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Structure of the Tshirege Member of the Bandelier Tuff at Mesita del Buey, Technical Area 54, Los Alamos National Laboratory

Description: The geological structure of the Tshirege Member of the Bandelier Tuff at Mesita del Buey, Technical Area 54, was examined using precise surveying of the contact between tuff units Iv and 2 for 3.5 km along the north wall of Pajarito Canyon and 0.6 km along the north wall of a tributary to Caiiada del Buey. Estimated structure contours on this contact indicate typical strikes of N40E to N70E along this part of Mesita del Buey, although the apparent stfike of the tuff is E-W at the western part of the survey. Typical dips are 1.OO to 2.0o to the east or southeast, with an estimated maximum dip of 3.2o near the west end of Material Disposal AreaG. Thirty seven faults with vertical displacements of 5 to 65 cm were observedin outcrops along the Pajarito Canyon traverse, and, due to the incomplete exposure of the contact between unit lV and unit 2, many more faults of this magnitude undoubtedly exist. The faults have a wide range in strike and have either down-to-the-west or down-to-the-east components of offset, although about 65% of the observed displacement is down-to-the-west or northwest. The general absence of larger-scale offsets or inflections along the contact between units lV and 2 in areas where the small-scale faults were observed suggests that they are not associated with major fault zones. Instead, these faults may record distributed secondary deformation across the Pajarito Plateau associated with large earthquakes on the main Pajarito fault zone 8 to 11 km to the west, or perhaps earthquakes on other faults in the region. The survey data also suggest that a 150 to 250 m wide zone of greater magnitude faulting is present near the west end of the traverse associated with a horst-and-graben structure displaying about 1.5 to 3.5 m of offset on ...
Date: December 1, 1998
Creator: LaDelfe, Carol; Broxton, David E.; Carney, John S. & Reneau, Steven L.
Partner: UNT Libraries Government Documents Department

Fracture Characteristics in a Disposal Pit on Mesita del Buey, Los Alamos National Laboratory

Description: The characteristics of fractures in unit 2 of the Tshirege Member of the Bandelier Tuff were documented in Pit 39, a newly excavated 13.7 m deep disposal pit at Material Disposal Area G on Mesita del Buey. The average spacing between fractures is about 1.0 to 1.3 m, the average fracture aperture is about 3 to 5 mm, and the average fracture dip is about 76o to 77o. Fracture spacing and dip in Pit 39 are generally consistent with that reported from other fracture studies on the Pajarito Plateau, although the fracture apertures in Pit 39 are less than reported elsewhere. Measured fracture orientations are strongly affected by biases imparted by the orientations of the pit walls, which, combined with a small data set, make identification of potential preferred orientations dlfflcult. The most prominent fracture orientations observed in Pit 39, about E-W and N20E, are often not well represented elsewhere on the Pajarito Plateau. Fracture fills contain smectite to about 3 m depth, and calcite and opal may occur at all depths, principally associated with roots or root fossils (rhizoliths). Roots of pifion pine extend in fractures to the bottom of the pit along the north side, perhaps indicating a zone of preferred infiltration of water. Finely powdered tuff with clay-sized particles occurs within a number of fractures and may record abrasive disaggregation associated with small amounts of displacement on minor local faults.
Date: December 1, 1998
Creator: Vaniman, David T. & Reneau, Steven L.
Partner: UNT Libraries Government Documents Department

[Evolution of Sedimentary Basins--Uinta and Piceance Basins: Chapters J and K]

Description: From abstract: This is a report on reconnaissance geologic mapping and isotopic dating of tuff beds in the Uinta Basin of Utah that show that Lake Uinta probably persisted into late Eocene time in the area east of Duchesne and Strawberry Reservoir.
Date: 1989
Creator: Bryant, Bruce; Naeser, Charles W.; Marvin, Richard F. & Mehert, H. H.
Partner: UNT Libraries Government Documents Department

Neutron and gamma (density) logging in welded tuff

Description: This Technical Implementation Procedure (TIP) describes the field operation, and the management of data records pertaining to neutron logging and density logging in welded tuff. This procedure applies to all borehole surveys performed in support of Engineered Barrier System Field Tests (EBSFI� ), including the Earge Block Tests (LBT) and Initial Engineered Barrier System Field Tests (IEBSFT) - WBS The purpose of this TIP is to provide guidelines so that other equally trained and qualified personnel can understand how the work is performed or how to repeat the work if needed. The work will be documented by the use of Scientific Notebooks (SNs) as discussed in 033-YMP-QP 3.4. The TIP will provide a set of guidelines which the scientists will take into account in conducting the mea- surements. The use of this TIP does not imply that this is repetitive work that does not require profes- sional judgment.
Date: September 12, 1998
Creator: Lin, W.
Partner: UNT Libraries Government Documents Department

