Orthogonal jointing during coeval igneous degassing and normal faulting, Yucca Mountain, Nevada

Dunne, William M.; Ferrill, David A.; Crider, Juliet G.; Hill, Brittain E.; Waiting, Deborah J.; Femina, P. C. La; Morris, Alan P.; Fedors, R.

doi:10.1130/b25231.1

Cited by 12 publications

(9 citation statements)

References 89 publications

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“…Curtis (1968) reports that the ash flows of Valley of Ten Thousand Smokes had compacted within 10 years of the eruption and that after 42 years all vigorous fumarolic activity at Katmai had ceased. Compaction and welding in the Tiva Canyon Tuff (100 m thick; Southwest Nevada Volcanic Field) likely ceased 1-10 years after deposition (Dunne et al 2003). The earliest-formed fractures were associated with gas-escape structures such as fumaroles, which occur with observable alteration and mineralization (e.g., Sheridan 1970;Keith 1991).…”

Section: Discussionmentioning

confidence: 99%

Fumarolic pipes in the Tshirege Member of the Bandelier Tuff on the Pajarito Plateau, Jemez Mountains, New Mexico

et al. 2012

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The objective of this study is to demonstrate the relationships among devitrification, vapor phase alteration, localization of gas emanations into fumarolic pipes, and initial deformation of the ash flow sheet during cooling and lithification. Utilizing a unique and temporary exposure of the Tshirege Member of the Bandelier Tuff near Los Alamos, New Mexico, we identify several zones of distinctly preserved fossil fumarolic activity. The fumarolic zones vary in width from a few centimeters to more than a meter. Almost ubiquitously, these zones demonstrate finesdepletion, induration of the margins, upward-flaring geometries, and intense fracturing of overlying geologic units. The fumaroles were preferentially located on post welding, early formed cooling joints that vented to the surface after the vapor phase alteration stage. The pipes were regularly spaced at distances of approximately 4.5 m (N-S) to 7 m (E-W). In turn the pipes were covered by a surge deposit and overlying tuff which rapidly lithified. The overlying tuff was then brecciated during continued fumarolic pipe emissions. Geochemical evaluations confirm the presence of high-temperature mineral (scapolite) indicative of transport of hot volcanic gases through these zones. The pipe centers and walls are depleted in SiO 2 , and enriched in Al 2 O 3 and FeO. The overlying tuff breccia zones are enriched in Al 2 O 3 , FeO and MgO, and depleted in SiO 2 , NaO, and K 2 O. From comparison to other ignimbrite cooling histories, the fissures, fumaroles, and structures observed all likely formed in the first few decades after the deposition of the upper Tshirege subunits. This may have significant implications as to timing of initial cooling fractures and subsequent consolidation of gas emission pathways.

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Section: Discussionmentioning

confidence: 99%

Fumarolic pipes in the Tshirege Member of the Bandelier Tuff on the Pajarito Plateau, Jemez Mountains, New Mexico

et al. 2012

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“…Similar, opallined horizontal fractures are described by Dunne et al (2003) in the Tiva Canyon Tuff; they attribute these fractures to faulting. However, these anastomosing fractures could also owe their origin to dynamic fractur ing.…”

Section: Role Of Gas Pressure In Fracturingmentioning

confidence: 91%

“…Dunne et al (2003) describe jointing in the on June 1, 2015 geosphere.gsapubs.org Downloaded from interior of the 100mthick Tiva Canyon Tuff at Yucca Mountain, Nevada. The earliest formed fractures are orthogonal vertical joints that have mm to cmdiameter tubes in their faces.…”

Section: Role Of Gas Pressure In Fracturingmentioning

confidence: 98%

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Relations between thermal history and secondary structures of ignimbrites exclusive of rheomorphism

Riehle¹

2015

Geosphere

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Newly calculated model density profiles of ignimbrites also provide model thermal his tories, which serve as a framework to help analyze the development of cooling joints, devitrification textures, and lithophysal cavi ties. Only those parts of sections of Rattle snake Tuff in central Oregon that resided >600 °C for at least two years show devitrifi cation. Low tensile strength means that joints form by thermoelastic contraction after cool ing by as little as 25 °C. This means that columnar joints formed in as little time as a few weeks after deposition of the Aravaipa Tuff in SE Arizona. Compaction is rapid as well, so both columnar jointing and compac tion are complete before the onset of devitri fication in deposits <40 m thick.A section of Rattlesnake Tuff shows strata bound occurrences of devitrified spots and cavities; devitrification appears to have begun at scattered spots. Most spots are bounded by crescentic cavities in formerly ductile shards. The equation for conductive cooling of a spherical heat source shows that for rock volumes larger than ~15 cm diam eter, the rate of cooling is insufficient to pre vent heating by latent heat by as much as 12 °C. Inflation therefore appears to have been caused by vapor released by devitri fication and its slight adiabatic expansion. Eventual wholesale devitrification of matrix resulted in moredevitrified spots scattered in less devitrified matrix. Lithophysal cavi ties in the Rattlesnake Tuff and in the Peach Springs Tuff in NW Arizona are more abun dant in lower density horizons, showing that cavity growth is favored in permeable zones between impermeable horizons.The Peach Springs Tuff and other depos its described in the literature have horizon tal joints that formed during cooling and whose origin has yet to be deterministically modeled. The longest joints are most closely spaced in the zone of cavities and formed after columnar joints. It is inferred that after formation, each vertical column responds independently to evolving stresses; at this time, asperities together with gas pressures accompanying cavity formation result in horizontal joints. Columnar joints do not completely relieve growing gas pressures during devitrification, likely because of seal ing by wholesale inflation of the rock mass and by mineral deposition.Some devitrified horizons of Rattlesnake Tuff and Peach Springs Tuff are densely frac tured, resulting in a rubbly surface. These small fractures show zigzag traces, bifur cations, abrupt terminations, and pinch andswell walls, similar to ductile fractures described by Eichhubl (2004). Their origin is interpreted to be the result of tensile stress due to porosity increase during later stages of devitrification.Closely adjacent sections of Rattlesnake Tuff at one site differ by 18% in thickness, reflecting buried paleotopography. Each sec tion is devitrified. The thicker profile has a zone of lithophysal cavities near its base; the thinner profile has few cavities. The greater thickness translates to only 0.18 MPa addi tional lithostatic p...

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“…), but it is unlikely that closely spaced 594 columnar joints control fault orientations broadly. Studies in welded ignimbrites suggest595 that the orientation of cooling joints in those rocks may influence fault orientation as well596 as initiation style (e.g Dunne et al, 2003;Gray et al, 2005;Soden and Shipton, 2013)…”

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confidence: 99%

The initiation of brittle faults in crystalline rock

Crider

2015

Journal of Structural Geology

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Orthogonal jointing during coeval igneous degassing and normal faulting, Yucca Mountain, Nevada

Cited by 12 publications

References 89 publications

Fumarolic pipes in the Tshirege Member of the Bandelier Tuff on the Pajarito Plateau, Jemez Mountains, New Mexico

Fumarolic pipes in the Tshirege Member of the Bandelier Tuff on the Pajarito Plateau, Jemez Mountains, New Mexico

Relations between thermal history and secondary structures of ignimbrites exclusive of rheomorphism

The initiation of brittle faults in crystalline rock

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