Oligocene through Pliocene Foraminifera from the Yakataga Reef Section, Gulf of Alaska Tertiary Province, Alaska

Abstract

Oligocene through Pliocene foraminifera in the Yakataga Reef section, Gulf of Alaska Tertiary Province, help reconstruct the depositional history of the upper Poul Creek and lower Yakataga formations. Biofacies patterns reflect middle bathyal conditions during the Oligocene and Early Miocene, a Middle Miocene hiatus and upper bathyal to shelfedge depths during the Late Miocene and Early Pliocene. A regressive episode in the lowermost Yakataga Formation may represent a terminal Miocene event. Surface water temperatures during the Late Miocene-Early Pliocene change upsection from cold subarctic to cool temperature. The foraminifera also indicate that the Poul Creek-Yakataga Formation contact is Late Miocene.