Stratigraphy and structure of volcanic rocks in drill hole USW-G1, Yucca Mountain, Nye County, Nevada

Spengler, R.W.; Byers, F.M.; Warner, Jeffrey

doi:10.3133/ofr811349

Cited by 44 publications

(27 citation statements)

References 3 publications

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“…Since core drilling data from the Yucca Mountain site indicate vertical and lateral variability (Spengler et al, 1981;Scott and Castellanos, 1984;Spengler and Chornack, 1984;Spengler, 1979), a single value for rock mass quality for any thermomechanical unit is not useful. Instead, a range of rock mass quality is estimated for each thermomechanical unit following the methodology proposed by Hardy and Bauer (1991).…”

Section: Di1 Definition For the Five Rock Mass Quality Categoriesmentioning

confidence: 99%

Rock mass mechanical property estimations for the Yucca Mountain Site Characterization Project; Yucca Mountain Site Characterization Project

Hardy¹,

Bauer²

1993

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Rock mass mechanical properties are important in the design of drifts and ramps. These properties are used in evaluations of the impacts of thermomechanical loading of potential host rock within the Yucca Mountain Site Characterization Project. Representative intact rock and joint mechanical properties were selected for welded and nonwelded tuffs from the currently available dat_ sources. Rock mass qualities were then estimated using both the Norwegian Geotechnica_ Institute (Q) and Geomechanics Rating (RMR) systems. Rock mass mechanical properties were developed based on estimates of rock mass quality, the current • knowledge of intact properties, and fracture/joint characteristics. Empirical relationships developed to correlate the rock mass quality indices and the rock mass mechanical properties were then used to estimate the range of rock mass mechanical properties.

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Section: Di1 Definition For the Five Rock Mass Quality Categoriesmentioning

confidence: 99%

Rock mass mechanical property estimations for the Yucca Mountain Site Characterization Project; Yucca Mountain Site Characterization Project

Hardy¹,

Bauer²

1993

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“…The samples were G-l-1436, a highly zeolitized ash-fall tuff from the Calico Hills unit, G-l-1883, a partially welded devitrified tuff from the Prow Pass unit, and G-l-1982, another partially welded devitrified tuff from the Prow Pass unit. 12 ' 13 The radionuclides were absorbed on the zeolite minerals, and smectite clays are contained in the tuff matrix. The mineralogic analyses of these samples are given in Table V.…”

Section: Table IV Mass Transfer Units For Crushed-tuff Columns (Determentioning

confidence: 99%

Assessment report on the kinetics of radionuclide adsorption on Yucca Mountain tuff

Rundberg¹

1987

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“…Beneath the Paintbrush Tuff, the principal stratigraphic units are in descending order: tuff of Calico Hills, Crater Flat Tuff (13.6 m.y. ), Tuff of Lithic Ridge, and a thick, unnamed sequence of ash-flow tufts and intercalated lavas (Spengler et aL, 1979(Spengler et aL, , 1981Maldonado and Koether, 1983;Carr et aL, 1984). Wells on Yucca Mountain have penetrated to depths of 1.8 km without leaving volcanic rocks.…”

Section: Geologic Setting Geologymentioning

confidence: 99%

Distribution and Chemistry of Diagenetic Minerals at Yucca Mountain, Nye County, Nevada

Broxton

Bish

Warren

1987

Clays and clay miner.

122

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Abstract--Yucca Mountain is being studied as a potential site in southern Nevada for an underground, high-level nuclear waste repository. A major consideration for selecting this site is the presence of abundant zeolites in Miocene ash-flow tufts underlying the region. Beneath Yucca Mountain four diagenetic mineral zones have been recognized that become progressively less hydrous with depth.Zone I, the shallowest zone, is 375-584 m thick in the central part of Yucca Mountain, but 170 m thick to the north. Zone I contains vitric tufts that consist of uualtered volcanic glass and minor smectite, opal, heulandite, and Ca-rich clinoptilolite. Zone II thins south to north from 700 to 480 m and is characterized by complete replacement of volcanic glass by clinoptilolite with and without mordenite, and by lesser amounts of opal, K-feldspar, quartz, and smectite. Zone III thins south to north from 400 to 98 m thick and consists of analcime, K-feldspar, quartz, and minor calcite and smectite. Heulandite occurs locally at the top of zone III in the eastern part of Yucca Mountain. Zone IV occurs in the deepest structural levels of the volcanic pile and is characterized by albite, K-feldspar, quartz, and minor calcite and smectite.Clinoptilolite and heulandites in zone I have uniform Ca-rich compositions (60-90 mole % Ca) and Si:AI ratios that are mainly between 4.0 and 4.6. In contrast, clinoptilolites deeper in the volcanic sequence have highly variable compositions that vary vertically and laterally. Deeper clinoptilolites in the eastern part of Yucca Mountain are calcic-potassic and tend to become more calcium-rich with depth. Clinoptilolites at equivalent stratigraphic levels on the western side of Yucca Mountain have sodic-potassic compositions and tend to become more sodium-rich with depth. Despite their differences in exchangeable cation compositions these two deeper compositional suites have similar Si:A1 ratios, generally between 4.4 and 5.0. Analcimes have nearly pure end-member compositions, typical of these minerals formed by diagenetic alteration of siliceous volcanic glass; however, K-feldspars are Si-rich compared to the ideal feldspar formula.Bulk-rock contents of Si, Na, K, Ca, and Mg of zeolitic tufts generally differ significantly from stratigraphically equivalent vitric tufts, suggesting that zeolite diagenesis took place in an open chemical system. Both the whole rock and the clinoptilolite are relatively rich in Ca and Mg in the eastern part of Yucca Mountain and rich in Na in the western part. The Ca-and Mg-rich compositions of the zeolitized tufts in the eastern part of Yucca Mountain may be due to cation exchange by the sorptive minerals with ground water partially derived from underlying Paleozoic carbonate aquifers.Diagenetic zones become thinner and occur at stratigraphically higher levels from south to north across Yucca Mountain, probably due to a higher geothermal gradient in the northern part of the area. The diagenetic zones were established when the geothermal gradient was greater than it ...

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Stratigraphy and structure of volcanic rocks in drill hole USW-G1, Yucca Mountain, Nye County, Nevada

Cited by 44 publications

References 3 publications

Rock mass mechanical property estimations for the Yucca Mountain Site Characterization Project; Yucca Mountain Site Characterization Project

Rock mass mechanical property estimations for the Yucca Mountain Site Characterization Project; Yucca Mountain Site Characterization Project

Assessment report on the kinetics of radionuclide adsorption on Yucca Mountain tuff

Distribution and Chemistry of Diagenetic Minerals at Yucca Mountain, Nye County, Nevada

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