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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. ...

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That dug well is a hand excavated well [16].?

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Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
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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 gypsum (Keyword) returned 450 results for the whole karstbase:
Showing 421 to 435 of 450
SALT KARST AND COLLAPSE STRUCTURES IN THE ANADARKO BASIN OF OKLAHOMA AND TEXAS, 2013, Johnson, K. S.

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


GYPSUM KARST CAUSES RELOCATION OF PROPOSED CEDAR RIDGE DAM, THROCKMORTON COUNTY, TEXAS, 2013, Johnson K. S. , Wilkerson J. M.

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


THE ROLE OF SULFATE-RICH SPRINGS AND GROUNDWATER IN THE FORMATION OF SINKHOLES OVER GYPSUM IN EASTERN ENGLAND, 2013, Cooper A. H. , Odling N. E. , Murphy Ph. J. , Miller C. , Greenwood Ch. J. , Brown D. S.

Heavily karstified gypsum and dolomite aquifers occur in the Permian (Zechstein Group) of Eastern England. Here rapid active gypsum dissolution causes subsidence and abundant sinkholes affect an approximately 140-km by 3-km area from Darlington, through Ripon to Doncaster. The topography and easterly dip of the strata feed artesian water through the dolomite up into the overlying gypsum sequences. The shallow-circulating groundwater emerges as sulfate-rich springs with temperatures between 9-12 oC, many emanating from sinkholes that steam and do not freeze in the winter (such as Hell Kettles, Darlington). Water also circulates from the east through the overlying Triassic sandstone aquifer. Calcareous tufa deposits and tufa-cemented gravels also attest to the passage and escape of this groundwater.The sizes of the sinkholes, their depth and that of the associated breccia pipes are controlled by the thickness of gypsum that can dissolve and by the bulking factors associated with the collapsed rocks. The presence of sulfate-rich water affects the local potability of the supply. Groundwater abstraction locally aggravates the subsidence problems, both by active dissolution and drawdown. Furthermore, the gypsum and dolomite karstification has local implications for the installation of ground-source heat pumps. The sulfate-rich springs show where active subsidence is expected; their presence along with records of subsidence can inform planning and development of areas requiring mitigation measures.


Isotopes of Carbon in a Karst Aquifer of the Cumberland Plateau of Kentucky, USA, 2013, Florea Lee J.

In this study, the concentration and isotopic composition of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) are measured in the karst groundwater of the Otter Creek watershed of the Cumberland Plateau of Kentucky, USA. Comparisons among these data and with the geochemistry of carbonate and gypsum equilibrium reactions reveal that DOC concentration is inversely related to discharge, multiple reaction pathways provide DIC with isotopic enrichment that may be directly related to mineral saturation, and oxidation of reduced sulfur is possible for dissolution. DOC is derived from C3 vegetation with an average δ13C DOC of ‒27‰. DIC in groundwater is derived from both pedogenic CO2  and HCO3 - from dissolved carbonate. At input sites to the karst aquifers DIC concentrations are expectedly low, less than 1 mmol/L, in waters that are undersaturated with respect to calcite. At the output of these karst aquifers DIC concentrations reach 3 mmol/L in waters that are at or above calcite saturation. Values of δ13C DIC range between ‒6.3 and ‒12.4‰ with CO2 degassing and calcite precipitation at some sites obfuscating a simple relationship between δ13C DIC, discharge, and mineral saturation. In addition, concentrations of DIC in sulfur seeps within the watershed range between 2–7 mmol/L with δ13C DIC values in some samples skewed more toward the anticipated value of carbonate bedrock than would be expected from reactions with carbonic acid alone. This suggests that the oxidation of reduced sulfur from shallow oilfield brines liberates bedrock DIC through reactions with sulfuric acid.