Core flow experiment protocol

Description: This letter report describes the current status of the core flow through apparatus and describes the protocol and test matrix to be followed during the initial experimental stage of radionuclide transport studies in the Integrated Testing task.
Date: December 1, 1997
Creator: Viani, B.E. & Martin, S.I.
Partner: UNT Libraries Government Documents Department

Report on laboratory tests of drying and re-wetting of intact rocks from the drift scale and single heater tests

Description: The primary focus of this report is the measurement of moisture retention curves of tuff as a function of temperature for both drying and re-wetting conditions. The report contains descriptions of experimental designs and procedures, data, observation, preliminary analyses, and future work. Knowledge of unsaturated transport properties is critical for understanding the movement of water through the unsaturated zone. Evaluation of the performance of a potential nuclear waste repository also depends on these properties. Moisture retention data are important input of numerical models of moisture movement in unsaturated porous media. Also important is the effect of sample history on the moisture retention curves, and whether or not there is significant hysteresis between wetting and drying measurements. This report addresses initial observations regarding this aspect of the research.
Date: January 1, 1998
Creator: Roberts, J.J.; Carlberg, E.; Pletcher, R. & Lin, W.
Partner: UNT Libraries Government Documents Department

Determination of mineral abundances in samples from the Exploratory Studies Facility, Yucca Mountain, Nevada, using x-ray diffraction

Description: Tuff samples collected from the Exploratory Studies Facility (ESF) were X-rayed to estimate relative mineral abundances. X-ray analysis was performed on sub-samples of specimens collected from both the Single Heater Test (SHT) and Drift Scale Heater Test (MT) that were used for thermomechanical measurements, as well as samples collected from cores retrieved from boreholes in the Drift Scale Test Area. The abundance of minerals that could affect the behavior of the host rock at repository relevant temperatures is of particular interest. These minerals include cristobalite, which undergoes a phase transition and volume change at elevated temperature (-250 {degree}C), and smectite and clinoptilolite that can dehydrate at elevated temperature with accompanying volume reduction. In addition, the spatial distribution of Si02 polymorphs and secondary minerals may provide evidence for deducing past fluid pathways. The mineral abundances tabulated here include data reported previously in three milestone reports but reanalyzed, as well as previously unreported data.
Date: January 13, 1998
Creator: Roberts, S. & Viani, B.
Partner: UNT Libraries Government Documents Department

Anisotropic behavior in 0.5m scale blocks of Topopah Spring tuff

Description: Laboratory tests on 0.5 meter scale blocks of Topopah Spring tuff were performed to determine fluid flow and mechanical behavior of samples containing fractures. Results include data for a comprehensive set of flow measurements through a rock sample containing a horizontally oriented fracture at uniaxial stress conditions up to 8 MPa at room temperature. Directional channeling, rather than mean fracture aperture, controls the flow. On the time scale of these experiments, inhibition is negligible.
Date: February 1, 1998
Creator: Blair, S. C. & Costantino, M. S.
Partner: UNT Libraries Government Documents Department

A Review of Degradation Behavior of Container Materials for Disposal of High-Level Nuclear Waste in Tuff and Alternative Repository Environments

Description: Corrosion resistance of materials in aqueous systems is reviewed from the perspective of their suitability as container materials for nuclear waste. A discussion of the chemistry and characterization of repository environments, namely, tuff and alternative environments (shale, limestone, and carbonate), is followed by a description of corrosion mechanisms. In this review, emphasis is placed on localized corrosion (e.g., stress corrosion cracking, crevice corrosion, and pitting) because localized corrosion is difficult to account for in design of components, but it is the life-limiting factor for many metallic and nonmetallic systems.
Date: June 1989
Creator: Maiya, P. S.
Partner: UNT Libraries Government Documents Department

Results of plug-flow reactor experiments with crushed tuff at 280C and 300C

Description: We report on the results to date for two plug-flow reactor experiments, PFR-11 and PFR-13, designed to simulate reactive transport chemical and physical processes. These experiments provide a physical model of idealized one dimensional plug flow and chemical reaction using deionized water and crushed Topopah Springs Tuff (Tsw2). Data consist of effluent ion concentrations and pH measurements taken at several times during both experiments and limited mineralogical analysis of post-test solid phases for PFR-11.
Date: September 2, 1999
Creator: Dibley, M J; Knauss, K G & Rosenberg, N D
Partner: UNT Libraries Government Documents Department

