Palynostratigraphic reassessment of the Late Devonian of Bjørnøya, Svalbard

Abstract

A comprehensive study of the Late Devonian palynostratigraphy of Bjørnøya, Svalbard Archipelago is presented. A total of 61 samples collected from 10 outcrops located along the eastern coast of the island were analyzed for palynology yielding a mid- to latest Famennian age. A reassessment of the existing palynostratigraphy of the Ursa Sandstone Unit of the Røedvika Formation was undertaken. As no independent age control exists for this succession, the palynological assemblages were correlated to well-calibrated palynological zonations from the Eastern and Western Europe. The middle to upper part of the Vesalstranda Member and the Kapp Levin Member were assigned a mid- to late Famennian age (CVa to VF biozones), and the middle to lower-upper part of the Tunheim Member was dated as latest Famennian in age (LL to LN biozones). For the first time, a palynological age was assigned to the upper part of the Kapp Levin Member. Correlation with other Arctic areas show close resemblance to Late Devonian assemblages from Europe and the Arctic region. However, differences in the stratigraphical ranges of several taxa were identified. In terms of Late Devonian paleophytogeographic provinces the miospore assemblages are assigned to the Northern Euroamerican Cornispora varicornata Realm for the mid-Famennian. A more cosmopolitan trend was recognized for the latest Famennian (Strunian), with assemblages including abundant Retispora lepidophyta. The paleobotanical affinities of the palynomorphs reveal a flora of lycopods and progymnosperms occupying this area during the Late Devonian, with Retispora lepidophyta becoming a common element in the latest Famennian.