CAVES AND KARST-LIKE FEATURES IN PROTEROZOIC GNEISS AND CAMBRIAN GRANITE, SOUTHERN AND CENTRAL SRI LANKA: AN INTRODUCTION, 2013, Osborne R. A. L. , Weliange W. S. , Jayasingha Pathmakumara, Dandeniya A. S. , Algiriya A. K. Prageeth P. & Pogson Ross E.

There has been little study of the geology and geomorphology of the caves and karst­like features developed in the Proterozoic gneiss and Cambrian granite of Sri Lanka. This lack of study is surprising given that caves and rockshelters in these rocks contain significant archaeological and cultural sites. Caves and karren, both mimicking those developed in carbonate rocks, have formed both in gneiss, which is the dominant rock type of the Proterozoic crust of the island and in granite. In addition to overhangs, boulder caves, soil pipes and tectonic caves, tunnel caves, arch caves and block breakdown caves of significant size are developed in siliceous rocks in Sri Lanka. while metamorphosed dolomites are interfoliated within the gneissic suite, simple removal of carbonate by solution from within the surrounding rock cannot account for all or most of the speleogenesis observed. while spalling and breakdown are responsible for cave enlargement, cave initiation is probably due to either phreatic solution of silicates and/or phantom rock processes. Speleothems and cave minerals including silicates, phosphates, gypsum, carbonates and niter are found in the caves. Active silicate speleothems are not restricted to joints and fissures and suggest that solution of silicates is currently occurring within the body of the rock in the vadose zone. while guano is the likely source of the phosphate, sulfate and nitrate, the source of the calcium in the carbonates remains unclear. Caves in the intrusive and metamorphic rocks of Sri Lanka are enigmatic. They are unexpectedly similar in appearance to their carbonate karst counterparts. Continuing research will allow them to hold a mirror to our understanding of speleogenesis, mineralization and sedimentation in carbonate karst caves.


A REVIEW ON HYPOGENE CAVES IN ITALY, 2014, De Waele J. , Galdenzi S. , Madonia G. , Menichetti M. , Parise M. , Leonardo Piccini , Sanna L. , Sauro F. , Tognini P. , Vattano M. Vigna B.

Although hypogene cave systems have been described since the beginning of the 20th century, the importance in speleogenesis of ascending fluids that acquired their aggressiveness from in-depth sources has been fully realized only in the last decades. Aggressiveness of waters can be related to carbonic and sulfuric acids and the related corrosion-dissolu­tion processes give rise to different types of caves and under­ground morphologies.

The abundance of hydrothermal springs and associated traver­tine deposits, and the widespread interaction between volcanic or sub-volcanic phenomena and karst in many sectors of the Ital­ian peninsula are a strong evidence of hypogene speleogenesis. Furthermore, researches on secondary minerals have allowed to discover hypogene caves formed by highly acidic vapors in sub­aerial environments, also showing that most of these caves have extremely rich mineral associations.

Despite this, until the late 1980s the only known important cave systems of clear hypogene origin in Italy were considered to be the ones hosted in the Frasassi Canyon and Monte Cucco, in which important gypsum deposits undoubtedly showed that sulfuric acid played an important role in the creation of voids (Galdenzi, 1990, 2001; Galdenzi & Maruoka, 2003; Menichetti et al., 2007). Afterwards many other caves were categorized as formed by the sulfuric acid speleogenesis throughout the entire Apennines. Following the broad definition of hypogene caves by Palmer in 1991, and the even more general one of Klimchouk in the last decade (Klimchouk, 2007, 2009), the number of caves considered of hypogene origin in Italy has grown rapidly. Figure 1 shows the hypogene karst systems of Italy, including, besides the well-known and published ones, also the known and less studied, and presumed hypogene cave systems (see also Table 1).

