Geology of the USW SD-9 Drill Hole, Yucca Mountain, Nevada
Total Page:16
File Type:pdf, Size:1020Kb
MO 0100 (2) 1996 Revi«*v grr1 Apprnu-tl 761 ?- for PQE/n-cyrl. SANDIA REPORT £U SAND96-2030 • UC-814 • ft Unlimited Release Printed September 1996 Yucca Mountain Site Characterization Project Geology of the USW SD-9 Drill Hole, Yucca Mountain, Nevada D. A. Engstrom, Christopher A. Rautman Prepared by Sandia National Laboratories Albuquerque, New Mexico 87185 and Livermore, California 94550 for the United States Department of Energy under Contract DE-AC04-94AL85000 0 Approved for public release;|pfetni5ution is unlimited. DISTRIBUTION OF THIS DOCUME^ IS SF2900QI8-81) DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. "Prepared by Yucca Mountain Site Characterization Project (YMSCP) par- ticipants as part of the Civilian Radioactive Waste Management Program (CRWM). The YMSCP is managed by the Yucca Mountain Project Office of the U.S. Department of Energy, DOE Field Office, Nevada (DOE/NV). YMSCP work is sponsored by the Office of Geologic Repositories (OGR) of the DOE Office of Civilian Radioactive Waste Management (OCRWM)." Issued by Sandia National Laboratories, operated for the United States Department of Energy by Sandia Corporation. NOTICE: This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Govern- ment nor any agency thereof, nor any of their employees, nor any of their contractors, subcontractors, or 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, prod- uct, or process disclosed, or represents that its use would not infringe pri- vately 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, recommendation, or favoring by the United States Government, any agency thereof or any of their contractors or subcontractors. The views and opinions expressed herein do not necessarily state or reflect those of the United States Govern- ment, any agency thereof or any of their contractors. Printed in the United States of America. This report has been reproduced directly from the best available copy. Available to DOE and DOE contractors from Office of Scientific and Technical Information PO Box 62 Oak Ridge, TN 37831 Prices available from (615) 576-8401, FTS 626-8401 Available to the public from National Technical Information Service US Department of Commerce 5285 Port Royal Rd Springfield, VA 22161 NTIS price codes Printed copy: A08 Microfiche copy: A01 SAND96-2030 Distribution Unlimited Release Category UC-814 Printed October 1996 Geology of the USW SD-9 Drill Hole, Yucca Mountain, Nevada Dale A. Engstrom Spectra Research Institute Albuquerque, New Mexico 87106 Christopher A. Rautman Geohydrology Department Sandia National Laboratories Albuquerque, New Mexico 87185 Abstract Drill hole USW SD-9 is one of several holes drilled under Site Characterization Plan Study 8.3.1.4.3.1, also known as the "Systematic Drilling Program," as part of the U.S. Department of Energy characterization program at Yucca Mountain, Nevada, which has been proposed as the potential location of a repository for high-level nuclear waste. The SD-9 drill hole is located in the northern part of the potential repository area, immediately to the west of the Main Test Level drift of Exploratory Studies Facility and south of the North Ramp decline. Drill hole USW SD-9 is 2223.1 ft (677.57 m) deep, and the core recov- ered essentially complete sections of ash-flow tuffs belonging to the Yucca Mountain, Pah Canyon, and Topopah Spring Tuffs of the Miocene Paintbrush Group. The hole cored the entire Calico Hills Formation, which underlies the Paintbrush Group, and all but the lowermost part of the Prow Pass Tuff of the Crater Flat Group. The drill hole was collared low in the welded portion of the Tiva Canyon Tuff; only 38.7 (11.8 m) of this formation was recovered. The Yucca Mountain Tuff is approximately 45-ft (13.7-m) thick, and the interior portion of this ash flow is partially welded. The Yucca Mountain Tuff thins to extinction south- ward. The Pah Canyon Tuff is 69.4 ft (21.15 m) thick and is completely nonwelded in this drill hole. The Topopah Spring Tuff consists of 1211.5 ft (369.25 m) of generally densely welded material; this is one of the thickest known sections of welded Topopah Spring Tuff at or near Yucca Mountain. Lithophysae are well developed locally within the parts of the Topopah Spring, and large lithophysal cavities up to several feet (many tenths of a meter) in diameter are present throughout roughly the lower two-thirds of the unit. This somewhat anomalous occurrence of very large lithophysal cavities, which is in addition to the better known presence of zones containing smaller, inch-scale (cm-scale) lithophysae within the Topopah Spring, may be related genetically to the greater thickness of the unit at this geographic location. The Calico Hills Formation in drill hole SD-9 consists of 341 ft (103.87 m) of nonwelded and