Grab samples, dart cores, and gravity cores from the Gulf of Alaska between Montague Island and Yakutat Bay were analyzed for benthic foraminifers. Robust specimens of Cassidulina californica, C. limbata, and Cibicides lobatulus are abundant in coarse sediment on Tarr Bank, Middleton Island platform, and along much of the outer shelf east of Kayak Island. This fauna may be relict, as it occurs in areas known from seismic profiles to be nearly devoid of the Holocene clayey silt which blankets much of the shelf. In several samples, glauconite associated with this fauna provides evidence for a low rate of sedimentation.

Another fauna, in which Epistominella pacifica occurs with Elphidium clavatum (typically a shallow-water, inner-shelf species), is found in Kayak Trough at depths ranging from 146 to 234 m and in Hinchinbrook Sea Valley at 205 m. Both of these depressions have topographic highs at their seaward terminations. In previous studies in other parts of the Gulf of Alaska, Epistominella pacifica is reported to be common above 300 m depth; however, farther south, off California, Oregon, and Washington, E. pacifica usually occurs at depths greater than 300 m. The association of E. pacifica and Elphidium clavatum might therefore be useful in determining paleoenvironments; their co-occurrence could indicate a depression, such as a trough or sea valley, somewhat restricted from open sea conditions

End_Page 447------------------------------

Seismic records show that the Holocene clayey silt, which is common on much of the shelf, is thin or absent on Pamplona Ridge and in the outer part of Bering Trough. Samples from these areas, in water depths ranging from 163 to 315 m, have abundances of E. clavatum of 10% or more, and Buccella is present. This fauna may indicate deposition at shallower depths during a Pleistocene lower stand of sea level.

End_of_Article - Last_Page 448------------