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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. ...

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. ...

Speleology in Kazakhstan

Shakalov on 11 Jul, 2012
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 burst is 1. periods of heavy rainfall [16]. 2. an explosive breaking of brittle rock material (e.g., rock burst in a deep mine tunnel).?

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Your search for mixing processes (Keyword) returned 8 results for the whole karstbase:
Formation of Willemite in Hydrothermal Environments, 2003, Brugger J, Mcphail Dc, Wallace M, Waters J,
Willemite (zinc silicate) is the main zinc mineral in some carbonate-hosted ore deposits (e.g., Franklin, New Jersey; Vazante, Brazil; Beltana, South Australia; Kabwe, Zambia). Recent interest in these unconventional zinc deposits has increased because of high zinc grades that exceed 40 wt percent, relatively low environmental impact of ore processing owing to the lack of acid-generating sulfides in the waste, and advances in ore processing technologies. In the past, most metallogenic studies proposed formation of willemite deposits by supergene or hypogene alteration of preexisting sulfide deposits. However, recent data on the Vazante, Beltana, and Kabwe deposits indicate willemite crystallization at temperatures in excess of 150{degrees}C, raising the possibility of primary precipitation from hydrothermal fluids. We use numerical geochemical modeling to examine the formation of willemite under hydrothermal conditions. Activity-activity diagrams reveal that, in the presence of dissolved sulfur and quartz, willemite instead of sphalerite will precipitate under oxidizing (e.g., hematite-stable, sulfate-predominant) and alkaline (pH higher than K feldspar-muscovite-quartz) conditions. Willemite also becomes more stable, relative to sphalerite, at high temperature, and willemite can coexist with magnetite at 300{degrees}C. The stabilities and solubilities of sphalerite, willemite, smithsonite, hydrozincite, and zincite were calculated for wide ranges of temperature (25{degrees}-300{degrees}C), chloride concentration, dissolved sulfur and carbon concentrations, pH, quartz saturation, and oxidation potential. Plots of the solubility of the different minerals as a function of two variables (e.g., temperature and redox state; pH and redox state) allow us to predict the effects of changing chemical conditions, which in turn permits an estimate of the efficiency of particular precipitation processes. Cooling is an effective process for precipitating sphalerite but not willemite, whereas pH increase (e.g., by acidic fluids reacting with carbonates) is effective for precipitating willemite but not sphalerite. Dynamic geochemical models that simulate physicochemical processes are used to understand the formation of the Beltana willemite deposit in the Adelaide geosyncline of South Australia. This small, high grade deposit (850,000 t at 36% Zn) is hosted in dolomite of the Cambrian Ajax Limestone, next to a tectonic contact with the diapiric, halite-bearing clastic sediments of the Callanna Group. The orebody is associated with hematite alteration and is characterized by the total absence of sulfides; willemite is the only zinc ore mineral, and the arsenate hedyphane (Ca2Pb3[AsO4]3Cl) is the main lead mineral. The model results show that willemite will precipitate in response to water-rock interaction and fluid mixing processes at temperatures above 120{degrees}C. The presence of arsenate in the hydrothermal fluid is likely to have been important at Beltana; in arsenate-absent models sulfate is reduced to sulfide by the precipitation of ferrous iron as hematite, resulting in the precipitation of sphalerite and galena. In contrast, in models including arsenate the reduction of sulfate to sulfide is inhibited and willemite is predicted to precipitate

A conceptual model of flow and transport in a karst aquifer based on spatial and temporal variations of natural tracers, 2003, Perrin, Jerome

