Biostratigraphic results of dart-coring in the western Gulf of Alaska, and their tectonic implications

Abstract

Age determinations are reported for microfossils from 56 dart-cores collected in 1978 from the Kodiak shelf. The ages suggest that rocks cropping out along Albatross Bank, at the shelf edge, are as old as middle or late Miocene, and that the anticline forming Albatross Bank, previously defined with multi- and single-channel seismic records, plunges northeastward in the sampled area. Foraminiferal paleobathymetry further suggests that m.ajor tectonic activity has occurred on the Kodiak shelf since the early or middle Pliocene, including two episodes of vertical movement--first subsidence on the order of 2000 m, then uplift of at least 3000 m. Microfossil ages and paleobathymetric determinations indicate an average uplift rate of 1000- 3000 m/m.y. for the seaward edge of the Kodiak shelf during the Quaternary.