Dinocyst stratigraphy of the latest Jurassic to Early Cretaceous of the Haldager No. 1 borehole, Denmark

Abstract

The dinocyst assemblages were obtained from selected core samples, between the depths 2505' and 3190', from the Haldager No. 1 borehole, onshore Denmark. It has been possible to apply the dinocyst zonation of Davey (1979) to these assemblages and they have been dated as Hauterivian (Early Cretaceous) to early Portlandian (Late Jurassic). The placing of the Cretaceous-Jurassic boundary between 2945' and 2989' differs significantly from its initial position in Sorgenfrei and Buch (1964) at 2706'. The present revised dating has subsequently been used by Michelsen (1978, p. 23) in his study of the Norwegian-Danish Basin. The study has necessitated the examination of many accurately dated samples of Early Cretaceous and Late Jurassic age from onshore eastern England and the results are incorporated in this paper. Detailed systematics, the key to a detailed stratigraphic breakdown, has necessitated the erection of 2 new genera ( Cymososphaeridium and Stiphrosphaeridium ), 12 new species and 2 new subspecies. In addition minor amendments are also made to the dinocyst zonation of Davey (op. cit.).