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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 malachite is a cave mineral - cu2(co3)(oh)2 [11].?

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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 enrichment (Keyword) returned 39 results for the whole karstbase:
Showing 1 to 15 of 39
Towards An Air Quality Standard For Tourist Caves : Studies of Carbon Dioxide Enriched Atmospheres In Gaden - Coral Cave, Wellington Caves, N.S.W., 1981, Osborne, R. Armstrong L.

Carbon dioxide enriched atmospheres are not uncommon in Australian caves and have posed a safety problem for cavers. Carbon dioxide enrichment of a tourist cave's atmosphere is a management problem which can only be approached when standards for air quality are applied. In Gaden - Coral Cave two types of carbon dioxide enrichment are recognised; enrichment by human respiration and enrichment from an external source. Standards for air quality in mines and submersible vehicles are applicable to tourist caves. A maximum allowable concentration of 0.5% carbon dioxide is recommended as the safe, but not the most desirable, air quality standard for tourist caves.


STABLE ISOTOPES IN CAVE POOL SYSTEMS - CARLSBAD-CAVERN, NEW-MEXICO, USA, 1990, Ingraham N. L. , Chapman J. B. , Hess J. W. ,
The stable isotopic ratios of drip water, pool water and water vapor collected in remote areas of Carlsbad Cavern, New Mexico, were used to develop a conceptual model of the hydrologic conditions of the cave pools. When considered in terms of open and closed pool systems, the data indicate that the pools in Carlsbad Cavern appear to leak more water than they evaporate. The pools in Carlsbad Cavern range between -43 and -31% in delta-D, -7.4 and -5.9% in delta-O-18, and have EC-values of 365-710 mu-S cm(-1). The water vapor is consistently 80-82% more depleted in D than associated pool water and appears to be under direct isotopic control by the pools. Most of the drip water ranges between -51 and -44% in delta-D, between -8.0 and -6.9% in delta-O-18, and have EC-values of 310-350 mu-S cm(-1), regardless of location of collection in the cave. Drip water collected on popcorn formations (which in this case are formed by evaporation of wall seep) have stable isotopic compositions similar to local pool water; however, they have EC-value of up to 1060 mu-S cm(-1). In addition, a small, closed pool near the Lake of the Clouds has stable isotopic compositions similar to those of the Lake and elevated EC-values of up to 9500 mu-S cm(-1). The degree of stable isotopic enrichment that evaporating waters can obtain in the Cavern is limited by exchange with the water vapor which, in turn, appears to be controlled by the pools

CONTRIBUTION TO THE GEOCHEMISTRY OF THE RARE-EARTH ELEMENTS IN THE KARST-BAUXITE DEPOSITS OF YUGOSLAVIA AND GREECE, 1991, Maksimovic Z. , Panto G. ,
Distribution of the rare earth elements (REE, including La-Lu, Y) along vertical profiles is presented for four well-studied karst-bauxite deposits from Yugoslavia and Greece. For one deposit from Jamaica, La and Y contents are given. All deposits display a downward enrichment of the REE culminating at the base, where authigenic REE minerals have been formed. This REE pattern is characteristic for karst-bauxites formed in situ through the bauxitization of argillaceous material collected in karstic depressions. In this way, the highest enrichment of the REE in the sedimentary cycle has been achieved. Both light REE (LREE) and heavy REE (HREE) were 'mobile' during the bauxitization process and were concentrated at the alkaline barrier of the carbonate footwall. In four out of five studied deposits, the ratios SIGMA-LREE/SIGMA-HREE and La/Y in bauxites decrease downwards, showing an enrichment of the HREE relative to LREE. A further fractionation of the REE took place in the formation of authigenic REE minerals, which exhibit a very high enrichment of LREE relative to HREE. In spite of this, these minerals and bauxites in four studied deposits have a general similarity of the REE distribution patterns, which indicate a close genetic relationship

