(Table 1) Silicoflagellate abundance in ODP Hole 186-1149A sediments

Silicoflagellate assemblages have been studied from Hole 1149A (northwestern Pacific, Ocean Drilling Program Leg 185) in a continuous record of pelagic clay from lithologic Unit I. The biostratigraphic framework of D. Bukry, adapted in this work, is calibrated to tropical and subtropical fossil floras. Four biozones and three subzones have been recognized (from the lower Pliocene Dictyocha fibula Zone to the Quaternary Dictyocha aculeata aculeata Zone), and their zonal boundaries have been calibrated to the magnetostratigraphic scale. In particular, the boundary between the Dictyocha perlaevis delicata and the Dictyocha perlaevis ornata Subzones approximates the Pliocene/Pleistocene boundary.