1. Faculty of Science, Yamagata University, 1-4-12 Kojirakawa, Yamagata 990-8560, Japan. Orcid 0000-0002-6541-1615
2. Hiruzen Institute for Geology and Chronology Co., Ltd., 2-5, Nakashima, Naka-ku, Okayama 703-8252, Japan
3. Mizunami Underground Research Laboratory, Japan Atomic Energy Agency, 1-64, Yamanouchi, Akiyo, Mizunami, Gifu 509-6132, Japan
4. Department of Earth and Environmental Science, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1, Kurokami, Chuo-ku, Kumamoto 860-8555, Japan