Search results for "Serpentinization"

showing 4 items of 4 documents

Thermomineral waters of Greece: geochemical characterization

2020

75 °C). In terms of pH most results vary from 5.5 to 823 °C) ii) warm (23 40 °C) iii) thermal (40 75 °C) and iv) hyperthermal (&gtfew springs show either very low pH (&lt10) proposing serpentinization processes. Regarding TDS concentrations collected waters can be subdivided into low salinity (up to 1.5 g/L) brackish (up to 20 g/L) and saline (up to 43 g/L). The medium high salinities can be justified by mixing with sea water and/or strong waterrock interaction processes. Isotope composition of O and H ranges from 12.7 to +2.7 ‰ SMOW and from 91 to +12 ‰ SMOW respectively and is generally comprised between the Global Meteoric Water Line and the East Mediterranean Meteoric Water Line. Only few water samples show a positive shift for δ18O possibly related to high temperature waterrock interaction processes. Carbon dioxide (18 997000 μmol/mol) or N2 (1100 989000 μmol/mol) or CH4 (&ltMany geothermal areas of Greece are located in regions affected by Miocene or Quaternary volcanism and in continental basins characterised by elevated heat flow. Moreover the majority of them is found along the coast as well as in islands of the Aegean Sea and thus thermal water is often brackish to saline due to marine intrusion into costal aquifer. In the present study almost 300 thermal and cold mineral water samples were collected along the Hellenic territory with their physicochemical parameters (temperature pH electrical conductivity and Eh) and the amount of bicarbonates (titration with 0.1N HCl) being determined in situ. Additionally gases found either in free or dissolved phase were sampled. Both water and gas samples were analysed at the INGVPa laboratories for major ions (Ion Chromatography) silica (Inductively Coupled Plasma Optical Emission Spectrometry) chemical composition of free and dissolved gases (Gas Chromatography) water isotopes (O and H) and carbon and helium isotopes of free and dissolved gases (Mass Spectrometry). The temperature of the investigated waters ranges from 6.5 to 98°C pH from 1.96 to 11.98 whilst Total Dissolved Solids (TDS) from 0.06 to 43 g/L. Based on the temperature parameter waters can be divided into four groups: i) cold (&lt0.5 913000 μmol/mol) are the prevailing gas species found in the studied sites. The δ13CCO2 values ranged from 20.1 to +8.5 ‰ whilst the isotope ratio of He from 0.21 to 6.71 R/RA.4) suggesting interaction with H2Srich gases or very high pH values (&gtSettore GEO/08 - Geochimica E Vulcanologia
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Water chemistry and abiogenic methane content of a hyperalkaline spring related to serpentinization in the Argolida ophiolite (Ermioni, Greece)

2018

Abstract Hyperalkaline mineral springs related to active continental serpentinization are a theme of growing interest since they may contain significant amounts of abiotic gas and have important implications for energy resource exploration, subsurface microbiology and astrobiology. We report the discovery of a new hyperalkaline (pH∼12) spring issuing in the Agioi Anargyroi monastery at Ermioni (Greece), connected to serpentinization of peridotites of the Argolis ophiolite. Two water samples have been collected from separated springs and analysed for the chemical composition of major, minor and trace elements, and isotopic composition (2H and 18O) of water by IC, ICP-OES, ICP-MS and IRMS, an…

Gas geochemistry010504 meteorology & atmospheric sciencesStratigraphyEarth scienceGeochemistryAquifer010502 geochemistry & geophysicsOceanographyOphiolite01 natural sciencesMethanechemistry.chemical_compoundSpring (hydrology)HydrogeochemistryGeophysicChemical composition0105 earth and related environmental sciencesgeographyBiologic methane oxidationgeography.geographical_feature_categoryMineralSerpentinizationGeologyStable isotopeAbiogenic petroleum originGeophysicschemistryAbiogenic methaneAnaerobic oxidation of methaneEconomic GeologyGeologyMarine and Petroleum Geology
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Multiple origins of methane in fluids circulating in the Othrys ophiolite, central Greece

2018

The complex geology of Greece includes two important parallel running ophiolitic belts. The Othrys Massif in central Greece belongs to westernmost of them. In and around this wide ophiolite outcrop, some cold hyperalkaline and some hypothermal (T < 40°C) alkaline springs are present. Thirty water samples were collected at 17 different sites and both bubbling and dissolved gases were analysed for their chemical (He, Ne, H2, O2, N2, CH4, C2H6, CO2 and H2S) and isotope (He, δ13C-CO2, δ 13C-CH4, δ 2H-CH4) composition. All samples except one have H2S contents below detection limit (10 μmol/mol), whilst H2 (from <2 to 2500 μmol/mol), CO2 (up to 26,000 but generally below 1000 μmol/mol) and …

continental serpentinization hyperalkaline springs bubbling and dissolved gasesSettore GEO/08 - Geochimica E Vulcanologia
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Geochemical characterisation of the alkaline and hyperalkaline groundwater in the Othrys Ophiolite Massif, central Greece

2021

The complex geology of Greece includes two important parallel running ophiolitic belts. The Othrys Massif in central Greece belongs to the westernmost of them. In the current study, 33 water samples from cold hyperalkaline and hypothermal (T < 40°C) alkaline springs and 30 gas samples (either dissolved or free) were collected at 17 different sites in and around this wide ophiolite outcrop, aiming to determine the origin of fluids and evidence gas-water-rock interaction processes taking place in the area. Water samples were analysed for their chemical (major ions and trace elements) and isotope (d18O-H2O, d2H-H2O) composition. They can be subdivided into alkaline (pH <11) of both Mg-Ca…

geographygeography.geographical_feature_categoryIsotopeChemistryStable isotope ratioOutcropGeologyMassif010502 geochemistry & geophysicsOphiolite01 natural sciencesContinental serpentinization Hydrogeochemistry Methane Stable isotopes Trace elementsMethaneAbiogenic petroleum originSettore GEO/08 - Geochimica E Vulcanologiachemistry.chemical_compoundEnvironmental chemistryGeneral Earth and Planetary SciencesGroundwater0105 earth and related environmental sciences
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