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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 speleogenesis is although the term literally means the birth, origin or mode of formation of caves, the full extent of speleogenesis includes all the changes that take place between the inception and the eventual destruction of an underground drainage system. it includes development phases during which the active drainage voids are too small to be considered caves as normally defined, as well as phases when the cave no longer functions as a drain, is enlarging only by collapse and, eventually, is being totally removed [9].?

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

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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

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Your search for roraima (Keyword) returned 8 results for the whole karstbase:
Quartzite Karst in Southeastern Venezuela, 1967, Haman Jon F. , Jefferson Gene L. , White William B.
Minor weathering forms on the Roraima Quartzite in the Carrao River Basin of Southeastern Venezuela have the appearance of the karren that form on limestone surfaces in karst terrains. Climatological and chemical evidence indicates that these forms were generated by a solutional mechanism and that this area thus exhibits a minor karst topography on quartzite.

Pseudo-karst dans les roches grso-quartzitiques de la formation Roraima (Gran Sabana, Venezuela), 1985, Pouyllau M. , Seurin M.
QUARTZITE PLATEAUX OF THE RORAIMA FORMATION (GRAN SABANA - VENEZUELA) - The high sandstone-quartzite plateaux of the Roraima period situated in the Gran Sabana region of south-east Venezuela have some specific macro- and micro-geomorphological characteristics. On one hand, this Precambrian sedimentary cover includes some spectacular relief consisting of high structural plateaux affected by major anticlines, synclines, and monoclines, partly dismantled by erosion. On the other hand, and on a smaller scale, pseudo-karst have developed on the surface (karren) and at depth (caves, shafts). Several hypotheses are put forward in an attempt to explain the genesis of this pseudo-karst.

Morphologie et volution des cavernes et formes superficielles dans les quartzites du Roraima, 1988, Galan C. , Lagarde J.
MORPHOGENESIS OF CAVES AND LANDFORMS IN THE PRECAMBRIAN QUARTZITE OF RORAIMA GROUP (VENEZUELA) - This paper describes caves and landforms developed in the Precambrian quartzite of the Roraima Group (1600-1800 My) in the Gran Sabana of Venezuela (cf. Pouyllau and Seurin, in Karstologia, 1985, n 5). High plateaus (Tepuys) are remnants of old erosional surfaces of Secondary-Tertiary age. The weathering of quartzite is produced in fissures by means of the dissolution of the intergranular siliceous cement. Depressions, fields of blocks and small towers, deep fissures characterise the edges of tepuys. Underground passages could be formed by dissolution, arenisation and piping from the fractures which dissect the tepuys. The part of hydrothermalism in speleogenesis is not proved.

Karst in siliceous rocks; Karst landforms and caves in the Auyn-Tepui Massif (Est. Bolivar, Venezuela)., 1995, Piccini Leonardo
During the expedition Tepuy 93'. six caves were explored in the precambrian quartzites of Roraima Group, in the Auyan-tepui massif. One of this caves reaches the depth of 370 m and a development of almost 3 km; its name is "Sima Auyan-tepui Noroeste" and it is currently the deepest cave in the world discovered in siliceous rocks The geological and morphological study of this cave has underlined again the importance of deep solutional weathering, along the network of fractures for the formation of caves in siliceous rocks. The different formation stages of the big superficial shafts, called "simas" were observed in some vertical collapse caves explored during the expedition, while galleries with phreatic forms were observed in the deep network of caves. All these deep forms involve karst processes of solution at least in the initial stage.

Karst-like landforms and hydrology in quartzites of the Venezuelan Guyana shield: Pseudokarst or 'real' karst?, 1999, Doerr Sh,
The surfaces of table mountains (Tepuis) in southeastern Venezuela display well-developed karst topography including caves, sinkholes and karren-features. Although the rock (orthoquartzite of the Precambrian Roraima Formation) has a very low solubility, active cave systems are present with passages more than one kilometre in length, descending to more than 300 metres depth. These dimensions are greater than any so far reported in quartzitic rocks. There is strong evidence that corrosive rather than erosive processes are responsible for the karstification. Thin-sections of rock samples show dissolution not only of the amorphous silica cement, but also of the crystalline quartz grains themselves. Together with field observations in and near an active cave system on the Kukenan Tepui, this indicates a close similarity between the processes active on the Venezuelan table mountains and karstification processes in rocks of greater solubility. A combination of factors including high precipitation (4000-7000 mm/year), rock of very high purity (98 % silica) and the absence of other significant geomorphological processes prevailing for at least several million years are thought to have enabled a spectacular karst landscape to evolve in a rock that in the past has been regarded as almost immune to chemical weathering

Sandstone caves on Venezuelan tepuis: Return to pseudokarst?, 2011, Aubrecht R. , Lanczos T. , Gregor M. , Schlogl J. , Smida B. , Liscak P. , Brewercarias C. H. , Vlek L.

