Calcareous nannofossil and planktic foraminiferal biostratigraphy of the Paleogene Iojima Group in the Takashima Coalfield, Nagasaki Prefecture, southwest Japan

Tatsuhiko Yamaguchi, Yuichiro Tanaka, Hiroshi Nishi

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The Paleogene Iojima Group is exposed in the Takashima coalfield of northwestern Kyushu, southwest Japan. The group is divided into four formations: the Okinoshima, Magome, Funazu, and Daimyoji formations (in ascending stratigraphic order). Among these strata, mudstone and muddy sandstone of the Okinoshima and Funazu formations contain a number of common age-diagnostic calcareous microfossils, nannofossils, and planktic foraminifers. Our biostratigraphic study of the Paleogene Iojima Group indicates that the Okinoshima Formation corresponds to calcareous nannofossil Zone CP14 and planktic foraminiferal Zones E10-E13; the Funazu Formation is assigned to Zones CP14-CP16. The Okinoshima and Funazu formations are assigned to the late middle Eocene and late middle Eocene to early Oligocene, respectively, suggesting that 1) the Okinoshiman molluscan Stage correlates with the middle Eocene, as proposed in previous studies; and 2) the Magome Formation, which includes coal-bearing strata, correlates with the Onga marine regression.

Original languageEnglish
Pages (from-to)223-236
Number of pages14
JournalPaleontological Research
Volume12
Issue number3
DOIs
Publication statusPublished - 2008 Sep 1
Externally publishedYes

Keywords

  • Biostratigraphy
  • Calcareous nannofossils
  • Eocene
  • Funazu Formation
  • Iojima Group
  • Okinoshima Formation
  • Planktic foraminifera

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Palaeontology

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