Year of Award


Document Type


Degree Type

Master of Science (MS)

Degree Name


Department or School/College

Department of Geosciences

Committee Chair

Marc Hendrix

Committee Co-chair

Michael Hofmann

Commitee Members

Marc Hendrix, Michael Hofmann, Micahel DeGrandpre


Frontier Formation, Wall Creek Member, Powder River Basin, Tisdale Anticline, Lateral Heterogeneity


University of Montana

Subject Categories

Geology | Sedimentology | Stratigraphy


The Upper Turonian Wall Creek Member (WCM) of the Frontier Formation is part of a series of marine sandstones that were deposited on the western flank of the Cretaceous Western Interior Seaway (KWIS). The KWIS was a low accommodation shallow-marine foreland basin system that included many large deltaic complexes on its western margin. Deposition of WCM deltaic deposits was strongly influenced by fourthorder glacioeustatic cycles, oceanographic circulation patterns, and tectonics related to the active Sevier fold and thrust belt to the west. An in-depth field study of the WCM was performed on the western flank of the Powder River Basin (PRB), WY, in exposures forming the eastern flank of the Tisdale Anticline, a Laramide structure. The goal of the field study is to document the lateral and vertical heterogeneities within the WCM sandstone, its architectural elements, and its stratigraphic surfaces and use these to develop a sequence stratigraphic framework. Results of this study improve the understanding of depositional processes of the WCM and its characterization as a petroleum reservoir within ~30km of active drilling and production of the WCM in the PRB. This study describes 8 facies: 1) laminated mudstone 2) interbedded siltstone and sandstone 3) hummocky cross-stratification 4) low-angle stratified sandstone 5) thinly interbedded sandstone and siltstone 6) heterolithic cross-bedded sandstone 7) mediumgrained heterolithic cross-bedded sandstone and 8) trough cross-bedded sandstone. These facies are consolidated into 4 facies associations: FA1) prodelta FA2) distal delta front FA3) middle delta front FA4) tidal bars/shoals. Facies characteristics, facies stacking patterns, and architectural surfaces/elements indicate two primary deltaic influences: 1) storm/wave dominated deltas and 2) tidally dominated deltas. Three incomplete stratigraphic sequences are observed from facies stacking patterns and stratal geometries. Sequence 1) transgressive systems tract 1 (TST1), highstand systems tract 1 (HST1), and falling stage systems tract 1 (FSST1); Sequence 2) transgressive systems tract 2 (TST2) and highstand systems tract 2 (HST2); Sequence 3) lowstand systems tract 1 (LST1).



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