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

Abstract

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. -from Authors