Lower Eocene Benthic Foraminifera and Paleoenvironment of the Outer Vøring Plateau, Norwegian Sea (DSDP Site 338)

Abstract

Analysis of early Eocene benthic foraminifers of DSDP Site 338 (Outer Voring Plateau, Norwegian Sea) revealed three benthic foraminiferal assemblage zones: a lower barren Zone; a middle Nodosariid Assemblage Zone, characterized by Midway-type benthic foraminifers; and an upper Vagulinopsis decorata Assemblage Zone, divided into a lower Pullenia quinqueloba Subzone and an upper Haplophragmoides Subzone. The V. decorata Assemblage Zone is also characterized by Midwaytype faunas, but benthic foraminiferal assemblages show an increasing proportion of deep water Velasco-type faunal elements. The fauna closely resembles age-equivalent benthic foraminiferal faunas from the North Atlantic (e.g. Rockall Plateau). From the poverty of planktonic foraminiferal assemblages and nannofloras it seems that similarities in benthic foraminiferal assemblages were probably not the result of an open marine connection across the Iceland-Faroe Ridge, but rather of migration through the epicontinental seas of NW Europe. The early Eocene subsidence history of Site 338 as inferred from benthic foraminiferal assemblages and lithostratigraphy confirms independent paleodepth estimates from backtracking and seismic stratigraphy and shows that this site has subsided during a maximum of 2.8 Ma from near sea level to upper bathyal depths. The maximum water depth must have been less than 500 m at the top of early Eocene and probably was in the order of 250 m.