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.
Highlights
This contribution to the project: "Jurassic - Lower Cretaceous stratigraphy and basin development of the Danish North Sea sector" deals with the biostratigraphy, based on dinoflagellates, of the Lower Cretaceous in the Danish part of the North Sea Central Trough.Danish Central Trough 20 km LEGEND
Discussion of ages Most of the dinoflagellates recorded from the Adda-1 well are shown in the range charts based on cutting samples and side-wall cores
The Late Cretaceous age is based on a dinoflagellate assemblage composed of a few Upper Cretaceous and several Tertiary species
Summary
This contribution to the project: "Jurassic - Lower Cretaceous stratigraphy and basin development of the Danish North Sea sector" deals with the biostratigraphy, based on dinoflagellates, of the Lower Cretaceous in the Danish part of the North Sea Central Trough (figs. 1, 2). This contribution to the project: "Jurassic - Lower Cretaceous stratigraphy and basin development of the Danish North Sea sector" deals with the biostratigraphy, based on dinoflagellates, of the Lower Cretaceous in the Danish part of the North Sea Central Trough In the second part an analysis of the dinoflagellate content of the Adda-1 and [1] wells is carried out and an age determination is presented. These two wells were selected because they are considered to contain the most complete Lower Cretaceous sections and because of their typical development of the various lithological units. Studied by the late Tove Birkelund and is included in the present volume
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