Upper Paleozoic stratigraphic sequences in the Western Interior, USA
Major depositional sequences in the upper Paleozoic (Mississippian through Permian) of the Western Interior reflect either tectonism, eustatic sea-level change, or both. The stratigraphic sequences approximate (1) the Lower Mississippian Lodgepole Limestone of the Madison Group, (2) the Lower and Upper Mississippian Mission Canyon Limestone in the Madison Group, (3) the Upper Mississippian Big Snowy Group, (4) the Lower and Middle Pennsylvanian Amsden Group, (5) the Middle Pennsylvanian and Lower Permian Minnelusa Group, and (6) the Middle and Upper Permian Park City Group. These upper Paleozoic sequences in the Western Interior seem to be intricately related to similar, third-order transgressive-regressive cycles in the Cordilleran region, but precise relationships of some sequence boundaries remain to be determined. Parasequence sets evidence minor eustatic oscillations within these six major Western Interior sequences. The widespread paraconformable contact between Permian and overlying Triassic strata on the Wyoming shelf indicates that this sequence boundary resulted primarily from eustatic marine regression. Overall, the upper Paleozoic sequences of the Western Interior were deposited in a stable epeirogenic framework that succeeded Devonian tectonism but were diastrophically affected again during the Pennsylvanian. The timing of these diastrophic events in the Western Interior seem to coincide with plate collision events along the eastern and southern margins of North America, but eustatic changes may be related to other causes.
- OSTI ID:
- 5099207
- Report Number(s):
- CONF-9305259--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 25:5; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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