mostly zeolitized tuffaceous materials. The hole cored 402.4 ft (122.65 m) of rocks belonging to the ash-flow sequences of the Prow Pass Tuff. The drill hole was stopped short of the base of the lowermost known ash-flow unit of the Prow Pass. Quantitative and semiquantitative data are included in this report for core recovery, rock-quality designation (RQD), lithophysal cavity abundance, and fracturing. These data are spatially variable, both Abstract within and among the major formational-level stratigraphic units. Nonwelded intervals in general exhibit higher recoveries and more intact (higher) RQD values than welded intervals. The most intact, highest- •RQD materials encountered within the Topopah Spring belong to the lower 33.3 ft (10.15 m) of the middle tiorilithophysal zone. Estimation of lithophysal cavity abundances is complicated by the existence of cavi- ties much larger than the core diameter; drilling through intervals of these large cavities produced exten- sive zones of "lost" core and rubble. This report includes quantitative data for the framework material properties of porosity, bulk and particle density,.and saturated hydraulic conductivity. Graphical analysis of variations in these laboratory hydrologic properties indicates first-order control of material properties by the degree of welding and the presence of zeolite minerals. Many major lithostratigraphic contacts are not well expressed in the material- property profiles; contacts of material-property units are related more to changes in the intensity of weld- ing. Approximate in-situ saturation data of samples preserved immediately upon recovery from the hole are included in the data tabulation. Geophysical data have been obtained for the upper approximately 1500 ft (450 m) of the USW SD-9 drill hole; the lower part of the hole below the Topopah Spring Tuff has not been logged. Geophysi- cal logs include density, gamma-ray, epithermal-neutron porosity, electrical-resistivity, and caliper profiles down to the base of the Topopah Spring Tuff. The bulk-density log provides the most lithologic informa- tion, and many of the lithologic subdivisions of the Paintbrush Group tuffs can be tied to distinctive changes in the density trace. Discrimination of welded from nonwelded rock types and of lithophysal zones and nonlithophysal zones is immediately apparent in the density log. Material-property units identi- fied using geophysical logs do not correspond in detail to the broader, genetic lithostratigraphic unit boundaries. Acknowledgments This work was performed for the U.S. Department of Energy, Office of Civilian Radioactive Waste Management, Yucca Mountain Site Characterization Project Office under contract EA9012M5X. Scientific investigations involving the Systematic Drilling Program are conducted under the descriptions of work contained in the Site Characterization Plan (DOE, 1988) and in Study Plan 8.3.1.4.3.1 (Rautman, 1993); the work-breakdown structure element is \.23.2.2.2.1. The planning document that directed this work activity is WA-0301; prior to the effective date of WA-0301, work activities for this WBS element were conducted under WA-0014. The information and data documented in this report was conducted under a fully qualified quality assurance program. Full details associated with all reported data may be located in the Yucca Mountain Site Characterization Project records using the data-tracking numbers (DTNs) pro- vided in the relevant sections of this report. Geology of the USW SD-9 Drill Hole, Yucca Mountain, Nevada Contents Abstract i Acknowledgments ii Introduction 1 Purpose of the Systematic Drilling Program 1 Regional Geologic Setting 2 Volcanic Stratigraphy 2 Petrogenesis and Zonation of Paintbrush Group Tuffs 3 Subdivisions of the Calico Hills Formation and Prow Pass Tuff (Crater Flat Group) 5 The USW SD-9 Drill Hole 6 Location 6 Drilling History 7 Method of Study 7 Geologic Logging and Core Description 7 Laboratory Material Properties 8 Geology of Drill Hole USW SD-9 8 Overview 8 Thermal/Mechanical Units 11 Structural Geology of SD-9 12 Lithophysal Zones 12 Rock Quality Considerations 14 Core Recovery 14 RQD (Rock Quality Designation) 16 Measured Lithophysal Cavity Information 18 Fracture Information 19 Framework Hydrologic Properties 23 Laboratory Techniques 23 Material-Properties Data 25 Geophysical Log Data 28 Density Log Response 28 Gamma-Ray Log Response 30 Epithermal Neutron Porosity Log Response 30 Dual-Induction Log Response 31 Caliper Log Response 31 Summary and Conclusions 32 References 33 Appendix A: Detailed Lithologic Descriptions 37 Tiva Canyon Tuff 38 Yucca Mountain Tuff 39 Pah Canyon Tuff 39 Topopah Spring Tuff 40 Calico Hills Formation 44 Prow Pass Tuff 45 Contents HI Geology of the USW SD-9 Drill Hole, Yucca Mountain, Nevada Introduction characterize the subsurface geoLogy of the pro- posed repository block.