More recently, in some of these caves detailed studies have been carried out including geomorphology, mineralogy, and geochem­istry. Sulfuric acid caves are known from many regions along the Apennine chain (Tuscany, Umbria, Marche, Latium, Campa­nia, Calabria) (Forti, 1985; Forti et al., 1989; Galdenzi and Me­nichetti, 1989, 1995; Galdenzi, 1997, 2001, 2009; Galdenzi et al., 2010; Piccini, 2000; Menichetti, 2009, 2011; Mecchia, 2012; De Waele et al., 2013b), but also from Piedmont, Apulia, Sicily (Vattano et al., 2013) and Sardinia (De Waele et al., 2013a). In this last region ascending fluids have also formed a hypogene cave in quartzite rock. Oxidation of sulfides can locally create hypogene cave morphologies in dominantly epigenic caves, such as in the Venetian forealps (this cave is not shown in Figure 1, being largely epigenic in origin) (Tisato et al., 2012). Ascend­ing fluids have also created large solution voids in Messinian gypsum beds in Piedmont, and these can be defined hypogene caves according to the definition by Klimchouk (Vigna et al., 2010). Some examples of hypogene cave systems due to the rise of CO2-rich fluids are also known in Liguria and Tuscany (Pic­cini, 2000). In the Alps and Prealps (Lombardy), some ancient high mountain karst areas exhibit evidences of an early hypo­gene origin, deeply modified and re-modeled by later epigenic processes. Hypogene morphologies are thus preserved as inac­tive features, and it is often difficult to distinguish them from epigenic ones.

At almost twenty years distance from the first review paper on hypogene cave systems in Central Italy by S. Galdenzi and M. Menichetti (1995), we give a review of the state-of-the-art knowledge on hypogene caves actually known from the whole of Italy


CONDENSATION CORROSION: MEASUREMENTS AND GEOMORPHIC EVIDENCE IN THE FRASASSI CAVES, 2014, Galdenzi S. , Jones D. , Macalady J.

The condensation of acidic waters on subaerial carbonate surfaces (condensation corrosion) can be an important speleogenetic agent under certain conditions (Cigna and Forti, 1986; Sarbu and Lascu, 1997). Specific morphologies associated with condensation corrosion include notches, niches, cupolas, megascallops and domes (Audra, 2009), and have been recognized in many caves from different regions of the world and from different geologic settings. Condensation corrosion can be particularly important in thermal caves, where temperature differences facilitate air convection and water condensation, as well as in sulphidic caves, where degassing and subsequent oxidation of hydrogen sulphide (H2S) gas provides a ready source of acidity to the subaerial cave environment.
In pioneering studies on the formation of sulphidic caves, condensation corrosion via H2S degassing and oxidation to sulphuric acid was considered the primary mechanism for speleogenesis (Principi, 1931; Egemeier, 1981). However, recent research has cast doubt on the importance of subaerial H2S oxidation for sulphidic cave formation (Engel et al., 2004). In the Frasassi cave system, Italy, morphological evidence for both subaerial and subaqueous limestone dissolution has been extensively documented (Galdenzi, 1990; Galdenzi and Maruoka, 2003). In particular, corrosion above the water table has resulted in the formation of massive gypsum deposits as well as specific passage morphologies. Measured rates by Galdenzi et al. (1997) corroborated morphological evidence that condensation corrosion is important at least under certain conditions. Therefore, in order to better define the role of subaerial processes in the Frasassi cave system, we quantified sulphide flux to the cave atmosphere in the modern cave environment, and documented morphological evidence for subaerial corrosion in the past


HOW DEEP IS HYPOGENE? GYPSUM CAVES IN THE SOUTH HARZ, 2014, Kempe, S.