National Uranium Resource Evaluation: Delta Quadrangle, Utah

Description: The Delta 1°x2° Quadrangle, Utah contains rocks which range in age from the Precambrian through the Holocene. It lies in the eastern part of the Basin and Range Province, approximately 85 mi southwest of Salt Lake City. Most known uranium resource potential lies in four geographic environments in two geographic areas. Favorable environments are: (1) Tertiary tuffaceous sandstone and conglomerate epigenetic disseminated deposits; (2) volcanic hydroallogenic environments containing uranium-mineralized altered tephra in the beryllium tuff member of the Miocene Spor Mountain Formation; (3) pipes or small diatreme structures in the Paleozoic limestones and quartzites on Spor Mountain, defined as Tertiary volcanogenic hydroallogenic environments; and, (4) alluvial-lacustrine placer environments, on the east and west sides of the Deep Creek Range adjacent to the quartz monzonite Ibapah stock. The significant volume of Miocene rhyolites and tuffs in the Quadrangle contain uncommonly large abundances of uranium and thorium.
Date: September 1982
Creator: Cadigan, Robert Allen & Ketner, Keith Brindley
Partner: UNT Libraries Government Documents Department

Postglacial Volcanic Deposits at Mount Baker, Washington, and Potential Hazards From Future Eruptions

Description: Abstract: Eruptions and other geologic events at Mount Baker during the last 10,000 years have repeatedly affected adjacent areas, especially the valleys that head on the south and east sides of the volcano. Small volumes of tephra were erupted at least four times during the past 10,000 years. Future eruptions like these could cause as much as 35 centimeters of tephra to be deposited at sites 17 kilometers from the volcano, 15 centimeters of tephra to be deposited 29 kilometers from the volcano, and 5 centimeters, 44 kilometers from the volcano. Lava flows were erupted at least twice during the last 10,000 years and moved down two valleys. Future lava flows will not directly endanger people because lava typically moves so slowly that escape is possible. Hot pyroclastic flows evidently occurred during only one period and were confined to the Boulder Creek valley. Such flows can move at speeds of as much as 150 kilometers per hour and can bury valley floors under tens of meters of hot rock debris for at least 15 kilometers from the volcano. Large mudflows, most of which contain hydrothermally altered rock debris, originated at Mount Baker at least eight times during the last 10,000 years. The largest mudflow reached 29 kilometers or more down the valley of the Middle Fork Nooksack River, west of the volcano, about 6,000 years ago. Extensive masses of hydrothermally altered rock that are potentially unstable exist today near the summit of the volcano, especially in the Sherman Crater-Sherman Peak area. Avalanches of this material could be triggered by stream explosions, earthquakes, or eruptions, or may occur because of slow-acting forces or processes that gradually decrease stability. Large avalanches could move downslope at high speed and could grade downvalley into mudflows. Floods caused by rapid melting of snow and ice ...
Date: 1978
Creator: Hyde, Jack H. & Crandell, Dwight Raymond
Partner: UNT Libraries Government Documents Department

Analysis of Fracture in Cores from the Tuff Confining Unit beneath Yucca Flat, Nevada Test Site

Description: The role fractures play in the movement of groundwater through zeolitic tuffs that form the tuff confining unit (TCU) beneath Yucca Flat, Nevada Test Site, is poorly known. This is an important uncertainty, because beneath most of Yucca Flat the TCU lies between the sources of radionuclide contaminants produced by historic underground nuclear testing and the regional carbonate aquifer. To gain a better understanding of the role fractures play in the movement of groundwater and radionuclides through the TCU beneath Yucca Flat, a fracture analysis focusing on hydraulic properties was performed on conventional cores from four vertical exploratory holes in Area 7 of Yucca Flat that fully penetrate the TCU. The results of this study indicate that the TCU is poorly fractured. Fracture density for all fractures is 0.27 fractures per vertical meter of core. For open fractures, or those observed to have some aperture, the density is only 0.06 fractures per vertical meter of core. Open fractures are characterized by apertures ranging from 0.1 to 10 millimeter, and averaging 1.1 millimeter. Aperture typically occurs as small isolated openings along the fracture, accounting for only 10 percent of the fracture volume, the rest being completely healed by secondary minerals. Zeolite is the most common secondary mineral occurring in 48 percent of the fractures observed.
Date: March 1, 2008
Creator: Prothro, Lance
Partner: UNT Libraries Government Documents Department

High-pressure mechanical properties of an Area 12, Nevada Test Site tuff

Description: The mechanical properties of tuff from instrument hole UG3, tunnel U12e.06 at the Nevada Test Site have been investigated to 1400 MPa, The shear strength increases from about 5 MHa unconfined to 12 MPa at 300 MPa mean pressure. A brittle-ductile transition was indicated at about 250 MPa. In uniaxial strain, the sample loads to the vicinity of the failure envelope and then is parallel to that envelope up to the highest stresses, 420 MPa. Hydrostatic pressure of 1400 MPa produces about 9% volume compression and 1.3% permanent compaction in this apparently saturated tuff. (auth)
Date: November 19, 1973
Creator: Duba, A.; Abey, A. E. & Heard, H. C.
Partner: UNT Libraries Government Documents Department

