Dinoflagellate cyst biostratigraphy of Upper Cretaceous strata from two wells in the Norwegian Sea

Abstract

Rich assemblages of dinoflagellate cysts from two sections in the Norwegian Sea provide a solid basis for a palynostratigraphic framework for the upper Albian to upper Maastrichtian succession in this area. The framework is based on a unique composite section combining samples from the shallow stratigraphic core 6711/4-U-1 and core-samples from well 6707/10-1, the latter filling in data from the intervals represented by hiatuses in core 6711/4-U-1. Seven previously described, and one new palynostratigraphic zone, are recognised. These are based on the relative abundances of prominent taxa together with top and base occurrences of selected age-diagnostic dinoflagellate cyst taxa. The zones and their ages in ascending order from the oldest to youngest comprise: the intra late Albian to intra early Cenomanian Subtilisphaera kalaalliti Interval Zone sensu Nøhr-Hansen (1993a); the intra early Cenomanian to intra late Cenomanian Palaeohystrichophora infusorioides–Palaeohystrichophora palaeoinfusa Interval Zone sensu Radmacher et al. (2014b); the Turonian to ?intra early Coniacian Heterosphaeridium difficile Interval Zone sensu Nøhr-Hansen (2012); the ?intra early Coniacian to late Santonian Dinopterygium alatum Interval Zone sensu Radmacher et al. (2014b); the early Campanian Palaeoglenodinium cretaceum Interval Zone sensu Radmacher et al. (2014b); the new intra Campanian Hystrichosphaeridium dowlingii–Heterosphaeridium spp. Interval Zone; the intra late Campanian Chatangiella bondarenkoi Interval Zone sensu Radmacher et al. (2014b) and the intra late Maastrichtian Wodehouseia spinata Range Zone sensu Nøhr-Hansen (1996). Comparison of the palynological events with records in adjacent regions enables correlation across similar paleolatitudes in the Northern Hemisphere.