Mineral assemblages and oxygen and sulphur fugacities in natural water-rock interaction processes

1984 ◽  
Vol 48 (4) ◽  
pp. 847-857 ◽  
Author(s):  
F. D'Amore ◽  
G. Gianelli
Keyword(s):  
Natural Water ◽  
Rock Interaction ◽  
Interaction Processes ◽  
Mineral Assemblages ◽  
Water Rock Interaction

scholarly journals Preliminary chemical characterization of groundwater in the Rome Municipality

2015 ◽  
Author(s):  
Luca Pizzino ◽  
Daniele Cinti ◽  
Monia Procesi ◽  
Alessandra Sciarra
Keyword(s):  
Chemical Elements ◽  
Central Italy ◽  
Chemical Characterization ◽  
Mineral Waters ◽  
Measured Temperature ◽  
Large Variability ◽  
Rock Interaction ◽  
Interaction Processes ◽  
Two Samples ◽  
Water Rock Interaction

In summer 2015 a geochemical survey on groundwater was carried out at 31 sampling points (wells and piezometers) belonging to the new “Official monitoring groundwater network of Rome Municipality” (GMNR). The following parameters were measured: temperature, pH, electrical conductivity (i.e. salinity) and alkalinity; these data were used to compute partial pressure of CO2 (pCO2). Furthermore, samples were collected to characterise waters from a chemical point of view (major elements). To implement our data - base, chemical analyses of 6 CO2 - rich mineral waters of Rome were considered. Hydrochemical survey was mainly devoted to: i) classify waters in chemical facies; ii) investigate the main water-rock interaction processes governing the water’s chemical evolution, also affected by variable amounts of dissolved CO2 and iii) define the pCO2 level in groundwater in the frame of the knowledge so far acquired in the Tyrrhenian sector of central Italy.. Groundwater shows a dominant Ca-HCO3 chemistry; some samples belong to Na-HCO3, Na-Cl and CaCl2 hydrochemical facies. In the dominant facies waters show a large variability in the abundance of chemical elements, in their salinity (ranging between 0.46 e 3.83 g/l) and pH (in the interval 5.87-7.22); these features are mainly due to different water-rock interaction processes together with the presence of variable CO2 contents. Na-HCO3 waters show the lowest salinity values (TDS up to 0.32 g/l) and strongly alkaline pH; cation exchange processes with clays, causing Na enrichment and Ca and Mg removal from solution, can be invoked to justify the observed chemistry. Waters of the Castel Fusano Natural Reserve (CFNR) belong to the Na-Cl and Ca-Cl2 facies; the different chemistry reflects the geochemical processes going on in the considered coastal aquifers such as: i) mixing between freshwater and saline waters of marine origin (fossil waters, seawater intrusion) and ii) cationic exchanges with clays that make up the less permeable sediments of the area. Two samples of the CFNR group have Ca-HCO3 chemistry and represent aquifers not affected by salinization processes. Calculated pCO2 distribution is highly variable, from low (0.03 bar) to high values (0.72 bar), implying different CO2 input (and origin) in the studied aquifers. Highest levels of carbon dioxide are linked to the degassing processes going on in the Tyrrhenian sector of Central Italy.

scholarly journals New orogenic type gold occurrences in the Uyanga ore knot (Central Mongolia)

2019 ◽  
Vol 98 ◽  
pp. 08020
Author(s):  
Ariunbileg Sodov ◽  
Olga Gaskova ◽  
Altansukh Gankhuyag ◽  
Dagva-Ochir Lkhagvasuren ◽  
Otgonbaatar Dorjsuren ◽  
...  
Keyword(s):  
Microprobe Analysis ◽  
Gold Deposits ◽  
Gold Content ◽  
Rock Interaction ◽  
Central Mongolia ◽  
Quartz Veins ◽  
Central Asian ◽  
Mineral Assemblages ◽  
Metallogenic Zone ◽  
Water Rock Interaction

The Khangay-Khentey belt is located in central Mongolia (Central Asian Orogenic Belt). The Uyanga ore knot district of the Khangay metallogenic zone are hosted by the lower-middle Devonian volcanogenic-sedimentary Erdenetsogt formation. The new Burgetei, Ult and Senjit gold occurrences were studied. The rocks of the Erdenetsogt formation have an irregular gold content: 0.96 g/t Au is determined in quartz vein (BG-7/16), Au content is highest up to 3.5 g/t in the quartzite-jasper (Ult-7/16 and Ult-9/16) cut by quartz veins in the Ult occurrence. The Senjit occurrence represents Au-Hg-Sb epizonal level of orogenic gold deposits structure with highest Hgand Sb content up to 8.5 ppm and 39 ppm respectively. The Au content of arsenic pyrite of the Burgetei and Ult is below the detection limit by electron microprobe analysis. The Au content of arsenopyrite of the Ult occurrence is highest (up to 238 ppm). The ore-mineral assemblages in the new gold occurrences reflect the differences between three explored sites, formed in the course of fluid evolution during the water-rock interaction. Variable concentrations of indicative elements (As, Te, Sb, Hg) and their ratios confirm this fact.

