Reconnaissance study of Upper Cretaceous to Miocene stratigraphic units and sedimentary facies, Kodiak and adjacent islands, Alaska, with a section on sedimentary petrography

Sandstone composition of the Valdez and Orca groups, Prince William Sound, Alaska

“…Finally, sedimentary facies, known only from reconnaissance mapping of Montague Island and from more detailed mapping on Hinchinbrook Island (Winkler, 1976), are similar to those described from the Sitkalidak Formation by Nilsen and Moore (1979) and Moore and Allwardt (1980). In general, the less deformed parts of the Sitkalidak Formation consist of thin, relatively shale-rich, graded beds with local occurences of thick, massive sandstone.…”

“…The rocks of Montague and Hinchinbrook Islands consist largely of facies C and D turbidites (as defined by Mutti and Ricci-Lucci, 1978) in which sandstone and shale contents are roughly equal or shale is dominant. Local slurried sandstone beds with scattered argillite fragments are present; such beds were described by Nilsen and Moore (1979) in the Sitkalidak Formation and are typical of interlobe and lobe-fringe sequences.…”

“…In general, the less deformed parts of the Sitkalidak Formation consist of thin, relatively shale-rich, graded beds with local occurences of thick, massive sandstone. These sequences are interpreted as having been deposited on an outer fan, lobe fringe, and basin plain by Nilsen and Moore (1979). Moore and Allwardt (1980) suggested that this facies association constitutes a slope-basin or slope-apron deposit.…”

Geologic map of Alaska

“…Originally included in the Narrow Cape Formation, it is now considered a distinctive, older unit. Nilsen and Moore (1979) report fossils are abundant but of low species diversity. Allison and Marincovich (1981;also Allison, 1978) indicate this unit "* * * was deposited in the outer neritic zone of the continental shelf."…”

“…The Aleutian Islands part of the unit potentially may correlate with the rocks of unit Tarcs, such as the Gunners Cove or Banjo Point Formations, although these are thought to be slightly older. On generalized map, included as part of unit Tsmo Tsti Siltstone of Trinity Islands (Tertiary, Miocene and Oligocene)-Highly bioturbated siltstone and very fine-grained sandstone that has sporadic conglomeratic layers (Nilsen and Moore, 1979). Originally included in the Narrow Cape Formation, it is now considered a distinctive, older unit.…”