Dinoflagellate cyst biostratigraphy of the Upper Cretaceous black mudstone between Niaqornat and Ikorfat on the north coast of Nuussuaq, West Greenland

Stratigraphical ranges and geographical distribution of dinoflagellate cysts and selected pollen species are described on the basis of analysis of approximately 75 samples from 5 surf ace and 3 subsurface sections of Late Cretaceous age from the north coast of Nuussuaq, West Greenland. The sections make up an approximately 500 m thick black mudstone succession, previously dated as Late Campanian to Maastrichtian on the basis of scattered ammonite occurrences.

The dinoflagellate cysts and pollen date the majority of the studied samples to Late Campanian and Maastrichtian, whereas a few samples have been dated as Coniacian-Late Santonian and Early Paleocene.

It has been possible to divide the Late Campanian and Maastrichtian strata into three intervals based on three distinguishable palynomorph assemblages. The diversity of the studied dinoflagellate cysts is relatively low to very low; approximately 57 species were recorded.

New finds of ammonites and the new study of the palynomorphs move the Cretaceous-Tertiary boundary from the base of what was previously called the "basal Danian conglomerate" at Annertuneq to approximately 118 m above the top of this conglomerate.