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Community news

Speleology in Kazakhstan

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

New publications on hypogene speleogenesis

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

The deepest terrestrial animal

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

Caves - landscapes without light

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

Did you know?

That suffosion doline is more accurate synonym for a type of subsidence doline, indicating formation by the suffosion, or downwashing, of the soil into an underlying fissure [9]. also known as shakehole.?

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


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Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
See all featured articles
Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
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Your search for crystals (Keyword) returned 111 results for the whole karstbase:
Showing 91 to 105 of 111
Minerogenetic mechanisms occurring in the cave environment: an overview, 2011,
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Onac Bogdan P. , Forti Paolo

Perhaps man’s first motivation to explore caves, beyond using them as shelter, was the search for substances that were not available elsewhere: most of them were minerals. However, for a long time it was believed that the cave environment was not very interesting from the mineralogical point of view. This was due to the fact that most cave deposits are normally composed of a single compound: calcium carbonate. Therefore, the systematic study of cave mineralogy is of only recent origin. However, although only a limited number of natural cavities have been investigated in detail, about 350 cave minerals have already been observed, some of which are new to science. The presence of such unexpected richness is a direct consequence of the variety of rocks traversed by water or other fluids before entering a cave and the sediments therein. Different cave environments allow the development of various minerogenetic mechanisms, the most important of which are double exchange reactions, evaporation, oxidation, hydration-dehydration, sublimation, deposition from aerosols and vapors, and segregation. The cave temperature and pH/Eh strictly control most of them, although some are driven by microorganisms. The cave environment, due to its long-term stability, can sometimes allow for the development of huge euhedral crystals, such as those found in the Naica caves (Mexico), but the presence of extremely small yet complex aggregates of different minerals is far more common. Future development in the field of cave mineralogy will likely be focused mainly on hydrothermal and sulfuric-acid caves and on the role played by micro-organisms in controlling some of the most important minerogenetic processes in caves


KRASOVA JASKYNA PRYA V STIAVNICKYCH VRCHOCH - HYDROTERMALNA SPELEOGENEZA V KARBONATOVOM PODLOZI MIOCENNEHO STRATOVULKANU, 2011,
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Bella P. , Sucha V. , Gaal E. , Kodera P.

A cave of hydrothermal origin in crystalline limestone has been investigated near Sklene Teplice Spa in the Stiavnicke vrchy Mts. located in Central Slovakia. Metamorphozed Middle Triassic carbonate rocks occur as a horizon in pre-volcanic basement of Middle Miocene volcanic formations. The hydrothermal origin of studied cave is documented by spherical and irregural oval phreatic morphology sculptured by ascending thermal water, metamorphic type of the host rocks and their hydrothermal alteration, occurrence of large calcite and quartz crystals, and hydrothermal clays with three mineral smectite-kaolinite, illite and goethite associations. The primary phases of speleogenesis in the crystalline limestones was caused by hydrothermal processes linked either to the emplacement of granodiorite subvolcanic intrusions during the Late Badenian time or to epithermal system of the Late Sarmatian time in the central zone of the Stiavnica stratovolcano. The described cave presents the remarkable' example of hydrothermal limestone cave associated with Miocene volcanism and magmatic intrusions in Central Slovakia.
 


Höhlen der Schwäbischen Alb als Pegelschreiber für Flussgeschichte und Tektonik in Südwestdeutschland seit dem Miozän, 2011,
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Strasser Marcel

In south western Germany the karstified plateau of the Swabian Alb consisting of Upper Jurassic limestones hosts numerous caves, dolines, and dry valleys. Known strath terraces, conglomerates, volcanoes, and impact craters within the study area already provided important time stamps for former studies reconstructing landscape history. It is widely understood, that spatial distribution of most karst features is closely related to the palaeo-water-table and its discontinuous lowering over time, which in turn is the result of incision and/or uplift. The situation of the Swabian Alb at the northern rim of the Northern Alpine Foreland Basin and east of the Rhine Graben valley is the reason for this uplift. Many caves can be used as gauge for vertical displacement, considering horizontal cave passages as product of a stationary palaeowater-table and vertical sections as result of falling base level. In contrast recent studies deal with a different type of speleogenesis independent of base level. This hypogenic speleogenesis must be discussed for the caves of the Swabian Alb. The recently discovered cave named Laierhöhle near Geislingen/Steige is a typical 3d-maze providing several horizontal levels. Passage pattern and distinctive corrosion features match with morphologies (feeders, rising wall- and ceiling channels, outlets) characteristical for hypogenic speleogenesis. However, artesian situations, hydrothermal water or confined aquifers as critical conditions for hypogenic speleogenesis can not be verified. Other features like horizontal passages, water table markers, key-hole-features, and massive stratified sediment bodies are pointing to an epigenic, water-table related speleogenesis. In this study therefore a mixed model for speleogenesis of Laierhöhle is presented, assuming a strong initial deep-phreatic corrosion along fractures and fissures, followed by intensive widening at the palaeo water-table resulting in the formation of horizontal passages. Correlations between horizontal cave-levels, valley-bottoms, strath-terraces, local conglomerates and other caves lead to new and more precise data on the fluvial history, changing drainage pattern, and the uplift of parts of southwest Germany.

