Micromorphology of carbonate-silica deposits from Trench 14 and Busted Butte, Yucca Mountain, NV

Conference · Thu Apr 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5435639

Butcher, P M; Cerling, T E ^[1]

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1. Univ. of Utah, Salt Lake City, UT (United States). Geology and Geophysics

The origin of banded carbonate-silica deposits in the vicinity of Yucca Mountain, NV is controversial and has been attributed to both downward percolating waters, subject to soil-forming processes, and to upward movement and discharge of hot or cold ground waters. Using petrographic and SEM techniques, deposits from Trench 14 were compared to pedogenic carbonates from Busted Butte and carbonate deposits from known modern and paleosprings to determine how they formed. Busted Butte and Trench 14 samples are nearly identical, and contain many common pedogenic micromorphological features such as alveolar texture, calcified needle fibers, tubes, and rhomb chains, peloids and pellets, and silica cementation. Alveolar texture, calcified tubes, and root tubules suggest biogenic mechanisms are important in carbonate formation. The spring carbonates contain greater amounts of sparry calcite in rims and pore fillings, shells, and few biogenic structures while lacking pedogenic features listed previously. This suggests that Trench 14 deposits were not formed by ground water, but by pedogenic processes in both vertically and horizontally oriented deposits. The presence of chemically distinct volcanic ash throughout Trench 14 and Busted Butte carbonate deposits, along with other detrital materials and pedogenic features in a finely banded manner, suggests the deposits were formed over long periods of time by surficial processes. These processes allowed incorporation of surface materials and developed of extensive root systems resulting in deposition of carbonate-silica deposits in the structures observed. No evidence of hydrothermal alteration of either wall rock or included detritus is observed.

• OSTI ID: 5435639
• Report Number(s): CONF-9305259--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

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CARBONATE ROCKS
DEVELOPED COUNTRIES
GEOLOGIC DEPOSITS
GEOLOGY
GEOMORPHOLOGY
GROUND WATER
HYDROGEN COMPOUNDS
MICROSTRUCTURE
MOUNTAINS
NEVADA
NORTH AMERICA
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OXYGEN COMPOUNDS
PETROGRAPHY
RADIOACTIVE WASTE FACILITIES
ROCKS
SEDIMENTARY ROCKS
SITE CHARACTERIZATION
USA
WATER
YUCCA MOUNTAIN