Catastrophic emplacement of the Heart Mountain block slide, Wyoming and Montana, USA

Research Article| May 01, 2005 Catastrophic emplacement of the Heart Mountain block slide, Wyoming and Montana, USA Edward C. Beutner; Edward C. Beutner 1Department of Earth and Environment, Franklin and Marshall College, Lancaster, Pennsylvania 17604, USA Search for other works by this author on: GSW Google Scholar Gregory P. Gerbi Gregory P. Gerbi 2Massachusetts Institute of Technology–Woods Hole Oceanographic Institute Joint Program in Oceanography, Cambridge, Massachusetts 02139, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Edward C. Beutner 1Department of Earth and Environment, Franklin and Marshall College, Lancaster, Pennsylvania 17604, USA Gregory P. Gerbi 2Massachusetts Institute of Technology–Woods Hole Oceanographic Institute Joint Program in Oceanography, Cambridge, Massachusetts 02139, USA Publisher: Geological Society of America Received: 21 Jul 2003 Revision Received: 06 Jun 2004 Accepted: 23 Jun 2004 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2005) 117 (5-6): 724–735. https://doi.org/10.1130/B25451.1 Article history Received: 21 Jul 2003 Revision Received: 06 Jun 2004 Accepted: 23 Jun 2004 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Edward C. Beutner, Gregory P. Gerbi; Catastrophic emplacement of the Heart Mountain block slide, Wyoming and Montana, USA. GSA Bulletin 2005;; 117 (5-6): 724–735. doi: https://doi.org/10.1130/B25451.1 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 The mechanism that allowed many tens of km of movement of the enormous block slide floored by the rootless Heart Mountain detachment fault in NW Wyoming has long been a puzzle. Carbonat-rich microbreccia that is widespread along the fault and in dikes in the upper plate contains accreted grains indistinguishable from those observed as fallout from volcanic eruption clouds (accretionary lapilli) and impact ejecta clouds and in intrusive diatremes. In these settings and also in industrial processing, accreted grains form when particles in a turbulent gaseous suspension containing limited water adhere to a nucleating grain or to each other. Elongate grains in thick microbreccia have strong but diverse shap-preferred orientations unlike those reported from other fault rocks but instead suggestive of turbulent flow, and the microbreccia contains layering and other features of sedimentary character that appear to record deposition from suspension rather than frictional processes along a fault. We suggest that frictional heating led to dissociation of carbonate rock along the fault, producing supercritical CO2 as the suspending medium. High CO2 pressure drastically reduced friction along the fault and allowed continuation of catastrophic movement, probably initiated by a volcanic or phreatomagmatic explosion, resulting in very large displacement on a low-dipping surface. Earlier slower sliding may have occurred but final emplacement was rapid (minutes) and spectacular. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.