Fluid inclusion studies of calcite veins from Yucca Mountain, Nevada, Tuffs: Environment of formation

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:113821

Roedder, E ^[1]; Whelan, J F ^[2]; Vaniman, D T ^[3]

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1. Harvard Univ., Cambridge, MA (United States)
2. Geological Survey, Denver, CO (United States)
3. Los Alamos National Lab., NM (United States)

Calcite vein and vug fillings at four depths (130-314m), all above the present water table in USW G-1 bore hole at Yucca Mountain, Nevada, contain primary fluid inclusions with variable vapor/liquid raitos: Most of these inclusions are either full of liquid or full of vapor. The liquid-filled inclusions show that most of the host calcite crystallized from fluids at <100{degrees}C. The vapor-filled inclusions provide evidence that a separate vapor phase was present in the fluid during crystallization. Studies of these vapor-filled inclusions on the microscope crushing stage were interpreted in an earlier paper as indicating trapping of an air-water-CO{sub 2} vapor phase at ``<100{degrees}C``. Our new studies reveal the additional presence of major methane in the vapor-filled inclusion, indicating even lower temperatures of trapping, perhaps at near-surface temperatures. They also show that the host calcite crystals grew from a flowing film of water on the walls of fractures open to the atmosphere, the vapor-filled inclusions representing bubbles that exsolved from this film onto the crystal surface.

• Research Organization: Geological Survey, Denver, CO (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AI08-92NV10874
• OSTI ID: 113821
• Report Number(s): CONF-940553--95; ON: DE96001461
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
CALCITE
FRACTURES
GEOLOGY
HIGH-LEVEL RADIOACTIVE WASTES
TUFF
UNDERGROUND DISPOSAL
YUCCA MOUNTAIN
Yucca Mountain Project