Stratigraphic and structural framework of Yucca Mountain, Nevada
- Geological Survey, Denver, CO (United States)
Sedimentary strata consist of highly folded and faulted 600 to 300-m.y.-old Late Proterozoic and Paleozoic rocks, and are estimated to reach a maximum thickness of about 11 km. One deep hole, drilled through the volcanic cover, suggests that the southern part of Yucca Mountain is underlain by Paleozoic dolomite. Gravity modeling reveals the presence of a conspicuous residual gravity low whose axis extends northeastward across the northern part of Yucca Mountain. The Miocene volcanic section thins significantly to the south. Most of the section is composed of alternating layers of nonwelded to densely welded rock, which impart a first-order stratigraphic anisotropy to the mountain that controls the distribution of several fundamental physical properties. Excavation of a repository for nuclear waste is being considered within the Topopah Spring Member of the Paintbrush Tuff. The member, as much as 350 m thick, is dominantly finely crystalline, highly fractured ash-flow tuff. Most major structural blocks are 1 to 4 km wide, tilted 5{degree} to 10{degree} eastward, and bounded by westward dipping high-angle faults. Blocks grade eastward to broken zones that appear to increase in width at the expense of intact parts of blocks toward the southern end of Yucca Mountain and may suggest differential movement along a low-angle extensional fault. Dominant geologic and geophysical features within the site area at Yucca Mountain that require further detailed study include: (1) the conspicuous northeast-trending gravity low, (2) the lateral variability of lithologic units, (3) the configuration, properties, and origin of the broken zones, and (4) the possible existence of a gently extensional fault, several kilometers beneath Yucca Mountain.
- DOE Contract Number:
- AI08-78ET44802
- OSTI ID:
- 138227
- Journal Information:
- Radioactive Waste Management and the Nuclear Fuel Cycle, Journal Name: Radioactive Waste Management and the Nuclear Fuel Cycle Journal Issue: 1-4 Vol. 13; ISSN 0739-5876; ISSN RWMCD4
- Country of Publication:
- Switzerland
- Language:
- English
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Related Subjects
58 GEOSCIENCES
AGE ESTIMATION
ANISOTROPY
BOREHOLES
DOLOMITE
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC MODELS
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GRAVITY SURVEYS
INCLINED STRATA
INFORMATION NEEDS
LITHOLOGY
MAPS
MIOCENE EPOCH
PALEOZOIC ERA
RADIOACTIVE WASTE FACILITIES
ROCK MECHANICS
SEDIMENTARY ROCKS
SITE CHARACTERIZATION
STRATA MOVEMENT
STRATIGRAPHY
THICKNESS
TUFF
VOLCANIC ROCKS
YUCCA MOUNTAIN
Yucca Mountain Project