292-13 Wave, Tidal, and Fluvial Influences in the Sedimentary Deposits of the Campanian (Late Cretaceous) Western Interior Seaway, USA

Abstract:

The Western Interior Seaway was a major epeiric marine body of water that linked the Arctic Ocean with the Gulf of Mexico during the last forty-million-years of the Cretaceous Period. The western coast of the Western Interior Seaway during the Campanian shows a wave and shelf bottom current-controlled association of lithofacies from the shoreface seaward to the relatively deep (less than 200 meters) basin. The facies associations comprise paralic, tide-influenced coastal environments; intensely burrowed, storm/wave processes-dominated prograding delta-fronts and shorefaces; heavily bioturbated glauconitic sandstones; and traction current-controlled, tidally influenced open-marine shelf and subaqueous delta deposits with dominantly southward paleocurrent directions. The persistence of southward paleocurrent directions indicates along-shelf sand-transport by strong bottom currents. Seafloor topography generated by Laramide block uplifts enhanced the transport of (often relatively coarse) sediments into the deeper parts of the basin, as well as controlled sediment dispersal patterns in this part of the seaway. The review of the typical Campanian depositional environments from paralic to shelf deposits suggest the common mix of fluvial, wave, and tidal processes at any given time with sea level as the main control of the locus of the dominant process, but with tectonics, geometry of the coast, and bathymetry amplifying a particular process locally.  

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