ABSTRACT: 200+ Billion Tons of Low Sulfur Coal in the Sagavanirktok Formation, North Slope, Alaska
S. B. Roberts, G. D. Stricker, R. H. Affolter
Coal deposits within the Upper Cretaceous-Tertiary Sagavanirktok Formation underlie a region of more than 8400 km2 in the east-central North Slope of Alaska. The coals are distributed within Maastrichtian and Paleocene fluvio-deltaic deposits of an east- to northeast-prograding delta system.
Recent investigations have focused on areal distribution and quality of the coals. Coal-bearing outcrops occur in an 80 km belt between the White Hills and Kavik River, and comprise clast-supported conglomerate, sandstone, siltstone, shale (mudstone), carbonaceous shale, and coal beds as thick as 7 m. Borehole data indicate that the coals extend northward to the Arctic coast and offshore, and eastward from the Kuparuk River to the Canning River where they pinch out in the Staines Tongue of the Sagavanirktok Formation. The major coal-bearing interval ranges from 220 m to 850 m in thickness, and more than half of the coal beds are greater than 1.5 m thick. Analyses of 55 coal outcrop samples indicate that the apparent rank ranges from lignite A to subbituminous B, with most being subbit minous C. Mean content of ash for the samples is 10.9%; mean content of sulfur is 0.39%.
Interpretation of data from drill holes penetrating the Sagavanirktok Formation in the Prudhoe Bay/Kuparuk region has resulted in a reevaluation of hypothetical coal resources to at least 200 billion metric tons. This value far exceeds previous estimates of 55 to 65 billion metric tons for this region of the North Slope.
AAPG Search and Discovery Article #91002©1990 AAPG Rocky Mountain Section Meeting, Denver, Colorado, September 16-19, 1990