In the course of Examinations of cave sediments spherical metallic particles were detected. These magnetic spherules are ablation-products from meteorites during impact. After fallout and flushing into karstic voids and caves the spherules got archived till today. Spherules within Laierhöhle, Laichinger Tiefenhöhle and Mordloch are supposed to originate from the impact event producing the impact craters Steinheimer Becken and/or the Nördlinger Ries 14.59 Ma ago. Within most of the cave sediments spherules are accompanied by crystals of titano-magnetite, which built during volcanic activity of the Urach-Kirchheim volcanic field. Both spherules and titano-magnetites are proxies for re-deposited Mid Miocene Sediments. In this study I could correlate speleogenetic with dated geomorphic features and thus came to a chronology of events. The Laierhöhle records five episodes of long-term stability of the karst water table covering the time-span from late Middle Miocene until the Pliocene/Pleistocene transition. The first two stable episodes can be dated to the late Middle Miocene and Late Miocene (horizontal levels 1 and 2a). An episode responsible for the formation of level 2b falls within Early Pliocene time. Levels 3a and 3b are spatially well separated but must have formed within a relatively short timespan towards the end of the Pliocene. In the working area, total depth of penetrative karstification was in the order of 120 m. This penetration has been accomplished over a period of approximately 12 Ma resulting in an average uplift rate of 0.01 mm/a.


MACROSCOPIC DIAGENETIC CHANGES IN LATE MIOCENE SPELEOTHEMS, WESTERN DESERT, EGYPT, 2012,
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Pickford, Martin

Understanding the diagenesis of speleothems is important on account of the fact that such deposits are often used for determining palaeoclimate parameters and for estimating the ages of speleothem growth. Impressive speleothem deposition of Vallesian age occurred in an immense palaeokarst network in the Western Desert, Egypt, the age of formation being determined on the basis of mammalian biochronology (fossils found in spelean clastic deposits intercalated between speleothems). Many of the Egyptian speleothems have been pervasively recrystallised internally, but their outer surfaces are usually well preserved except in the formations which were buried in clastic deposits, in which case the entire speleothem can be recrystallised. The recrystallisation results in large crystals (up to 20 cm diameter) growing radially outwards from the centre of stalagmites and stalactites, or at right angles to the outer surface of flowstone deposits. It is clear that crystal growth occurred without change of volume. Although the recrystallisation of speleothems in the Western Desert of Egypt resulted in the development of unusually large calcite crystals, it does indicate that diagenesis may be an important process that needs to be taken into account before speleothems in other karst systems can be used as raw material for unravelling palaeoclimatic and geochronological parameters. The gross morphology of the Egyptian speleothems is described in order to put on record the effects of diagenesis on them. The geochemistry of the speleothems remains to be studied.


Diagenesis of a drapery speleothem from Castaar Cave: from dissolution to dolomitization, 2012,
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Martnprez A. , Martngarca R. , Alonsozarza A. M.

