A new high northern latitude dinocyst-based magneto-biostratigraphic calibration for the Norwegian-Greenland Sea

A refined dinoflagellate cyst biostratigraphy has been developed for the Oligocene successions from two high latitude Northern Hemisphere sites from the Norwegian-Greenland Sea (i.e., Ocean Drilling Program Leg 162, Hole 985A and Leg 151, Hole 908A), and this has been calibrated to newly developed magnetic polarity stratigraphies for both sites. These two new stratigraphic schemes provide important new temporal and spatial frameworks for understanding high latitude climate variability during the transition from greenhouse to icehouse climate states. We show that several of the dinoflagellate cyst marker events used in mid-latitudes stratigraphies (e.g., Distatodinium biffii, Saturnodinium pansum, Artemisiocysta cladodichotoma) demonstrate diachroneity at the high latitude sites. We hypothesize that this diachroneity is due to increased meridional thermohaline gradients related to oceanographic gateway evolution and/or cooling of the Northern Hemisphere high latitudes during the Oligocene. Furthermore, we are able to more accurately constrain the age and duration of a major hiatal surface found in many northern high latitude locations, confirming the regional nature of this hiatal surface and dating it from the late Oligocene to mid-Miocene.