Palynology of the Rupelian to Burdigalian (Oligocene to Lower Miocene) interval of tha Alma-1X well, Danish North Sea

A palynological study of cuttings samples from the North Sea well Alma-IX documents for the first time the dinoflagellate cyst and acritarch assemblage in the Oligocene to Lower Miocene interval of the Central North Sea. The interval is characterised by a poor foraminifera assemblage yielding a relatively low stratigraphic resolution, whereas the palynomorph assemblage is rich. Two hundred and three microplankton taxa were encountered in the study interval. The distribution of dinoflagellates and acritarchs in the well suggests a subdivision of the Oligocene to Lower Miocene interval into 24 zones based on first downhole occurrence of key taxa. The subdivision lends support from unpublished consultancy report data from several other wells in the Danish North Sea. However, as the subdivision builds on published data from one well only, it is considered informal until more documentation is at hand. Four new species and one new subspecies are described from the study interval: Amphorosphaeridium almae Schiøler sp. nov., Dalella rota Schiøler sp. nov., Filisphaera pachyderma Schiøler sp. nov., Pentadinium corium Schiøiler sp. nov. and Spiniferites pseudofurcatus verrucosus Schiøler ssp. nov. Pseudospiniferites manumii Lund, 2002 is emended and transferred to the genus Spiniferites.