A drapery speleothem (DRA-1) from Castañar Cave in Spain was subjected to a detailed petrographical study in order to identify its primary and diagenetic features. The drapery’s present day characteristics are the result of the combined effects of the primary and diagenetic processes that DRA-1 underwent. Its primary minerals are calcite, aragonite and huntite. Calcite is the main constituent of the speleothem, whereas aragonite forms as frostwork over the calcite. Huntite is the main mineral of moonmilk which covers the tips of aragonite. These primary minerals have undergone a set of diagenetic processes, which include: 1) partial dissolution or corrosion that produces the formation of powdery matt-white coatings on the surface of the speleothem. These are seen under the microscope as dark and highly porous microcrystalline aggregates; 2) total dissolution produces pores of few cm2 in size; 3) calcitization and dolomitization of aragonite result in the thickening and lost of shine of the aragonite fibres. Microscopically, calcitization is seen as rhombohedral crystals which cover and replace aragonite forming mosaics that preserve relics of aragonite precursor. Dolomitization results in the formation of microcrystalline rounded aggregates over aragonite fibres. These aggregates are formed by dolomite crystals of around 1 μm size. The sequence of diagenetic processes follows two main pathways. Pathway 1 is driven by the increase of saturation degree and Mg/Ca ratio of the karstic waters and is visible in the NW side of the drapery. This sequence of processes includes: 1) aragonite and huntite primary precipitation and 2) dolomitization. Pathway 2 is driven by a decrease in the degree of saturation of calcite and aragonite and Mg/Ca ratio of the cave waters, and it is observed in the SE side of the drapery. The diagenetic processes of the second pathway include: 1) calcitization of aragonite; 2) incomplete dissolution (micritization) of both aragonite and calcite; 3) total dissolution. This study highlights the importance of diagenetic processes on speleothems and their complexity. The correct interpretation of these processes is crucial for the understanding of possible changes in the chemistry of waters, temperature, or pCO2 and so is critical to the correct interpretation of the paleoenvironmental significance of speleothems.


Speleothem microstructure/speleothem ontogeny: a review of Western contributions, 2012,
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White William B.

Mineral ontogeny is the study of the growth and development of mineral deposits in general and, in the present context, speleothems in particular. Previous researchers, mainly in Russia, have developed a nomenclatural hierarchy based on the forms and habits of individual crystals and the assembly of individual crystals into both monomineralic and polymineralic aggegates (i.e. speleothems). Although investigations of the growth processes of speleothems are sparse, there is a large literature on growth processes of speleothem minerals and related crystals in the geochemical and materials science literature. The purpose of the present paper is to sort through the various concepts of crystal growth and attempt to relate these to observations on speleothems and to the Russian conceptual framework of mineral ontogeny. For calcite, the most common mineral in speleothems, the activation energy for two dimensional nucleation (required for the growth of large single crystals) is almost the same as the activation energy for three- dimensional nucleation (which would result in the growth of many small crystals). Calcite growth is highly sensitive to minor impurities that may poison growth in certain crystallographic directions or may poison growth altogether. Extensive recent research using the atomic force microscope (AFM) provides many details of calcite growth including the transition from growth on screw dislocations to growth by two-dimensional nucleation. The deposition of aragonite speleothems requires metastable supersaturation curve and is usually ascribed to the impurities Mg2+ and Sr2+. AFM studies reveal that Mg2+ poisons calcite growth by blocking deposition sites on dislocations, thus allowing supersaturation to build up past the aragonite solubility curve. Sr2+ precipitates as a Sr-rich nucleus with the aragonite structure which acts as a template for aragonite growth. The different morphology of gypsum speleothems can be explained by the different growth habit of gypsum. Examples of twinned growth, dendrite growth, and spherulitic growth are common in the crystal growth literature and can be used to interpret the corresponding cave forms. Interpretation of monomineralic aggregate growth follows from individual crystal mechanisms. Interpretation of polymineralic aggregate growth requires knowing the evolving chemistry which in turn requires new methods for the sampling and analysis of microliter or nanoliter quantities of fluid.


Involvement of Bacteria in the Origin of a Newly Described Speleothem in the Gypsum Cave of Grave Grubbo (Crotone, Italy), 2012,
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Cacchio P. , Ercole C. , Contento R. , Cappuccio G. , Martinez M. P. , Del Gallo M. , Lepidi A.

 

Microorganisms have been shown to be important active and passive promoters of redox reactions that influence the precipitation of various minerals, including calcite. Many types of secondary minerals thought to be of purely inorganic origin are currently being reevaluated, and microbial involvement has been demonstrated in the formation of pool fingers, stalactites and stalagmites, cave pisoliths, and moonmilk. We studied the possible involvement of bacteria in the formation of a new type of speleothem from Grave Grubbo Cave, the third-largest gypsum cave in Italy. The speleothem we studied consisted of a large aggregate of calcite tubes having a complex morphology, reflecting its possible organic origin. We isolated an abundant heterotrophic microflora associated with this concretion and identified Bacillus, Burkholderia, and Pasteurella spp. among the isolates. All of the isolates precipitated CaCO3 in vitro in the form of calcite. Only one of the isolates solubilized carbonate. The relative abundance of each isolate was found to be directly related to its ability to precipitate CaCO3 at cave temperature. We suggest that hypogean environments select for microbes exhibiting calcifying activity. Isotopic analysis produced speleothem d13C values of about – 5.00%, confirming its organic origin. The lightest carbonates purified from B4M agar plates were produced by the most abundant isolates. SEM analysis of the speleothem showed traces of calcified filamentous bacteria interacting with the substrate. Spherical bioliths predominated among the ones produced in vitro. Within the crystals produced in vitro, we observed bacterial imprints, sometimes in a preferred orientation, suggesting the involvement of a quorum-sensing system in the calcium-carbonate precipitation process.


