Chris King

Magnetostratigraphic correlation of Paleogene sequences from northwest Europe and North America

Using all available biostratigraphic information and our own extensive magnetostratigraphic database, we have attempted to assess the synchronicity of depositional cycles recorded in the Paleogene epicontinental deposits on both sides of the North Atlantic as stage two of a four-stage global assessment of the eustatic sea-level model. Our conclusion is that the depositional histories of the U.S. Gulf of Mexico–Atlantic coastal plain and the North Sea basin show many similarities, on a variety of time scales, over the interval 60–46 Ma. Considering the tectonic imprint of the northeast Atlantic opening on the North Sea basin sea-level record for part of this time, it must give some weight to the claim that eustasy is the dominant mechanism controlling deposition on passive continental margins.

Dinoflagellate cyst events and depositional history of the Paleocene/Eocene boundary interval in the southern North Sea Basin

High-resolution stratigraphic and micropalaeontological investigations of 30 outcrop and borehole sections throughout Belgium and northern France (Fig. 1) have documented a complex mid-Paleocene to early Eocene depositional history, marked by many discontinuities and major biotic and lithofacies changes (Steurbaut et al. 1998, and in prep.). In the present paper the aquatic palynological stratigraphic record across the Paleocene/ Eocene boundary in northwestern Europe is summarised (pollen and spores are not discussed) and correlated to a revised lithostratigraphic and sequence stratigraphic framework (lithostratigraphy based on Steurbaut 1998).

Preliminary results of a foraminiferal analysis of a core from Østerrende, Denmark

The subject of this paper is the transitional Palaeocene–Eocene section in the continuously cored borehole DGI83101, Østerrenden, Store Bælt, Denmark. As the core spans this time period and is a presumably complete section, it offers an excellent opportunity to try locate and describe the local North Sea Basin expression of the global events of benthic extinction, a negative shift in the C values, and an increase of kaolinite. The core was lithoand biostratigraphically (palynology) analysed by Nielsen et al. (1986). The section investigated in this study covers the Holmehus Formation, the “Østerrende Clay” (informal unit), the “Glauconitic Silt” (informal unit), and part of the Haslund member of the Ølst Formation. Nielsen et al. (1986) showed that the content of kaolinite increases to about 15% in the “Glauconitic Silt” (a single sample), however, later measurements have not been able to relocate this kaolinite peak (Heilmann-Clausen pers. com.). The dinoflagellate analysis (Nielsen et al. 1986) showed a peak in the genus Apectodinium at the base of the Ølst Formation. The succession of events (kaolinite peak followed by Apectodinium spp. influx) was also mentioned by Knox (1996). It was therefore very interesting to observe the expression of foraminiferal faunas in this interval. The core was resampled in 1998 at approximately 30 cm intervals, and samples were taken for studies of benthic foraminifera, palynology, C isotopes, clay minerals, and paleomagnetism. This note presents the preliminary results of the foraminiferal analysis. At present every third sample has been analysed for the microfossil content. The assemblages are generally dominated by sponge spicules. The changes in the foraminiferal faunas roughly occurs at the lithological boundaries (Fig. 1). In the lowermost sample of the Holmehus Fm. the fauna is totally dominated by Usbekistania charoides. The percentage of this species drops dramatically at the lithological boundary between the Holmehus Fm. and the “Østerrende Clay”. Spiroplectammina spectabilis has its last occurrence at the top of the Holmehus Fm. In the “Østerrende Clay” the fauna is rich and characterised by the presence of Verneuilinoides subeocaenus and Verneuilinulla? spp. Another very interesting feature is the presence of a few calcareous foraminifera in the lower half of this lithological unit. In the “Glauconitic Silt” the fauna is distinguished by the content of primitive Cyclamminids. The topmost sample contained a primitive fauna dominated by tubular foraminifera. One of the samples from the unit was nearly barren and only contained a few primitive agglutinated foraminifera. In the Ølst Fm. the samples are generally barren of foraminifera but flat diatoms with the silica preserved are present. An occasional influx of Verneuilinoides subeocaenus is seen. Some of the faunal development in the Østerrende core was also observed in the Bovlstrup borehole (Laursen & Andersen 1997): S. spectabilis had its top occurrence at the typical sediments of the Holmehus Fm., whereas the transitional interval between distinctive sediments of Holmehus Fm. and the characteristic Ølst Fm. was dominated by V. subeocaenus. The transitional interval at Bovlstrup could tentatively be correlated with the “Østerrende Clay”. However the remaining part of the Østerrende core cannot be correlated with Bovlstrup. The preliminary dinoflagellate analysis of the Bovlstrup borehole suggests that the section was incomplete. The present analysis of the Østerrende core supports this as no primitive Cyclamminids were found in Bovlstrup and no Coscinodiscus sp. 1 and 2, and Evolutinella sp. 2 were encountered in the studied section. The big primitive Cyclamminids have not previously been recorded from onshore sections, but are also observed in a very few wells in the lowermost parts of the Sele Formation in the central North Sea, and Charnock & Jones (1997) also recorded them from the dinoflagellate Apectodinium augustum Zone. These first preliminary results from the cored DGI83101 show an unusually expanded section with several key events recorded. The core may be important for correlation with the North Sea and for illustrating the Palaeocene/Eocene transition in this area.