KINETIC ENRICHMENT OF STABLE ISOTOPES IN CRYOGENIC CALCITES, 1992, Clark Id, Lauriol B,
The C-13 and O-18 contents of cryogenic calcites formed by expulsion during the freezing of bicarbonate groundwaters are examined. Samples from karst caves within the permafrost region of northern Yukon, Canada, have deltaC-13-values as high as 17.0 parts per thousand, representing the most isotopically enriched freshwater carbonates yet reported. To account for such enrichments, calcium bicarbonate solutions were frozen and sublimated under controlled laboratory conditions. The rapid rate of reaction is shown to effectively preclude isotopic equilibration during bicarbonate dehydration, resulting in a kinetic partitioning of C-13 between CO2 and CaCO3. We find a value of 31.2 1.5 parts per thousand for 1000ln13alpha(KIE)(13alpha(KIE) = 1.032), which is considerably greater than the equilibrium fractionation factor (13epsilon(CaCO3-CO2)) of 10.3 parts per thousand at 0-degrees-C. This kinetic isotope effect (KIE) represents the ratio of the absolute reaction rate constants (13k(d)/12k(d)) for the two isotopic species during the dehydration of dissolved bicarbonate. Similar results for deltaO-18-values confirm that the reaction proceeds without isotope exchange. The KIE of O-18 is determined to be 1.006 for this reaction at 0-degrees-C. These data are compared with the KIE which occurs during the reverse reaction: CO2 hydroxylation by reaction with OH- in hyperalkaline waters

DISSOLUTION OF ARAGONITE-STRONTIANITE SOLID-SOLUTIONS IN NONSTOICHIOMETRIC SR(HCO3)2-CA(HCO3)2-CO2-H2O SOLUTIONS, 1992, Plummer L. N. , Busenberg E. , Glynn P. D. , Blum A. E. ,
Synthetic strontianite-aragonite solid-solution minerals were dissolved in CO2-saturated nonstoichiometric solutions of Sr(HCO3)2 and Ca(HCO3)2 at 25-degrees-C. The results show that none of the dissolution reactions reach thermodynamic equilibrium. Congruent dissolution in Ca(HCO3)2 solutions either attains or closely approaches stoichiometric saturation with respect to the dissolving solid. In Sr(HCO3)2 solutions the reactions usually become incongruent, precipitating a Sr-rich phase before reaching stoichiometric saturation. Dissolution of mechanical mixtures of solids approaches stoichiometric saturation with respect to the least stable solid in the mixture. Surface uptake from subsaturated bulk solutions was observed in the initial minutes of dissolution. This surficial phase is 0-10 atomic layers thick in Sr(HCO3)2 solutions and 0-4 layers thick in Ca(HCO3)2 solutions, and subsequently dissolves and/or recrystallizes, usually within 6 min of reaction. The initial transient surface precipitation (recrystallization) process is followed by congruent dissolution of the original solid which proceeds to stoichiometric saturation, or until the precipitation of a more stable Sr-rich solid. The compositions of secondary precipitates do not correspond to thermodynamic equilibrium or stoichiometric saturation states. X-ray photoelectron spectroscopy (XPS) measurements indicate the formation of solid solutions on surfaces of aragonite and strontianite single crystals immersed in Sr(HCO3)2 and Ca(HCO3)2 solutions, respectively. In Sr(HCO3)2 solutions, the XPS signal from the outer approximately 60 angstrom on aragonite indicates a composition of 16 mol% SrCO3 after only 2 min of contact, and 14-18 mol% SrCO3 after 3 weeks of contact. The strontianite surface averages approximately 22 mol% CaCO3 after 2 min of contact with Ca(HCO3)2 solution, and is 34-39 mol% CaCO3 after 3 weeks of contact. XPS analysis suggests the surface composition is zoned with somewhat greater enrichment in the outer approximately 25 angstrom (as much as 26 mol% SrCO3 on aragonite and 44 mol% CaCO3 on strontianite). The results indicate rapid formation of a solid-solution surface phase from subsaturated aqueous solutions. The surface phase continually adjusts in composition in response to changes in composition of the bulk fluid as net dissolution proceeds. Dissolution rates of the endmembers are greatly reduced in nonstoichiometric solutions relative to dissolution rates observed in stoichiometric solutions. All solids dissolve more slowly in solutions spiked with the least soluble component ((Sr(HCO3)2) than in solutions spiked with the more soluble component (Ca(HCO3)2), an effect that becomes increasingly significant as stoichiometric saturation is approached. It is proposed that the formation of a nonstoichiometric surface reactive zone significantly decreases dissolution rates

