Planktonic foraminiferal zonation in the Cretaceous Yezo Group, Central Hokkaido, Japan

Hiroshi Nishi*, Reishi Takashima, Takayuki Hatsugai, Tsunemasa Saito, Kazuyoshi Moriya, Atsuhito Ennyu, Toshiaki Sakai

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

59 Citations (Scopus)


The mudstone of the Yezo Group exposed in Central Hokkaido yields abundant microfossils of calcareous nannofossils, foraminifers, radiolarians and dinoflagellates. Benthic foraminifers consisting of both agglutinated and calcareous species occur abundantly and consistently throughout the sequence, while specimens of planktonic foraminifers are generally fewer than benthics in all samples. We recognized the following 13 planktonic foraminiferal zones assigned to the late Aptian to early Campanian in the Oyubari and Haboro-Kotanbetsu areas; (1) Globigerinelloides spp., (2) Ticinella primula, (3) Biticinella breggiensis, (4) Rotalipora subicinensis-Rotalipora ticinensis, (5) Rotalipora appenninica, (6) Rotalipora globotruncanoides, (7) Rotalipora cushmani (8), Whiteinella archaeocretacea (9) Helvetoglobotruncana helvetica, (10) Marginotruncana pseudolinneiana, (11) Marginotruncana sinuosa, (12) Contusotruncana fornicata, (13) Globotruncana arca. The Globigerinelloides spp. to H. helvetica Zones (late Aptian to early Turonian) can be correlated with standard zones in the Tethyan regions, whereas the assemblages from the M. pseudolinneiana to G. arca zones lack tropical zonal markers of Dicarinella concavata, D. asymetrica and Globotruncanita elevata in many studied sections. The scarcity or lack of tropical zonal species during the late Turonian to early Campanian suggests that the Oyubari and Haboro-Kotanbetsu regions in Hokkaido were located in the Transitional to Boreal biogeographical provinces.

Original languageEnglish
Pages (from-to)867-886
Number of pages20
JournalJournal of Asian Earth Sciences
Issue number8
Publication statusPublished - 2003 Jun
Externally publishedYes


  • Biostratigraphy
  • Cretaceous
  • Hokkaido
  • Japan
  • Planktonic foraminifers

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes


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