Depositional environment of a Late Jurassic reefal limestone and mode of occurrence of rudist individuals from Youra Peninsula, eastern Oita Prefecture (Kyushu Island, southwest Japan)

DOI Web Site Web Site 37 References
  • Kakizaki Yoshihiro
    Division of Earth Sciences, Graduate School of Social and Cultural Studies (Present: Graduate School of Integrated Science for Global Society), Kyushu University Present address: Gas Hydrate Research Laboratory, Organization for the Strategic Coordination, Meiji University
  • Furuyama Seishiro
    Division of Earth Sciences, Graduate School of Social and Cultural Studies (Present: Graduate School of Integrated Science for Global Society), Kyushu University Present address: Institute of Geology and Geoinformation, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology
  • Kano Akihiro
    Division of Earth Sciences, Graduate School of Social and Cultural Studies (Present: Graduate School of Integrated Science for Global Society), Kyushu University

Bibliographic Information

Other Title
  • 大分県東部・四浦半島に分布する後期ジュラ紀の礁性石灰岩の堆積環境と厚歯二枚貝の産状
  • オオイタケン トウブ ・ ヨンウラ ハントウ ニ ブンプ スル コウキ ジュラキ ノ ショウセイ セッカイガン ノ タイセキ カンキョウ ト コウシ ニマイガイ ノ サンジョウ

Search this article

Abstract

Lithofacies and biofacies of a rudist-bearing reefal limestone from the uppermost Jurassic Tsui Formation on the Youra Peninsula, eastern Oita Prefecture, southwest Japan, were quantitatively examined. The 35-m-thick limestone section displays a vertical transition from a reefal fauna in the lower-middle part (dominated by hermatypic corals and stromatoporoids) to the upper part (characterized by abundant rudists, corals, and chaetetids). Lithological features and faunal compositions indicate an oligotrophic shallow-water depositional environment in a calm setting on a small carbonate mound. In the upper part of the section, requieniidine rudists (Epidiceras speciosum) occur densely in layers 0.5‒1.5 m thick, forming biostromes with corals. Reconstructed ecological features of Late Jurassic Epidiceras are similar to those of Triassic megalotondntid and Cretaceous requieniid rudists, but differ greatly from those of primitive uncoiled hippuritidine rudists (‘Valletia’ cf. auris) reported from another Torinosu-type limestone in the Shirokawa area, Shikoku Island, southwest Japan (Upper Jurassic-lowermost Cretaceous). These results suggest that rudists had already ecologically diverged in the late Late Jurassic, during an early stage of their evolutionary history.

Journal

References(37)*help

See more

Related Projects

See more

Keywords

Details 詳細情報について

Report a problem

Back to top