that such a strategy is effective. In the Texas Hill Country, runoff from the Edwards Plateau recharges the highly productive and regionally vital Edwards Aquifer. The dominant woody plant on the Plateau is Ashe juniper (Juniperus ashei Buchholz). To understand how woody plant cover may affect the amount and timing of runoff in this region, we monitored streamflow from nine small (3- to 6-ha) watersheds over a 13-year period. After the first two years (initial observations), 100% of the shrub cover was removed from three of the watersheds and similar to70% from another three. Following these treatments we continued to monitor runoff for four years, suspended monitoring for four and a half years, and then resumed monitoring for an additional three years. Runoff from these nine first-order watersheds generally accounted for <5% of the total precipitation and occurred entirely as stormflow (there was no baseflow before or after treatment). Some runoff was generated as subsurface flow, as indicated by hydrographs showing prolonged runoff (typically lasting hours longer than the rainfall). We evaluated the influence of woody plant cover on streamflow by comparing streamflow during the four-year treatment period with that during the posttreatment period (when considerable recovery of woody plants had taken place). Our findings indicate that changes in woody plant cover had little influence on the amount, timing, or magnitude of streamflow from these watersheds. On the basis of this work and other observations in the region, we hypothesize that, for small watersheds, changes in shrub cover will have little or no effect on streamflow except where springs are present

A gray system model for studying the response to climatic change: The Liulin karst springs, China, 2006, Hao Yonghong, Yeh Tian Chyi, Gao Zongqiang, Wang Yanrong, Zhao Ying,
SummaryGray system theory uses a black-gray-white color spectrum to describe a complex system whose characteristics are only partially known or known with uncertainty. In this study, we use gray system theory to investigate the relation between precipitation and spring flows in a karst region in China. The gray incidence analysis was applied to the Liulin Springs, Shanxi Province, China to analyze the time-lag between spring flow and precipitation. The results showed that the average groundwater residence time at Liulin Spings is about 4 years. The gray system GM(1,2) model was subsequently used as a predictive tool for spring discharge. It was found that model predictions are in agreement with observed data. This study also shows that the discharge of the Liulin Springs primarily responds to climate change; anthropogenic impacts are secondary. The continuous decline of water level in the karst aquifer and waning of spring discharges in semi-arid regions of China might be largely a response of the groundwater system to the decline in regional precipitation over the past two decades

U-series dating and taphonomy of Quaternary vertebrates from Brazilian caves, 2006, Auler As, Pilo Lb, Smart Pl, Wang X, Hoffmann D, Richards Da, Edwards Rl, Neves Wa, Cheng H,
The geochronology and taphonomy of internationally important fossil bearing cave deposits were studied, both in the semi-arid Northern Bahia area and the subtropical southeastern Lagoa Santa area of Brazil. Taphonomic analysis suggests that the processes responsible for bone accumulation in the Brazilian caves vary between sites, and taphonomic bias can therefore be significant in causing differences in faunal composition. In the Toca da Boa Vista caves the presence of single articulated skeletons, and the entrance-related distribution indicate that random penetration of animals is the main mechanism of fossil accumulation, a process that biases the assemblage to smaller species, and takes place over extended time periods. In nearby Toca dos Ossos cave transport by runoff in the cave river is predominant, and biases the fauna remains to larger more robust bones and species. Deposition probably also occurred only at times of enhanced runoff giving a more contemporaneous assemblage. Similar processes were responsible for emplacement of the copious fossil remains in the more humid Lagoa Santa area, where terrigenous fossil deposits are found intercalated by massive speleothem calcite layers. In this area runoff under a drier climate probably accounts for the sediment emplacement inside caves. In both areas the mode of emplacement implies bias in the fossil record, resulting in fossil assemblages that do not mirror surface faunas, limiting palaeoenvironmental reconstruction.Mass spectrometric U-series analysis of speleothem calcite overlaying fossil remains gives minimum ages for fossil deposition. These ages confirm the previous view that many of the deposits derive from the late glacial, but also show that much older material (some > 350,000[no-break space]yr) is also present. The habitat requirements of critical fossil species such as bats and monkeys strongly suggest that they derive from much wetter periods when forest cover was present in the currently semi-arid Northern Bahia area. Taphonomy exerts a major control on the diversity and mode of emplacement of cave fossil deposits in eastern Brazil and thus detailed sedimentological and hydrological studies coupled with a sound geochronological approach are essential in quantifying the relative importance of each taphonomic processes before faunal and palaeoecological interpretations can be attempted

KARST SURFACE FEATURES OF THE HARD LAMINATED CRUST (CALICHE HARDPAN) IN THE MERSIN AREA, SOUTHERN TURKEY, 2010, Eren Mushin & Hat?poglubagci Zubeyde
The study area is located in the Mersin province where caliches are widespread and occur in a variety of forms such as powdery, nodular, tubular, fracture-infill, laminar crust, hard laminated crust (caliche hardpan), pisolithic crust. The hard laminated crust shows distinctive karst surface features of karren. These include kamenitza, rillenkarren, solution pit and solution enlarged fracture (kluftkarren). First two karst features are common and closely associated with dome- and ridge-like morphologies termed caliche tepees or pseudo-anticlines. Kamenitzas or solution basins are dish-shaped depressions with flat bottom and sharp and overhanging sides which resulted from ponding water mostly at the top of caliche tepees. Rillenkarren are solutional flutes separated by sharp angular ridges, with length of less than 15 cm. They are well developed on the inclined surfaces of surface irregularities at or near the top of caliche tepees and form from sheet flow. Solution pits are narrow, cylindrical shaped karst troughs formed by stemflow drainage beneath trees. The kluftkarrens are products of dissolution by channelised surface water flowing along a fracture. The coexistence of caliche and karst features is important to indicate a climatic change from semiarid to humid conditions.

