Photographs and analytical data of the lower part of the Hakobuchi Formation, Yezo Group, Hokkaido

dataset

posted on 2025-10-30, 08:52 authored by Koh Kubomi, Mitsuhiro Nagata, Sota NikiSota Niki, Takafumi Hirata

Fig. A1. a) Examples of Cathodoluminescence (CL) images of zircon grains from the sample HOY-2. White open circles show measurement spot (25 μm). The 238U–206Pb age of each spot is indicated. Scale bar is 100 μm. Yellow numbers indicate the Th/U ratio of zircon grains. b) Wetherill Concordia diagram of sample HOY-2. Red solid circles indicate adopted ages. Blue open circles indicate nonadopted ages. Fig. A2. Biostratigraphic and geochronological correlations between the Upper Cretaceous (lower Campanian) to Upper Paleogene (Thanetian) in Hokkaido based on ammonoids, inoceramids, dinoflagellates, foraminifers, and zircon U–Pb and FT ages of tuffs. (modified from Ando, 2003; Ando and Takahashi, 2024; Kubomi and Nagata, 2025). The geological timescale used for Figure A2 is from Cohen et al. (2024). Abbreviations Gp.: Group, Fm.: Formation. Mbr.: Member. Md.: Mudstone. Ammonoids: Bo: Baculites cf. occidentalis, Bs: Baculites subanceps, Ck: Canadoceras kossmati, Cm: Canadoceras multicostatum,Dd: Desmophyllites diphylloides, Gh: Gaudryceras hamanakense, Gi: Gaudryceras izumiense, G. n. sp.: Gaudryceras n. sp. (Ando et al., 2001), Ms: etaplacenticeras subtilistriatum, Nh: Nostoceras hetonaiense, Pp: Polyptychoceras psudogaultinum, Tp: Tetragonites popetensis, Pf: Pachydiscus flexuosus, Ph: Pachydiscus hidakaensis. Inoceramids: Ia: Inoceramus amakusensis, Ib: Inoceramus balticus, Ij: Inoceramus japonicus, Ik: Inoceramus kushiroensis, Is: Inoceramus shikotanensis, Isp.: Inoceramus sp., Sh: Sphenoceramus hetonaianus, Sn: Sphenoceramus naumanni, So: Sphenoceramus orientalis, Ss: phenoceramus schmidti, Ssp.: Sphenoceramus sp. Fossil zone: 1) Toshimitsu et al. (1995); Shigeta et al. (2019); Shigeta and Maeda. (2023), 2) Urakawa area: Kanie and Sakai (2002); Shigeta et al. (2016), 3) Hobetsu area: Takashima et al. (2004); Hayashi et al. (2011), 4) Oyubari area: Takashima et al. (2004); Ando et al. (2007); This study, 5) Yubari area: Kubomi et al. (2023), 6) Chikubetsu-Obira area: Hattori (1965); Moriya and Hirano (2001); Takashima et al. (2004), 7) Teshio-nakagawa area: Takahashi et al. (2003); Ando et al. (2010); Shigeta and Tsutsumi (2018), 8) Nakatonbetsu area: Ando et al. (2001); Ando and Tomosugi (2005); Shigeta and Tsutsumi (2019), 9) Soya Hill area: Ando and Ando (2002); Shigeta et al. (2017). Zircon U–Pb and FT ages: a) 76.0 ± 1.3 Ma (N = 29, 95% conf., MSWD = 1.9); Shigeta et al. (2016), b) 75.1 ± 0.9 Ma (N = 35, 95% conf., MSWD = 1.7); Shigeta et al. (2016), c) 79.8 ± 0.8 Ma (N = 7, 2σ, MSWD = 1.2); This study, d) 64.1 ± 1.1 Ma (N = 8, 2σ, MSWD = 1.6); Kubomi et al. (2023), e) 67.4 ± 3.2 Ma (N = 29, 1σ; FT); Kurita et al. (1992), f) 80.2 ± 0.8 Ma (N = 29, 95% conf., MSWD = 0.8); Shigeta and Tsutsumi (2018), g) 69.8 ± 0.8 Ma (N = 25, 95% conf., MSWD = 1.2); Shigeta and Tsutsumi (2019), h) 73.0 ± 1.8 Ma (N = 8, 95% conf., MSWD = 1.7); Shigeta et al. (2017), i) 70.5 ± 1.1 Ma (N = 15, 95% conf., MSWD = 1.5); Shigeta et al. (2017). Abbreviations FT: Fission Track, 95% conf.: 95% confidence interval. References; <ul><li>Ando, H., 2003, Stratigraphic correlation of Upper Cretaceous to Paleocene forearc basin sediments in Northeast Japan: cyclic sedimentation and basin evolution. J. Asian Earth Sci., 21, 921–935. <a href="https://doi.org/10.1016/S1367-9120(02)00111-6" rel="noreferrer" target="_blank">https://doi.org/10.1016/S1367-9120(02)00111-6</a></li><li>Ando, H., Kurihara, K. and Takahashi, K., 2007, Depositional facies changes along the Yezo forearc basin transect and Cenomanian-Turonian oceanic anoxic event horizon: Yubari and Mikasa. J. Geol. Soc. Japan, 113, S185–S203.