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Stratigraphy and depositional environment of middle member of Minnelusa formation, Central Powder River basin, Wyoming

Conference · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:5589573

Regional correlations of the middle member of the Minnelusa Formation (middle Upper Pennsylvanian) shed new light on the stratigraphic relationships of Pennsylvanian rocks in the central Powder River basin and serve as the basis for a regional depositional model. The two main factors influencing the depositional environments of the middle Minnelusa were paleogeography and sea level change. In the southeastern and south-central parts of the area, the proximity of the Lusk embayment and fluctuations in sea level caused frequent flooding of a broad, flat sabkha surface over which isolated dune complexes were migrating. The sediments deposited were subtidal carbonates and black shales interbedded with supratidal dolomites, evaporites, and eolian sandstones. Farther north, closer to the sand source, the dune complexes were larger, more continuous, and were affected only by major transgressive events. Laterally extensive eolian sands were also deposited to the west. The lack of black shales and presence of sandy dolomites with Skolithus burrow, however, suggests more normal marine conditions and deposition on a sand-dominated tidal flat.

Research Organization:
Univ. of Wyoming, Laramie
OSTI ID:
5589573
Report Number(s):
CONF-8408161-
Journal Information:
Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 68:7; ISSN AAPGB
Country of Publication:
United States
Language:
English