Neogene silicoflaggelates in ODP Leg 104 holes

A quantative study was made of silicoflagellates recovered from Sites 642 (lower Miocene-upper Pliocene), 643 (lower Miocene-upper Miocene), and 644 (upper Pliocene-Quaternary) on the Voring Plateau. Although disconformities are present in these sequences, they represent a much more complete record of the Neogene than was recovered previously in the Norwegian Sea by DSDP Leg 38. Silicoflagellates are rare or absent for glacial sequences younger than 2.65 Ma, and generally sparse and poorly preserved in the lower upper Pliocene and upper Miocene. Lower and middle Miocene assemblages are diverse and generally well preserved. Temporal changes in the silicoflagellate assemblage are indicative of major paleoceanographic changes in the Norwegian Sea. A regional zonation for the Neogene of the Norwegian Sea is proposed, consisting of eleven zones: Naviculopsis lata Zone, N. quadrata Zone (emended), N. ponticula Zone (emended), Distephanus speculum hemisphaericus Zone (new), Caryocha ernestinae Zone (new), Bachmannocena circulus var. apiculata/Caryocha Zone (new), Distephanus crux scutulatus Zone (new), Bachmannocena diodon nodosa Zone (new), Distephanus boliviensis Zone (new), Ds. jimlingii Zone (elevated from subzonal to zonal status) with Subzones a and b (new), and Ds. speculum Zone (new). The ranges and abundances of over 100 species and morphotypes are tabulated.