New and Revised Cretaceous and Tertiary Stratigraphic Nomenclature, East-Central Colville Basin, North Slope, Alaska

By

C.G. (Gil) Mull (Alaska Division of Oil and Gas), D.W. Houseknecht, and K.J. Bird (U.S. Geological Survey)

Stratigraphic nomenclature of the Brooks Range and east-central Colville basin has evolved over a period of more than 80 years as numerous geologists progressively unraveled the stratigraphic and structural history of northern Alaska. Consequently, current publicly available mapping is at a variety of scales and incorporates diverse styles of structural annotation and stratigraphic nomenclature that later studies have in some cases shown to be invalid or unnecessarily complicated. We are revising and compiling new unified geologic quadrangle maps of the northern flank of the Brooks Range and Colville basin at uniform scale and cartographic style, with consistent stratigraphic nomenclature. In the process of this compilation, utilizing modern sequence stratigraphic concepts, we have abandoned some of the existing Cretaceous and Tertiary formation names, redefined the boundaries of others, and defined some new units.

We abandon several formation and member names of the mid- to Upper Cretaceous Nanushuk Group (Albian to Cenomanian) and the Upper Cretaceous Schrader Bluff Formation (Santonian to Campanian (?)).We elevate the Upper Cretaceous Tuluvak Tongue of the Prince Creek Formation (Turonian to Coniacian) to formation status and revise its base, and redefine the top of the Prince Creek Formation to include some Paleocene rocks. Three members of the Paleocene to Eocene Sagavanirktok Formation are recognized. The new stratigraphic nomenclature and revised geologic maps will be released on the Internet in digital format by the USGS as they are completed (follow links atwww.usgs.gov) and by the Alaska Division of Geological and Geophysical Surveys in both digital and hard copy.

AAPG Search and Discovery Article #90008©2002 AAPG Pacific Section/SPE Western Region Joint Conference of Geoscientists and Petroleum Engineers, Anchorage, Alaska, May 18–23, 2002.