Palynological dating of Upper Cretaceous to middle Eocene strata in the Sagavanirktok and Canning formations, North Slope of Alaska

Abstract

This report provides palynological data and age interpretations for six outcrop areas (Ivishak River, Echooka River, Shaviovik anticline, Toolik River-White Hills, Marsh Creek anticline, and Jago River) and parts of four well sections (the Arco Ugnu SWPT-1 well, the Arco West Sak River #23 well, the Mobil West Staines State #1 well, and the Mobil et al. West Kadleroshilik Unit #1 well) on the North Slope of Alaska. The described pollen assemblages are Maastrichtian to Eocene in age. A new, latest Maastrichtian pollen subzone is proposed based on samples from the Ugnu SWPT-1 core. The Cretaceous-Tertiary (K-T) boundary in the core, and in cuttings from the Arco West Sak River #23 well, can easily be picked using the abrupt Terminal Cretaceous Extinction Event. If an unconformity is present at the K-T boundary in the Ugnu SWPT-1 well core, it is probably a minor one at least with regard to the loss of Cretaceous strata. Cretaceous samples collected near the K-T boundary along the Ivishak River, the Echooka River, and in the Shaviovik anticline area were found to be late but not necessarily latest Maastrichtian in age. At least in some places on the North Slope, it appears that lowermost Paleocene strata are present, but such a determination is difficult or impossible to make using ditch (cuttings) samples.