Karst aquifers represent an important groundwater resource world-wide. They are highly vulnerable to contamination due to fast transport through the system and limited attenuation of contaminants. The two main hydrogeological approaches developed for studying flow and transport are: inference of the
system structure from karst spring hydrographs and chemographs; numerical modelling of flow and transport using a theoretical distribution of flow and transport field parameters. These two approaches lack of validation by detailed field measurements and observations. The main objective of this thesis is to “fill the gap” existing between field and model data. Observations of flow and transport parameters at several locations within the system were used to develop a conceptual model. This model was then compared to the existing models.
The main field test site is the Milandre karst aquifer, located in the Swiss tabular Jura. Natural tracers (major ions, oxygen-18, specific conductance) and discharge were measured on the underground river, its main tributaries, percolation waters, and the main spring. These data were collected on a long-term basis in order to assess the spatial variability of the parameters, and on a short time scale (i.e. flood events) in order to investigate the dynamic processes. Complementary sites (Brandt and Grand Bochat) were used for more observations at the base of the epikarst.
The proposed conceptual model considers four sub-systems: the soil zone, the epikarst, the unsaturated zone, and the phreatic zone. Each has its own specificity with respect to flow and transport. The soil zone controls the actual infiltration into the system. It contributes efficiently to groundwater storage. It mixes quickly stored water with fresh infiltrated water. Its thickness determines land-use: thick soils are generally cultivated whereas thin soils are under forested areas. The solutes concentration of soil waters depends on land-use for pollution-related parameters (nitrate, chloride, sulfate, potassium, sodium). Moreover the soil zone is the main source of CO2 which controls the limestone dissolution-related parameters. The epikarst zone contributes largely to groundwater storage. It distributes groundwater into vadose flow through conduits, and base flow through low permeability volumes (LPV) in the unsaturated zone. It is the sub-system where dissolution-related parameters are mostly acquired.
The unsaturated zone is seen as a transmissive zone connecting the epikarst to the horizontal conduit network of the phreatic zone. In case of flood events, some dissolution still occurs in this sub-system.
The phreatic zone is the partly flooded conduit network draining groundwater to the spring. It collects waters issued from the unsaturated zone, mixes the tributaries, and drain the water towards the discharge area. The role of phreatic storage appears to be limited for both hydraulics and transport.
Tributary mixing is a prominent process that shapes spring chemographs during flood events. In steady-state conditions, base flow is mainly sustained by the epikarst reservoir. Tracer concentrations are stable as the chemical equilibrium is already reached in the epikarst. Waters issued from the different tributaries mix in the conduit network, and the spring chemistry is the result of this mixing.
During flood events, transient flow induces non-linear mixing of the tributaries. The respective contributions of the tributaries change throughout the flood, and the spring chemographs vary accordingly. In case of important recharge, waters issued from other sources than the epikarst participate to the flood. First, soil water reaches the phreatic zone. Its characteristics are a dampened isotopic signal, and ionic concentrations differing from those of the epikarst. Second, fresh water directly issued from rainfall, may reach the phreatic zone. Its characteristics are a varying isotopic signal, and diluted ionic concentrations. The mixing components participating to the flood are controlled by the actual infiltration volume (or height). The limestone dissolution process is effective for the fresh and soil components of flow. However mixing processes play a more important role than dissolution for shaping the spring chemographs.
From a practical point of view, the project confirmed the prominent role of the soil zone and the epikarst on the solute transport in karst systems. This was already integrated in karst vulnerability mapping methods recently developed (EPIK, PI, VULK).

http://doc.rero.ch/record/2604/files/these_PerrinJ.pdf


Nonsulfide and sulfide-rich zinc mineralizations in the Vazante, Ambrsia and Fagundes deposits, Minas Gerais, Brazil: Mass balance and stable isotope characteristics of the hydrothermal alterati, 2007, Soares Monteiro Lena Virgí, Nia, Bettencourt Jorge Silva, Juliani Caetano, De Oliveira Tolentino Flvio
The Vazante Group hosts the Vazante nonsulfide zinc deposit, which comprises high-grade zinc silicate ore (ZnSiO4), and late-diagenetic to epigenetic carbonate-hosted sulfide-rich zinc deposits (e.g. Morro Agudo, Fagundes, and Ambrósia). In the sulfide-rich deposits, hydrothermal alteration involving silicification and dolomitization was related with ground preparation of favorable zones for fluid migration (e.g. Fagundes) or with direct interaction with the metalliferous fluid (e.g. Ambrósia). At Vazante, hydrothermal alteration resulted in silicification and dolomite, siderite, jasper, hematite, and chlorite formation. These processes were accompanied by strong relative gains of SiO2, Fe2O3(T), Rb, Sb, V, U, and La, which are typically associated with the nonsulfide zinc mineralization. All sulfide-rich zinc ores in the district display a similar geochemical signature suggesting a common metal source from the underlying sedimentary sequences. Oxygen and carbon isotope compositions of hydrothermally altered rocks reveal a remarkable alteration halo at the Vazante deposit, which is not a notable feature in the sulfide-rich deposits. This pattern could be attributed to fluid mixing processes involving the metalliferous fluid and channelized meteoric water, which may control the precipitation of the Vazante nonsulfide ore. Sulfide deposition resulted from fluid?rock interaction processes and mixing between the ascending metalliferous fluids and sulfur-rich tectonic brines derived from reduced shale units.

MANAGING AQUIFER RECHARGE (MAR): ASSESSMENT OF GROUNDWATER RESOURCES IN THE SAND, 2007, Kim Thoa Nguyen Thi, Giuseppe Arduino, Paolo Bono, Nguyen Van Giang, Phan Thi Kim Van, Bui Tran Vuong, Dinh Thi Bich Lieu, Brun Clarissa, Chiara Fiori, Fabrizio Gherardi, Francesca Zucco
Extensive geophysical, hydrological and isotopic investigations, including drilling campaigns, long term pumping tests and continuous monitoring of ground water levels in 4 monitoring wells, show that the sand dunes formation is characterized by the occurrence of an unconfined porous aquifer, of variable thickness (40 to 60 m), emerging at ground level in depressed morphological areas (20 to 30 m a.s.l.) where it forms intradune wetlands or natural reservoirs (lakes), and discharging directly to the sea through single springs (up to 200 l/s), linear springs and mostly by diffuse seepage along the shoreline (approximate discharge equal to 30 l/s per km). Hydrochemical and isotopic characterization of surface and groundwater in different periods, shows that the sand dunes aquifers, with electrical conductivity ranging from 50 to 500 μS/cm, are composed of different water types, characterized by complex mixing processes. The site chosen for the artificial recharge, where a 162 days pumping test has been carried out, proved that the use of the bank filtration technique has considerably improved the quality of water, originally highly contaminated by colibacteria. The well field developed within the present project is now capable of supplying 220 m3/day of good water quality to the Hong Phong community, recurrently affected by severe droughts. This project is part of UNESCO-IHP (International Hydrological Programme) and IMET (Italian Ministry for the Environment and Territory) Water Programme for Africa, Arid and Water Scarce zone - Viet Nam component funded by IMET. Funds for the Viet Nam project were also made available from the Vietnamese Government, and from ICSU, the International Council for Science and UNESCO Office Jakarta.