Germany currently features 20 caves in sulfate rocks (gypsum and anhydrite) longer than 200 m. Most of them occur either in the Werra-Anhydrite or in the Hauptanhydrite of the evaporitic Zechstein series (Upper Permian). One occurs in the Jurassic Münder Mergel and two in the Triassic Grundgips. The longest, the Wimmelburger Schlotten, is 2.8 km long with a floor area of 24,000 m2. All caves, except four, occur in the South Harz, where the Zechstein outcrop fringes the uplifted and tilted Variscian Harz. These caves can be divided into three general classes: (i) epigenic caves with lateral, turbulent water flow, and (ii) shallow or (iii) deep phreatic caves with slow convective density-driven dissolution. The latter were discovered during historic copper-shale mining and called “Schlotten” by the miners; most of them are not accessible any more. Shallow phreatic caves occur in several areas, most notably in the Nature Preserve of the Hainholz/Beierstein at Düna/Osterode/Lower Saxony. Here, we sampled all water bodies in May 1973 and monitored 31 stations between Nov. 23rd, 1974, and April 24th, 1976, with a total 933 samples, allowing us to characterize the provenance of these waters. These monitoring results were published only partially (PCO2 data, see Kempe, 1992). Here, I use the data set to show that the Jettenhöhle (the largest cave in the Hainholz) has been created by upward moving, carbonate-bearing, groundwater of high PCO2. Even though the cave has now only small cave ponds and essentially is a dry cave above the ground water level, it is a hypogene cave because of the upward movement “of the cave-forming agent” (sensu Klimchouk, 2012). Likewise, the Schlotten are created by water rising from the underlying carbonate aquifer, but under a deep phreatic setting


HYPOGENE SPELEOGENESIS AND CO2: SUGGESTIONS FROM KARST OF ITALY, 2014, Menichetti, M.

The carbon dioxide produced in the soil and dissolved in the percolation water is considered as the main agent for karstification in the carbonate rocks. Superficial morphologies and underground caves are product of the corrosion of the limestone, while carbonate speleothems is the other end member of the process.
Hypogene speleogenesis driven by deep seated fluids is the cave formation processes for the main karst systems in the Apennines of Italy. Hydrogen sulfide and endogenic carbon dioxide are the main agents for underground karst corrosion and the soil carbon dioxide plays a secondary rule. The limestone corrosion driven by hydrogen sulfide produces gypsum deposits in caves that could be assumed as the indicator of the hypogene speleogenesis. The action of endogenic carbon dioxide in the cave formation, especially if it operates at lower temperature, is not easy to detect and the resulting cave morphology is not helpful to recognize the cave formation process.
The main sources of carbon dioxide in the underground karst system in the Apennines of Italy can be related to different processes driven by the endogenic fluids emissions. The crustal regional degassing seems to be the prevalent source for carbon dioxide in the karst massifs with the main release in the groundwater. Hydrogen sulfide and methane oxidation, possibly mediated by bacteria activity, are other sources in the buried Cenozoic sediments. Releasing of carbon dioxide along the faults and in the fractures occurring in the carbonate rocks is an important source, especially in the seismically active area. Finally, thermogenic reactions with carbonate rocks are well known as one of the main production mechanism of carbon dioxide released in the atmosphere.
Data from carbon dioxide monitoring in several caves show a relevant contribution of the endogenic carbon dioxide (about 75 %) in the karst system which drives the speleogenesis reactions and shapes the underground morphologies.


HYPOGENE VS EPIGENE CAVES: THE SULFUR AND OXYGEN ISOTOPE FINGERPRINT, 2014, Onac, B. P.

