The aim of this study is to determine the relationship between intrusion of granite bodies, thermal metamorphism, and landslides. Omine granites and Kumano acid igneous rocks are widely distributed in the central to southern parts of the Kii Peninsula. These basic rock bodies have been active between 14 to 15 Ma. Research on the thermal history of hot springs and mines has progressed, and the estimation of large-scale high-temperature fluids in underground areas is often used in analysis.
Many landslides and collapses have been found in the Shimanto belt, which was deposited in the Cretaceous of the Mesozoic Era. It has been suggested that the location where landslides are concentrated is related to the location of granite bodies, but this has not been comprehensively investigated.
In this study, we focused on the illite crystallinity and physical characteristics of mudstone in the Ryujin and Miyama formations in the Shimanto belt and the adjacent Kumano formation, and verified the range of the thermal influence of Miocene igneous complexes and the location of landslides. Based on the results, it was clarified that there is a clear relationship between the distribution of illite crystallinity, and the location of landslides.
