New Insights on the Sequence Stratigraphic Architecture of the Dakota Formation in Kansas–Nebraska–Iowa from a Decade of Sponsored Research Activity

Abstract

The Cretaceous Dakota Formation in the areas of Kansas, Nebraska, and Iowa contains a rich and well-preserved microflora of fossil palynomorphs. A comprehensive listing of these taxa is presented in this publication as part of a continuing effort to develop a refined biostratigraphic scheme for mid-Cretaceous terrestrial deposits in North America. The Dakota Formation in this region contains four distinctive Albian-Cenomanian palynostratigraphic zones that are used to partition the unit into successive depositional cycles, and each zone records deposition in fluvial-estuarine environments. The late Albian Kiowa-Skull Creek depositional cycle at the base of the Dakota Formation is recognized throughout the study area, and is also recognized in other parts of the Cretaceous North American Western Interior basin. The overlying newly recognized latest Albian "Muddy-Mowry Cycle" is formally defined for the first time in this paper and correlates with depositional cycles recognized by other workers in other parts of the Western Interior basin. The Cenomanian lower Greenhorn Cycle is already widely recognized by many other workers throughout the Western Interior basin. Laterally extensive thin zones of pervasive carbonate mineral cementation are noted in fluvial-estuarine deposits in the Dakota Formation. They are believed to have formed as synsedimentary cements that precipitated below estuarine marine-flooding surfaces in settings related to discharging paleoground waters. The existence of these early diagenetic cementation zones has important implications for the recognition of diagenetic barriers and baffles to modern fluid flow in the Dakota Formation. New stable isotopic data on these authigenic cements are reported in this paper and add to a body of published data on the δ18O of mid-Cretaceous paleoprecipitation in North America.

Florivory of Early Cretaceous flowers by functionally diverse insects: implications for early angiosperm pollination

“…The localities are distributed along a younger to older north-northeast to south-southwest transect [11] (electronic supplementary material, figure S1). The localities were deposited along the eastern coast of the North American Mid Cretaceous Seaway that extended from the Gulf of Mexico to the Canadian Arctic [12,13].…”

A Glimpse Into the Cenomanian: Palynology of the Arlington Archosaur Site, Late Cretaceous Western Interior Seaway, Texas, USA

“…We propose that this zone is probably equivalent to Unit 4 described from the Dakota Formation (Rawn & Witzke, 1995, in Ludvigson et al, 2010, in which Cicatricosisporites crassiterminatus has its first appearance and angiosperms show a marked increase in diversity.…”

Taphonomy and palaeoenvironmental interpretation of a new amber-bearing outcrop from the mid-Cretaceous of the Maestrazgo Basin (E Iberian Peninsula)

“…A late Albian age is also supported by the occurrence of the ostracod species Platycythereis degenerata, which is found in the late Albian of the Basque-Cantabrian Basin and other localities from the Iberian Ranges (López-Horgue et al, 1999;Schudack & Schudack, 2009). However, a late Albian-Cenomanian age is supported by the presence of the morphospecies Microreticulatisporites sacalii, which appears in strata of that age in Europe and North America (Ravn, 1986;Ludvigson et al, 2010). In addition, the occurrence of angiospermous pollen grains similar to those described as Dichastopollenites?…”