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Barrier and back-barrier environments of deposition of the Upper Cretaceous Almond Formation, Rock Springs Uplift, Wyoming

Journal Article · · Mt. Geol.; (United States)
OSTI ID:7071452
Detailed analysis of the detrital rocks associated with coal deposits in the upper part of the Upper Cretaceous Almond Formation of the Mesaverde Group has resulted in the identification of coal depositional settings. The several lithofacies indicate that depositional environments of this interval in the upper part of the Almond Formation include shoreface, barrier island, tidal inlet, tidal delta, washover fan, tidal flat, lagoon, tidal creek, overbank, pond, and marsh. Tidal delta, tidal-inlet-channel, washover-fan, and tidal-creek deposits significantly affected back-barrier accretion and lagoon filling. The complete filling of the lagoon led to coalescing of marsh on the back side of the barrier island with the marsh on the landward side of the lagoon. Thin, discontinuous coal beds which rapidly grade into carbonaceous shale formed in the marsh in close proximity to the barrier island. Thin to thick, laterally extensive coal beds that locally grade into carbonaceous shale formed in the marsh on emergent levee, overbank, and bayfill deposits at the landward side of the lagoon. Deposition of the above detrital deposits as well as tidal-creek channel sandstones caused splitting and merging of the coal beds. The depositional process and rate of sedimentation and subsidence in the depositional basin influenced to some degree the lateral variation of the coal beds. Minability and resource potential of coal beds in the Almond Formation can be better assessed if the precise distribution of the sedimentary environments is recognized.
Research Organization:
Geological Survey, Denver
OSTI ID:
7071452
Journal Information:
Mt. Geol.; (United States), Journal Name: Mt. Geol.; (United States) Vol. 15:2; ISSN MOGEA
Country of Publication:
United States
Language:
English