Element and isotope mobility during water–rock interaction processes

2005 ◽  
Vol 30 (17-18) ◽  
pp. 993-996 ◽  
Author(s):  
Cedric Corteel ◽  
Andrea Dini ◽  
Annette Deyhle
Keyword(s):  
Rock Interaction ◽  
Interaction Processes ◽  
Water Rock Interaction

Mylonites of the South Armorican Shear Zone: Insights for crustal-scale fluid flow and water–rock interaction processes

2012 ◽  
Vol 56-57 ◽  
pp. 86-107 ◽  
Author(s):  
Romain Tartèse ◽  
Philippe Boulvais ◽  
Marc Poujol ◽  
Thomas Chevalier ◽  
Jean-Louis Paquette ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Shear Zone ◽  
The South ◽  
Rock Interaction ◽  
Interaction Processes ◽  
Water Rock Interaction

scholarly journals Water–rock interactions in the Bruchsal geothermal system by U–Th series radionuclides

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Lena Kölbel ◽  
Thomas Kölbel ◽  
Ulrich Maier ◽  
Martin Sauter ◽  
Thorsten Schäfer ◽  
...  
Keyword(s):  
Reservoir Characterization ◽  
Isotopic Fractionation ◽  
Reservoir Rock ◽  
Geothermal System ◽  
Specific Information ◽  
Radium Isotopes ◽  
Rock Interaction ◽  
Removal Time ◽  
Interaction Processes ◽  
Water Rock Interaction

Abstract Uranium and thorium decay series disequilibria in deep geothermal brines are a result of water–rock interaction processes. The migratory behavior of radionuclides provides valuable site-specific information and can therefore be an important tool for reservoir characterization and sustainable management of geothermal sites. In this study, we present data from long-term monitoring of naturally occurring 238U, 232Th and 235U series radionuclides analyzed in brine samples collected from the Permo-Triassic sedimentary reservoir rock at the Bruchsal geothermal site (SW Germany). The results show that radionuclides of the elements radium (226Ra, 228Ra, 224Ra, 223Ra), radon (222Rn), and lead (210Pb, 212Pb) are rather soluble in brine, while isotopes of uranium (238U, 234U, 235U), thorium (232Th, 228Th, 230Th), polonium (210Po), and actinium (227Ac, 228Ac) have low solubilities and are mostly immobile. Activities of radium isotopes in the geothermal brine exceed those of their thorium progenitors (average 226Ra = 29.9 Bq kg−1, about 103 times that of its 230Th parent). Modelling the observed disequilibria allows the following conclusion on water–rock interaction processes: (1) supply from alpha-recoil depends on isotope half-life because it is limited by the rate of diffusion through microfractures causing isotopic fractionation. (2) Radium retardation due to adsorption is low (226Ra/222Rn = 1.3) resulting in adsorption–desorption rate constants in the order of 10−10 s−1 for k1 and 10−9 for k2. (3) Scavenging of 226Ra from brine can best be explained by co-precipitation with barite resulting in an observed 226Ra anomaly in the solids of the reservoir section. The precipitation rate constant amounts to ca. 3.4 × 10−8 s−1 corresponding to a mean removal time of radium from brine by mineral precipitation to approximately 1 year.

scholarly journals Geochemical Modeling of Water-Rock Interaction Processes in the Pollino National Park

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
C. Apollaro ◽  
I. Fuoco ◽  
L. Bloise ◽  
E. Calabrese ◽  
L. Marini ◽  
...  
Keyword(s):  
National Park ◽  
Reaction Path ◽  
Geochemical Modeling ◽  
Analytical Data ◽  
Path Modeling ◽  
Rock Interaction ◽  
Interaction Processes ◽  
Comparison Of The Results ◽  
Reaction Path Modeling ◽  
Water Rock Interaction

This work is aimed at reconstructing the water-rock interaction processes controlling the geochemical characteristics of the shallow or relatively shallow groundwaters of the Pollino National Park, based on the data acquired for 105 water samples from local springs. Reaction path modeling of rock dissolution was carried out in a purely stoichiometric mode for the main lithotypes cropping out in the study area, that is, limestone, Mg-limestone, dolomite, serpentinite, Al-silicate fraction of calcschist, and carbonate fraction of calcschist. Reaction path modeling was carried out in a purely stoichiometric mode, considering the rocks of interest as materials of known stoichiometry and unknown thermodynamic properties. Calculations were carried out assuming a closed system for secondary solid phases whereas an open system was assumed for gases, O2(g) and CO2(g). Comparison of the results of geochemical modeling and the analytical data acquired for the groundwaters of the Pollino National Park shows that concentrations of major solutes, SiO2, Li, Al, and Fe of the different chemical types of waters, are explained by the dissolution of pertinent lithotypes. Moreover, the detected concentrations of Al, Cl, F, NO3, and SO4 are within the threshold values recommended by WHO.

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