A GEOCHEMICAL STUDY OF MINERAL SPRINGS IN THE ARDECHE REGION - GEOTHERMIC IMPLICATIONS
The Ardeche region possesses a large number of mineral springs, cold or lukewarm. The region has been studied previously. A geological and hydrogeological study has placed the different springs in the proper tectonic context. The objective of the present geochemical study was to obtain a better picture of the deep hydrothermal circulation and of the deep temperatures. 5 systems can be recognized: + the Prade basin + the upper valley of the Ardeche + the township of Vals + the springs north of Vals, the valley of the Volane and of the Bessorgues + the Eyrieux basin Some springs fall outside these groups. Deep reservoir temperatures are estimated on basis of the chemical composition of the waters as well as on the isotopic composition of some of the components. These estimates give some abnormally high temperatures (100-200 degrees C). There is a smooth changing of the deep reservoir temperatures. It decreases in the SSW-NNW direction starting in the Prades basin and the region of Neyrac-les-Bains. The low emergence temperatures can be explained by intensive mixing with surface water and with the frequently very low flow rates. The oxygen and hydrogen isotope determinations give estimates of the recharge heights of the reservoir and therefore clues to the hydrogeology of the region. The study concludes with the recommendation of two drill sites; one near Neyrac-les-Bains and one in the Prades basin.
Bibliographic Reference: EUR 9705 FR, MF, (1985), 74 P., BFR 150, EUROFFICE, LUXEMBOURG, POB 1003
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Record Number: 1989123087300 / Last updated on: 1987-01-01
Available languages: fr