Deformation associated with the movement of the Muddy Mountain overthrust in the Buffington window, southeastern Nevada

Research Article| November 01, 1977 Deformation associated with the movement of the Muddy Mountain overthrust in the Buffington window, southeastern Nevada WILLIAM G. BROCK; WILLIAM G. BROCK 1AMOCO Production Company, Security Life Building, Denver, Colorado 80202 Search for other works by this author on: GSW Google Scholar TERRY ENGELDER TERRY ENGELDER 2Lamont-Doherty Geological Observatory, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar Author and Article Information WILLIAM G. BROCK 1AMOCO Production Company, Security Life Building, Denver, Colorado 80202 TERRY ENGELDER 2Lamont-Doherty Geological Observatory, Palisades, New York 10964 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1977) 88 (11): 1667–1677. https://doi.org/10.1130/0016-7606(1977)88<1667:DAWTMO>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation WILLIAM G. BROCK, TERRY ENGELDER; Deformation associated with the movement of the Muddy Mountain overthrust in the Buffington window, southeastern Nevada. GSA Bulletin 1977;; 88 (11): 1667–1677. doi: https://doi.org/10.1130/0016-7606(1977)88<1667:DAWTMO>2.0.CO;2 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 The Muddy Mountain overthrust, exposed in the Buffington window, southeastern Nevada, consists of a Paleozoic carbonate sheet thrust over Mesozoic Aztec Sandstone, with a molasse filling topographic lows. Evidence suggests that the thrust sheet moved across an erosional surface and that the molasse may have been a forethrust debris. A sharp contact with gouge marks the fault surface. The base of the overthrust sheet is a tectonic breccia containing injections of gouge that are rooted at the contact. Thrust-related changes in the underlying rocks related to proximity of the thrust plane include (1) increase in abundance of microfractures and decrease in grain size due to cataclastic deformation; (2) increase in intensity of macrofracturing parallel and at a low angle to the contact; (3) increase in degree of induration; (4) loss of well-defined bedding planes and color contrast within the Aztec Sandstone; and (5) slabs of dolomite sheared from the upper plate. Laboratory mechanical tests in conjunction with field observations suggest that the shear strength of the undeformed Aztec Sandstone was lower than the frictional strength of the sandstone sliding on quartz gouge. Therefore, cataclastic deformation within a 10- to 100-m-thick zone accompanied the initial advance of the thrust sheet. Following induration, which strengthened the cataclastic sandstone, slip was localized at the thrust contact. During this later stage the high permeability of the fractured upper plate and the Aztec Sandstone suggests that fluid communication with the surface at the leading edge of the thrust was rapid and, therefore, the advance of the thrust could not have been aided by high pore pressure. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.