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Low accommodation depositional systems in the Cenomanian of the Western Interior Seaway, Nebraska and Utah
Cenomanian sandstone units contain proven and economically significant hydrocarbon plays throughout the Western Interior of North America. They record deposition throughout the Cretaceous Western Interior Seaway (KWIS) and preserve relatively condensed, laterally and vertically complex stratigraphic records of multiple cycles of sediment accumulation. The dominant mechanisms driving relative sea-level fluctuations associated with these cycles are poorly understood. Regional stratigraphic frameworks have been developed form parts of the Western Interior, but an up-to-date basin-wide stratigraphic framework is lacking. Research gaps remain in southeastern Utah and northwestern Nebraska. ^ This study presents a basin-wide stratigraphic framework for these sandstone units and the characterization of the J Sandstone (early Cenomanian) in the subsurface of northwestern Nebraska and the Dakota Sandstone (middle to late Cenomanian) in outcrops around the Henry Mountains in southeastern Utah. ^ Some of the cycles preserved in these units can be correlated over long distances (e.g. J Sandstone in eastern Nebraska and Kansas correlates with the Muddy (J) Sandstone in eastern Colorado and the upper Mesa Rica Sandstone of northeastern New Mexico), which implies that eustacy was a dominant driving mechanism. Unlike previously thought, sandstone units to the north and south are older than sandstone units in eastern Colorado, which suggest that deposition occurred diachronously from north toward the south and from south toward the north by progressive flooding of the Boreal and Tethyan Seas, respectively. ^ The J Sandstone of northwestern Nebraska and Dakota Sandstone of southeastern Utah are not coeval with each other, but together span the entire Cenomanian. They represent analogous fluvial-estuarine to shallow marine depositional environment and low accommodation settings driven by topography and slow subsidence on the tectonically stable Eastern Platform and by tectonism on the western Forebulge of the KWIS, respectively. The units contain multiple cycles of sediment accumulation and exemplify the lateral variability observed in outcrops versus the vertical complexities observed in subsurface core and wireline logs. ^ Fluvial/estuarine sandstones in these units represent viable vectors for future hydrocarbon exploration.^
Antia-Barrero, Jonathan, "Low accommodation depositional systems in the Cenomanian of the Western Interior Seaway, Nebraska and Utah" (2009). ETD collection for University of Nebraska - Lincoln. AAI3360492.