Abstract The benthic foraminifera have been studied from a large number of samples collected from successions both in, and close to, the Brazos River (Falls County, Texas, U.S.A.) and from the cliffs of Stevns Klint (south of Copenhagen, Denmark). The sections from the Brazos River contain extensive and nearly continuous outcrops, recording the so-called “event” deposits and the Cretaceous–Paleogene boundary. Micropaleontological analysis of samples taken from the Mullinax-1 core, and some of the exposures in the Brazos River (and tributaries), have been investigated for benthic and planktic foraminifera, all of which are indicative of relatively shallow shelf conditions. The benthic foraminifera suffer a significant loss of diversity at the level of the “event” deposits, which appear to predate the micropaleontological Cretaceous–Paleogene boundary, but no mass extinction is recorded. The agglutinated taxa almost disappear at this level, and the faunal changes indicate that there may have been a shallowing at that time. The benthic foraminifera from Stevns Klint are very different from those recorded in Texas, being typical of assemblages in the chalk facies of northwestern Europe. At the base of the Højerup Member (previously known as the Grey Chalk) there are significant changes in the benthic assemblage, again suggestive of a shallowing event at the level of two closely spaced hardgrounds, which often merge into a single horizon. The “event” deposits of the Brazos River successions may, therefore, be related to events associated with the hardground horizon at Stevns Klint, and the evidence for this interpretation is presented. This, and other, correlations provide data for the construction of a sequence stratigraphy for the Cretaceous–Paleogene boundary interval.

Abstract: Late Cretaceous-Danian cool-water carbonate deposition in northwest Europe lasted for more than 35 my and covered an area of about 5,250,000 km 2 with east-west and north-south extents of at least 3,500 km and about 1,500 km, respectively. Maximum thicknesses of the succession amount to more than 2 km. The region was situated between paleolatitudes 35° 50° N, and the study area, comprising the Danish Basin and its margins, was situated at about 45° N. The relatively deep-water basinal sediments are mainly coccolithic chalks with a sparse benthic fauna. The shallow-marine faunas are of high diversity, belong to the Boreal Realm and are dominated by bryozoans, echinoids, bivalves, brachiopods, ser- pulids, and in the Danian also azooxanthellate scleractinian corals and octocorals. Marginal Tethyan influence is only seen in the Early Campanian and Late Maastrichtian. The succession represents one of the largest and longest-lived accumulations of cool-water carbonates on earth. A transect from the paleo-coastline to the basin shows a succession of broad facies belts deposited on a gentle, distally steepened, carbonate ramp. Three carbonate factories are recognized. High-diversity oyster bank communities flourished along the rocky shorelines and represent the first factory which produced skeletal gravels and coarse-grained sands. These sediments pass offshore into cross-bedded, well-sorted skeletal sands deposited in sub- aqeous dune fields which migrated parallel to the shore. Further offshore, the clastic carbonate belt gives way to the second carbonate factory represented by a broad belt of bryozoan wackestones and packstones deposited in impressive mound complexes in relatively deep water below the photic zone. The proportion of coccolithic chalk ooze increases in a seaward direction, the mounds become smaller and more mud-rich, and the slope and basin are dominated by pure coccolithic chalk with few benthic fossils. The pelagic chalk represents the third carbonate factory. Large, asymmetric bryozoan wackestone and packstone mounds of Early Danian age are beautifully exposed in the cliff, Stevns Klint, where they overlie smaller, matrix-rich wackestone mounds of latest Maastrichtian age. The bryozoan mounds migrated towards the southeast, parallel to the coastline and towards the nutrient-carrying currents by combined progradation and aggradation. The mounds overlap and interfinger and form complexes separated by erosion surfaces and hardgrounds developed during falls in relative sea level. A sequence stratigraphic model is proposed for cool-water carbonate ramps in an arid climate. It is characterized by the symmetrical packaging of facies dominated by simple landward-seaward shifts of facies belts, lack of facies differentiation between lowstand and transgressive systems tracts, and absence of karst features at the sequence boundaries due to the arid climate and calcite-dominated mineralogy.