Aquifer chemistry of four high-temperature geothermal systems in Iceland

The deep water feeding wet-steam wells in four high-temperature geothermal areas in Iceland have highly variable salinity as reflected in the chlorine concentrations which vary from 20 to 19000 ppm. Using available values for equilibrium constants, the activities of 26 chemical species involving the major components of the reservoir water have been calculated and quantitative evaluations of solute/ solute, mineral/solute chemical equilibria in these geothermal systems have been made.The unflashed reservoir water is just saturated with calcite. The saline geothermal waters, which represent heated sea-water, are just saturated with anhydrite, but the dilute waters, which are of meteoric origin, are somewhat undersaturated with this mineral. The fluoride mobility is thought to be limited by an ionic exchange reaction where F^? replaces some of the OH^? in the layered silicates. The pH of the unflashed reservoir water is governed by ionic exchange equilibrium in which all the major cations participitate. At a given temperature it seems likely that the activity of one cation fixes the activities of all the other major cations and hydrogen ion. If this is so and we take all the other chemical equilibria which have been demonstrated to exist for granted, it turns out that the major element composition of the unflashed high-temperature geothermal waters is controlled by two independent variables only. These variables are the temperature and the supply to the water of the incompatible element chlorine, incompatible indicating that this element is not incorporated in the geothermal minerals.     

Temperature and pressure determinations in the Venus atmosphere by means of high-resolution spectra from 1 to 2.5 μm

Twenty-one bands of CO₂ and the 2-0 band of CO were analyzed for best temperature and pressure fits from Venus spectra obtained with the “Connes” interferometer at the Steward Observatory 2.25-m telescope during the spring of 1971. An average temperature of 241 ± 7°K, an effective pressure of 0.12 ± 0.06 atm, and an average two-way transmission abundance of 3 km-amagat were determined. No difference in temperature or pressure between hot bands, a double hot band, and regular bands was found. Our results were compared to model calculations for a reflecting layer and scattering atmosphere. The results indicate that, most likely, spectroscopic line formation occurs in a relatively clear space above a scattering cloud layer with a reasonably well-defined upper boundary.     

IV. Bücher- und Zeitschriftenschau

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Parallelisierung des südosteuropäischen Pliozäns

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Zur Frage über die Ursachen geotektonischer Bewegungen

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Bücher- und Zeitschriftenschau

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IV. Stratigraphie Die fazielle Einstufung fossilführender Sedimente

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Geologische Konsequenzen einer Erdentstehung auf kaltem Wege

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