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Enviroscan Ukrainian Institute of Speleology and Karstology


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Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That hydrography is the geographical description of water bodies on the earth's surface [16].?

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.
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Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
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Your search for sahara (Keyword) returned 17 results for the whole karstbase:
Showing 1 to 15 of 17
Flow of fossil groundwater, 1977,
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Bourdon Dj,
The great groundwater basins of North Africa and Arabia extend over an area of some 6.5 million square kilometres. Gradients on the isopiezometric surfaces of their confined ground-waters are generally interpreted as indicating present-day flow of groundwater. Can such flow occur in basins where most or all of the groundwater is fossil and where effective infiltration and recharge may have ceased some 10 000 years ago? Assuming that there is indeed no current recharge in these arid and sem-arid regions, the paper identifies seven groups totalling 12 possible mechanisms which can contribute in varying degrees to maintaining flow of groundwater long after effective recharge has ceased. These are: (i) Residual heads; (ii) Tilting of basin; (iii) Compaction effects, in terms of sediment loading, basalt loading and water loading/unloading; (iv) Thermal drive; (v) Gas drive; (vi) Lowering of discharge level, by tectonic displacement, by pressure bursts and by collapse of cover; and (vii) Evaporation in the discharge zone, such as lowering of lake levels and evaporation from sabkhas. Nine additional mechanisms were considered but rejected. Combinations of these mechanisms can produce heads inducing flow of fossil groundwater, but appear to be insufficient to account for present hydraulic regimes without some current surface recharge. The findings have direct application to studies leading to the development, use and management of these major water resources of the arid zones of the Sahara and Arabia

Hydrogeology of the Umm Er Radhuma aquifer, Saudi Arabia, with reference to fossil gradients, 1982,
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Bakiewicz W, Milne Dm, Noori M,
Much of North Africa and the Arabian peninsula, lying in the Saharan climate zone, are underlain by huge tabular sandstone and carbonate aquifers, ranging in age from Cambrian to Tertiary. These are often saturated with water of reasonable quality and form very valuable resources in an area often desperately short of water. The Palaeocene Umm Er Radhuma carbonate aquifer is one such formation which has been the subject of intensive recent investigation. The formation contains groundwater of a reasonable quality, has adequate transmission and storage characteristics and hence considerable potential for future development. The origin of the water in such aquifers is the subject of continuing controversy. It is not disputed that the water is moving under the influence of regional groundwater gradients but origins of these gradients are the subject of considerable argument. On the one hand, there are those who hold that the presently observed gradients are fossil remnants of conditions created by a much wetter climatic regime prevalent some thousands of years ago. Against this are those who maintain that the gradients, at least in part, reflect a present day system with groundwater discharge in approximate dynamic equilibrium with recharge. This paper examines the hydrogeology of a typical Middle Eastern formation of the disputed kind, the Umm Er Radhuma aquifer in Saudi Arabia, and, with the aid of analytical and numerical models, attempts to resolve the problem of the origin of the observed groundwater gradients and to discover the extent to which the past must influence present day plans for future development

Polydesmide et Craspedosomides cavernicoles nouveaux de France et du Maroc (Myriapoda; Diplopoda)., 1985,
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Mauris Jean Paul
This is a description of the affinities and biogeographic significance of three new cavernicolous species of Diplopoda from France and Morocco. One species apparently belongs to the Polydesmida (family Paradoxosomidae) and the other two to Craspedosomida (families Caratosphydae and Chordeumidae). 1) Eviulisoma abadi n.sp. is distinguished from other species of this genus by total depigmentation, by the characters of the gonopodial orifice and the male gonopods, by the low number of segments (19) and by its geographic isolation (Morocco) and ecology (Kef Aziza cave). This justifies the establishment of a new sub-genus, Jeekelosoma. The other species of this genus are found in equatorial Africa and the east. E. abadi is the first paleoarctic species of this genus and is the second paleoarctic species of the tribe Eviulisomidi after Boreviulisoma liouvillei Brol.). It is also the first known from a cave. Like the two other known species of Paradoxosomidae known from the southwest of the paleoarctic zone, Boreviulisoma liouvillei Brol. and Oranmorpha guerinii (Gerv.) the new species is indicative of originating in the Ethiopian region at a time when the Sahara was not a barren desert. 2) Ceratosphys maroccana n.sp. from Gouffre Friouato (Morocco) probably is not an epigean troglophile; it is the southernmost species of this genus which is normally found in France and Spain. This is apparently a remnant of a small group of species from the south of Spain that constitute a sub-genus Proceratosphys Mau. and Vincente. 3) Orthochordeumella leclerci n.sp. (caves of Ardche, France) manifest the presence unique in this genus of cavernicolous characters including depigmentation and extreme length of antennae and is the only truly troglobitic species of this genus. Other characters are less distinctive but it is possible to distinguish this species by sexual characteristics from other species, notably that from the neighbouring geographic area, O. cebennica (known only from the Ardche region) which is troglophilic. The other three species are found in epigean forest habitats, one in the Pyrenees, the other two in the Tyrol, the Swiss Jura, Baden and the northeast of France and Belgium.

