Neogene Silicoflagellate Biostratigraphy of the Japan Sea Coastal Region, with Reference to DSDP Hole 438A
The biostratigraphic distribution of Neogene silicoflagellates in the Japan Sea coastal region has been investigated and compared with reference to Deep Sea Drilling Project Leg 57, Site 438, Hole 438A. The extraction of the stratigraphic ranges of diagnostic silicoflagellate species demonstrates the reliability of the selected silicoflagellate datum levels for a long-distance correlation. Eleven silicoflagellate datum levels are proposed on the basis of the first and last appearances, and also the level of a rapid decrease, of the diagnostic silicoflagellate taxa. Based on these datum levels, Miocene to Pliocene outcrop sections from Japan can be biostratigraphically divided into the following twelve zones, in ascending order : Mesocena apiculata Assemblage-zone, Corbisema triacantha Interval-zone, Distephanus stauracanthus Range-zone, Distephanus parvus Interval-zone, Mesocena hexalitha Range-zone, Distephanus pseudocrux Interval-zone, Distephanus praetakayanagii Range-zone, Dictyocha pseudofibula Interval-zone, Distephanus takayanagii Interval-zone, Distephanas jimlingii Interval-zone, Paramesocena circulus Interval-zone and Dictyocha neopseudofibula Assemblage-zone. The proposed silicoflagellate datum levels and zones are correlated with the subsurface sequence observed from DSDP Hole 438A, and are further correlated with those of previous works reported mainly from the circum-Pacific regions. In addition, interconnected the established silicoflagellate zonation is cross-correlation with the diatom zonation recognized in the area. Forty-five species are identified with the aid of optical and scanning electron microscopes, based on the morphological characters of basal pikes and surface micro-ornamentations. Eight species are described as new : Dictyocha neopseudofibula, Dictyocha pacifica, Distaphanus kitamurae, Distephanus lingii, Distephanus miocenica, Distephanus praetakayanagii, Distephanus takayanagii and Distephanus uchioi.
- 東北大學理科報告. 地質學 = The science reports of the Tohoku University. Second series, Geology
東北大學理科報告. 地質學 = The science reports of the Tohoku University. Second series, Geology 59(1), 1-A49, 1988-06-20