**<a href="https://doi.org/10.5575/geosoc.113.S185" rel="noreferrer" target="_blank">https://doi.org/10.5575/geosoc.113.S185</a></li><li>Ando, H. and Takahashi, M., 2024, Reconstruction of the Cretaceous continental arc-trench system of the Japanese Islands: A basis for Cretaceous palaeoenvironmental studies. In, Hart, M. B., Batenburg, S. J., Huber, B. T., Price, G. D., Thibault, N., Wagreich, M. et al. eds., Cretaceous Project 200 Volume 1: The Cretaceous World. Geol. Soc., Lon., Spec. Publ., 544, 203–257.</li><li>Ando, H., Tamura, Y. and Takamatsu, D., 2010, Fourth‐to third‐order cycles in the Hakobuchi Formation: shallow‐marine Campanian final deposition of the Yezo Group, Nakagawa area, northern Hokkaido, Japan. Isl. Arc, 19, 567–589.<a href="https://doi.org/10.1111/j.1440-1738.2010.00716.x" rel="noreferrer" target="_blank">https://doi.org/10.1111/j.1440-1738.2010.00716.x</a></li><li>Ando, H. and Tomosugi, T., 2005, Unforcomity between the Upper Maastrichtian and Upper Paleocene in the Hakobuchi formation, north Hokkaido, Japan: a major time gap within the Yezo forearc basin sediments. Cretaceous Res., 26, 85–95.<a href="https://doi.org/10.1016/J.CRETRES.2004.11.001" rel="noreferrer" target="_blank">https://doi.org/10.1016/J.CRETRES.2004.11.001</a></li><li>Ando, H., Tomosugi, T. and Kanakubo, T., 2001, Upper Cretaceous to Paleocene Hakobuchi Group, Nakatonbetsu area, northern Hokkaido: lithostratigraphy and megafossil biostratigraphy. J. Geol. Soc. Japan, 107, 142–162.**<a href="https://doi.org/10.5575/geosoc.107.142" target="_blank">https://doi.org/10.5575/geosoc.107.142</a></li><li>Ando, M. and Ando, H., 2002, Depositional facies and megafossil biostratigraphy of the Upper Cretaceous Hakobuchi Group in the Soya Hill area, northern Hokkaido. Bull. Nakagawa Mus. Nat. Hist., 5, 1–21.**</li><li>Cohen, K. M., Harper, D. A. T. and Gibbard, P. L., 2024. ICS International Chronostratigraphic Chart 2024/12. Int. Commission Stratigr., IUGS, <a href="" target="_blank">https://stratigraphy.org/ (visited: 2025/6/22)</a>.</li><li>Hattori, Y., 1965, A find of ammonites from the Haranosawa Formation at the Chikubetsu colliery in Hokkaido. J. Geol. Soc. Japan, 71, 149–151.**<a href="https://doi.org/10.5575/geosoc.71.149" target="_blank">https://doi.org/10.5575/geosoc.71.149</a></li><li>Hayashi, K., Nishi, H., Takashima, R., Tomosugi, T. and Kawabe, H., 2011, Geology and foraminiferal biostratigraphy of Upper Cretaceous sequences in southern central Hokkaido, Japan. J. Geol. Soc. Japan, 117, 14–34.<a href="https://doi.org/10.5575/geosoc.117.14" target="_blank">https://doi.org/10.5575/geosoc.117.14</a></li><li>Kanie, Y. and Sakai, A., 2002, Geology of the Urakawa District. Quadrangle Series, 1: 50000, Geol. Surv. Japan, AIST, 43p.**</li><li>Kubomi, K. and Nagata M., 2025, Regional stratigraphic correlation of the Hakobuchi Formation of the Yezo Group in Hokkaido: Reconstruction based on stratigraphy, fossils, and geochronology. Bull. Hokkaido Mus., 10, 1–22.**</li><li>Kubomi, K., Nagata, M., Ota, H., Miyata, K. and Otoh, S., 2023, Discovery of Early Paleocene (Danian) tuff from the Yezo Group in the Yubari area, Hokkaido, Northeast Japan. J. Geol. Soc. Japan, 129, 453–460.<a href="https://doi.org/10.5575/geosoc.2023.0011" target="_blank">https://doi.org/10.5575/geosoc.2023.0011</a></li><li>Kurita, Y., Ichinoseki, T. and Hiramatsu, C, 1992, Geologic age the Sankebetsu and Haboro Formations, Haboro area, northern Hokkaido. J. Geol. Soc. Japan, 98, 259–266.