Lower Cretaceous dinoflagellate biostratigraphy in the Danish Central Trough

Abstract

This study deals with Lower Cretaceous biostratigraphy based on dinoflagellates in the Central Trough (Danish North Sea sector). The stratigraphical distribution in Northwestern Europe of the species used in the analysis is evaluated on the basis of the literature, and a dinoflagellate range chart for the Lower Cretaceous of Northwestern Europe is presented. Two wells, Adda-1 and 1-1, containing a complete marine Lower Cretaceous sequence, are biostratigraphically analysed, primarily on the basis of ditch cutting samples. All six Lower Cretaceous stages are identified and their probable positions in the wells are indicated. Additional sections which cover minor parts of the Lower Cretaceous are analysed in the wells M-8, V-1, E-1 and Adda-2 (mainly based on cores and sidewall cores). The ammonite Simbirskites (Craspedodiscus) cf. gottschei, indicating the Hauterivian gottschei Zone, is described from the Adda-2 well. The lithostratigraphical and seismic stratigraphical units of the Central Trough are dated within the framework of dinoflagellate and ammonite stratigraphy. The dinoflagellate species are systematically documented in photographic plates with remarks concerning their identification where necessary. udy deals with Lower Cretaceous biostratigraphy based on dinoflagellates in the Central Trough (Danish North Sea sector). The stratigraphical distribution in Northwestern Europe of the species used in the analysis is evaluated on the basis of the literature, and a dinoflagellate range chart for the Lower Cretaceous of Northwestern Europe is presented. Two wells, Adda-1 and 1-1, containing a complete marine Lower Cretaceous sequence, are biostratigraphically analysed, primarily on the basis of ditch cutting samples. All six Lower Cretaceous stages are identified and their probable positions in the wells are indicated. Additional sections which cover minor parts of the Lower Cretaceous are analysed in the wells M-8, V-1, E-1 and Adda-2 (mainly based on cores and sidewall cores). The ammonite Simbirskites ( Craspedodiscus) cf. gottschei, indicating the Hauterivian gottschei Zone, is described from the Adda-2 well. The lithostratigraphical and seismic stratigraphical units of the Central Trough are dated within the framework of dinoflagellate and ammonite stratigraphy. The dinoflagellate species are systematically documented in photographic plates with remarks concerning their identification where necessary.