Late Albian Kiowa-Skull Creek Marine Transgression, Lower Dakota Formation, Eastern Margin of Western Interior Seaway, U.S.A.

Sequence stratigraphic controls on synsedimentary cementation and preservation of dinosaur tracks: Example from the lower Cretaceous, (Upper Albian) Dakota Formation, Southeastern Nebraska, U.S.A.

“…Marine palynomorphs were recovered from interstratified carbonaceous mudstones and shales, indicating this region was periodically inundated by marine waters ( Table 2). The geographic relationship of the Jefferson County localities is along a northeast-southwest trend, one that is concordant with the depositional geometry of this portion of the Dakota Formation outcrop belt (Witzke and Ludvigson, 1994;Brenner et al, 2000). These relationships coupled with a pre-Dakota Formation topographic study of the region by Joeckel et al (2005) indicate these localities lay within the same paleo-fluvial/ estuarine valley.…”

“…Terrestrial strata have been subdivided into palynostratigraphic units, which are largely coincident with marine cycles of the Western Interior Seaway (Ravn and Witzke, 1995) (Table 1). The horizons sampled as part of this study are situated approximately 5 m above the "D 1 " unconformity identified by Brenner et al (2000) and are interpreted to be part of the Muddy Cycle (sensu Scott et al, 1998) or the "J Sequence" of Hamilton (1994). The Muddy Cycle followed the Kiowa-Skull Creek Cycle, recognized by estuarine and fluvial deposits that extend hundreds of kilometers from the seaway edge into central Iowa.…”

“…Proximal fluvial strata of the Dakota Formation are interpreted to have been deposited within a series of incised valleys, while the distal deposits likely accumulated in a near-shore marine environment (Brenner et al, 2000). The eastern margin of the Cretaceous Western Interior Seaway was the stable cratonic margin of a foreland basin (Figure 2, inset).…”

“…Dakota Formation lithologies at the Starr Pit and Bosewell Pit sections were part of a regional study that identified three depositional cycles within the Dakota Formation (Brenner et al, 2000). Temporal control of the Dakota Formation along the eastern margin of the Cretaceous Western Interior Seaway is largely determined by the interfingering relationship of nonmarine strata with marine facies, where molluscan and foraminiferal biozonations are coupled with ash radiochronology.…”

“…Dakota Formation sandstone bodies examined from Jefferson County, Nebraska are interpreted to have been deposited as a bar complex in a fluvial-estua- rine environment (Brenner et al, 2000). Marine palynomorphs were recovered from interstratified carbonaceous mudstones and shales, indicating this region was periodically inundated by marine waters ( Table 2).…”