The classical epigene speleogenetic model in which CO2 is considered the main source of acidity has been challenged over the last three decades by observations that revealed cave passages unrelated to groundwater drainage routes and surface topography. Most of these passages show unusual morphologies, such are cupolas, floor feeders (i.e., inlets for deep-seated fluids), and huge irregular-shaped rooms that terminate abruptly, and often a rich and diverse mineral association. A hypogenetic speleogenetic pathway was proposed for this group of caves.
The presence of abundant gypsum deposits in caves with one or more of the passage morphologies listed above, have prompted scientists to suggest a new theory (i.e., sulfuric acid speleogenesis, SAS) of cave development. In the hypogenic SAS model, the source of acidity is the sulfuric acid produced by oxidation of H2S (originating from sulfate reduction or petroleum reservoirs) near or at the water table, where it dissolves the limestone bedrock and precipitates extensive gypsum deposits. SAS is now thoroughly documented from numerous caves around the world, with the best examples coming from the Guadalupe Mountains (NM), Frasassi caves (Italy), selected caves in France, Cueva de Villa Luz (Mexico), and Cerna Valley (SW Romania).
To date, discrimination between epigene and hypogene speleogenetic pathways is made using cave morphology criteria, exotic mineral assemblages, and the predominantly negative δ34S values for the cave sulfates. This presentation highlights the role sulfur and oxygen stable isotope analyses have in discriminating between epigene and hypogene caves.
Based on a number of case studies in caves of the Cerna Valley (Romania), we found that relatively S-depleted isotopic composition of cave minerals alone does not provide enough information to clearly distinguish SAS from other complex speleogenetic pathways. In fact, δ34S values of SAS by-products depend not only on the source of the S, but also on the completeness of S redox reactions. Therefore, similar studies to this are needed to precisely diagnose SAS and to provide information on the S cycle in a given karst system.
Integrating cave mineralogy, passage morphology, and geochemical studies may shed light on the interpretation of polygenetic caves, offering clues to processes, mechanisms, and parameters involved in their genesis (sulfate-dominated).


ISOTOPIC STUDIES OF BYPRODUCTS OF HYPOGENE SPELEOGENESIS AND THEIR CONTRIBUTION TO THE GEOLOGIC EVOLUTION OF THE WESTERN UNITED STATES, 2014, Polyak V. J. , Asmerom Y. , Hill C. A. , Palmer A. N. , Provencio P. P. , Palmer M. V. , Mcintosh W. C. , Decker D. D. , Onac B. P.

Hypogene speleogenesis in the western United States is associated with a deep source of water and gases that rise and mix with shallow aquifer water. Caves are formed below the surface without surface expressions (ie, sinkholes, sinking streams), and byproducts of speleogenesis are precipitated during the late phase of hypogene speleogenesis. These byproducts provide geochemical and geochronological evidence of a region’s geologic history and include gypsum rinds and blocks, elemental sulfur, halloysite-10Å, alunite, natroalunite, and other sulfur-related minerals. The following speleogenetic and speleothemic features are common: alteration rinds, crusts, mammillaries, folia, rafts, and cave spar. The types of hypogene speleogenesis vary and many can be expressed in space and time in relation to paleo-water tables. We identify two general types: (1) H2S-H2SO4-dominated speleogenesis that takes place predominantly near a paleo-water table (a few meters above and below), and (2) CO2-dominated speleogenesis that mostly takes place 10s to 100s of meters below a paleo-water table, with latest-stage imprints within meters of the water table.
The Kane caves in Wyoming, and the Guadalupe Mountains caves in New Mexico and West Texas, are examples of H2S-H2SO4-dominated speleogenesis (also known as sulfuric acid speleogenesis, SAS), where deposits of H2S- and H2SO4-origin are the obvious fingerprints. The Grand Canyon caves in Arizona and Glenwood Caverns in Colorado are examples of CO2-dominated systems, where H2SO4 likely played a smaller role (Onac et al., 2007). Deeper-seated geode-like caves, like the spar caves in the Delaware Basin area, are probably CO2-dominated, and have formed at greater depths (~0.5 ± 0.3 km) below paleo-water tables. Caves in the Black Hills, South Dakota are composite and complex and show evidence for multiple phases of hypogene speleogenesis. In areas such as the Grand Canyon region, these paleo-water tables, when they existed in thick carbonate rock stratigraphy and especially at the top of the thick carbonate rock strata, were likely regionally relatively flat in the larger intact tectonic blocks.
Geochemical studies of these deposits are providing information about the timing of speleogenesis through U-Th, U-Pb, and Ar-dating. In addition, tracer data from isotopes of C, O, S, Sr, and U are indicators of the sources of water and gases involved in speleogenesis. From these studies, novel canyon incision and landscape evolution interpretations are appearing in the literature. Beyond this, the study of these byproduct materials seems to show evidence that the deeply sourced water and gases involved in hypogene speleogenesis in the western United States are generated during tectonic and volcanic activity, and may be related to mantle processes associated with formation of the Rocky Mountains, Colorado Plateau, Basin and Range province, and Rio Grande Rift.


