Paleoceanographic affinities of radiolarian faunas in late Aalenian time (Middle Jurassic) recorded in the Jurassic accretionary complex of Japan

Noritoshi Suzuki, Kaoru Ogane

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

A total of 140 polycystine radiolarians (84 nassellarians and 56 spumellarians; called Mn-03 assemblage herein) were identified from a manganese nodule in mudstone of the chert-clastic sequence distributed in the Jurassic accretionary complex of the Kuzumaki- Kamaishi Belt, Northern Kitakami Mountains, Northeast Japan. The horizon yielding this well-preserved assemblage was correlated to the uppermost part of the radiolarian JR4 Zone (the Upper Aalenian, Middle Jurassic) on the basis of the presence of Tricolocapsa tegiminis , the probable decendant of Laxtorum (?) jurassicum , and the absence of L. (?) jurassicum and Tricolocapsa plicarum . The Mn-03A assemblage is of high diversity but shows nearly half of the diversity of the contemporaneous assemblage which was reported from manganese nodules in another Jurassic accretionary complex of the Mino Belt in Japan. Both assemblages are considered to have been derived from the same province due to faunal similarity. The difference between both assemblages is explained by lower productivity in the depositional region of the Mn-03A assemblage. Comparison of the Mn-03A assemblage to the contemporaneous assemblage indicates that the fauna lived in the equatorial to lower latitudinal zone of the Pacific Superocean in late Aalenian time.

Original languageEnglish
Pages (from-to)343-357
Number of pages15
JournalJournal of Asian Earth Sciences
Volume23
Issue number3
DOIs
Publication statusPublished - 2004 Jul 1

Keywords

  • Accretionary complex
  • Japan
  • Jurassic
  • Kuzumaki-Kamaishi belt
  • Manganese nodule
  • Northern Kitakami mountains
  • Paleoceanography
  • Radiolaria

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes

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