Using classic outcrops to revise sequence stratigraphic models: Reevaluating the Campanian Desert Member (Blackhawk Formation) to lower Castlegate Sandstone interval, Book Cliffs, Utah and Colorado, USA

A multi-decade-long high-resolution outcrop study has revealed that the Campanian Desert Member (Blackhawk Formation) to lower Castlegate Sandstone interval in the Book Cliffs of Utah and Colorado (western USA) does not fit the conventional sequence stratigraphic model. Differences include temporally linked, laterally adjoining nearshore terrestrial and shallow marine facies belts with conformable lateral and vertical facies transitions, correlation of coals with flooding surfaces, parasequence-scale channel incisions into foreshore-shoreface sandstones, shoreface incised channels consistently overlain by coal-bearing coastal plain mudstones, and abundant flat-topped rooted foreshore sandstones. Contrary to the findings of previous studies, there is no evidence for sediment bypass, third-order sequence boundaries, large-scale incised valley fills, or significant sea-level fall. Similar nearshore terrestrial to shallow marine settings worldwide should be critically reexamined in light of the alternative sequence stratigraphic model presented herein.