Silicate karst landforms of the southern Sahara, 1987,
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Busche D. , Erbe W.

Phnomnes karstiques dans les roches siliceuses au Niger oriental, 1994,
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Sponholz, B.
In North-eastern Niger karstic features occur commonly in siliceous rocks (sandstone, silcretes, iron crusts crystalline). On the base of geomorphological field studies and micromorphological analyses karst forming caused by rock solution is verified The results render possible the dating of the main karstification period in Early Tertiary. The widespread distribution of similar results indicates the dependence of karstification on palaeoclimatic conditions. Actually, the karstic systems influence significantly the development of other landforms.

Sources et hydrosystmes karstiques des rgions arides et semi-arides, essai gographique, 2000,
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Nicod, Jean
SPRINGS AND KARSTIC HYDROSYSTEMS IN THE ARID AND SEMI-ARID AREAS. A GEOGRAPHICAL ESSAY - The patterns of the main springs and hydrosystems in the deserts and surroundings are sorted, according to their geomorphological situation (piedmont, coastal or inner plateau), to structure of the aquifers and working of groundwater (storage capacity, artesian systems) and to the hydrochemical criteria particularly the solute load in Mg2+, SO42- and Cl-. From the best known examples, the main problems on the genesis and working of the karstic hydro-systems in arid environment are discussed: - the incidence of tectonic stress and paleokarstic and paleoclimatic inheritances; - the recent periods of recharge (in Northern Sahara and Near and Middle East); - the interactions in ionic solutions and hyper-karstic processes: particular_ly with the strong acid, H2SO4, the "double solvency effect", and the mixing water corrosion near the salt water wedge in the coastal karsts.

The Sahara-East Mediterranean dust and climate connection revealed by strontium and uranium isotopes in a Jerusalem speleothem, 2004,
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Frumkin A, Stein M,
This paper explores the potential of Sr and U isotope systems in speleothems as tracers of eolian dust transport and hydrological conditions. The study focuses on a speleothem from Jerusalem spanning the past 220 kyr. This speleothem provides a precisely dated record of dust flux from the Sahara to the East Mediterranean. Enhanced dust flux and Terra Rossa soil development are reflected by elevated 87Sr/86Sr ratios in the speleothem (0.7082-0.7086), while lower 87Sr/86Sr ratios (~0.7078) indicate higher contribution of the local bedrock due to low dust flux and low soil accumulation. The strontium isotope system in the speleothem is a robust monitor of the Sahara monsoon-modulated climate, since dust uptake is related to development or reduction in vegetation cover of Sahara soil. The [234U/238U] activity ratios in the speleothem range between 1.12 and 1.0. The high activity values may indicate selective removal of 234U from the soil while the low values converge to the bedrock. The migration of 234U to the cave reflects mainly the regional hydrological conditions that are modulated by the North Atlantic-Mediterranean climate system. Thus, the speleothem provides a combined record of the monsoon-North Atlantic climatic systems. Long-term stability in glacial 87Sr/86Sr ratios (0.70830.0001 over the past 220 kyr) suggests an overall similarity in eolian dust sources, and uniformity in the synoptic conditions that dominate the dust storm tracks during glacial periods

Africa, Sub-Saharan, 2004,
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Brook G. A.

The Sahara - East Mediterranean dust and climate connection revealed by strontium and uranium isotopes in a Jerusalem speleothem, 2004,
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Frumkin, A. , And Stein, M.
This paper explores the potential of Sr and U isotope systems in speleothems as tracers of eolian dust transport and hydrological conditions. The study focuses on a speleothem from Jerusalem spanning the past 220 kyr. This speleothem provides a precisely dated record of dust flux from the Sahara to the East Mediterranean. Enhanced dust flux and Terra Rossa soil development is reflected by elevated 87Sr/86Sr ratios in the speleothem (0.7082-6), while lower 87Sr/86Sr ratios (~0.7078) indicate higher contribution of the local bedrock due to low dust flux and low soil accumulation. The strontium isotope system in the speleothem is a robust monitor of the Sahara monsoon-modulated climate, since dust uptake is related to development or reduction in vegetation cover of Sahara soil. The [234U/238U] activity ratios in the speleothem range between 1.12 and 1.0. The high activity values may indicate selective removal of 234U from the soil while the low values converge to the bedrock. The migration of 234U to the cave reflects mainly the regional hydrological conditions that are modulated by the North Atlantic-Mediterranean climate system. Thus, the speleothem provides a combined record of the Monsoon - North Atlantic climatic systems. Long-term stability in glacial 87Sr/86Sr ratios (0.70831 over the past 220 kyr) suggests an overall similarity in eolian dust-sources, and uniformity in the synoptic conditions that dominate the dust storm tracks during glacial periods.