Ce-anomalies in the textural components of upper Cretaceous karst bauxites from the Apulian carbonate platform (southern Italy), 1997, Mongelli G. ,
The chemical and mineralogical composition of Upper Cretaceous Apulian karat bauxites (southern Italy) and their textural components, i.e. ooids and matrix, has been studied. The bulk samples are composed of boehmite, hematite, anatase and kaolinite. The samples collected along a vertical profile show a downward enrichment for the elements Rb, Sr, Ba, Ni and Cr. A similar distribution is observed in deposits bauxitized in situ at the expense of matrix-like material collected in the karst zone. The ooids consist mainly of hematite with minor boehmite and anatase, whereas in the matrix boehmite prevails on hematite, kaolinite and anatase. In the void fillings in the matrix there is a Ca-fluorocarbonate having a Ce/Ce* of 5.8. The ooids, with the exception of Ce, are enriched in REE and show a higher (La/Yb)(ch) ratio relative to the matrix. The matrix exhibits a large positive Ce-anomaly whereas the ooids have negative Ce-anomaly. The Ce fractionation between the textural components can be explained assuming: (1) Ce oxidation and cerianite precipitation in the uppermost part of the deposits; (2) scavenging of REE from Ce-depleted percolating solutions by the iron oxide, inducing both REE-enrichment and Ce-negative anomalies in ooids; (3) remobilization of cerium as fluoride complex, as a consequence of more acidic conditions in the uppermost part of the deposit, and precipitation of Ce3 as fluorocarbonate mineral toward the carbonate bedrock barrier, at alkaline pH. Alternatively, the cerium remobilization, possibly as a carbonate-fluoride complex, could be due to an Eh decrease, favoured by a rise of the groundwater level. (C) 1997 Elsevier Science B.V

Groundwater circulation and geochemistry of a karstified bank-marginal fracture system, South Andros Island, Bahamas, 1997, Whitaker Fiona F. , Smart Peter L. ,
On the east coast of South Andros Island, Bahamas, a major bank-marginal fracture system characterised by vertically extensive cavern systems (blue holes) is developed sub-parallel to the steep-sided deep-water re-entrant of the Tongue of the Ocean. In addition to providing a discharge route for meteoric, mixed and geochemically evolved saline groundwaters, a strong local circulation occurs along the fracture system. This generates enhanced vertical mixing within voids of the fracture system, evidenced by the increasing mixing zone thickness, and the thinning and increasing salinity of brackish lens waters from north to south along the fracture system. Furthermore, tidally driven pumping of groundwaters occurs between the fracture and adjacent carbonate aquifer affecting a zone up to 200 m either side of the fracture.The resultant mixing of groundwaters of contrasting salinity and within and along the fracture system and with the surrounding aquifer waters, together with bacterial oxidation of organic matter, generates significant potential for locally enhanced diagenesis. Undersaturation with respect to calcite within the fresh (or brackish)-salt water mixing zone is observed in the fracture system and predicted in the adjacent aquifer, while mixing between the brackish fracture lens and surrounding high fresh waters causes dissolution of aragonite but not calcite. The latter gives rise to considerable secondary porosity development, because active tidal pumping ensures continued renewal of dissolutional potential. This is evidenced by calcium and strontium enrichment in the brackish lens which indicates porosity generation by aragonite dissolution at a maximum rate of 0.35% ka-1, up to twice the average estimated for the fresh water lens. In contrast saline groundwaters are depleted in calcium relative to open ocean waters suggesting the formation of calcite cements.The development of a major laterally continuous cavernous fracture zone along the margin of the carbonate platform permits enhanced groundwater flow and mixing which may result in generation of a diagenetic `halo' at a scale larger than that generally recognised around syn-sedimentary fractures in fossil carbonates. This may be characterised by increased secondary porosity where a relative fall in sea-level results in exposure and formation of a meteoric groundwater system, or cementation by `marine' calcite both below this meteoric system, and where the bank surface is flooded by seawater

