Appalachian Blue Ridge cover sequence ranges at least into the Ordovician

Abstract

Research Article| March 01, 1993 Appalachian Blue Ridge cover sequence ranges at least into the Ordovician James F. Tull; James F. Tull 1Department of Geology, Florida State University, Tallahassee, Florida 32306 Search for other works by this author on: GSW Google Scholar William I. Ausich; William I. Ausich 2Department of Geological Sciences, Ohio State University, Columbus, Ohio 43210 Search for other works by this author on: GSW Google Scholar Mark S. Groszos; Mark S. Groszos 1Department of Geology, Florida State University, Tallahassee, Florida 32306 Search for other works by this author on: GSW Google Scholar Troy W. Thompson Troy W. Thompson 1Department of Geology, Florida State University, Tallahassee, Florida 32306 Search for other works by this author on: GSW Google Scholar Author and Article Information James F. Tull 1Department of Geology, Florida State University, Tallahassee, Florida 32306 William I. Ausich 2Department of Geological Sciences, Ohio State University, Columbus, Ohio 43210 Mark S. Groszos 1Department of Geology, Florida State University, Tallahassee, Florida 32306 Troy W. Thompson 1Department of Geology, Florida State University, Tallahassee, Florida 32306 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1993) 21 (3): 215–218. https://doi.org/10.1130/0091-7613(1993)021<0215:ABRCSR>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation James F. Tull, William I. Ausich, Mark S. Groszos, Troy W. Thompson; Appalachian Blue Ridge cover sequence ranges at least into the Ordovician. Geology 1993;; 21 (3): 215–218. doi: https://doi.org/10.1130/0091-7613(1993)021<0215:ABRCSR>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 SocietyGeology Search Advanced Search Abstract The first direct evidence that stratified rocks of the central core of the southern Appalachian Blue Ridge range in age into the Paleozoic comes from a pelmatozoan echinoderm column discovered within a unit directly above the Murphy Marble in North Carolina. Before this discovery most geologists had considered all stratified rocks of the Blue Ridge east of the frontal imbricate thrust blocks to be Late Proterozoic or Early Cambrian(?). The echinoderm fragment is in a lower amphibolite facies interbedded mica schist-impure marble zone that lies directly above the Murphy Marble. Rocks above the Murphy Marble are dominantly turbiditic metaclastic rocks with minor carbonate and metavolcanic rocks, interpreted as having formed within a successor basin unconformably above upper Precambrian rift facies and lower Paleozoic drift facies rocks of the Laurentian passive margin. An upper bound for the age of the successor basin in the Murphy belt has not been established; similar sequences in the Talladega belt to the southwest, and possibly the Foothills belt to the west, range at least into the Devonian. Most Appalachian tectonic models assert that during the Taconic orogeny a Middle Ordovician synorogenic clastic wedge, now located in the easternmost Tennessee foreland salient, was derived by erosion from the metamorphosed pre-Ordovician Blue Ridge basement and cover sequence to the east, which was uplifted as part of an advancing Taconic crystalline thrust wedge. The presence of Ordovician or younger rocks described here, which were deposited east of the proposed Taconic orogenic front, suggests the need to modify models for Taconic clastic wedge formation in the southern Appalachians. The results presented here also suggest that peak metamorphism in the region was post-Ordovician, and thus was probably not contemporaneous with the Taconic orogeny, as previously thought. 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.