Stratigraphic and tectonic implications of the Middle Miocene Shichiyama Formation, Tottori Group, eastern Tottori Prefecture, Japan

Key Points

• The aim is to clarify the stratigraphy and tectonics of the Middle Miocene Shichiyama Formation in Tottori Prefecture.
• Conducted geological surveys and analyses of rock compositions.
• Performed zircon U-Pb and K-Ar dating on rocks.
• Classified the formations into different types based on composition and age.
• Identified the Shichiyama Formation's stratigraphy dating back to 15.3–15.1 million years ago.
• Confirmed volcanic and marine sediments, with inferred eruptive sources near Mount Shichiyama.
• Noted a lack of direct tectonic links between the transitions in stratigraphy and folding observed offshore.