Research theme for competitive and other funds (4)：
2021 - 2025 Environmental changes during the Latest Cretaceous Mass Extinction Event recorded in the complete K/Pg boundary sequence discovered firstly in East Asia
2020 - 2023 Paleoenvironmental studies of terrestrial and marine sequences in Northwest Pacific region during Paleocene-Eocene Thermal Maximum.
2018 - 2022 Improvement of Cretaceous Geologic Time Scale
2014 - 2017 Detecting trace of paleo-tsunami event from the bed form on the seafloor of a coastal shelf
Papers (34)：
Yoshihiro Kase, Mahito Watanabe, Keiichi Hayashi, Wataru Hirose, Tohru Danhara, Hideki Iwano, Takafumi Hirata. Zircon FT and U-Pb ages of Neogene tuffs and tuffaceous sandstones and their stratigraphic implication in Memanbetsu and adjacent areas, Hokkaido, Japan. The Journal of the Geological Society of Japan. 2024. 130. 1. 1-15
Reishi Takashima, Hiroshi Nishi, Toshiro Yamanaka, Yuji Orihashi, Yasuyuki Tsujino, Xavier Quidelleur, Keiichi Hayashi, Ken Sawada, Hideto Nakamura, Takuto Ando. Establishment of upper cretaceous bio- and carbon isotope stratigraphy in the northwest pacific ocean and radiometric ages around the albian/cenomanian, coniacian/santonian and santonian/campanian boundaries. Newsletters on Stratigraphy. 2019. 52. 3. 341-376
Kei Ioki, Yuichiro Tanioka, Gentaro Kawakami, Yoshihiro Kase, Kenji Nishina, Wataru Hirose, Kei'ichi Hayashi, Ryo Takahashi. Fault model of the 12th century southwestern Hokkaido earthquake estimated from tsunami deposit distributions. EARTH PLANETS AND SPACE. 2019. 71
Tateshita Yuki, Sawada Ken, Ando Takuto, Nakamura Hideto, Hayashi Keiichi. Terrestrial paleoenvironmental variations reconstructed by organic geochemical analyses of coal sediments in the Upper Cretaceous Hakobuchi Formation of Hobetsu area, Hokkaido, Japan. Annual Meeting of the Geological Society of Japan. 2019. 2019. 302
Tateshita Yuki, Sawada Ken, Miyata Yuma, Nakamura Hideto, Hayashi Keiichi. Terrestrial paleoenvironment reconstructed by biomarker analyses of coaly sediments in the Cretaceous Hakobuchi Formation, Hokkaido, Japan. Abstracts of Annual Meeting of the Geochemical Society of Japan. 2017. 64. 0. 109-109
Tateshita Yuki, Sawada Ken, Ando Takuto, Nakamura Hideto, Hayashi Keiichi. Reconstruction of sedimentary environment of coal beds by organic matter analyses of sediments from the Cretaceous Hakobuchi Formation, Yezo Group, Hokkaido, Japan. Annual Meeting of the Geological Society of Japan. 2017. 2017. 0. 192-192
Nishi Hiroshi, Takashima Reishi, Orihashi Yuji, Yamanaka Toshiro, Iryu Yasufumi, Takayanagi Hideko, Hayashi Keiichi. Cretaceous standard chronostratigraphic framework based on integrated stratigraphy of planktic foraminifer and carbon isotope and U-Pb age of the Yezo Group and the Vocontian Basin sequence. Annual Meeting of the Geological Society of Japan. 2013. 2013. 0. 364-364
Takashima Reishi, Kuwabara Sato, Nishi Hiroshi, Orihashi Yuji, Hayashi Keiichi. Preliminary study of Cretaceous tephrochronology in Japan. Annual Meeting of the Geological Society of Japan. 2013. 2013. 0. 367-367
Kuwabara Sato, Takashima Reishi, Nishi Hiroshi, Hayashi Keiichi. Correlation of the tuff beds in the Cretaceous Yezo Group in Hokkaido. Annual Meeting of the Geological Society of Japan. 2013. 2013. 0. 630
