Distribution of radiolarians from ODP Leg 128 holes

The modern fauna was gradually established only in the Pleistocene. No attempt was made to establish the radiolarian zonation because of low species diversity and the absence of generally recognized index forms in the North Pacific.

In the diagenetically altered quartz section, however, a radiolarian assemblage correlative to the middle Miocene Cyrtocapsella tetrapera Zone of western Honshu was identified from Hole 799B.