delta N-15 of nitrate derived from explosive sources in a karst aquifer beneath the Ammunition Burning Ground, Crane Naval Surface Warfare Center, Indiana, USA, 1998, Dignazio Fj, Krothe Nc, Baedke Sj, Spalding Rf,
Military institutions involved in the production and demolition of explosives, propellants, and pyrotechnics have the potential to degrade groundwater aquifers through the addition of numerous contaminants including nitrate. A nitrate plume has been identified in a karst aquifer beneath the Ammunition Burning Ground (ABG) at the Crane Naval Surface Warfare Center, Indiana, USA. Wells located in the vicinity of surface impoundments and bum pans used for treatment of explosive materials show the highest concentrations of nitrate ranging from 11.2 to 19.6 mg l(-1) as NO3-. Little is known about the isotopic composition of nitrates originating from these processes. Eight wells within the ABG were sampled and analyzed for nitrogen isotopic composition of nitrate. An enrichment in the delta(15)N (delta(15)N = .9, .0, .1. and .5 parts per thousand) occurred at four wells located near the primary areas of disposal activities within the ABG. Four wells located near the outer limits of the ABG had delta(15)N values significantly lower than those observed in the central area of the ABG (delta(15)N = .0, .1, .6, and .0 parts per thousand). Soil samples and burn-pan ash samples were collected and analyzed for the nitrogen isotopic composition of nitrate. Three soil nitrate samples had low delta(15)N values of -1.7, -1.8. and .2 parts per thousand. The burn-pan ash sample produced nitrate with a delta(15)N value of .9 parts per thousand. The observed enrichment in delta(15)N from samples taken from wells located near the ABG has been postulated to be a result of photodegradation or biochemical modification of RDX and TNT contaminated sludges and volatilization of NH3 in storage lagoons within the ABG. (C) 1998 Elsevier Science B.V. All rights reserved

Evaluation of terra rossa geochemical baselines from Croatian karst regions, 1999, Miko S. , Durn G. , Prohic E. ,
In karst regions of Croatia, regolith is the only favourable medium for geochemical mapping. Mediterranean climate and good drainage due to hard, fissured, permeable limestones and dolomites result in a spacious distribution of terra rossa (FAO-luvisols and cambisols) - a polygenetic type of soil. Samples of terra rossa from coastal and inland Croatian Dinaric karst terrains were collected during the initial studies for the Geochemical Map of Croatia at a density of 1 site/25 km(2). A total of 87 terra rossa soil samples taken from a depth of 5-25 cm together with 27 samples from deeper profiles (down to 850 cm) were analysed for total Al, Ba, Ca, Co, Cr, Cu, Fe, Ga, La, Mg, Mn, Ni, Pb, Na, Sr, Ti, V and Zn concentrations. A stoichiometric approach was applied by modeling of terra rossa baselines on the basis of Linear regressions of metals on Al and the calculation of enrichment factors (EF and CEFs) on the basis of soil standards. A noticeable enrichment of Pb was found in surface samples compared to the terra rossa deeper in the soil profile. Using these baseline relationships, an attempt is made to partition terra rossa metal concentrations into natural and anthropogenic fractions. Also, the models from both polluted and less polluted (uninhabited) karstic terrains improve the comparability of element contents through correction of variable background concentrations. A comparison of elemental concentrations revealed that due to contributions of bauxite debris, a number of studied samples is enriched in Cr and Ni (also with variable amounts of boehmite). The corrections will serve to reduce data variability and to increase the detection of spatial and temporal differences presented on the geochemical maps. (C) 1999 Elsevier Science B.V. All rights reserved

Speleothem evidence for Holocene fluctuations of the prairie-forest ecotone, north-central USA, 1999, Denniston Rf, Gonzalez La, Baker Rg, Asmerom Y, Reagan Mk, Edwards Rl, Alexander Ec,
Carbon and oxygen isotopic trends from seven Midwestern speleothems record significant offsets in the timing of middle-Holocene vegetation change. Interactions of dry Pacific and moist Gulf of Mexico air masses maintained a sharp moisture gradient across Iowa, Minnesota, and Wisconsin such that the arrival of prairie was offset by 2000 years between caves and pollen sites located only 50 km apart. Oxygen isotopes shift concomitantly with carbon in most cases, although these changes are believed to represent increased evaporative enrichment of 18O prior to infiltration during the prairie period

Evidence for Geomicrobiological Interactions in Guadalupe Caves, 2000, Northup, D. E. , Dahm, C. N. , Melim, L. A. , Spilde, M. N. , Crossey, L. J. , Lavoie, K. H. , Mallory, L. M. , Boston, P. J. , Cummingham, K. I. , Barns, S. M.
Caves in the Guadalupe Mountains offer intriguing examples of possible past or present geomicrobiological interactions within features such as corrosion residues, pool fingers, webulites, u-loops, and moonmilk. Scanning electron microscopy, transmission electron microscopy, molecular biology techniques, enrichment cultures, bulk chemistry, and X-ray diffraction techniques have revealed the presence of iron- and manganese-oxidizing bacteria in corrosion residues, which supports the hypothesis that these organisms utilize reduced iron and manganese from the limestone, leaving behind oxidized iron and manganese. Metabolically active populations of bacteria are also found in punk rock beneath the corrosion residues. Microscopic examination of pool fingers demonstrates that microorganisms can be inadvertently caught and buried in pool fingers, or can be more active participants in their formation. Enrichment cultures of moonmilk demonstrate the presence of a variety of microorganisms. Humans can have a deleterious impact on microbial communities in Guadalupe caves