Resolving the Richat enigma: Doming and hydrothermal karstification above an alkaline complex, 2005,
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Matton Guillaume, Jebrak Michel, Lee James K. W. ,
The Richat structure (Sahara, Mauritania) appears as a large dome at least 40 km in diameter within a Late Proterozoic to Ordovician sequence. Erosion has created circular cuestas represented by three nested rings dipping outward from the structure. The center of the structure consists of a limestone-dolomite shelf that encloses a kilometer-scale siliceous breccia and is intruded by basaltic ring dikes, kimberlitic intrusions, and alkaline volcanic rocks. Several hypotheses have been presented to explain the spectacular Richat structure and breccia, but their origin remains enigmatic. The breccia body is lenticular in shape and irregularly thins at its extremities to only a few meters. The breccia was created during karst dissolution and collapse. Internal sediments fill the centimeter- to meter-scale cavities. Alkaline enrichment and the presence of Cretaceous automorphous neoformed K-feldspar demonstrate the hydrothermal origin of these internal sediments and their contemporaneity with magmatism. A model is proposed in which doming and the production of hydrothermal fluids were instrumental in creating a favorable setting for dissolution. The circular Richat structure and its breccia core thus represent the superficial expression of a Cretaceous alkaline complex with an exceptionally well preserved hydrothermal karst infilling at its summit

Resolving the Richat enigma: Doming and hydrothermal karstification above an alkaline complex , 2005,
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Matton G. , Jebrak M. , Lee J. K. W.

Resolving the Richat enigma: Doming and hydrothermal karstification above an alkaline complex, 2005,
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Matton G. , Jbrak M. , Lee J. K. W.

The Richat structure (Sahara, Mauritania) appears as a large  dome at least 40 km in diameter within a Late Proterozoic to Ordovician  sequence. Erosion has created circular cuestas represented  by three nested rings dipping outward from the structure. The  center of the structure consists of a limestone-dolomite shelf that  encloses a kilometer-scale siliceous breccia and is intruded by basaltic  ring dikes, kimberlitic intrusions, and alkaline volcanic  rocks. Several hypotheses have been presented to explain the spectacular  Richat structure and breccia, but their origin remains enigmatic.  The breccia body is lenticular in shape and irregularly thins  at its extremities to only a few meters. The breccia was created  during karst dissolution and collapse. Internal sediments fill the  centimeter- to meter-scale cavities. Alkaline enrichment and the  presence of Cretaceous automorphous neoformed K-feldspar demonstrate  the hydrothermal origin of these internal sediments and  their contemporaneity with magmatism. A model is proposed in  which doming and the production of hydrothermal fluids were instrumental  in creating a favorable setting for dissolution. The circular  Richat structure and its breccia core thus represent the superficial  expression of a Cretaceous alkaline complex with an  exceptionally well preserved hydrothermal karst infilling at its  summit.


Desert speleothems reveal climatic window for African exodus of early modern humans, 2007,
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Vaks, A. , Barmatthews, M. , Ayalon, A. , Matthews, A. , Halicz, L. And Frumkin, A.
One of the first movements of early modern humans out of Africa occurred 130?100 thousand years ago (ka), when they migrated northward to the Levant region. The climatic conditions that accompanied this migration are still under debate. Using high-precision multicollector?inductively coupled plasma?mass spectrometry (MC-ICP-MS) U-Th methods, we dated carbonate cave deposits (speleothems) from the central and southern Negev Desert of Israel, located at the northeastern margin of the Saharan-Arabian Desert. Speleothems grow only when rainwater enters the unsaturated zone, and this study reveals that a major cluster of wet episodes (the last recorded in the area) occurred between 140 and 110 ka. This episodic wet period coincided with increased monsoonal precipitation in the southern parts of the Saharan- Arabian Desert. The disappearance at this time of the desert barrier between central Africa and the Levant, and particularly in the Sinai-Negev land bridge between Africa and Asia, would have created a climatic ?window? for early modern human dispersion to the Levant.

