Late Neogene radiolarian biostratigraphy in the subarctic Northwest Pacific

The radiolarian assemblages recovered from Upper Miocene and Pliocene sequences at DSDP Sites 192, 302 and 438A and from an onshore section in northern Japan lack many of the species used as zonal markers in low and middle latitudes. A new high-latitude radiolarian zonation based on nine easily recognized events is proposed. Forty-five radiolarian events are identified and the sediment accumulation rate curve of Site 438A allows most of these events to be correlated with the geochronologic time scale. Five new species, Lithelius barbatus, Cycladophora nakasekoi, Cycladophora sakaii, Dictyophimus robustus and Lychnocanoma parallelipes, are described.