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

Research Article| December 01, 2003 Orthogonal jointing during coeval igneous degassing and normal faulting, Yucca Mountain, Nevada William M. Dunne; William M. Dunne 1Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee 37996, USA Search for other works by this author on: GSW Google Scholar David A. Ferrill; David A. Ferrill 2Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA Search for other works by this author on: GSW Google Scholar Juliet G. Crider; Juliet G. Crider 3Department of Geology, Western Washington University, Bellingham, Washington 98225, USA Search for other works by this author on: GSW Google Scholar Brittain E. Hill; Brittain E. Hill 4Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA Search for other works by this author on: GSW Google Scholar Deborah J. Waiting; Deborah J. Waiting 4Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA Search for other works by this author on: GSW Google Scholar Peter C. La Femina; Peter C. La Femina 4Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA Search for other works by this author on: GSW Google Scholar Alan P. Morris; Alan P. Morris 5Department of Earth and Environmental Sciences, University of Texas, San Antonio, Texas 78249, USA Search for other works by this author on: GSW Google Scholar Randall W. Fedors Randall W. Fedors 6Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA Search for other works by this author on: GSW Google Scholar Author and Article Information William M. Dunne 1Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee 37996, USA David A. Ferrill 2Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA Juliet G. Crider 3Department of Geology, Western Washington University, Bellingham, Washington 98225, USA Brittain E. Hill 4Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA Deborah J. Waiting 4Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA Peter C. La Femina 4Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA Alan P. Morris 5Department of Earth and Environmental Sciences, University of Texas, San Antonio, Texas 78249, USA Randall W. Fedors 6Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA Publisher: Geological Society of America Received: 07 Aug 2002 Revision Received: 18 Apr 2003 Accepted: 19 May 2003 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2003) 115 (12): 1492–1509. https://doi.org/10.1130/B25231.1 Article history Received: 07 Aug 2002 Revision Received: 18 Apr 2003 Accepted: 19 May 2003 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation William M. Dunne, David A. Ferrill, Juliet G. Crider, Brittain E. Hill, Deborah J. Waiting, Peter C. La Femina, Alan P. Morris, Randall W. Fedors; Orthogonal jointing during coeval igneous degassing and normal faulting, Yucca Mountain, Nevada. GSA Bulletin 2003;; 115 (12): 1492–1509. doi: https://doi.org/10.1130/B25231.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract An orthogonal system of tube-bearing joints constitutes the oldest fractures in the Tiva Canyon Tuff at Yucca Mountain, Nevada. The joints formed within a month of ignimbrite deposition, prior to major degassing. The system consists of (1) narrow, persistent, northeast-striking joint swarms with trace lengths typically greater than 5 m and between-joint spacings of less than 20 cm and (2) northwest-striking swarms that have a more en echelon geometry and greater between-joint spacings compared to the northeast-striking swarms. Between-swarm spacing for both trends is ∼50 m. Questions concerning the joints include the following: (1) What was the origin of driving stress(es) for formation of the joints, particularly as their orientations were not consistent with the regional stress geometry at the time of their formation? (2) What mechanism caused the horizontal principal stresses to be reoriented so as to yield an orthogonal geometry? (3) What insights can be developed for predicting joint geometry in unexposed rock volumes by understanding joint origin? These questions are important because the joints and other fractures may affect the performance of a proposed high-level nuclear waste repository within Yucca Mountain.To address these questions, we use new and existing field data about joint geometry and the relationships of joints to degassing structures, numerical modeling of fault behavior, and work by previous authors. Our interpretation begins with the initial ignimbrite eruption and deposition during caldera collapse. The ignimbrites were deposited over a preexisting topography that possibly included a shallow northwest-trending basin in the Yucca Mountain area. During initial ignimbrite cooling, joint swarms formed as elements of orthogonal fumarolic ridge systems where degassing was associated with vertical dilation. Both joint sets have unusual tubes that are interpreted to have formed during dilation and segmentation of joint faces resulting from lithophysae inflation in the cooling ignimbrite deposit. Modeling supports the interpretation that a combination of regional stresses and stress related to slip on local normal faults controlled the orientation of the joint swarms and favored the formation of the northeast-striking joints first. The faults might have moved in a stress field already perturbed by caldera collapse. Formation of the northwest-striking joints occurred after a local 90° switch of horizontal principal stress directions due to the presence of the northeast-striking swarms, possibly aided by differential compaction across the northwest-trending basin. Tube- bearing joints occur in all lithophysae-bearing lithostratigraphic units of the Topopah Spring Tuff, which is the stratigraphic interval for the proposed nuclear waste repository within Yucca Mountain. We conclude that the tube-bearing joints formed in the same manner and share similar geometric characteristics, adding a persistent joint population to the overall fracture system that influences hydrological and mechanical properties. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.