**<a href="https://doi.org/10.5575/geosoc.98.259" target="_blank">https://doi.org/10.5575/geosoc.98.259</a></li><li>Moriya, K. and Hirano, H., 2001, Cretaceous stratigraphy in the Chikubetsu area, Hokkaido. J. Geol., Soc., Japan, 107, 199–214. **<a href="https://doi.org/10.5575/geosoc.107.199" target="_blank">https://doi.org/10.5575/geosoc.107.199</a></li><li>Shigeta, Y., Izukura, M. and Nishimura, T., 2019, Campanian (Late Cretaceous) ammonoids and inoceramids from the Ribira River area, Hokkaido, northern Japan. Bull. Natl. Mus. Nat. Sci. Monographs, 50, 1–139.</li><li>Shigeta, Y., Izukura, M., Nishimura, T. and Tsutsumi, Y., 2016, Middle and late Campanian (Late Cretaceous) ammonoids from the Urakawa area, Hokkaido, northern Japan. Paleont. Res., 20, 322–366.<a href="https://doi.org/10.2517/2016PR004" target="_blank">https://doi.org/10.2517/2016PR004</a></li><li>Shigeta, Y., Izukura, M. and Tsutsumi, Y., 2017, An early Maastrichtian (latest Cretaceous) ammonoid fauna from the Soya Hill area, Hokkaido, northern Japan. Bull. Hobetsu Mus., 32, 7–41.</li><li>Shigeta, Y. and Tsutsumi, Y., 2018, U–Pb age of the Sphenoceramus schmidti Zone (middle Campanian, Cretaceous) in Hokkaido, northern Japan. Bull. Natl. Mus. Nat. Sci., Ser. C, 44, 13–18.</li><li>Shigeta, Y. and Tsutsumi, Y., 2019, U–Pb age of the Pachydiscus flexuosus Zone (Maastrichtian, Cretaceous) in the Nakatonbetsu area, Hokkaido, northern Japan. Bull. Natl. Mus. Nat. Sci., Ser. C, 45, 29–36.</li><li>Shigeta, Y. and Maeda, H., 2023, Late Maastrichtian (latest Cretaceous) ammonoids from the Naiba area, southern Sakhalin, Russian Far East. Paleont. Res., 27, 277–309.<a href="https://doi.org/10.2517/PR210021" target="_blank">https://doi.org/10.2517/PR210021</a></li><li>Takahashi, A., Hirano, H. and Sato T., 2003, Stratigraphy and fossil assemblage of the Upper Cretaceous in the Teshionakagawa area, Hokkaido, northern Japan J. Geol., Soc., Japan, 109, 77–95.**</li><li>Takashima, R., Kawabe, F., Nishi, H., Moriya, K., Wani, R. and Ando, H., 2004, Geology and stratigraphy of forearc basin sediments in Hokkaido, Japan: Cretaceous environmental events on the northwest Pacific margin. Cretaceous Res., 25, 365–390.<a href="https://doi.org/10.5575/geosoc.109.77" target="_blank">https://doi.org/10.5575/geosoc.109.77</a></li><li>Toshimitsu, S., Matsumoto, T., Noda, M., Nishida, M. and Maiya, S., 1995, Towards an integrated mega-, micro-, and magneto-stratigraphy of the Upper Cretaceous in Japan. J. Geol., Soc., Japan, 101, 19–29.**<a href="https://doi.org/10.5575/geosoc.101.19" target="_blank">https://doi.org/10.5575/geosoc.101.19</a></li></ul>* in Japanese with English title ** in Japanese with English abstract Table A1. LA-MC-ICPMS analytical settings and conditions for U–Pb zircon dating. References; <ul><li>Jackson, S. E., Pearson, N. J., Griffin, W. L., and Belousova, E. A., 2004, The application of laser ablation-inductively coupled plasma-mass spectrometry to in situ U–Pb zircon geochronology. Chem. Geol.,211, 47–69.<a href="https://doi.org/10.1016/j.chemgeo.2004.06.017" rel="noreferrer noopener" target="_blank">https://doi.org/10.1016/j.chemgeo.2004.06.017</a></li><li>Jochum, K. P., Stoll, B., Herwig, K., Amini, M., Abouchami, W., and Hofmann, A. W., 2005, Lead isotope ratio measurements in geological glasses by laser ablation-sector field-ICP mass spectrometry (LA-SF-ICPMS).Intern.J.Mass Spectrometry,242, 281–289.<a href="https://doi.org/10.1016/j.ijms.2004.11.019" rel="noreferrer noopener" target="_blank">https://doi.org/10.1016/j.ijms.2004.11.019</a></li></ul>Table A2. The U–Pb isotopic data of HOY-2 (tuff sample) and secondary reference zircons. C (D): adopted (non-adopted) data.