Geoelectrical Characterization of Sulphate Rocks, 2012,
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Guinea Maysounave, Ander

Gypsum rocks are widely exploited in the world as industrial minerals. The purity of the gypsum rocks (percentage in gypsum mineral –CaSO4•2H2O- in the whole rock) is a critical factor to evaluate the potential exploitability of a gypsum deposit. It is considered than purities higher than 80% in gypsum are required to be economically profitable. Gypsum deposits have been studied with geoelectrical methods; a direct relationship between the electrical resistivity values of the gypsum rocks and its lithological composition has been established, with the presence of lutites being the main controlling factor in the geoelectrical response of the deposit. This phenomenon has been quantified by means of a combination of theoretical calculations, laboratory measurements and field data acquisition. A geoelectrical classification of gypsum rocks defining three types of gypsum rocks has been elaborated. Anhydrite (CaSO4) is frequently found in gypsum quarries and in no-outcropping sulphates. Because of its highest hardness than gypsum it supposes a problem for the extraction of gypsum; the fronts of the quarries in which anhydrite is found are stopped at the moment when it appears. The electrical properties of calcium sulphates have been studied by means of geoelectrical methods. The conductivity of crystals has been tested in laboratory. A direct relationship between the electrical conductivity values of the calcium sulphate rocks and its lithological composition has been established being the lutitic matrix the main controlling factor when it is percolant (connected at long range). When the rock is matrix dominant, the electrical resistivity trend is bond to the Hashin-Shtrikman lower bound for multiphase systems. On the other hand, when the rock is calcium sulphate dominant the trend shows the one of the Hashin-Shtrikman upper bound. A geoelectrical classification for calcium sulphate rocks has been elaborated. With this classification it is possible to differentiate between calcium sulphate rocks with different composition according to their electrical resistivity value. Glauberite (Na2Ca(SO4)2) is nowadays exploited as industrial mineral. Glauberite rocks usually have high lutite content in their composition, together with other evaporictic minerals as gypsum, anhydrite or halite among others. There is no reference to the conductivity of glauberite rocks in the bibliography, but due to their impurity it is expected to observe values as the observed for other sulphates in the matrix domain (less than 55% in purity). Two areas of the Ebro river basin (the Zaragoza and La Rioja sectors) have been studied by means of electrical resistivity tomography profiles, in which glauberite has been found in boreholes. As example of application for the study of sulphate deposits, an electrical resistivity tomography survey has been carried out in the Pira Gypsum member (SE of Catalan margin of the Tertiary Ebro Basin, Spain). Additionally, a continuous coring drill was performed in order to support the study. Electrical imaging has been successfully applied to identify the gypsum deposits interlayered in lutite units. Another resistivity survey has been carried out in an active gypsum quarry in the Gelsa Gypsum unit (Zaragoza, N Spain). During the extraction of the rock, the most important parameters to know are the purity changes in the deposit. Sudden changes in the purity make the processing of the raw material less profitable. The performed profiles have shown different gypsum layers from which the purest layers have been identified. Electrical resistivity tomography lines are useful in prospection of gypsum deposits. However, electrical imaging prospection should be supported by an accurate petrological study of the deposits, in order to properly interpret the resistivity profiles.


