Stratigraphy of the Upper Jurassic to lowermost Cretaceous in the Rødryggen-1 and Brorson Halvø-1 boreholes, Wollaston Forland, North-East Greenland

Two shallow cores drilled in northern Wollaston Forland provide a combined section covering the upper Kimmeridgian (Upper Jurassic) – Barremian (Lower Cretaceous) comprising the Bernbjerg, Lindemans Bugt, Palnatokes Bjerg and Stratumbjerg Formations. A new unit, the Storsletten Member, is established within the Lindemans Bugt Formation. The black mudstone dominated intervals are dated primarily by dinoflagellates and ammonites, whereas the calcareous mudstones of the Palnatokes Bjerg Formation – sandwiched between the black mudstones – are dated by calcareous nannofossils. The stratigraphy demonstrates an almost complete succession in the Rødryggen-1 core representing a deeper position in the basin, i.e. without the latest Jurassic rift climax hiatus predicted in previous models for the eastern part of the Wollaston Forland basin. The Brorson Halvø-1 core on the other hand represents a position closer to a block crest where unconformities developed. The cores provide key biostratigraphic sections for the Jurassic–Cretaceous boundary interval in the Arctic.