[H-QR04] Quaternary, Diachronic dynamics of human-environment interactions

[HQR04-P03] Wide spreading tephras in lower-most part of the Osaka Group in hilly land along right bank of the Kizu River, southern district of Kyoto prefecture, central Honshu

*Taku Komatsubara¹, Akira Furusawa², Kiyohide Mizuno¹, Muneki Mitamura³, Yasufumi Satoguchi⁴ (1.Institute of Geology and Geoinformation, Advanced Industrial Science and Technology, 2.Furusawa Geological Survey Co. Ltd., 3.Osaka City University, 4.Lake Biwa Museum)

Keywords:Osaka group, wide spreading tephra, Early Pleistocene

1 Introduction
There are several tephras in the lower most part of the Osaka Group, in the hilly land along right bank of the Kizu River (e.g. Ikeda et al., 2013). Previous studies made clear that the Yamashiro 4 tephra is correlated to the Mushono tephra (Msn-Jwg4) by Satoguchi et al., (2013) and Ide 1 tehpra is correlated to the Fugenji (Ebisutoge-Fukuda:Ebs-Fukuda) tephra by Ikeda (2002). We carried out measuring refractive index, analysis major and minor element chemical components of the volcanic glass, and made clear that the lowermost Yamashiro 4 tephra is correlated to the Azokoen 4 tephra (Naya and Mizuno, 2020) in the Busshi Formation in western Kanto region.

2. Tephras in the Hill along the right bank of the Kizu River and their chemical components.
There are 6 tephras (Yamashiro 1 to 4 and Ide 1 and 2) in the Osaka Group in the study area. The Yamashiro 1 and 4 and the Ide 1 tephras are glassy tephra with larger than 20 cm in thickness. All of these tephras contain mud, and their sedimentary structures show that they deposited under circumstances in running water.

References
Ikeda et al. (2013) Chigaku Kenkyu, 61, 73-92.
Ikeda (2002) Chigaku Kenkyu, 51, 31-39.
Satoguchi et al. (2013) 120 th Proc. Geol. Soc. Jp., 68.
Naya and Mizuno (2020) Jour. Geol. Soc. Jp., 126, 183-204.
Yoshikawa (1984). Geosci. Osaka City Univ., 27, 1-47.