This report covers 36 collections from the Mississippian rocks in the Lisburne Peninsula, northwestern Alaska. All the identifiable fossils indicate a Late Mississippian age, ranging from Mamet Foram Zone 13 to, possibly, Zone 18. This cover the full range of time represented by the Alapah Limestone in the central Brooks Range and, naturally, fits into the stratigraphic scheme presented by Armstrong and others (1981) for the rocks along the coast of the peninsula. In that paper, and in later revisions by Armstrong and Mamet (1977), the Nasorak Formation is shown to be of Zone 15-16i age, the overlying Kogruk Formation ranges from Zones 16s to Zone 18, and the older isolated Lisburne rocks, assigned to the Kogruk, are Zone 13 and possibly 14 in age. The Nasorak represents a dark, cherty shaly limestone facies that interrupts the platform carbonates of the Kogruk in late Visean time. Similar facies relations occur in the Alapah Limestone of the central Brooks Range.

References:

Armstrong, A.K., Mamet, B.L., and Dutro, J.T., Jr., 1971, Lisburne Group, Cape Lewis-Niak Creek, northwestern Alaska: U.S. Geol. Survey Prof. Paper 750-B, p. B23-B34.

Armstrong, A.K., and Mamet, B.L., 1977, Carboniferous Microfacies, Microfossils, and Corals, Lisburne Group, Arctic Alaska: U.S. Geol. Survey Prof. Paper 849, 144 p., 47 pls. [1978]