Upper Cretaceous arc-trench gap sedimentation on the Alaska Peninsula

The Upper Cretaceous geology of the Alaska Peninsula is consistent with the principles of convergent-margin tectonics. The upper Campanian to lower Maestrichtian Coal Valley Member of the Chignik Formation and the approximately correlative Chignik Formation and the Hoodoo Formation as exposed in the Port Moller area represent deposition in an arc-trench gap. These units are interpreted as sedimentary facies deposited in different environments of deposition: alluvial fan to flood plain (Coal Valley Member); inner neritic continental shelf (Chignik Formation); and outer neritic continental shelf to bathyal continental slope (Hoodoo Formation). The sandstones together with massively bedded conglomerates in the Hoodoo Formation probably accumulated as turbidites.