Thalassionsira castanea, a new diatom species useful for the Late Miocene diatom biostratigraphy in the North pacific

摘要

A new stratigraphically useful Neogene diatomspecies Thalassiosira castanea is described. The species has avery short range in the lower part of the Upper Miocene of the N.kamtchatica Zone. The first occurrence of this species iscoincident with the boundary between this zone and theunderlying Rocuxia californica Zone, and hence it is a goodmarker for this boundary.