Dinoflagellate cyst stratigraphy of the Lower Cretaceous Jydegard Formation, Bornholm, Denmark.

Abstract

Two Danish Geological Survey boreholes in the Lower Cretaceous fine-grained Rodbjerg Member (Jydegard Formation) in the Nyker fault-block on Bornholm have yielded dinoflagellate cysts which can date the sequence as latest Ryazanian to earliest Valanginian. Two dinoflagellate zones are identified, a lower Gochteodinium villosa Zone and an upper Pseudoceratium pelliferum Zone. The age assignment is in agreement with previous ostracod datings. One new dinoflagellate cyst species, Mendicodinium rugarum, is erected and one monospecific genus and the species is emended, Lagenorhytis-L. delicatula. The morphology and distribution of Sentusidinium pelionese, Cantulodinium speciosum and aff. Chalmydophorella nyei are discussed. -Author