ALASKA NORTH SLOPE DIGITAL MAP PROJECT

The initial, rudimentary geologic maps of northern Alaska are barely 100 years old. Systematic geologic mapping of the foothills and northern front of the Brooks Range was only undertaken because of the urgency to understand petroleum potential in the wake of WWII. For the past 50+ years, the combined efforts of the U.S. Geological Survey (USGS) and the Alaska Division of Geological and Geophysical Surveys (ADGGS) have resulted in a mixture of maps by numerous authors at a variety of scales and cartographic standards, utilizing a diverse stratigraphic nomenclature. These deficiencies stem largely from the remoteness of the region, which led to geographically isolated fieldwork, and the paucity of resources for integrating disparate work products.

The USGS northern Alaska digital map project is intended to produce an integrated set of geologic maps across the region at a uniform scale and cartographic style, incorporating consistent modern stratigraphic nomenclature. Maps are being compiled from published USGS and DGGS maps and unpublished maps provided by the oil industry, and are augmented and revised by addition of new reconnaissance field data and reinterpretation of modern Color IR aerial photography.

Publication of a tier of five 1:250,000-scale quadrangles from Umiat on the central Arctic North Slope to Point Lay on the Chukchi Sea is currently under way. These maps span the transition from the deformed rocks of the northern foothills of the Brooks Range into the undeformed rocks of the Arctic coastal plain. Rocks exposed in this area are part of the mid-Cretaceous to Tertiary Brookian Sequence, a thick succession of deep marine through nonmarine deposits that fill the Colville foreland basin north of the Brooks Range thrust belt. These strata contain significant reservoir rocks as well as oil- and gas-prone source rocks, and are known to hold petroleum in both stratigraphic and structural traps. Release of the digital geologic maps will enhance the regional understanding of the stratigraphy and structure of the Brookian system, and in addition will provide Federal, State, and Native managers with a basic geologic framework for making land- and resource-use decisions in a broad region of the National Petroleum Reserve in Alaska (NPRA) and adjacent State and Native lands.