Vuataz, François

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Métadonnées seulement
Le forage géothermique de Thonex (Canton de Genève): Aspects stratigraphiques, tectoniques, diagénéitiques, géophysiques et hydrogéologiques
(1995)
Jenny, Jacques
;
Burri, Jean-Paul
;
Muralt, Reto
;
Pugin, André
;
Schegg, Roland
;
Ungemach, Pierre
;
Vuataz, François
;
Wemli, Roland
Métadonnées seulement
Isotope geochemistry of thermal and non-thermal waters in the Géologie et hydrogéologiealles Caldera, Jemez Mountains, Nothern New-Mexico
(1986)
Vuataz, François
;
Goff, Fraser
Métadonnées seulement
Intégration des méthodes hydrochimiques, géologiques et géophysiques pour la prospection d'une nouvelle ressource en eau thermale. Cas d'Yverdon-les-Bains, Pied du Jura
(1997)
Muralt, Reto
;
Vuataz, François
;
Schoenborn, Gregor
;
Sommaruga, Anna
;
Jenny, Jacques
Métadonnées seulement
Multiparameter logging in a shallow heterogeneous alluvial aquifer (Wallis Canton, Switzerland)
(2002)
Schurch, Marc
;
Vuataz, François
Métadonnées seulement
Émergence d'eau thermale et mélanges avec des eaux souterraines froides dans la gorge de la Dala à Leukerbad (Valais, Suisse)
(1994)
Muralt, Reto
;
Vuataz, François
Métadonnées seulement
The Swiss Deep Heat Mining (DHM) project: drilling of the first exploration borehole in Basel
(2001)
Vuataz, François
;
Häring, Markus
Métadonnées seulement
The isotopic and chemical composition of CO2-rich thermal waters in the Mont-Dore region (Massif-Central, France)
(1997)
Pauwels, Helene
;
Fouillac, Christian
;
Goff, Fraser
;
Vuataz, François
Chemical and isotope compositions of fluid samples, collected between 1974 and 1986 from 52 springs or shallow boreholes located in the Mont-Dore region (Massif Central, France), were examined. Some springs and wells were sampled several times during this period. The fluids emerge from Quaternary volcanic rocks or Paleozoic granite at temperatures between 4 and 62 degrees C, and the origin of the H2O is meteoric. The waters can be classified into three groups: bicarbonate fluids, mixed bicarbonate-chloride fluids (with a mineralization up to 8 g/l), and acid-sulfate fluids. Only two fluids contain sufficient Cl- to be considered as 'mature' waters. Previous work has demonstrated that they all contain partly mantle-derived CO2 gas, and that the CO2-rich gas phase and bicarbonate-chloride waters are separated at substantial depth. Mineralized fluids circulate at depth and undergo several processes, such as cooling or dilution with recent freshwater, during their ascent to the surface. Therefore, the CO2-rich gas phase can be partly dissolved in the freshwater, or in deep fluids after their dilution. This process leads to the dissolution of surrounding rocks; such dissolution is discussed on the basis of major-element concentrations (Na, K, Ca, Mg), as well as the Sr 87/86 isotope ratio. Dissolution of S-bearing minerals has also been demonstrated. The presence of the CO2-rich gas phase also leads to isotope exchange between CO2 and H2O. Some mineralized fluids are less affected by these processes than others, in which case they display the chemical and isotopic characteristics of the original deep fluids. It was shown that the applicability of geothermometer calculations for these waters is hampered by several processes that modify the chemical composition. However, some geothermometers can be used for estimating the temperature of the deep fluids using the chemical composition of the less modified fluids. They indicate that fluids emerging from volcanic rocks in the Dordogne valley reach temperatures of around 100- 130 degrees C at depth, while the temperature of the fluid that issues from the granite at Saint-Nectaire is 160-175 degrees C at depth. (C) 1997 Elsevier Science Ltd.
Métadonnées seulement
Hydrogeochemistry of the Qualibou Caldera Geothermal System, St. Lucia, West Indies
(1984)
Goff, Fraser
;
Vuataz, François
Métadonnées seulement
A strontium isotope study of the VC-1 core hole and associated hydrothermal fluids and rocks from Valles Caldera, Jemez Mountains, New-Mexico
(1988)
Vuataz, François
;
Goff, Fraser
;
Fouillac, Christian
;
Calvez, Jean-Yves
Métadonnées seulement
Geochemical indicators to determine relations between spring behaviour and water losses of a divergence tunnel
(2001)
Schurch, Marc
;
Vuataz, François
Hydraulic and geochemical relations between a subthermal, SO4-rich spring (Q6) and water losses of a divergence tunnel indicate that both features are hydraulically connected. The divergence tunnel, crossing the evaporite rocks of the Penninic Pontis-Nappe (anhydrite, gypsum, dolomitic limestones) in the Rhone River valley (Central Wallis, Switzerland), deviates water from the Rhone River at a rate of up to 62 m(3)/s. The recharge rate of weakly mineralized water exfiltrating from the divergence tunnel and flowing to the Q6 spring varied between 0.5 and 5 l/s, depending on seasonal variations of the discharge in the divergence tunnel. Methods used to determine the degree of connection included discharge measurements, continuous and monthly water quality measurements, and geochemical modelling. Hydrochemical indicators of particular significance include major inorganic ions, as well as temperature, pH, calcite and gypsum saturation indices. Following the divergence tunnel decommissioning in August 17 1998, simultaneous rises in spring temperature from 13.0 to 13.7 degreesC and electrical conductivity from 2430 to 2600 muS/cm were recorded. A decline in spring discharge from 10 to 6.7 l/s was also observed.

Vuataz, François

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