The Mount Copleston Limestone, a new Lower Devonian formation in the Shublik Mountains, northeastern Brooks Range, Alaska

A new stratigraphic unit, the Mount Copleston Limestone, is proposed for the rocks that heretofore comprised the Devonian part of the uppermost member of the Nanook Limestone. It is bounded by unconformities, so that it overlies beds of the Nanook Limestone that range in age from as old as Middle(?) Ordovician to as young as Late Ordovician and underlies Lower Mississippian strata of the Endicott Group. It is of Emsian age, and conodonts from the unit indicate a biostratigraphic range from the gronbergi to serotinus Zones, inclusive. The fauna and carbonate rock types of the Mount Copleston Limestone suggest that it formed in a shallow-water, partially restricted, inner-platform environment. -from Authors