Alteration History Studies in the Exploratory Studies Facility, Yucca Mountain, Nevada, USA

Levy, S.S.; Norman, David I.

doi:10.1557/proc-412-783

Cited by 12 publications

(5 citation statements)

References 6 publications

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“…In other locations, the transitional zones are characterized and modeled appropriately, so, for example, abrupt discontinuities arising from discretization in modeling matrix properties do not result in unrealistic diversion or ponding of water where the actual changes in properties are gradual (Moyer et al, 1996). Some glass has been altered to clays and zeolites in several locations where lithologic transitions have caused high liquid saturations, there was an ancient water table or perched water zone, weathering following deposition has produced alteration, or locally in welded tuffs where moderate‐temperature alteration occurred during cooling (Levy, 1984; Broxton et al, 1987; Bish and Aronson, 1993; Buesch et al, 1995; Levy et al, 1996; Buesch and Spengler, 1998). Various amounts of vapor‐phase corrosion and mineralization have occurred in numerous lithostratigraphic units (Buesch and Spengler, 1999a, 1999b), and these processes (and products) can change properties with depth.…”

Section: Generalized Lithostratigraphy (Buesch Et Al 1996b) Corresmentioning

confidence: 99%

Characterization of Unsaturated Zone Hydrogeologic Units using Matrix Properties and Depositional History in a Complex Volcanic Environment

Flint

Buesch

2006

Vadose Zone Journal

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Characterization of the physical and unsaturated hydrologic properties of subsurface materials is necessary to calculate flow and transport for land use practices and to evaluate subsurface processes such as perched water or lateral diversion of water, which are influenced by features such as faults, fractures, and abrupt changes in lithology. Input for numerical flow models typically includes parameters that describe hydrologic properties and the initial and boundary conditions for all materials in the unsaturated zone, such as bulk density, porosity, and particle density, saturated hydraulic conductivity, moisture-retention characteristics, and field water content. We describe an approach for systematically evaluating the site features that contribute to water flow, using physical and hydraulic data collected at the laboratory scale, to provide a representative set of physical and hydraulic parameters for numerically calculating flow of water through the materials at a site. An example case study from analyses done for the heterogeneous, layered, volcanic rocks at Yucca Mountain is presented, but the general approach for parameterization could be applied at any site where depositional processes follow deterministic patterns. Hydrogeologic units at this site were defined using (i) a database developed from 5320 rock samples collected from the coring of 23 shallow (,100 m) and 10 deep (500-1000 m) boreholes, (ii) lithostratigraphic boundaries and corresponding relations to porosity, (iii) transition zones with pronounced changes in properties over short vertical distances, (iv) characterization of the influence of mineral alteration on hydrologic properties such as permeability and moisture-retention characteristics, and (v) a statistical analysis to evaluate where boundaries should be adjusted to minimize the variance within layers. Model parameters developed in this study, and the relation of flow properties to porosity, can be used to produce detailed and accurate representations of the core-scale hydrologic processes ongoing at Yucca Mountain.

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Section: Generalized Lithostratigraphy (Buesch Et Al 1996b) Corresmentioning

confidence: 99%

Characterization of Unsaturated Zone Hydrogeologic Units using Matrix Properties and Depositional History in a Complex Volcanic Environment

Flint

Buesch

2006

Vadose Zone Journal

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“…Because the matrix permeability of these rocks is so low, it is common to find high saturations due to concentration of water flowing from higher porosity rocks to lower porosity rocks and permeability barrier effects. There are often low-temperature alteration minerals associated with these rocks, but there are also zones with high-temperature alteration materials (Levy, 1996). Devitrified, densely welded rocks have microfractures that are occasionally sampled in core and typically do not contain alteration minerals.…”

Section: Lithologic Featuresmentioning

confidence: 99%

Characterization of hydrogeologic units using matrix properties, Yucca Mountain, Nevada

1998

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DISCLAIMERThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, m mmendation. or favoring by the United States Government or any agency thereof.