SPELEOGENESIS BY THE SULFIDIC SPRINGS AT NORTHERN SIERRA DE CHIAPAS, MEXICO, BASED ON THEIR WATER CHEMISTRY, 2014, Rosaleslagarde L. , Boston P. J.

Conspicuous brackish sulfidic springs have been described at the northern Sierra the Chiapas, Mexico. These springs are produced by a mixture between regional and local groundwater flow paths. The regional groundwater has an average Total Dissolved Ions of 3081 mg/L so it has a brackish composition. This brackish water is saturated with respect to calcite and dolomite but undersaturated with respect to gypsum, anhydrite and halite. The mass balance and the discharge rate are used to quantify the mass and volume of minerals that are dissolved by the brackish spring water following Appelo and Postma (1993). This quantification will allow comparing the various speleogenetic mechanisms in the area. This is considering the composition of the spring water is relatively constant over time, as it is suggested by periodic measurements at the Cueva de Villa Luz springs during the last 10 years.
Sulfur isotopes in the water are consistent with anhydrite dissolution as the main source of the sulfate to the brackish spring water. Thus, the average 6 mol/L of sulfate in the brackish springs are produced by dissolution of 6 mol of anhydrite after subtracting the sulfate that could result from evapotranspiration of rainwater. Each liter of brackish water dissolved an average of 882 mg of anhydrite, which are equivalent to dissolving 0.36 cm3 of this mineral considering a density of 2.981 g/cm3. Additionally, using the average brackish water discharge rate of 144 L/s, an average of 57 g of anhydrite are being dissolved each second per every liter of brackish water. This is a minimal value because some of the sulfate in the water is used by sulfate-reducing bacteria in the subsurface to produce the hydrogen sulfide in the spring water. The anhydrite subject to dissolution is found interbedded in the Cretaceous carbonates, either from the subsurface at 4,000 m below sea level to the carbonate outcrops.
Similarly, we can calculate the volume of halite that is being dissolved by the brackish springs, considering chloride is a conservative element and subtracting the chloride concentration from the rainwater from that of the spring water following Appelo & Postma (1993). The 22 mol/L of chloride in the brackish water can result from dissolution in the subsurface of 22 moles or 1.3 g of halite per liter of brackish water. This mass of halite dissolved is equal to 0.59 cm3 considering a density of 2.168 g/cm3. Alternatively, 118 g of halite are dissolved per second per each liter of brackish water if we use the average discharge rate of 144 L/s.
Even when the brackish springs are oversaturated with respect to calcite and dolomite, their dissolution is still possible due to the common ion-effect of calcium after anhydrite dissolution and by mixing of waters with different compositions. A range of 10 to 80 % of brackish water from the regional aquifers mixes with fresh water from the local aquifer based on their water chemistry. Additionally, sulfuric acid speleogenesis occurs due to the oxidation of hydrogen sulfide to sulfuric acid.
Finally, the increase in the chloride concentration of the fresh water springs with respect to the concentration in rainwater was used to estimate that from the 4000 mm/y of annual precipitation, only 4%, 158 to 182 mm/y, recharge the aquifers. This low percentage is slightly higher than the 3.3% recharge in marls, marly limestone, silts and clays (Sanz et al., 2011), probably because of the relatively small area of carbonate outcrops over the entire region and the lack of recharge in altitudes higher than 1500 m above sea level.
Sulfuric acid is the most obvious speleogenetic mechanism occurring in the caves of the northern Sierra de Chiapas, Mexico due to the high hydrogen sulfide concentration in the spring water. In addition, the location of the springs at a zone of regional and local discharge where waters from different composition converge and mix, and the amount of mixing calculated suggests mixing is also an important speleogenetic mechanism. However, the depth and the time constrains at which these two hypogenic mechanisms occur is still unknown. The relatively low rainwater recharge rate suggests epigenesis is limited. Most likely, the porosity created by dissolution of anhydrite and halite in the subsurface is occluded by the precipitation of calcite. Chemical modeling and petrography will help to elucidate the order of the reactions occurring in the subsurface.


