The Appalachian-Ouachita rifted margin of southeastern North America

Abstract

Research Article| March 01, 1991 The Appalachian-Ouachita rifted margin of southeastern North America WILLIAM A. THOMAS WILLIAM A. THOMAS 1Department of Geology, University of Alabama, Tuscaloosa, Alabama 35487 Search for other works by this author on: GSW Google Scholar Author and Article Information WILLIAM A. THOMAS 1Department of Geology, University of Alabama, Tuscaloosa, Alabama 35487 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1991) 103 (3): 415–431. https://doi.org/10.1130/0016-7606(1991)103<0415:TAORMO>2.3.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 A. THOMAS; The Appalachian-Ouachita rifted margin of southeastern North America. GSA Bulletin 1991;; 103 (3): 415–431. doi: https://doi.org/10.1130/0016-7606(1991)103<0415:TAORMO>2.3.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 Promontories and embayments along the late Precambrian-early Paleozoic Appalachian-Ouachita continental margin of south-eastern North America are framed by a northeast-striking rift system offset by northwest-striking transform faults. Inboard from the continental margin, basement fault systems have two sets of orientation; one is northeast parallel with rift segments, and the other is northwest parallel with transform faults.Late Precambrian clastic and volcanic syn-rift rocks overlie Precambrian basement rocks along the Appalachian Blue Ridge. Lower Cambrian sandstone at the base of a transgressive passive-margin succession over-steps the rift-fill successions and basement rocks, defining the time of transition from an active rift to a passive margin along the Blue Ridge. Locally thick Early Late Cambrian and older sedimentary rocks fill downthrown blocks of the intracratonic Mississippi Valley-Rough Creek-Rome graben system and Birmingham basement fault system. These basement fault systems, which indicate north-west-southeast extension like the Blue Ridge rift, are overstepped by Upper Cambrian strata. The northwest-striking Southern Oklahoma fault system is interpreted to be a transform fault that propagated into the continent from the Ouachita rift. Early and Middle Cambrian rift-related igneous rocks along the fault system and adjacent Precambrian basement are overstepped by Upper Cambrian sandstone.The differences in age of rift-related rocks suggest a spreading-center shift at the beginning of the Cambrian Period from the Blue Ridge rift to the Ouachita rift southwest of the Alabama-Oklahoma transform fault. From Early to Early Late Cambrian, a small component of extension propagates north-eastward to form the intracratonic fault systems northeast of the transform fault, but most of the extension of the Ouachita rift was transformed along the Alabama-Oklahoma transform fault to the Mid-Iapetus Ridge outboard from the Blue Ridge passive margin. 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.