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This report discusses the palynomorph (pollen, fungal spore) analysis of 39 outcrop samples from the Sagavanirktok Formation at six localities in its type region on the North Slope of Alaska. 1 The analyses were performed to obtain information mainly about the ages but also about the environments of deposition and provenance of the sediments. Sampling localities and their pollen/fungal spore ages, as determined here, were: Franklin Bluffs (early to middle Eocene), Sagwon Bluffs area (early and late(?) Paleocene), Ivishak River (late Maastrichtian or early Paleocene), Shaviovik anticline area (Paleocene), Kavik River (upper Maastrichtian or early Paleocene), and Toolik River-White Hills (Campanian or Maastrichtian; Paleocene). The present samples demonstrate well the rise in angiosperm taxon diversity on the North Slope of Alaska from very low at the beginning of the Paleocene to very high in the Eocene.

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. A range chart is compiled for pollen distributions from the middle Paleocene to the lower Eocene in the Canadian Arctic based on published sources, and, using this chart, two samples from the Toolik River-White Hills were found to be probably late Paleocene and probably middle Paleocene, respectively. Ditch samples were analyzed from the Mobil West Staines State #1 well, just west of the Arctic National Wildlife Refuge, and it is shown that upper Paleocene strata are present in the well section. Ditch samples were analyzed from the Mobil et al. West Kadleroshilik Unit #1 well, a short distance east of Franklin Bluffs on the Sagavanirktok River. The presence of middle and upper Paleocene strata could not be demonstrated in this well section; thus, it is possible but not provable that Eocene rocks rest directly on lower Paleocene rocks in this area. It has been found that the practice of consulting palynologists, studying palynomorphs in ditch samples, who pick the top of the Paleocene at the uppermost occurrence or uppermost consistent occurrence of Paraalnipollenites alterniporus, produces only an approximately dated correlation marker because the actual range top of the species is in the lower Eocene. Samples from the Marsh Creek anticline and the Jago River are shown to contain pollen assemblages similar to those of early to middle(?) Eocene age in the Franklin Bluffs on the Sagavanirktok River. angiosperm pollen. However, counts to determine relative frequencies of palynomorph groups were only made using >7 pm residues. All residues were mounted in glycerine jelly.

COVER Exposures of the sandstone-dominated lower part of the tertiary Green River formation seen in the Gate Canyon area on the afternoon of day 2. Frequently fluctuating lake levels resulted in this sequence of interbedded delta plain in marginal lacustrine deposits. The pronounced lateral acretion bedding common in this part of the Green River formation formed in both fluvial and deltaic environments.

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