Distribution of quaternary radiolaria in the Navarin Basin geologic province, Bering Sea

Radiolarians from the surface sediments of the Navarin Basin geologic province in the western part of the Bering Sea are more diverse and abundant than previous reports indicate. The shelf is dominated by two spongy radiolarian species groups (Stylochlamydium venustum and Spongotrochus glacialis groups), while the slope has more diversity. The distributions can in part be explained by present oceanographic conditions. Studies of five cores along the slope show that there is a faunal change within the top 5 m of sediment. The spongy radiolarians are more abundant in recent sediments but gradually decrease downcore as Cycladophora davisiana becomes the dominant species, which probably reflects an environmental change. The disappearance of Lynchnocanoma grande in the area occurred around 17,000 to 34,000 y BP, but more research is needed to confirm whether the extinction is a useful biostratigraphic marker.