부산대학교 도서관

Reaction of granodiorite from the Fenton Hill Hot Dry Rock Geothermal Site with distilled water at 300/sup 0/C and 345 bars total pressure for 8 months has produced many morphological and chemical effects. Eight polished rock disks were mounted on a tantalum pedestal inside a 500 ml autoclave. The autoclave is part of a circulation system designed for operation to 400/sup 0/C and 345 bars. Solution samples were taken at 32, 56, 176, 368, 752, 1544, 3104, and 5816 hr. Rock disks were removed also at the latter four times. The reactivity of phases was found to be quartz/microcline/plagioclase/mafics, opaques and trace phases. Quartz was removed congruently. The albite component of the plagioclase was dissolved essentially congruently changing plagioclase from oligoclase (fresh) to bytownite (8 mo.). Microcline showed congruent dissolution. Other phases were inert. Secondary mineralization included phillipsite, thomosonite, and vermiculite.