Analyse spatiale de l´infiltration en domaine karstique méditerranéen de type semi-aride: cas du massif des Béni Snassen (MaAnalyse spatiale de l´infiltration en domaine karstique méditerranéen de type semi-aride: cas du, 2010, Tayebi A. , Jaillet S. , Gasquet D. , Bouabdellah M.


Groundwater in the Arab Middle East , 2012, Wagner, Wolfgang

The region covering the Arabian Peninsula and the adjoining northern Arabian countries coincides approximately with a specific large geologic struCture: the Arabian Plate. Politically the region includes the countries of the Arabian Peninsula together with the northern Arab countries: AI Mashreq - the eastern part of the caliphate or of the Arab World. In a geographic political view the region may be denominated Arab Middle East (Ash Sharq al Awsat) or Western Asia.
The Arab Middle East with an area of 3.7 million lan2 forms a small subcontinent between the Mediterranean Sea, Red Sea, Arabian Sea, the Gulf and, in the north, the Zagros-Taurus mountain chains. About 90% of the region are semiarid to arid steppe or desert areas. As perennial rivers exist only in the northern and western margins of the Arab Middle East, the use of groundwater resources is an essential basis for the economic development and survival of the countries. The
region includes 12 Arab countries; water demand/supply previews indicaTe precarious siruations in the near future for mosu of these countries.
The idea ci compiling a book on "Groundwater in the Arab Middle East" arose from the professional activities of the author as hydrogeologist in the services of the German Government between 1965 and 1998, much of which was devoted to groundwater projectS in the Middle East. The information presented in the book is based on reviews of a large number of publications, reportS and documents as well as on field experience in various Arab countries.
The groundwater projects in the Middle East, in which the author had the
chance to panicipate, were carried out in the framework of Technical Cooperation between national or international institutions of the region and the Federal Institute of Geosciences and Natural Resources, BGR, Hannover, partly in connection with activities of the German Agency for Technical Cooperation, GTZ, Eschbom. The projects were sponsored by the Ministry for Economic Cooperation and Development, Bonn. Regional information on groundwater conditions in the Middle East were obtained, in panicular, through long-term assigrunents of  the author to international institutions: The Arab Centre for the Studies of Arid Zones and Dry Lands of the Arab League (ACSAD), Damascus, and the United Nations Economic and Social Commission for Western Asia (ESCWA), Amman and Beirut. 


The climatic cyclicity in semiarid-arid central Asia over the past 500,000 years, 2012, Cheng H. , Zhang P. Z. , Sptl C. , Edwards R. L. , Cai Y. J. , Zhang D. Z. , Sang W. C. , Tan M. , An Z. S.

Central Asia is currently a semiarid-arid region, dominated by the Westerlies. It is important to understand mechanisms of climate and precipitation changes here, as water availability in the region is crucial today and in the future. High-resolution, absolutely-dated oxygen isotope (d18O) records of stalagmites from Kesang Cave characterize a dynamic precipitation history over most of the past 500,000 years. This record demonstrates, for the first time, that climate change in the region exhibits a processional rhythm with abrupt inceptions of low d18O speleothem growth at times of high Northern Hemisphere summer insolation followed by gradual d18O increases that track decreases of insolation. These observations and interpretations contrast with the interpretation of nearby, but higher elevation ice core records. The absolutely-dated cave d18O shifts can be used to correlate the regional climate variability by providing chronological marks. Combined with other paleoclimate records, the Kesang observations suggest that possible incursions of Asian summer monsoon rainfall or related moisture into the Kesang site and/or adjacent areas during the high insolation times may play an important role in changing orbital-scale hydrology of the region. based on our record, arid climate will prevail in this region for the next several millennia, providing that anthropogenic effects do not supersede natural processes.


Quaternary alluvial sinkholes: Record of environmental conditions of karst development, examples from the Ebro Basin, Spain , 2012, Soriano M. A. , Luzon A. , Yuste A. , Pocovı, A. , Perez A. , Simon J. L. , Gil H.

The central Ebro Basin is an exceptional region for studying karstification through time and under different environmental conditions, as sinkholes have been developing since the Early Pleistocene. Knowledge of active sinkholes is complemented with research on paleosinkholes and contemporary deposits. Sedimentological, mineralogical, geomorphological and structural approaches permit interpretation of the natural environmental conditions that favored karst in the past and the main genetic mechanisms involved. The sedimentary features of Pleistocene terraces indicate that they were deposited by a gravel braided fluvial system characterized by higher water and sediment availability than today, probably related to meltwater flows coming from glaciated source areas, mainly in the Pyrenees. Genesis of paleosinkholes was mainly linked to this high water supply. Some of them acted as small lakes where fine sediments are exceptionally well conserved to give clues about environmental conditions. The neoformation of palygorskite and sepiolite suggests arid to semiarid climatic conditions, in agreement with the idea of cold glacial episodes. During Pleistocene times, development of sinkholes was influenced by tectonics. Currently, the genesis and evolution of numerous sinkholes are also influenced by water supplies from human activities such as irrigation or urbanization, sharply changing the nearly steady state exhibited in the past


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, 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.


Results 16 to 26 of 26
You probably didn't submit anything to search for