Neogene dinoflagellate cysts from Davis Strait, offshore West Greenland

Abstract

The Qulleq-1 exploration well was drilled offshore West Greenland in the year 2000. The well penetrated Neogene sediments and a limited number of samples were studied for their content of dinoflagellate cysts in order to determine the age of the succession. Other relevant data from the region are restricted to ODP cores drilled in the late 1980s in Baffin Bay and Labrador Sea so all new information is important. The horizontally stratified Cenozoic succession drapes the crests of rotated fault-block of Cretaceous sediments. Four stratigraphical units were discriminated in the Neogene succession: Upper Pliocene, Lower Pliocene, Upper Miocene and Middle Miocene. A ∼40 Myr hiatus separates Neogene from Palaeogene sediments, and Miocene sediments are separated from Pliocene sediments by a ∼2 Myr hiatus. The dinoflagellate flora is comparable to other North Atlantic sites but is depleted in terms of recovery. The fairly rich Miocene flora diminishes in the Lower Pliocene and almost disappears in the Upper Pliocene, probably reflecting deterioration of the climate. The dinoflagellate assemblages indicate deposition in open marine environments. Both Middle and Upper Miocene assemblages are characterised by abundant Operculodinium giganteum, Operculodinium centrocarpum, Spiniferites pseudofurcatus, Habibacysta tectata, Pyxidiniopsis pastilliformis, Labyrinthodinium truncatum and Spiniferites spp. The Pliocene assemblages are characterised by the stepwise disappearance of Miocene dinoflagellates; Cymatiosphaera spp., Nematosphaeropsis spp. and Impagidinium spp. become dominant in poor assemblages. Reworked spores, pollen and dinoflagellate cysts from Upper Palaeozoic, Mesozoic and Palaeogene sources are abundant throughout the Neogene.