Microfaunal analysis of the Late Quaternary deposits of the Nortern Bering Sea

Abstract

Holocene microfaunal associations and distribution patterns define three inner-shelf (<20m) biofacies in Norton Sound, northern Bering Sea. The first biofacies is composed of typical bay faunas dominated by the species Eggerella advena, Buccella frigida, Ammotium cassis, and Reophax dentaliformis. The second biofacies contains bay to inner-shelf faunas indicative of deeper, more marine waters; such inner-shelf species as Reophax arctica, R. fusiformis, Spiroplectammina biformis, and Textularia torquata dominate. The third biofacies, common in deltaic areas with high sedimentation rates and freshwater input, is characterized by abundant Elphidium orbiculare and E. clavatum. The distribution of other microfaunal groups (diatoms, ostracods, tintinnids, and fragments of larger invertebrates and plants) corresponds to current and sedimentary patterns. These Holocene facies relations are the basis for interpreting early Holocene and late Pleistocene environmental conditions in the northeastern Bering Sea area. Within older deposits the sequence of biofacies can be used to interpret the Holocene transgressive cycle in Norton Sound. Norton Sound cores provide evidence of two marine transgressions and a varying river input.