Fission track age for MT1 tuff bed and paleoenvironment in the Upper Pliocene Mita Formation, Toyama Prefecture, central Japan

DOI Web Site Web Site 4 Citations 26 References
  • Goto Takashi
    Department of Materials Creation and Circulation Technology, Interdisciplinary Graduate School of Science and Engineering，Shimane University
  • Nasuno Shinji
    Department of Geoscience, Interdisciplinary Faculty of Science and Engineering, Shimane University
  • Irizuki Toshiaki
    Department of Geoscience, Interdisciplinary Graduate School of Science and Engineer ing，Shimane University
  • Ohira Hiroto
    Department of Geoscience, Interdisciplinary Graduate School of Science and Engineer ing，Shimane University
  • Hayashi Hiroki
    Department of Geoscience, Interdisciplinary Graduate School of Science and Engineer ing，Shimane University

Bibliographic Information

Other Title
  • 富山県の上部鮮新統三田層におけるMT1凝灰岩層のフィッショントラック年代と古環境
  • トヤマケン ノ ジョウブ センシントウ ミタソウ ニ オケル MT1 ギョウカイガンソウ ノ フィッショントラック ネンダイ ト コ カンキョウ
  • Fission track age for MT1 tuff bed and paleoenvironment in the Upper Pliocene Mita Formation, Toyama Prefecture, central Japan (in Japanese with English abstract)

Search this article

Abstract

The Pliocene Mita Formation outcrops in the Yatsuo-machi area of Toyama City, Toyama Prefecture, Japan. This formation containsthree key tuff beds (OT3, MT1, and MT2); two of these beds, OT3 and MT2, previously yielded ages of 5.2 ± 0.5 Ma and 2.2-2.3 Ma, respectively. This study focuses on the geology of the area surrounding the Akae-gawa River in the Hirabayashi region, and provides new fission track ages for the MT1 tuff exposed at two study sites in this area. These new data are combined with new fossil ostracod and planktonic foraminiferal faunal data to reconstruct the paleoenvironment during deposition of the MT1 tuff. This study presents new ages of 3.5 ± 0.2 and 3.4 ± 0.2 Ma for the MT1 tuff at the two sites that form the focus of this study. Integrating these data with the results of previous studies indicates that the first warm-water molluscs within the Mita Formation lived between 3.66 and ca. 3.4 Ma. Microfossil assemblage data from the study area also indicate that the paleoenvironment in the study site changed from a cool-water bay or shallow sea to an open temperate shallow sea setting, with warm-water ostracod species present in the uppermost horizon of the formation.

Journal

Citations (4)*help

See more

References(26)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top