Normal-fault boundary of an Appalachian basement massif?: Results of COCORP profiling across the Pine Mountain belt in western Georgia

Abstract

Research Article| September 01, 1987 Normal-fault boundary of an Appalachian basement massif?: Results of COCORP profiling across the Pine Mountain belt in western Georgia K. D. Nelson; K. D. Nelson 1Institute for the Study of the Continents (INSTOC), Snee Hall, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar J. A. Arnow; J. A. Arnow 1Institute for the Study of the Continents (INSTOC), Snee Hall, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar M. Giguere; M. Giguere 1Institute for the Study of the Continents (INSTOC), Snee Hall, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar S. Schamel S. Schamel 2Earth Sciences & Resources Institute, University of South Carolina, Columbia, South Carolina 29208 Search for other works by this author on: GSW Google Scholar Author and Article Information K. D. Nelson 1Institute for the Study of the Continents (INSTOC), Snee Hall, Cornell University, Ithaca, New York 14853 J. A. Arnow 1Institute for the Study of the Continents (INSTOC), Snee Hall, Cornell University, Ithaca, New York 14853 M. Giguere 1Institute for the Study of the Continents (INSTOC), Snee Hall, Cornell University, Ithaca, New York 14853 S. Schamel 2Earth Sciences & Resources Institute, University of South Carolina, Columbia, South Carolina 29208 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1987) 15 (9): 832–836. https://doi.org/10.1130/0091-7613(1987)15<832:NBOAAB>2.0.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation K. D. Nelson, J. A. Arnow, M. Giguere, S. Schamel; Normal-fault boundary of an Appalachian basement massif?: Results of COCORP profiling across the Pine Mountain belt in western Georgia. Geology 1987;; 15 (9): 832–836. doi: https://doi.org/10.1130/0091-7613(1987)15<832:NBOAAB>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 SocietyGeology Search Advanced Search Abstract Recent seismic reflection profiling in western Georgia and adjacent eastern Alabama, conducted by the Consortium for Continental Reflection Profiling (COCORP), shows that reflections commonly associated with the Appalachian detachment do not continue southeastward beneath the Pine Mountain belt. Rather, these reflections terminate abruptly on the north side of the belt, along the downdip projection of the Towaliga fault. This observation is difficult to reconcile with the basement duplex interpretation traditionally applied to the Pine Mountain belt and to all other Appalachian interior basement massifs. An alternative interpretation, consistent with the reflection data and with local surface geologic relations, is that the Towaliga fault is, at least in its later evolution, a large northwest-dipping normal fault that cuts the Piedmont allochthon, Appalachian detachment, and Grenville basement. Where crossed by the COCORP profile, this fault has an inferred average dip of about 54° and offsets Grenville basement about 9 km. This interpretation is consistent with the view that the Pine Mountain belt is a structural window through the Piedmont allochthon. However, it implies that much of the structural relief on the basement exposed in the window is due to late normal faulting rather than to thrust imbrication alone. If correct, this has several important implications for Appalachian geology: (1) It implies that normal faulting of late Paleozoic and/or Mesozoic age has played a much more important role in the development of the exposed southern Appalachians than has generally been considered to date. (2) Grenville basement exposed in the Pine Mountain belt has been attached to North America since Precambrian time; it does not represent a Paleozoic accreted terrane. (3) The Appalachian detachment may be exposed around the periphery of the Pine Mountain belt and hence may be available for direct observation at this locality. 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.