Geology of Metamorphosed Carbonates, Sukakpak Mountain, Brooks
Range, Alaska

Elizabeth Barnett and Amy Winchester
Department of Geology and Geography
Mt. Holyoke College

Sukakpak Mountain is located along the Dalton Highway which cuts through the Brooks Range of northern Alaska, linking Fairbanks to Prudhoe Bay. The massive marble cliffs are predominantly formed by Skajit Limestone of Middle to Late Devonian age. This area is considered part of the Hammond Subterrane which was fragmented by faults during Late Jurassic-Early Cretaceous thrusting events. The rocks have experienced several episodes of metamorphism relating to Devonian intrusions and the later thrusting events (Huber, 1988). Sukakpak Mountain is evidence of such deformation as it is now a meta-sedimentary overturned synform truncated and faulted against a non-conformable Cambrian-Ordovician calcareous chlorite-mica-quartz-schist (Mull and Adams, 1985). In addition, numerous small-scale folds ranging from less than one centimeter to meters in length are visible throughout the mountain.

Our project was funded by the Fairbanks, Alaska Bureau of Land Management as part of a larger research project surveying regions designated Areas of Critical Environmental Concern bordering the Dalton Highway Corridor. Plots of land within these regions were selected for detailed geologic and ecological studies. Our field study included constructing a detailed geologic map of Sukakpak Mountain and locating potential mineral licks for Dall sheep. We have extended the study of the carbonate meta-sedimentary rocks into a detailed analysis in progress of the petrography as well as a lab study of potential conodont microfossil content. We hope to add our results to the evolving geologic history of the Sukakpak Mountain area.
________________________________________________________________________

References Cited:

Huber, J. A., 1988, The Geology and Mineralization of the Sukakpak Mountain Area, Brooks Range, Alaska: MS Thesis. University of Alaska, Fairbanks, Alaska.

Mull, C. G., and Adams, K. E., 1985, Dalton Highway, Yukon River to Prudhoe Bay, Alaska, Guidebook 7, Volume 1. Alaska Division of Geological and Geophysical Surveys, Fairbanks, Alaska.