Venezuelan table mountains (tepuis) host the largest arenite caves in the world. The most frequently used explanation of their origin so far was the "arenization" theory, involving dissolution of quartz cement around the sand grains and subsequent removing of the released grains by water. New research in the two largest arenite cave systems - Churi-Tepui System in Chimanta Massif and Ojos de Cristal System in Roraima Tepui showed that quartz dissolution plays only a minor role in their speleogenesis. Arenites forming the tepuis are not only quartzites but they display a wide range of lithification and breakdown, including also loose sands and sandstones. Speleogenetic processes are mostly concentrated on the beds of unlithified sands which escaped from diagenesis by being sealed by the surrounding perfectly lithified quartzites. Only the so-called "finger-flow" pillars testify to confined diagenetic fluids which flowed in narrow channels, leaving the surrounding arenite uncemented. Another factor which influenced the cave-forming processes by about 30% was lateritization. It affects beds formed of arkosic sandstones and greywackes which show strong dissolution of micas, feldspars and clay minerals, turning then to laterite ("Barro Rojo"). The main prerequisite to rank caves among karst phenomena is dissolution. As the dissolution of silicate minerals other than quartz appears to play not only a volumetrically important role but even a trigger role, these arenitic caves may be ranked as karst.


Dokumentation von zwei Quarzithhlen am Roraima Tepui (Brasilien, Guyana) , 2011, Plan L. , Hlzel M. , Auler A.
The Gran Sabana extends over the area between the Amazonas and Orinoco River in the northern part of South America. There about hundred table mountains (locally named Tepuis) are rising above the wet savannah plain. One of these, the Roraima Tepui, is situated at the triple border junction of the states of Brazil, Guyana and Venezuela. The plateau is built up of sandstones and quartzites of palaeoproterozoic age (c. 1.9 Billion years). Several caves which have mainly developed due to mechanical erosion of not or just partly lithified sandstone layers have been explored. The aim of a Brazilian Austrian expedition in November 2010 was to visit caves in the southern part of the Roraima Tepui and search for new caves in the less accessible northern part. The Cueva Ojos de Cristal (or Sistema Roraima Sur) was visited. With a mapped length of 16.1 km it is the biggest quartzite cave known in the world. Two caves were mapped, the Hotel Coati and the Lake Gladys Cave, which are the highest lying documented caves of Guyana and Brazil respectively. The Hotel Coati is situated in the north of the Tepui and is a cave often used as a bivouac. It is a shaft, acting as ponor, which is accessible through galleries aligned at rectangularly arranged fissures. North of that cave, in the Guyanese part, the single lake on the plateau, the Lake Gladys is situated at 2665 m a.s.l. There, the Lake Gladys Cave with a total length of 68 m is draining the lake. The entrance lies behind a boulder fall and water disappears into a sump. At the Roraima Tepui there are other not docu - mented objects so far, as the shaft ponor El Fosso (The Pit). Even though no major systems were found during this short expe - dition, the potential of finding further caves in the northern part seems still good.

Structural and lithological guidance on speleogenesis in quartz–sandstone: Evidence of the arenisation process, 2014,

A detailed petrographic, structural and morphometric investigation of different types of caves carved in the quartz–sandstones of the “tepui” table mountains in Venezuela has allowed identification of the main speleogenetic factors guiding cave pattern development and the formation of particular features commonly found in these caves, such as funnel-shaped pillars, pendants and floor bumps. Samples of fresh and weathered quartz–sandstone of the Mataui Formation (Roraima Supergroup) were characterised through WDS dispersive X-ray chemical analyses, picnometer measurements, EDAX analyses, SEM and thin-section microscopy. In all the caves two compositionally different strata were identified: almost pure quartz–sandstones, with content of silica over 95% and high primary porosity (around 4%), and phyllosilicate-rich quartz–sandstone, with contents of aluminium over 10% and low primary porosity (lower than 0.5%). Phyllosilicates are mainly pyrophyllite and kaolinite. SEMimages on weathered samples showed clear evidence of dissolution on quartz grains to different degrees of development, depending on the alteration state of the samples. Grain boundary dissolution increases the rock porosity and gradually releases the quartz grains, suggesting that arenisation is a widespread and effective weathering process in these caves. The primary porosity and the degree of fracturing of the quartz–sandstone beds are the main factors controlling the intensity and distribution of the arenisation process. Weathering along iron hydroxide or silt layers, which represent inception horizons, or a strata-bounded fracture network, predisposes the formation of horizontal caves in specific stratigraphic positions. The loose sands produced by arenisation are removed by piping processes, gradually creating anastomosing open-fracture systems and forming braided mazes, geometric networks or main conduit patterns, depending on the local lithological and structural guidance on the weathering process. This study demonstrates that all the typical morphologies documented in these quartz–sandstone caves can be explained as a result of arenisation, which is guided by layers with particular petrographic characteristics (primary porosity, content of phyllosilicates and iron hydroxides), and different degrees of fracturing (strata-bounded fractures or continuous dilational joints).

 


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