Evidence for an unsaturated-zone origin of secondary minerals in Yucca Mountain, Nevada

Conference · Sun Apr 29 04:00:00 EDT 2001

OSTI ID:794106

Whelan, Joseph F ^[1]; Roedder, Edwin; Paces, James B

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1. U.S. Geological Survey, Denver, CO

The unsaturated zone (UZ) in Miocene-age welded tuffs at Yucca Mountain, Nevada, is under consideration as a potential site for the construction of a high-level radioactive waste repository. Secondary calcite and silica minerals deposited on fractures and in cavities in the UZ tuffs are texturally, isotopically, and geochemically consistent with UZ deposition from meteoric water infiltrating at the surface and percolating through the UZ along fractures. Nonetheless, two-phase fluid inclusions with small and consistent vapor to liquid (V:L) ratios that yield consistent temperatures within samples and which range from about 35 to about 80 C between samples have led some to attribute these deposits to formation from upwelling hydrothermal waters. Geochronologic studies have shown that calcite and silica minerals began forming at least 10 Ma and continued to form into the Holocene. If their deposition were really from upwelling water flooding the UZ, it would draw into question the suitability of the site as a waste repository.

• Research Organization: U.S. Geological Survey, Denver, CO (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AI08-97NV12033
• OSTI ID: 794106
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
CALCITE
DEPOSITION
GEOLOGIC FRACTURES
GROUND WATER
HIGH-LEVEL RADIOACTIVE WASTES
MINERALOGY
MINERALS
ORIGIN
RADIOACTIVE WASTE FACILITIES
SECONDARY
SILICA
SITE CHARACTERIZATION
UNSATURATED ZONE
YUCCA MOUNTAIN