Zur Mikrobiologie von Bergmilch, 2012,
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Reitschuler C. , Schwarzenauer T. Lins P. , Wagner A. O. , Sptl C. , Illmer P.
Moonmilk is a plastic mineral formation, which can be found inside cave systems all around the world. These deposits mainly consist of microscopic calcite crystals and show a very high water content. However, the association of microorganisms is remarkable, which seem to play a crucial role in the formation process. The present study applies a combination of culture-based methods and DNA analysis and is to our knowledge the first attempt to investigate this phenomenon in an Alpine cave, in Austria. Central questions include (i) the origin of the occurring microorganisms, (ii) their supply with energy and nutrients, (iii) their role in course of the formation of the deposits, and (iv) their structure and organization. The investigations within the Hundalm Eis- und Tropfsteinhhle in Tyrol revealed that a complex, heterotroph-dominated, psychrophilic microbial com munity, con - sisting of archaea, bacteria and fungi is associated with moonmilk, with partly high microbial abundances. Via living cultivation microorganisms could be proved in all 29 samples, with individual (bacterial) numbers of up to one million per ml moonmilk. The remarkable number of pigmented species could be an indication for the origin from a light-exposed surficial habitat. Molecular biological methods proved that even more organisms inhabit this habitat as was suggested after the culture-based investigations. One million archaea per ml were detected in some samples. The detection of different organic acids partially in appreciable amounts is an indication for biological activity and could also give a hint to the energy and nutrient inputin this system.

Rapidcreekite in the sulfuric acid weathering environment of Diana Cave, Romania, 2013,
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Onac B. P. Effenberger H. S. Wynn J. G. Povară, I.

The Diana Cave in SW Romania develops along a fault line and hosts a spring of hot (Tavg = 51 °C), sulfate-rich, sodium-calcium-chloride bearing water of near-neutral pH. Abundant steam and H2S rises from the thermal water to condensate on the walls and ceiling of the cave. The sulfuric acid produced by H2S oxidation/hydrolysis causes a strong acid-sulfate weathering of the cave bedrock generating a sulfate-dominated mineral assemblage that includes rapidcreekite, Ca2(SO4)(CO3)•4H2O closely associated with gypsum and halotrichite group minerals. Rapidcreekite forms bundles of colorless tabular orthorhombic crystals elongated along [001] and reaching up to 1.5 mm in length. For verifying the hydrogen bond scheme and obtaining crystal-chemical details of the carbonate group a single-crystal structure refinement of rapidcreekite was performed. Its unit-cell parameters are: a = 15.524(2), b = 19.218(3), c = 6.161(1) Å; V = 1838.1(5) Å3, Z = 8, space group Pcnb. Chemi¬cal composition (wt%): CaO 35.65, SO3 24.97, CO2 13.7, H2O 23.9, Na2O 0.291, MgO 0.173, Al2O3 0.07, total 98.75%. The empirical formula, based on 7 non-water O atoms pfu, is: Ca1.98Na0.029Mg0.013 Al0.004(S0.971 O4)(C0.97O3)•4.13H2O. The d34S and d18O values of rapidcreekite and other cave sulfates range from 18 to 19.5‰ CDT and from –9.7 to 7.8‰ SMOW, respectively, indicating that the source of sulfur is a marine evaporite and that during hydration of the minerals it has been an abundant 18O exchange with percolating water but almost no oxygen is derived from O2(aq). This is the first descrip¬tion of rapidcreekite from a cave environment and one of the very few natural occurrences worldwide. We also report on the mineral stability and solubility, parameters considered critical to understand the co-precipitation of carbonates and sulfates, a process that has wide applications in cement industry and scaling prevention.


PROBLEMS OF VALORIZATION AND MANAGEMENT OF THE GIANT GEODE OF PULPI (ALMERIA, SE SPAIN) , 2013,
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Calaforra, Josemaria

The Giant geode of Pulpí (Almería, SE Spain) hosts some of the most outstanding selenite crystals of the world and the largest ones discovered in Europe. Pinacoidal high-purity selenite crystals up to 2 metres long cover totally its walls, floor and ceiling. The cave void where the geode was formed is in an abandoned mine 3 km far from the coastline and 50 m deep from the surface. The peculiar genesis could be related to the mixing processes between hydrothermal fluids and salt water in the aquifer. The discovery (December 2000) was considered an important highlight in the geological heritage of Spain but not many things have been done since 10 years. Projects developed for their conservation were paralysed and no legal figure of protection is active nowadays. Only the interest of touristic valorisation is still alive but in reality the initial tourist projects are stopped. Only one previous project of “waste mining removal” is active. Nevertheless this project is partially provoking a controversial effect: the destruction and/or decontextualization of some surface mining remains. No doubt the Geode has a tourist interest, which must be tempered by environmental restrictions limiting the public visits. First results demonstrated that a continuous visit of two or three people for more than 10 min- utes provokes the appearance of condensation and risks of corrosion of the gypsum crystals. Although any tourist adaptation must not permit direct visits to the geode indoor and levels/contents like Hg and Rn must be controlled. Regrettably, communication to the authorities of this special situation decreased their interest for the protection and touristization. The present proposal is to highlight not only the geode but the mining environment showing that valorization of this geological-natural heritage is still feasible.


