Larger marine diatom fossils were examined from 12 samples collected from Neogene marine sediments distributed in the northern and central areas of Honshu Island, Japan. The diatoms were separated into smaller and larger sizes through a sieve of 63 µm. Depositional ages were determined for the samples on the basis of the Neogene North Pacific diatom biochronology of smaller diatoms, ranging from the diatom zones NPD3A (uppermost, 16.6–16.7 Ma), NPD4A (15.8–15.9 Ma, 14.6–14.8 Ma), NPD5C (10.0–11.4 Ma) and NPD7Bb (3.5–5.5 Ma). Fifty-three larger diatom taxa in 23 genera were identified including 42 typical larger diatom taxa in 17 genera. Typical larger diatoms are: Triceratium (10 taxa), Aulacodiscus (6 taxa), Biddulphia (5 taxa), Actinocyclus (3 taxa), Coscinodiscus (3 taxa), Auliscus (2 taxa), Campylodiscus (2 taxa), Isthmia (2 taxa) and Arachnoidiscus, Cerataulus, Craspedodiscus, Endictya, Hyalodiscus, Leudugeria, Rutilaria, Sticutodiscus and Surirella (1 taxon each). Forty-eight larger diatoms are shown in plates with remarks on 17 taxa. This study has elucidated the general compositions of Neogene larger marine diatom assemblages in Japan, which are completely different from those of smaller diatom assemblage.
抄録全体を表示