The North Pacific advanced Oligocene to lower Miocene diatom stratigraphy

The current state of the North Pacific Oligocene and lower Miocene diatom stratigraphy is reviewed and its significant progress of the past 10-15 years is detailed. Biostratigraphic research in the region of the last decade demonstrates a real efficiency of the Oligocene to early Miocene diatom zonation based mainly on the materials from deep-sea cores. Significance of diatom zonation and its application for dating and subdivision of the Oligocene and lower Miocene sequences which previously proved difficult are discussed. The possibility of application of the oceanic zonation in studies of onshore stratigraphic sequences is emphasized. It is shown that in the North Pacific diatoms representing siliceous microplankton are the best biostratigraphic tool for age determination and correlation of the Oligocene and lower Miocene marine sediments lacking calcareous planktonic microfossils. Compilation of available diatom data from different localities allows a new correlation scheme to be proposed for the North Pacific Oligocene and lower Miocene.