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Diatom biostratigraphy of the Middle Miocene Kinone and lower Amatsu Formations in the Boso Peninsula, central Japan.

1997; Japanese Association for Petroleum Engineers; Volume: 62; Issue: 3 Linguagem: Inglês

10.3720/japt.62.215

1881-4131

Mahito Watanabe, Masaki Takahashi,

Paleontology and Stratigraphy of Fossils

Diatom biostratigraphy is established for the Middle Miocene Kinone and lower Amatsu Formations in Boso Peninsula, central Japan. Diatom zones of Denticulopsis lauta Zone through D. praedimorpha Zone are recognized in 15 calcareous nodules out of 79 collected samples in the study area. The middle and upper part of the Kinone Formation is assigned to Denticulopsis lauta and Denticulopsis hyalina Zones. The Crucidenticula nicobarica Zone is recognized at around the boundary between Kinone and Amatsu Formations. The lower Amatsu Formation is assigned to Denticulopsis praedimorpha Zone. The diatom biostratigraphy established in this study can be correlated directly with the calcareous microfossil biostratigraphy previously reported. Based on the integrated biostratigraphy of the study area it is revealed that the sedimentation rate decreased abruptly around the boundary between the Kinone and Amatsu Formations.