Integrating seismic reflection and geological data and interpretations across an internal basement massif: The southern Appalachian Pine Mountain window, USA

Abstract

Research Article| May 01, 2005 Integrating seismic reflection and geological data and interpretations across an internal basement massif: The southern Appalachian Pine Mountain window, USA John H. McBride; John H. McBride 1Department of Geology, Brigham Young University, P.O. Box 24606, Provo, Utah 84602-4606, USA Search for other works by this author on: GSW Google Scholar Robert D. Hatcher, Jr.; Robert D. Hatcher, Jr. 2Department of Earth and Planetary Sciences, University of Tennessee, 306 Earth and Planetary Sciences Building, Knoxville, Tennessee 37996-1410, USA Search for other works by this author on: GSW Google Scholar William J. Stephenson; William J. Stephenson 3U. S. Geological Survey, M.S. 966, P.O. Box 25046, Denver, Colorado 80225, USA Search for other works by this author on: GSW Google Scholar Robert J. Hooper Robert J. Hooper 4ConocoPhillips, P.O. Box 2197, Houston, Texas 77252-2197, USA Search for other works by this author on: GSW Google Scholar Author and Article Information John H. McBride 1Department of Geology, Brigham Young University, P.O. Box 24606, Provo, Utah 84602-4606, USA Robert D. Hatcher, Jr. 2Department of Earth and Planetary Sciences, University of Tennessee, 306 Earth and Planetary Sciences Building, Knoxville, Tennessee 37996-1410, USA William J. Stephenson 3U. S. Geological Survey, M.S. 966, P.O. Box 25046, Denver, Colorado 80225, USA Robert J. Hooper 4ConocoPhillips, P.O. Box 2197, Houston, Texas 77252-2197, USA Publisher: Geological Society of America Received: 24 Dec 2002 Revision Received: 03 Sep 2003 Accepted: 13 May 2004 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2005) 117 (5-6): 669–686. https://doi.org/10.1130/B25313.1 Article history Received: 24 Dec 2002 Revision Received: 03 Sep 2003 Accepted: 13 May 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 John H. McBride, Robert D. Hatcher, William J. Stephenson, Robert J. Hooper; Integrating seismic reflection and geological data and interpretations across an internal basement massif: The southern Appalachian Pine Mountain window, USA. GSA Bulletin 2005;; 117 (5-6): 669–686. doi: https://doi.org/10.1130/B25313.1 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 southern Appalachian Pine Mountain window exposes 1.1 Ga Grenvillian basement and its metasedimentary Paleozoic(?) cover through the allochthonous Inner Piedmont. The issue of whether the crustal block inside the window was either transported above the master Appalachian (late Alleghanian) décollement or is an autochthonous block that was overridden by the décollement has been debated for some time. New detrital zircon geochronologic data from the cover rocks inside the window suggest this crustal block was derived from Gondwana but docked with Laurentia before the Alleghanian event. Reprocessed deep seismic reflection data from west-central Georgia (pr- and poststack noise reduction, amplitude variation analysis, and prestack depth migration) indicate that a significant band of subhorizontal reflections occurs almost continuously beneath the window collinear with the originally recognized décollement reflections north of the window. A marked variation in the décollement image, from strong and coherent north of the window to more diffuse directly beneath the window, is likely a partial consequence of the different geology between the Inner Piedmont and the window. The more diffuse image beneath the window may also result from imaging problems related to changes in topography and fold of cover (i.e., signal-to-noise ratio). Two alternative tectonic models for the Pine Mountain window can partially account for the observed variation in the décollement reflectivity. (1) The Pine Mountain block could be truncated below by a relatively smooth continuation of the décollement. The window would thus expose an allochthonous basement duplex or hors-block thrust upward from the south along the Late Proterozoic rifted continental margin. (2) The window represents localized exhumation of autochthonous basement and cover along a zone of distributed intrabasement shearing directly beneath the window. Either model is viable if only reflector geometry is considered; model (1) is favored if both geometry and kinematics of Blue Ridge–Piedmont thrust sheet emplacement are incorporated. In either model, the southern margin of the window merges to the west with the Iapetan early Alleghanian Central Piedmont suture, which juxtaposes North American–affinity Piedmont rocks to the north and exotic Panafrican rocks of the Carolina (Avalon) terrane to the south. Immediately south of the window, this suture dips southward and merges in the lower crust with the late Alleghanian suture joining the Appalachians with Gondwana. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.