Navarin basin, a large structural basin filled in places with more than 12,000 m of sediment, underlies the Bering Sea continental shelf about 100 km from the Koryak coast, U.S.S.R. The shelf in this region is relatively flat with a pronounced shelf-slope break at about 200 m. In contrast, the continental slope is incised by three large canyons.

Little is known about the sediment and microbiota in the Navarin basin province because preveious work in the Bering Sea has been concentrated in the eastern and southern areas. More than 100 gravity cores and grab samples were collected during the summer of 1980 from the basin, adjacent slope, and nearby canyons in water depths ranging from about 80 to 3,300 m. Cores as long as 6 m contain predominantly clastic mud and sand. This preliminary U.S. Geological Survey sampling program is the first attempt in the Navarin province in which the three microorganism groups--diatoms, radiolarians, and foraminifers--are used to obtain paleogeographic information and to establish age-datum planes.

Diatoms, the most abundant micro-organisms in the cores, are useful for defining glacial events and sea level fluctuations, and for establishing depth of deposition. Radiolarians are more abundant in the deeper shelf area, and are used to delineate paleogeographical boundaries and biostratigraphic events in the Navarin province. Calcareous foraminifers are abundant in the cores from even the deepest stations, but diversity is low. Shallow-water benthic foraminifers recovered in deep water indicate downslope movement of sediment. Study of these three micro-organism groups provides a more complete picture of the benthic and planktonic communities and thereby leads to a more accurate paleoecologic interpretation of Navarin basin.

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