ON THE ROLE OF HYPOGENE SPELEOGENESIS IN SHAPING THE COASTAL ENDOKARST OF SOUTHERN MALLORCA (WESTERN MEDITERRANEAN), 2009, Gines J. , Gines A. , Fornos J. , Merino A. , Gracia F.

The Migjorn region is one of the main karst areas in the island of Mallorca (Balearic Archipelago, Western Mediterranean) and has abundant coastal caves developed in Upper Miocene reefal carbonate rocks. In general terms it is an eogenetic karst platform in which littoral mixing dissolution processes usually represent the most important speleogenetic mechanism to be considered. Nevertheless, recent explorations in Cova des Pas de Vallgornera (Llucmajor Municipality), that nowadays has development exceeding 59 km of passages, raise interesting questions about the genesis of this outstanding littoral cave. An artificial entrance located at about 500 m from the coast line gives access to a complex assemblage of chambers and galleries, partially drowned by brackish waters, whose spatial disposition and morphological characteristics are strongly conditioned by the internal architecture of the Upper Miocene reef. The inner part of the cave consists of an extensive network of galleries that contain morpho-sedimentary features pointing to the possible participation of hypogene speleogenesis in the excavation of the system. Solutional features related to rising flow are abundant, together with Mn- and Fe-rich deposits and some minerals not known up to the l present in other caves of the region. The hypogene speleogenesis mechanisms that may have acted in Cova des Pas de Vallgornera could be associated with the feeble geothermal anomalies existing currently in the Llucmajor platform, related to important SW-NE faults which delimit the Campos subsidence basin in the southern end of Mallorca Island. The genesis of the cave system seems to be a complex matter including, besides coastal mixing processes and epigenic meteoric recharge, the participation of hypogene speleogenesis in an eogenetic unconfined setting.


Mixing of water in a carbonate aquifer, southern Italy, analysed through stable isotope investigations, 2013, Petrella E. , Celico F.

Mixing of water was analysed in a carbonate aquifer, southern Italy, through stable isotope investigations (18O,δ2H). The input signal (rainwater) was compared with the isotopic content of a 35-meter groundwater vertical profile, over a 1-year period. Within the studied aquifer, recharge and flow are diffuse in a well-connected fissure network.

At the test site, the comparison between input and groundwater isotopic signals illustrates that no efficient mixing takes place in the whole unsaturated zone, between the fresh infiltration water and the stored water.

When analysing the stable isotope composition of groundwater, significant variations were observed above the threshold elevation of 1062 m asl, while a nearly constant composition was observed below the same threshold. Thus, temporal variations in stable isotope composition of rainwater are completely attenuated just in the deeper phreatic zone.

On the whole, taking into consideration also the results of previous studies in the same area, the investigations showed that physical characteristics of the carbonate bedrock, as well as aquifer heterogeneity, are factors of utmost importance in influencing the complete mixing of water. These findings suggest a more complex scenario at catchment scale.


Geochemistry and isotope geochemistry of the Monfalcone thermal waters (northern Italy): inference on the deep geothermal reservoir, 2013, Petrini R. , Italiano F. , Ponton M. , Slejko F. F. , Aviani U. , Zini L.

Geochemical investigations were carried out to define the origin of the low- to moderate-temperature thermal waters feeding the Monfalcone springs in northern Italy. Chemical data indicate that waters approach the composition of seawater. Mixing processes with cold low-salinity waters are highlighted. The δ18O and δD values are in the range −5.0 to −6.4 ‰, and −33 to −40 ‰, respectively, suggesting the dilution of the saline reservoir by karst-type freshwaters. A surplus of Ca2+ and Sr2+ ions with respect to a conservative mixing is ascribed to diagenetic reactions of the thermal waters with Cretaceous carbonates at depth. The measured Sr isotopic composition (87Sr/86Sr ratio) ranges between 0.70803 and 0.70814; after correction for the surplus Sr, a 87Sr/86Sr ratio indicating Miocene paleo-seawater is obtained. The dissolved gases indicate long-lasting gas–water interactions with a deep-originated gas phase of crustal origin, dominated by CO2 and marked by a water TDIC isotopic composition in the range −5.9 to−8.8 and helium signature with 0.08 < R/Ra < 0.27, which is a typical range for the crust. A possible scenario for the Monfalcone thermal reservoir consists of Miocene marine paleowaters which infiltrated through the karstic voids formed within the prevalently Cretaceous carbonates during the upper Eocene emersion of the platform, and which were entrapped by the progressive burial by terrigenous sediments.


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


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