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The AAPG/Datapages Combined Publications Database
CSPG Special Publications
Abstract
Boundaries and Correlations
Devonian-Mississippian boundary relations along the Cratonic margin of the United States
Abstract
The time-stratigraphic relations of the Devonian-Mississippian boundary in the United States are an intriguing problem which has received much attention without any clear universal solution. Standard time-equivalence and correlation are based on a succession of faunas in the Rhine-Meuse region of Germany, France, and Belgium, e.g., Late Devonian Famennian, transitional Etroeungt, and Lower Carboniferous Tournaisian (Mississippian). Type sections in the United States (Mississippi Valley, New York and elsewhere) are compared to this standard.
Sedimentary environments around the cratonic margin of the United States (geosynclines flanking the Transcontinental Arch and cratonic platforms) are similar and have in common dark bituminous-carbonaceous shales. This widespread lithology occurs in the Ohio, New Albany, Chattanooga, Woodford, Pilot, Sappington, Bakken and Exshaw Formations. Extracratonic tectonic activity, Acadian (Appalachian Geosyncline and Catskill Delta) and Antler (Cordilleran Geosyncline) Orogenies have introduced oxidized clastic sediments into the transgressive dark muds. Eugeosynclinal or fondothemic dark cherts and black shales with radiolarians occur in the Arkansas and Caballos Novaculites (Oklahoma and Texas), Slaven Chert (Nevada), and Besa River Formation (British Columbia).
Age-dating based on fossil faunas and floras is complicated by recurring facies faunas, reworked mixed assemblages, stratigraphic leaks, lack of fossils in critical beds, time-stratigraphic geographic circumstances from place to place, or some combination of the above. The important ammonoid guide genus Wocklumeria has not been recognized in North America and seemingly equivalent conodont faunas are apparently equivocal. Thus, it is difficult to relate this boundary to one or more physical characteristics of the rocks (lithofacies, unconformities, etc.). The conodonts are probably the most reliable faunal element. However the total faunal and floral distribution across this boundary may require examination in order to arrive at a solution. Based on all available evidence, the authors favour placing the boundary at the base of the Louisiana-Upper Saverton faunal zone in the type Mississippi Valley section and equivalent positions elsewhere.
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