PALEOHYDROGEOLOGY OF YUCCA MOUNTAIN BY FLUID INCLUSIONS AND STABLE ISOTOPES

摘要

Studies of fluid inclusions in secondary mineralsrn(calcite, fluorite, quartz) from the Yucca Mountainrnunsaturated zone have demonstrated that at least part ofrnthese minerals was deposited from aqueous fluids withrnelevated temperatures (ca. 35 to 85°C) that circulated inrnthe mountain after the host tuffs cooled to ambientrntemperatures. Isotopic and fluid inclusion data suggestrnanoxic reducing environment at early stages of mineralrngrowth. These thermal fluids cannot be related to the 15-rn12 Ma-old silicic volcanism. Hydrothermal activityrnrecorded by inclusions in minerals represents FEPrn(feature, event, process) that has yearly probability ofrnoccurrence exceeding regulatory value of 10~(-8). Inrncompliance with 10 CFR Part 63, this activity must bernincorporated into and evaluated within the YuccarnMountain Performance Assessment.