Geology of drill hole USW VH-2, and structure of Crater Flat, southwestern Nevada

Carr, W.J.; Parrish, L.D.

doi:10.3133/ofr85475

Cited by 27 publications

(38 citation statements)

References 6 publications

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“…Rock-avalanche breccias are intercalated between the 12.7 Ma Tiva Canyon Tuff and the 11.7 Ma rhyolite of Fluorspar Canyon in the western part of Crater Flat, in the subsurface (Carr and Parrish, 1985), and on the surface in the eastern part of the Bullfrog Hills domain, on the north flank of Bare Mountain (new field data, this study). These breccias are proximal deposits composed of clasts of Paleozoic carbonates and the oldest Tertiary (14-to-> 15 Ma) sedimentary rocks; the < 14-Ma volcanic rocks are absent; the best exposed deposits demonstrably thicken and coarsen toward the range, indicating that Bare Mountain is the source of these breccias.…”

Section: Analysis Of the Structure Of Bare Mountain: Evidence For Tecmentioning

confidence: 99%

“…Basaltic volcanism began in the southwest part of Crater Flat basin during the 11.6-to-10 Ma interval, forming a thick, areally extensive sheet of layered lava flows and lesser scoria cones from which K-Ar ages of 11.3 Ma and 10.5 Ma have been obtained (Carr and Parrish, 1985;Swadley and Carr, 1987; Figure 11). These basalts are largely buried and their distribution is therefore based primarily on aeromagnetic data (V. Langenheim, USGS, written comm., 1994).…”

Section: To About 10 Mamentioning

confidence: 99%

“…The published alternative conceptions of the tectonic framework of the Yucca Mountain area are too numerous to review in detail, but they can be summarized in three end-member categories, according to the dominant process that is used to explain the major structural features of the Crater Flat/Yucca Mountain domain. According to one theory, Crater Flat formed as a caldera complex (Carr, 1982;Carr and Parrish, 1985;W. Carr and others, 1986;Carr, 1990).…”

Section: Definition Of Crater Flat Basinmentioning

confidence: 99%

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Tectonic evolution of the Crater Flat basin, Yucca Mountain region, Nevada

Fridrich¹

1998

Open-File Report

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Yucca Mountain is an arcuate, multiple-fault-block ridge on the rim of Crater Rat in southern Nevada. The ridge and alluvial flat are structurally linked and together constitute the Crater Flat structural basin. This late Cenozoic basin is located on the south flank of the southwest Nevada volcanic field, which in turn lies along the northeast margin of the Walker Lane belt, a northwest-trending zone of irregular topography and structure between the Sierra Nevada and the northern Basin and Range province. The Crater Flat basin is filled dominantly by the major ash-flow tuff sheets erupted from the central caldera complex of the volcanic field, at the north boundary of the basin. Relations in the volcanic rocks, including tilting, faulting, unitthickness changes, and vertical-axis rotations, provide a detailed record of the tectonic history of Crater Flat and adjacent structural domains.Strata within Crater Flat basin are tilted dominantly eastward to southeastward along a closely spaced system of mostly west-to northwest-dipping normal faults. This tilted-domino structural style resembles that of many areas of extreme extension and detachment faulting. However, in Crater Flat, as in much of the volcanic field, this style is developed at moderate to low percentages of extension, such that detachment faulting appears unlikely. Crater Flat formed by a combination of east-west to southeast-northwest extension and northwest-directed dextral deformation, the latter of which is indicated by oblique slickenlines on most intrabasin normal faults and paleomagnetic evidence of oroflexural bending along a northwest-trending axis through the basin. The spatial variation in the percentage of extension and in the degree of vertical-axis rotation within the Crater Flat domain resembles that of a triangular pull-apart basin. A major strike-slip fault(s) may be associated with this basin but, if so, it is somehow concealed. The caldera complex at the north boundary of Crater Flat influenced the structures of this basin by locally modifying the regional stress regime and by doming the rocks peripheral to the calderas; however, the structures of Crater Flat basin are products of regional tectonism, not of caldera collapse.The new field evidence gathered in this study thus does not support previous suggestions that Crater Flat formed through the action of some single concealed master structure, such as a regional detachment fault, a caldera ring-fracture zone, or a major strike-slip fault. This is not to say that any of those three features are necessarily absent. Rather, the major conclusion at this point is that Crater Flat basin is a hybrid feature; its geometry reflects the combination of structural influences that are specific to its setting on the flank of a large caldera complex, at the boundary between the Walker Lane belt and the northern Basin-and-Range province, and at the periphery of a major domain -to the west -of extreme extension associated with detachment faulting.In the Crater Flat region, belts of active e...

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Section: Analysis Of the Structure Of Bare Mountain: Evidence For Tecmentioning

confidence: 99%

Section: To About 10 Mamentioning

confidence: 99%

Section: Definition Of Crater Flat Basinmentioning

confidence: 99%

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Tectonic evolution of the Crater Flat basin, Yucca Mountain region, Nevada

Fridrich¹

1998

Open-File Report

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“…Isotopic ages on a correlative brecciated basaltic dike from a trench on the saddle west of the Little Prow yields a date of 1 0±0.4 Ma (Carr and Parrish, 1985). The dike that intruded along the Solitario Canyon Fault near the Little Prow is itself brecciated along the fault and implies that movement along the Solitario Canyon Fault both pre-dated and post-dated the dike (Scott, 1990).…”

Section: Regional Settingmentioning

confidence: 99%

Bedrock geologic map of the central block area, Yucca Mountain, Nye County, Nevada

Day¹,

Potter²,

Sweetkind³

et al. 1998

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“…Isotopic dating (K-Ar) of a basaltic dike that intrudes the Solitario Canyon fault at Little Prow yields an age of 10±0.4 Ma (Carr and Parrish, 1985). This dike is itself brecciated along the fault, implying that movement along the Solitario Canyon Fault both predated and postdated the emplacement of the dike (Scott, 1990).…”

Section: Stratigraphic Settingmentioning

confidence: 99%

Bedrock geologic map of the Yucca Mountain area, Nye County, Nevada

1998

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Geology of drill hole USW VH-2, and structure of Crater Flat, southwestern Nevada

Cited by 27 publications

References 6 publications

Tectonic evolution of the Crater Flat basin, Yucca Mountain region, Nevada

Tectonic evolution of the Crater Flat basin, Yucca Mountain region, Nevada

Bedrock geologic map of the central block area, Yucca Mountain, Nye County, Nevada

Bedrock geologic map of the Yucca Mountain area, Nye County, Nevada

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