Stratigraphy of Maastrichtian Foraminiferida from the United Kingdom; the Maastrichtian of Norfolk

Abstract

Onshore Maastrichtian strata in the United Kingdom are limited to a few small, isolated blocks of chalk floating within glacial sediments on the Norfolk coast. Isolated outcrops of Campanian and Maastrichtian chalks used to be available around Norwich but the majority of these exposures are now badly degraded. Offshore, in the North Sea Basin, there are complete chalk successions that range throughout the Upper Cretaceous and Lower Cenozoic. There is a limited succession of Maastrichtian chalks exposed on the north coast of Northern Ireland below the Cenozoic flood basalts. In the Western Approaches Basin, Maastrichtian and Danian chalks are known from exploration wells and core samples. West of the United Kingdom a number of DSDP/ODP boreholes have penetrated the Upper Cretaceous succession.

Beginning in the Cenomanian, in southeast England, the whole of the Upper Cretaceous is within the chalk facies, possibly one of the longest intervals of relatively stable environment in the geological record. The Foraminiferida of the chalk have been studied for more than a hundred years and therefore the fauna is exceptionally well known and fully documented. Fifty years ago, the benthonic Foraminiferida were identified as having the potential to provide a viable zonation of the chalk facies and we now have precise, cross-basinal correlation using these taxa.

The planktonic fauna is restricted by both palaeolatitude and water depth. The latter appears to be the most influential as the faunas from onshore are more limited than those recorded from the deeper waters of the North Sea Basin and the Atlantic Margin. Even with this restricted fauna, however, it is still possible to develop a general correlation with the standard Tethyan zonation based on planktonic taxa.