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Title: Distribution and chemistry of fracture-lining minerals at Yucca Mountain, Nevada

Abstract

Yucca Mountain, a >1.5-km-thick sequence of tuffs and subordinate lavas in southwest Nevada, is being investigated as a potential high-level nuclear waste repository site. Fracture-lining minerals have been studied because they may provide information on past fluid transport and because they may act as natural barriers to radionuclide migration within the fractures. Cores from seven drill holes have been studied to determine the distribution and chemistry of minerals lining fractures at Yucca Mountain. Fracture-lining minerals in tuffs of the Paintbrush Group, which is above the static water level at Yucca Mountain, are highly variable in distribution, both vertically and laterally across the mountain, with the zeolites mordenite, heulandite, and stellerite widespread in fractures even though the tuff matrix is generally devitrified and nonzeolitic. Where heulandite occurs as both tabular and prismatic crystals in the same fracture, the two morphologies have different compositions, suggesting multiple episodes of zeolite formation within the fractures. Manganese-oxide minerals within the Paintbrush Group are rancieite and lithiophorite. The silica polymorphs (quartz, tridymite, and cristobalite) generally exist in fractures where they exist in the matrix, suggesting that they formed in the fractures at the same time they formed in the matrix. Fluorite, calcite, and opal occur overmore » tridymite in some lithophysal cavities. Calcite also occurs over zeolites in fractures unrelated to lithophysal cavities and is often the youngest mineral in a given fracture. The clays smectite, palygorskite, and sepiolite are common in fractures in the Paintbrush Group in drill core USW GU-3; smectite is an abundant fracture-coating mineral in all drill cores at Yucca Mountain.« less

Authors:
; ;
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
176769
Report Number(s):
LA-12977-MS
ON: DE96004206; TRN: 96:003777
DOE Contract Number:  
W-7405-ENG-36
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Dec 1995
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; 58 GEOSCIENCES; YUCCA MOUNTAIN; UNDERGROUND FACILITIES; SITE CHARACTERIZATION; HIGH-LEVEL RADIOACTIVE WASTES; UNDERGROUND DISPOSAL; SPENT FUELS; DRILL CORES; GEOLOGIC FRACTURES; PETROGRAPHY; TUFF; ZEOLITES

Citation Formats

Carlos, B A, Chipera, S J, and Bish, D L. Distribution and chemistry of fracture-lining minerals at Yucca Mountain, Nevada. United States: N. p., 1995. Web. doi:10.2172/176769.
Carlos, B A, Chipera, S J, & Bish, D L. Distribution and chemistry of fracture-lining minerals at Yucca Mountain, Nevada. United States. https://doi.org/10.2172/176769
Carlos, B A, Chipera, S J, and Bish, D L. 1995. "Distribution and chemistry of fracture-lining minerals at Yucca Mountain, Nevada". United States. https://doi.org/10.2172/176769. https://www.osti.gov/servlets/purl/176769.
@article{osti_176769,
title = {Distribution and chemistry of fracture-lining minerals at Yucca Mountain, Nevada},
author = {Carlos, B A and Chipera, S J and Bish, D L},
abstractNote = {Yucca Mountain, a >1.5-km-thick sequence of tuffs and subordinate lavas in southwest Nevada, is being investigated as a potential high-level nuclear waste repository site. Fracture-lining minerals have been studied because they may provide information on past fluid transport and because they may act as natural barriers to radionuclide migration within the fractures. Cores from seven drill holes have been studied to determine the distribution and chemistry of minerals lining fractures at Yucca Mountain. Fracture-lining minerals in tuffs of the Paintbrush Group, which is above the static water level at Yucca Mountain, are highly variable in distribution, both vertically and laterally across the mountain, with the zeolites mordenite, heulandite, and stellerite widespread in fractures even though the tuff matrix is generally devitrified and nonzeolitic. Where heulandite occurs as both tabular and prismatic crystals in the same fracture, the two morphologies have different compositions, suggesting multiple episodes of zeolite formation within the fractures. Manganese-oxide minerals within the Paintbrush Group are rancieite and lithiophorite. The silica polymorphs (quartz, tridymite, and cristobalite) generally exist in fractures where they exist in the matrix, suggesting that they formed in the fractures at the same time they formed in the matrix. Fluorite, calcite, and opal occur over tridymite in some lithophysal cavities. Calcite also occurs over zeolites in fractures unrelated to lithophysal cavities and is often the youngest mineral in a given fracture. The clays smectite, palygorskite, and sepiolite are common in fractures in the Paintbrush Group in drill core USW GU-3; smectite is an abundant fracture-coating mineral in all drill cores at Yucca Mountain.},
doi = {10.2172/176769},
url = {https://www.osti.gov/biblio/176769}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Dec 01 00:00:00 EST 1995},
month = {Fri Dec 01 00:00:00 EST 1995}
}