The role of evaporites in the genesis of base metal sulphide mineralisation in the Northern Platform of the Pan-African Damara Belt, Namibia: geochemical and fluid inclusion evidence from carbonate wa, 2000, Chetty D, Frimmel He,
The Otavi Mountain Land is a base metal sulphide ore province in northern Namibia where deposits are hosted by platform carbonates of the Otavi Group in a foreland fold-and-thrust belt on the northern edge of the Pan-African Damara Belt. Deposits have been classified as the Berg Aukas- or Tsumeb-types, based on differences in ore association? stratigraphic position and geochemistry of ores and gangue carbonates. Mineralisation at these deposits is accompanied by carbonate alteration in the form of dolomite and calcite veins, carbonate recrystallisation, calcitisation and carbonate silicification. Based on cathodoluminescence imaging, trace and rare earth element (REE), O and C isotope, and fluid inclusion data, a series of carbonate generations, constituting wall rock alteration around the Tsumeb and Kombat (Tsumeb-type) and Berg Aukas (Berg Aukas-type) deposits, was established. Similar data obtained on the recently discovered Khusib Springs deposit indicate a strong affinity to Tsumeb-type deposits. Tsumeb-type deposits are distinguished from Berg Aukas-type deposits by having trace element and REE concentrations that are significantly higher in the alteration products compared to the carbonate host rocks. Only around Tsumeb-type deposits a relative enrichment in light REE is noted for the hydrothermal carbonate generations that are cogenetic with the main stage of mineralisation. Microthermometric results from fluid inclusions in carbonate alteration phases and associated quartz indicate relatively high salinity (17-33 wt% NaCl equivalent) for the main mineralising and subsequent sulphide remobilisation stages at the deposits investigated. Estimated mineralisation temperatures are significantly higher for Tsumeb-type deposits (370-405 degrees C) with early sulphide remobilisation in Tsumeb at 275 degrees C, whereas they are lower at Berg Aukas (up to 255 degrees C). Fluid inclusion leachate analysis suggests that most of the observed salinity can be ascribed to dissolved, predominantly Ca- and Mg-carbonates and chlorides with subordinate NaCl. Na-Cl-Br leachate systematics indicate a derivation of the fluid salinity from the interaction with evaporitic rocks en route. Tsumeb-type mineralisation is interpreted to be derived from fluids expelled during Pan-African orogeny in the more intensely deformed internal zones of the Damara Belt further south. When the high salinity fluids reached the carbonate platform after having scavenged high concentrations of base metals, base metal sulphide precipitation occurred in zones of high porosity, provided by karst features in the carbonate sequence. Results obtained for the Berg Aukas-type deposits emphasise their derivation from basinal brines, similar to Mississippi Valley-type deposits, and confirm that mineralisation of the Berg Aukas- and Tsumeb-types are both spatially and temporally distinct