Present-day sedimentary facies in the coastal karst caves of Mallorca island (western Mediterranean), 2009,
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Forns J. J. , Gins J. , And Grcia F.
In spite of the increasing number of papers on cave sediments published during the last few decades, no one has focused from a sedimentological point of view on the processes that take place specifically within the coastal karst areas of carbonate islands. The objective of the present investigations is to deal with the sedimentary processes that take place inside two littoral caves of Mallorca (western Mediterranean), characterizing the different facies existing in the particular geological, geochemical, and hydrological setting that represents this very specific cave sedimentary environment. The recent exploration of extensive underwater galleries and chambers into some outstanding coastal caves of the island, has permitted the recognition of important accumulations of present-day sedimentary infillings in their drowned passages. Both the Pirata-Pont- Piqueta cave system and the Cova de sa Gleda have floors covered by muddy and/or sandy sediments which, in a wide sense, fit into two well-differentiated categories. On one hand we have allochthonous reddish mud sediments (mainly siliciclastic) and on the other hand autochthonous yellowish carbonate mud or sands. The mixing of both materials is also frequent as well as the accumulation of large blocks and debris due to the breakdown of roof and cave walls. A series of 21 manual cores was obtainedby scuba-divers in both caves, in order to collect the full thickness of sedimentary fill. Soil samples at the entrance of the two caves, as well as rock samples of the walls of both sites, were also obtained for a later comparison. Several sedimentary facies can be distinguished, which include coarse-grained deposits (entrance facies and breakdown blocks), fine-grained siliceous sediments (silts and muddy deposits with very variable organic matter content), carbonate deposits composed of calcite raft accumulations and/ or weathering-released limestone grains, and mixed facies including diverse proportions of the other sediment types. There are also some relict deposits composed of siliceous red silts, which are affected by polygonal desiccation cracks. In all the cases, the siliciclastic elements (quartz and feldspars, mainly) are related to rain events supplying dust of Saharan origin. The deposits and facies described herein correspond to different sedimentary environments that can be individualized inside the caves (collapse entrances, breakdown chambers, fully drowned passages and chambers, pools with free water surface), and reflect very specific hydrological, geochemical, and mechanical processes related to the coastal nature of the studied karst caves.

Middle-Late Quaternary paleoclimate of northern margins of the Saharan-Arabian Desert: reconstruction from speleothems of Negev Desert, Israel, 2010,
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Vaks Anton, Barmatthews Miryam, Matthews Alan, Ayalon Avner, Frumkin Amos

Speleothems in arid and hyper-arid areas of Negev Desert, Israel, are used in paleoclimate reconstruction of northern margins of Saharan-Arabian Desert, focused on the following objectives: 1) precise U–Th dating of the timing of speleothem growth as an indicator of periods of humid climate, i.e. positive effective precipitation; 2) the origin of rainfall using the speleothem δ18O and changes in spatial pattern of speleothem deposition and speleothem thickness along a north–south transect; 3) changes of vegetation cover based on speleothem δ13C variations.

During the last 350 ka major humid periods, referred to herein as Negev Humid Periods (NHP), occurred in the central and southern Negev Desert at 350–310 ka (NHP-4), 310–290 ka (NHP-3), 220–190 ka (NHP-2), and 142–109 ka (NHP-1). NHP-4, NHP-2 and NHP-1 are interglacial events, whereas NHP-3 is associated with a glacial period. During NHP-1, 2 and 3 the thickness and volume of the speleothems decrease from the north to the south, and in the most southern part of the region only a very thin flowstone layer formed during NHP-1, with no speleothem deposition occurring during NHP-2 and 3. These data imply that the Eastern Mediterranean Sea was the major source of the rainfall in northern and central Negev. More negative speleothem δ18O values, relative to central parts of Israel (Soreq Cave) are attributed to Rayleigh distillation because of the increasing distance from the Mediterranean Sea. Speleothem deposition during the NHP-4 in the southern Negev was more intensive than in most of the central Negev, suggesting the prominence of the tropical rain source.

Decrease in speleothem δ13C during NHP events indicates growth of the vegetation cover. Nevertheless, the ranges of δ13C values show that the vegetation remained semi-desert C4 type throughout the NHPs, with an additional significant carbon fraction coming from the host rock and the atmosphere. These observations, together with small thickness of the speleothem layers, favor that NHP events consisted of clusters of very short humid episodes interspersed with long droughts.

NHP events were contemporaneous with climate periods with monsoon index of ≥51 (cal/cm2 × day) and with the formation of sapropel layers in the Mediterranean Sea. Such simultaneous intensification of the monsoon and Atlantic-Mediterranean cyclones is probably related to the weakening of the high pressure cell above sub-tropical Atlantic Ocean, which enabled more rainfall to penetrate into the Saharan-Arabian Desert from the north and south. The contemporaneous occurrence of the NHP events and the increased monsoon rainfall could have opened migration corridors, creating climatic “windows of opportunity” for dispersals of hominids and animals out of the African continent.


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