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The AAPG/Datapages Combined Publications Database
AAPG Bulletin
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Late Mississippian conodonts recovered from two sections of the Lisburne Group exposed along the Ongoveyuk River, western St. Lawrence Island, are few, poorly preserved, yet relatively diverse. At the West Fork and East Fork Ongoveyuk sections, the lower, dark-colored, cherty beds yield conodonts that belong in the upper part of Lane Faunal Unit 8. They are correlatives of the upper St. Louis Formation in the Mississippi River Valley and, in northwest Alaska, are equivalent to the upper Nasorak and Kogruk Formations (Lisburne Group) along Nasorak Creek near Point Hope, and the Kogruk Formation at Trail Creek, De Long Mountains, Misheguk Mountain quadrangle. The upper, light-colored, thicker-bedded interval at the West Fork exposure yields conodonts assignable to Lane Faun l unit 9 of latest Meramecian and earliest Chesterian age. This fauna occurs widely over North America in beds that correlate with the Ste. Genevieve Limestone in the Mississippi River Valley. On the Lisburne Peninsula, this interval correlates with at least a portion of the Kogruk Formation exposed at Niak Creek and Cape Lewis north of Point Hope. Conodont alteration indices (CAI) are very high and variable, ranging from 5.5 to 8.0, suggesting they resulted from contact rather than regional metamorphism.
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