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“…The rock magnetic properties of the TC Tuff are documented by abundant published data (Egli & Lowrie, ; Jackson et al, ; Rosenbaum, , ; Rosenbaum & Rivers, ; Rosenbaum & Snyder, ; Schlinger et al, , ; Till et al, ; Worm & Jackson, ), and the geologic setting of the TC Tuff has been extensively studied due to its proximity to the potential nuclear waste repository at Yucca Mountain (Buesch et al, ; Flint et al, ; Frizzell & Shulters, ; Gibson et al, ; Istok et al, ; Levy et al, ; Moyer et al, ; Rautman & Engstrom, ). In this paper, we present the first paleointensity results from the basal vitric zone TC Tuff, as well as previously unpublished rock magnetic results from two new sections.…”

Section: Introductionmentioning

confidence: 99%

Absolute Paleointensity Study of Miocene Tiva Canyon Tuff, Yucca Mountain, Nevada: Role of Fine‐Particle Grain‐Size Variations

Abdulghafur

Bowles

2019

Geochem Geophys Geosyst

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Fine-grained, Ti-poor titanomagnetite in the~12.7 Ma Tiva Canyon (TC) Tuff systematically increases in grain size from superparamagnetic (SP) at the flow base to single domain (SD) at a few meters height. This allows us to examine the role of grain-size variation on paleointensity, within the transition from SP to stable SD. We present magnetic properties from two previously unreported sections of the TC Tuff, as well as Thellier-type paleointensity estimates from the lowermost~7.0 m of the flow. Magnetic hysteresis, frequency-dependent susceptibility, and thermomagnetic data show that sample grain-size distribution is dominated by SP in the lower~3.6 m, transitioning upwards to mostly stable SD. Paleointensity results are closely tied to stratigraphic height and to magnetic properties linked to domain state. SD samples have consistent absolute paleointensity values of 28.5 ± 1.94 μT (VADM of 51.3 ZAm 2 ) and behaved ideally during paleointensity experiments. The samples including a significant SP fraction have consistently higher paleointensities and less ideal behavior but would likely pass many traditional quality-control tests. We interpret the SD remanence to be a primary thermal remanent magnetization but discuss the possibility of a partial thermal-chemical remanent magnetization if microcrystal growth continued at T < T c and/or the section is affected by post-emplacement vapor-phase alteration. The link between paleointensity and domain state is stronger than correlations with water content or other evidence of alteration and suggests that the presence of a significant SP population may adversely impact paleointensity results, even in the presence of a stable SD fraction. Plain Language SummaryThe strength-or intensity-of Earth's magnetic field changes over geologic time, and these changes are important in learning about the internal evolution and processes of Earth's core. These "paleointensity" variations are recorded in many Earth materials, including volcanic ash flows, sometimes called "tuffs." Magnetic minerals in these flows acquire a magnetization proportional to Earth's field strength when they cool. The approximately 12 million-year-old Tiva Canyon Tuff in the western United States contains very fine-grained magnetite particles, the size of which increases upwards from the base of the flow. This small size is typically considered ideal for a paleointensity recorder, and the systematic size variation allows us to test effect of grain size on the paleointensity estimation across the lower end of the size spectrum. Samples collected from the lowermost 7 m of the Tiva Canyon Tuff were subjected to laboratory experiments designed to recover paleointensity. We find that the smallest particles perform poorly in the experiments and do not produce consistent results, while the slightly larger particles perform ideally and provide a consistent answer. This tells us that smaller is not always better, and there is a very narrow grain size range that will produce accurate results.

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Alteration History Studies in the Exploratory Studies Facility, Yucca Mountain, Nevada, USA

Cited by 12 publications

References 6 publications

Characterization of Unsaturated Zone Hydrogeologic Units using Matrix Properties and Depositional History in a Complex Volcanic Environment

Characterization of Unsaturated Zone Hydrogeologic Units using Matrix Properties and Depositional History in a Complex Volcanic Environment

Characterization of hydrogeologic units using matrix properties, Yucca Mountain, Nevada

Absolute Paleointensity Study of Miocene Tiva Canyon Tuff, Yucca Mountain, Nevada: Role of Fine‐Particle Grain‐Size Variations

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