Deposits of Pre-1980 Pyroclastic Flows and Lahars from Mount St. Helens Volcano, Washington

Description: From introduction: This report describes the character, origin, age, and extent of deposits of pyroclastic flows and lahars that were formed at Mount St. Helens before 1980, and their stratigraphic relations to other rocks and deposits of volcanic and glacial origin.
Date: 1987
Creator: Crandell, Dwight Raymond
Partner: UNT Libraries Government Documents Department

Numerical experiments on the probability of seepage intounderground openings in heterogeneous fractured rock

Description: An important issue for the performance of underground nuclear waste repositories is the rate of seepage into the waste emplacement drifts. A prediction of this rate is particularly complicated for the potential repository site at Yucca Mountain, Nevada, because it is located in thick, unsaturated, fractured tuff formations. Underground opening in unsaturated media might act as capillary barriers, diverting water around them. In the present work, they study the potential rate of seepage into drifts as a function of the percolation flux at Yucca Mountain, based on a stochastic model of the fractured rock mass in the drift vicinity. A variety of flow scenarios are considered, assuming present-day and possible future climate conditions. They show that the heterogeneity in the flow domain is a key factor controlling seepage rates, since it causes channelized flow and local ponding in the unsaturated flow field.
Date: April 15, 1998
Creator: Birkholzer, J.; Li, G.; Tsang, C.F. & Tsang, Y.
Partner: UNT Libraries Government Documents Department


Description: A simplified mechanical model is used to simulate the deformation of a scoria cone due to pressurization of magma in a feeder conduit. The scoria cone is modeled as consisting of a cone of stabilized scoria with an axial region of loose scoria (height h{sub 1}), all overlying a vertically oriented cylindrical conduit intruded into rhyolite tuff country rock. For our analyses, the conduit is filled with basalt magma, usually with the upper length (h{sub 2}) solidified. The style of deformation of the cone depends on both h{sub 1} and h{sub 2}. If magma is prevented from hydrofracturing out of the conduit (as, for example, might be the case if the magma is surrounded by a solidified, but plastically deformable layer acting as a gasket backed up by the brittle country rock) pressures in the magma can build to 10s of MPa. When h{sub 1} is 100 m, not unusual for a small isolated basaltic cinder cone, the magma pressure needed to destabilize the cone when molten magma extends all the way to the original ground surface (h{sub 2} = 0) is only about one-third of the pressure when the upper part of the conduit is solidified (h{sub 2} = 25m). In the former case, almost the entire upper third of the cone is at failure in tension when the configuration becomes unstable. In the latter case, small portions of the surface of the cone are failing in tension when instability occurs, but a large volume in the central core of the cone is failing in shear or compressions. These results may provide insight into the status of volcanic plumbing, either past or present, beneath scoria cones. Field observations at the Lathrop Wells volcano in southern Nevada identify structures at the outer edge just below the crater rim that appear ...
Date: August 26, 2005
Creator: Gaffney, E.S.; Damjanac, B.; Krier, D. & Valentine, G.
Partner: UNT Libraries Government Documents Department

Review of the geological and structural setting near the site of the proposed Transuranic Waste Facility (TRUWF) Technical Area 52 (TA-52), Los Alamos National Laboratory

Description: Because of Los Alamos National Laboratory’s proximal location to active geologic structures, assessment of seismic hazards, including the potential for seismic surface rupture, must occur before construction of any facilities housing nuclear or other hazardous materials. A transuranic waste facility (TRUWF) planned for construction at Technical Area 52 (TA-52) provides the impetus for this report. Although no single seismic hazards field investigation has focused specifically on TA-52, numerous studies at technical areas surrounding TA-52 have shown no significant, laterally continuous faults exhibiting activity in the last 10 ka within 3,000 ft of the proposed facility. A site-specific field study at the footprint of the proposed TRUWF would not yield further high-precision data on possible Holocene faulting at the site because post-Bandelier Tuff sediments are lacking and the shallowest subunit contacts of the Bandelier Tuff are gradational. Given the distal location of the proposed TRUWF to any mapped structures with demonstrable Holocene displacement, surface rupture potential appears minimal at TA-52.
Date: October 1, 2007
Creator: Schultz-Fellenz, Emily S. & Gardner, Jamie N.
Partner: UNT Libraries Government Documents Department