Determining gypsum growth temperatures using monophase fluid inclusions - Application to the giant gypsum crystals of Naica, Mexico: COMMENT, 2014, Garofalo P. S. , Forti P. , Günther D.

Deep conduit flow in karst aquifers revisited, 2014, Kaufmann Georg, Gabrovšek Franci, Romanov Douchko

Caves formed in soluble rocks such as limestone, anhydrite, or gypsum are efficient drainage paths for water moving through the aquifer from the surface of the host rock towards a resurgence. The formation of caves is controlled by the physical solution through dissociation of the host rock by water or by the chemical solution through reactions of the host rock with water enriched with carbon dioxide. Caves as large underground voids are simply the end member of secondary porosity and conductivity characterizing the aquifer.

Caves and their relation to a present or past base level are found both close to a past or present water table (water-table caves) and extending far below a past or present water table (bathy-phreatic caves). One explanation for this different speleogenetic evolution is the structural control: Fractures and bedding partings are preferentially enlarged around more prominent faults, thus the fracture density in the host rock controls the speleogenetic evolution. This widely accepted explanation [e.g. Ford and Ewers, 1978] can be extended by adding other controls, e.g. a hydraulic control: As temperature generally increases with depth, density and viscosity of water change, and particularly the reduction of viscosity due to the increase in temperature enhances flow. This hypothesis was proposed by Worthington [2001, 2004] as a major controlling factor for the evolution of deep-bathyphreatic caves.

We compare the efficiency of structural and hydraulic control on the evolution of a cave passage by numerical means, adding a third control, the chemical control to address the change in solubility of the circulating water with depth. Our results show that the increase in flow through deep bathy-phreatic passages due to the decrease in viscosity is by far outweighted by effects such as the decrease in fracture width with depth due to lithostatic stress and the decrease in solubility with depth. Hence, the existence of deep bathy-phreatic cave passages is more likely to be controlled by the structural effect of prominent faults.


Speleothems in Cova des Pas de Vallgornera: their distribution and characteristics within an extensive coastal cave from the eogenetic karst of southern Mallorca (Western Mediterranean)., 2014, Merino A. , Ginés J. , Tuccimei P. , Soligo M. , Fornós J. J.

The abundance and variety of speleothems are undoubtedly among the remarkable features of Cova des Pas de Vallgornera, the longest cave system in Mallorca Island developed in the eogenetic karst of its southern coast. Due to the monotonous carbonate lithology of the area, most of the speleothems are composed of calcite and in a few cases aragonite, although other minerals are also represented (e.g., gypsum, celestine, barite.). However, in spite of the rather common mineralogy of the speleothems, its distribution results strongly mediated by the lithologic and textural variability linked to the architecture of the Upper Miocene reefal rocks. Apart from a vast majority of speleothem typologies that are ubiquitous all along the cave system, some particular types are restricted to specific sections of the cave. In its landward inner passages, formed in the low permeability back reef facies, a great variety of speleothems associated to perched freshwater accumulations stands out, as well as some non frequent crystallizations like for example cave rims. On the other hand, the seaward part of the cave (developed in the very porous reef front facies) hosts conspicuous phreatic overgrowths on speleothems (POS), which are discussed to show their applications to constrain sea level changes. The factors controlling the distribution of speleothems found in Cova des Pas de Vallgornera are discussed along the paper, focusing the attention on the lithologic, hydrogeologic and speleogenetic conditionings; at the same time some uncommon speleothems, not found in any other cave in Mallorca, are also documented from this locality. Finally, a cognizant endeavour has been undertaken to illustrate with photographs the most remarkable speleothem types represented in the cave.


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