Sedimentology of Permian upper part of the Minnelusa Formation, eastern Powder River basin, Wyoming, and a comparison to the subsurface

Journal Article · Thu Apr 01 04:00:00 EST 1993 · Mountain Geologist; (United States)

OSTI ID:6024621

Schenk, C J; Schmoker, J W; Fox, J E

Outcrops of the Permian upper part of the Minnelusa Formation near Beulah, Wyoming consist of dolomite, gypsum, and sandstone units deposited in transgressive-regressive cycles. Three depositional cycles are partly exposed in the Simons Ranch anticline near Beulah, and provide an opportunity to view fades of the upper Minnelusa Formation in three dimensions. The cycles observed in outcrop were informally labelled cycle 1, cycle 2, and cycle 3 in ascending stratigraphic order. Cycle 2 contains a basal, laterally extensive sabkha sandstone and an overlying, laterally restricted sandstone that represents a preserved eolian-dune complex. The eolian-dune sandstone of cycle 2 was partially reworked during the marine transgression that initiated cycle 3. The eolian-dune deposit grades laterally into an apron of contorted and massive-bedded sandstones that formed as water-saturated sands liquified and slumped from the margins of the eolian dune. The partially reworked eolian-dune topography was covered by gypsum beds of cycle 3. The sandstone of cycle 3 is interpreted as a laterally continuous sabkha sandstone. West Mellott field (secs. 8, 9, T52N, R68W) represents a subsurface example of the facies and facies relationships observed in outcrop. The eolian-dune sandstone of the C cycle, which was partially reworked by the transgression of the B cycle, produces oil at West Mellott. The draping of dolomite and anhydrite of the B cycle on the eolian-dune sandstone of the C cycle is analogous to the draping of gypsum on dune sand in cycle 2 in outcrop.

• OSTI ID: 6024621
• Journal Information: Mountain Geologist; (United States), Journal Name: Mountain Geologist; (United States) Vol. 30:2; ISSN MOGEA2; ISSN 0027-254X
• Country of Publication: United States
• Language: English

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