STRONTIUM ISOTOPE RATIOS (87SR/86SR) IN GYPSUM SPELEOTHEMS FROM THE NAICA MINE CAVES (CHIHUAHUA, MEXICO): GENETIC IMPLICATIONS, 2013,
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Gzquez Fernando, Calaforra Jos Maria, Garcacasco Antonio, Sanna Laura, Forti Paolo

The 87Sr/86Sr ratio of several gypsum speleothems from the caves of the Naica Mine (Chihuahua, Mexico) has been determined in order to evaluate the origin of the saline solution from which they precipitated. The 87Sr/86Sr ratios of the huge selenite crystals from the Cristales Cave (-290 m Level) and of the gypsum core of the “espadas” speleothems from the Espadas Cave (-120 m Level) are 0.707337 and 0.708343, respectively. These values are slightly higher than that of the carbonate host rock (0.7072) as well as that of the Tertiary felsic dikes emplaced in the carbonate sequence (0.7080). They are also lower than those expected for crystallization from seepage water solutions (>0.7090). Therefore, the 87Sr/86Sr values determined for the speleothems at Naica suggest that gypsum in these caves precipitated from a mixture of infiltration water and thermal water. The 87Sr/86Sr ratio of gypsum speleothems is regarded as a useful indicator to infer the rela- tive contribution of meteoric deep thermal water solutions during the genesis of the Naica’s gypsum speleothems.


THE CAVES IN THE UNDERGROUND QUARRIES OF MON CALVO DASTI PIEDMONT (ITALY), 2013,
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Vigna Bartolomeo, De Waele Jo, Banzato Cinzia

Many quarries for the extraction of gypsum are located in the hills of the Monferrato area (central eastern Piedmont). Close to the village of Moncalvo, Asti Province, a subterranean quarry of more than 20 km long is present. During the excavations a fracture from which water gushed at a pressure of 3 atm has been intercepted in 2005. The underground works have been suspended immediately and, after only a few hours a water flow comprised between 3000 and 4000 Ls-1 has flooded the quarry tunnels filling a volume of over 60,000 m3. After more than one month of pumping the flooded areas have been made accessible again, revealing a thin rock diaphragm that separated the quarry tunnel from a natural cave, which failed under the high hydraulic pressure. Through this small gap it has been possible to access an extensive karst network that previously was completely submerged. During the following quarry operations a second natural cave has been encountered, belonging to the same system but physically divided from the first cave by some metres of sediments. The total development of this cave system is around 1 km. The exploration of these caves has allowed to gather an interesting set of observations that have contributed to elaborating a speleogenetic model. The first information regards the impressive

amount of snottites present along the walls of the caves, and the overall thickness of gypsum rock subdued to weathering, reaching up to 30 cm. There are many morphologies that clearly demonstrate the caves being formed in phreatic conditions, such as pendants and corrosion cupola, but also flat corrosion bevels and V-shaped cross-sections, further evidences of formation in saturate conditions. The stratigraphic asset of the area surely has played a fundamental role in the formation of these karst systems. From bottom to top there is a thick shale sequence, and a thin discontinuous and extremely well karstified marly limestone bed that seemed to have enhanced the hydrological flow in the above lying gypsum beds. The principal cave systems are formed in between the first and second bed of gypsum, along a shaly finely stratified interbed rich in organic material. On the floor of the main passage there are many rather small subvertical conduits that develop up to the underlying limestone bed thus favoring the upward movement of water and the dissolution of the gypsum rocks. The subterranean excavations also have intercepted other caves, most of them of much smaller size, often reaching some cubic metres in size and partially filled with large gypsum crystals, grown by the continuous but slow feeding of slightly supersaturated waters.


Determining gypsum growth temperatures using monophase fluid inclusions Application to the giant gypsum crystals of Naica, Mexico: COMMENT, 2013,
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Garofalo Paolo S. , Forti P. , Gnther D.

Determining gypsum growth temperatures using monophase fluid inclusions Application to the giant gypsum crystals of Naica, Mexico: COMMENT, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Garofalo Paolo S. , Forti P. , Gnther D.

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