Geochemical and mineralogical characteristics of Fe-Ni- and bauxitic-laterite deposits of Greece, 2000, Eliopoulos Dg, Economoueliopoulos M,
Contiguous vertical sample profiles from Ni-laterite deposits with in situ features (Kastoria, Profitis Ilias, and Tsouka) and allochthonous Ni- and bauxitic-laterite deposits in contact with basement limestone (Nissi) and bauxitic-laterites lying on peridorite (Parhari) were analyzed for major, trace (including Tn and U), rare earth and platinum-group elements (REE and PGE, respectively). In addition, minerals with emphasis to chromite grains found as residual components in these laterites, inherited from the ophiolitic parent rocks, were analyzed by microprobe. Low Al2O3, TiO2, REE, Th and U contents are common features of the Kastoria, Bitincka and Tsouka deposits. Tn contrast, elevated REE contents are present in the karst-type bauxitic- and Ni-laterite ores of Nissi and bauxitic-laterites of Parhari. The bauxitic-laterite deposit of Nissi attains REE contents of thousands parts per million in samples from the contact between the lowest part of the bauxitic-laterite and the footwall limestone. Highest contents of Th and U are found in the bauxitic-laterites, with Th ranging from 4 to 28 ppm and U from 4 to 66 ppm. In general, increasing Al contents are accompanied by elevated Ti, REE, Tn and U contents at the Parhari and Nissi laterite deposits. Goethite, is the dominant mineral in all Ni-laterite profiles studied, while boehmite co-existing with goethite is common in the bauxitic-laterites at Nissi and Parhari. Goethite exhibits variable Al contents, while the Al/Fe ratio increases towards the top of the profiles. The PGE concentrations are generally low, ranging from less than 100 ppb to a few hundred parts per billion. The lowest values - lower than in the bedrock - were recorded in the saprolite zone. A certain enrichment in Pt (up to 48 ppb), Pd (7 ppb), and Au (16 ppb) is recorded in the reddish altered peridotite overlying the saprolite zone at Profitis Ilias. The Fe-Ni ore overlying the reddish altered peridotite has the highest Os values (14 ppb), Ir (32 ppb), Ru (66 ppb), Rh (20 ppb), Pt (86 ppb), and Pd (186 ppb). Gold contents are below 36 ppb. An increasing Pt/Pd ratio from 3.0 in Fe-Ni-laterites to 6.0 in bauxitic-laterites is apparent. Both whole rock compositions and mineral chemistry of laterites indicate that major controlling factors of the composition of the bauxitic-laterites are the conditions during transportation/deposition of the weathered material and during diagenesis/metadiagenesis stage rather than parent mafic ophiolitic rocks. The comparison between the primary composition of chromite in the saprolite zone and the overlying Fe-Ni ore may provide evidence for the discrimination between Fe-Ni ore linked to in situ weathering and ore derived by transportation to some extent of elastic and chemical material. (C) 2000 Elsevier Science B.V. All rights reserved

Element geochemistry of weathering profile of dolomitite and its implications for the average chemical composition of the upper-continental crust - Case studies from the Xinpu profile, northern Guizho, 2000, Ji H. B. , Ouyang Z. , Wang S. J. , Zhou D. Q. ,
Geochemical behavior of chemical elements is studied in a dolomitite weathering profile in upland of karst terrain in northern Guizhou. Two stages can be recognized during the process of in situ weathering of dolomitite: the stage of sedentary accumulation of leaching residue of dolomitite and the stage of chemical weathering evolution of sedentary soil. Ni, Cr, Mo, W and Ti are the least mobile elements with reference to Al. The geochemical behavior of REE is similar to that observed in weathering of other types of rocks. Fractionation of REE is noticed during weathering, and the two layers of REE enrichments are thought to result from downward movement of the weathering front in response to changes in the environment. It is considered that the chemistry of the upper part of the profile, which was more intensively weathered, is representative of the mobile components of the upper curst at the time the dolomitite was formed, while the less weathered lower profile is chemically representative of the immobile constitution. Like glacial till and loess, the 'insoluble' materials in carbonate rocks originating from chemical sedimentation may also provide valuable information about the average chemical composition of the upper continental crust

Hydrochemistry of the Cesme geothermal area in western Turkey, 2001, Gemici U, Filiz S,
Hydrochemical characterization of thermal waters discharged from springs and wells in the Cesme geothermal area show that there are two groups. One is of thermal waters from a lower aquifer composed of Triassic karst limestones, which are the main potential reservoir of the area. They are of Na-Cl type and between 37 and 62degreesC and have total dissolved solids (TDS) with around 35 000 mg/l. The other group are thermal waters derived from an upper aquifer formed by Neogene terrestrial sediments. These have lower discharge temperatures (37-40degreesC) and lower TDS values due to their having mixed with local groundwater before emerging. The isotopic and chemical data shows that the initial aqueous solution is a mixture of modern seawater and meteoric water in various proportions. Enrichment in delta(18)O and deltaD values and tritium contents (8 1 TU) of thermal waters reflect a rapid circulation and the contribution of modern seawater. The thermal waters are undersaturated with respect to gypsum but oversaturated, or around equilibrium, with respect to dolomite and calcite. Several chemical geothermometry techniques applied to Cesme geothermal waters gave estimated reservoir temperatures of around 85-100degreesC. (C) 2001 Elsevier Science B.V. All rights reserved

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