Prince Creek Formation

Unit symbol: TKpc
Age range lower Tertiary, Paleocene, to Upper Cretaceous, Campanian (83.6 to 56 Ma)
Lithology: Sedimentary
Group name: Prince Creek Formation
Consists of light colored nonmarine sandstone interbedded with carbonaceous mudstone, coal, and bentonite (Mull and others, 2003). Sandstone is dominantly very fine- to fine-grained and variably tuffaceous and contains grains primarily of quartz and black to gray chert (Mull and others, 2003). Lower part of formation contains distinctive beds of medium- to coarse-grained sandstone that locally contains lenses of pebble to cobble conglomerate. According to Mull and others (2003), unit represents a fluvial, meandering stream environment with interbedded marginal- and shallow-marine intervals. Includes dinosaur-bone-bearing beds at Ocean Point on the Colville River. Includes rocks of the now-abandoned Kogosukruk Tongue and the lower part of the Sagwon Member of the Sagavanirktok Formation as revised by Mull and others (2003) in northern Alaska. Unit originally included two nonmarine tongues, the lower of which is now defined as the Tuluvak Formation (unit Ktu herein)

Source map information

Source map Gillis, R.J., Decker, P.L., Wartes, M.A., Loveland, A.M., and Hubbard, T.D., 2014, Geologic map of the south-central Sagavanirktok Quadrangle, North Slope, Alaska: Alaska Division of Geological & Geophysical Surveys Report of Investigation 2014-4, 24 p., 2 sheets, scale 1:63,360. doi:10.14509/29138
Symbol TKpc
Unit name PRINCE CREEK FORMATION, UPPER PART
Description Rock types are consistent with those described above, consisting of a broad range of poorly consolidated, light olive–brown-weathering sandstone, pebbly sandstone, siltstone, mudstone, carbonaceous shale, bentonite, and coal. The coarser sandstones are composed largely of quartz and black chert, have a salt-and-pepper appearance, commonly with carbonaceous fragments, leaf fossils, and silicified wood, are thin- to thick-bedded, commonly trough cross-bedded (meter-scale bedsets), and typically exhibit a blocky or upward-fining profile. These sandstones form lenticular to laterally extensive benches and cliffs up to 10 m (33 ft) or more in thickness, interpreted as having been deposited in generally east-flowing meandering river channels. Such units have good visible porosity and probably permeability, but are difficult to sample for porosity and permeability analysis due to their weak induration; some beds are heavily oil stained at several places south of VABM Gard at Sagwon Bluffs. Finer-grained strata and coals are generally thin- to medium-bedded, recessive weathering, and are best exposed along Sagwon Bluffs and in other smaller cutbanks adjacent to more resistant sandstones; these units are assigned to a variety of non-channelized nonmarine environments, including lacustrine, levee, crevasse splay, swamps, mires, and soil-forming environments (Flaig and van der Kolk, in press). Following the revision of mapping criteria by Mull and others (2003), the upper part of the Prince Creek Formation is distinguished from the lower part of the overlying Sagwon Member of the Sagavanirktok Formation by its brownish hues, bentonite, coal, smaller maximum clast diameter, lower clast concentration, and less diverse clast composition. The change in clast composition across the upper contact is consistent with the interpretation of Mull and others (2003) that it is probably a sequence-bounding unconformity. Nonmarine rocks at the base of the upper part of the Prince Creek Formation interfinger with marine facies of the upper part of the Schrader Bluff Formation. Where observed in outcrop above the west bank of the Ivishak River about 1.3 km south of VABM Hak, this contact is gradational over several meters. Scant palynomorph data (IRF Group, 2008, unpublished report) suggest the age of the main part of the Prince Creek Formation at Sagwon Bluffs ranges from late Campanian (?) to Paleocene. However, the questioned Campanian age call likely reflects reworked older pollen as it conflicts with Paleocene ages reported by Frederiksen and others (1996, 1998), some of which are from beds lower in the section. It also conflicts with Maastrichtian ages reported by Frederiksen and others (1998) in strata mapped with confidence here as uppermost Schrader Bluff Formation about 1 km (0.6 mi) south of VABM Hak on the Ivishak River. In the absence of more precise biostratigraphic or radiometric control from the lower part of the unit, its local age range is probably Maastrichtian to Paleocene.
Lithology Sedimentary

Correlated geologic units

Label TKpc
Description Prince Creek Formation, shelf deposits, restricted to only old Kogosukruk tongue
Geologic age Campanian to Paleocene
Geologic setting Sedimentary, continental
Lithology Form Importance
Sandstone < Clastic < Sedimentary Bed Major
Claystone < Mudstone < Clastic < Sedimentary Carbonaceous Indeterminate, major
Bentonite < Claystone < Mudstone < Clastic < Sedimentary Bed Indeterminate, major
Coal < Sedimentary Bed Incidental