ONTOGENETIC MINERALOGY OF SECONDARY MINERALS AT YUCCA MOUNTAIN, NEVADA

摘要

Ontogenetic studies indicate that calcite, quartz,rnchalcedony, opal, fluorite and zeolite found in openrncavities in the unsaturated zone at Yucca Mountain werernformed from fluids with varying activity ratios of SiO2,rnHCO_3rn-, F, PO_3rn-, SO_4~2. Details of crystal morphologyrnindicate submerged state of growth for calcite and quartz.rnAlong with elevated temperatures of growth determined byrnfluid inclusions (up to 85°C at early stages), this impliesrnthe environment of the low-temperature hydrothermalrnsystem, rather than that of the gravitation driven flow ofrnwater films in the unsaturated zone.