Mineral-fluid interaction in the Reykjanes and Svartsengi geothermal systems, Iceland

Journal Article · · American Journal of Science; (United States)

DOI:https://doi.org/10.2475/ajs.293.7.605· OSTI ID:5682980

Lonker, S W ^[1]; Franzson, H; Kristmannsdottir, H ^[2]

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1. Australian National Univ., Canberra (Australia)
2. Grensasvegur 9, Reykjavik (Iceland)

Physical observations on features such as temperature, pressure, and formation permeability are integrated with alteration intensity, fluid and secondary mineral compositions, and textures to show the most important thermal, chemical, hydrodynamic, and kinetics factors that control the evolution of two Icelandic geothermal systems, the Reykjanes and Svartsengi systems. There is an increase in alteration intensity and the abundance of fracture and vesicle fillings, a decrease in the abundance of primary minerals, and more extensive compositional heterogeneity near many aquifers, which are defined by circulation losses and temperature and pressure profiles. Features such as resorption and overgrowth textures, absence of systematic element partitioning, metastability, and undersaturation/supersaturation are widespread and are indicative of mineral-mineral and mineral-fluid disequilibrium. The composition of chlorite is more sensitive to changes in the physico-chemical conditions of the fluid compared to other secondary minerals. Chlorite geothermometry is used to map out the temperature patterns and extract information on permeability variations. In many chlorite-filled vesicles, chlorite grains show a systematic rim-to-core increase in temperatures derived from chlorite compositions and grain size and a decrease in smectite content due to heating of cooler waters or late pulses of hot, reduced fluids. Both systems are cooling due to heat source decay, cooler water incursions, or both. The results of this study will be useful in testing experimental studies and computer models of seawater-basalt reaction and recognizing the thermal, chemical, kinetics, and hydrodynamic factors that control secondary alteration in submarine hydrothermal systems. 118 refs., 20 figs., 8 tabs.

• OSTI ID: 5682980
• Journal Information: American Journal of Science; (United States), Journal Name: American Journal of Science; (United States) Vol. 293:7; ISSN AJSCAP; ISSN 0002-9599
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150200* -- Geology & Hydrology of Geothermal Systems
58 GEOSCIENCES
580000 -- Geosciences
AQUIFERS
CHLORITE MINERALS
CLAYS
COMPUTERIZED SIMULATION
DATA
DEVELOPING COUNTRIES
ENERGY SYSTEMS
EUROPE
EXPERIMENTAL DATA
FLUID MECHANICS
GEOTHERMAL SYSTEMS
GEOTHERMOMETRY
HYDRODYNAMICS
HYDROGEN COMPOUNDS
HYDROTHERMAL SYSTEMS
ICELAND
INFORMATION
ISLANDS
MECHANICS
MINERALS
NUMERICAL DATA
ORIGIN
OXYGEN COMPOUNDS
PULSES
ROCK-FLUID INTERACTIONS
SATURATION
SEAWATER
SILICATE MINERALS
SIMULATION
SMECTITE
SUPERSATURATION
WATER
WESTERN EUROPE