Geological characteristics of ancient Sīma stone heritage in Khon Kaen Geopark, Northeastern Thailand

Sandstone artifacts and Sīma stones are widely distributed across the Khon Kaen Geopark in northeastern Thailand; however, their geological characteristics and provenance have not been systematically studied. Lithologic and petrographic analyses reveal that sandstones from Ban Ruea are classified as sublitharenite, while those from Tham Phra Kho Khat exhibit characteristics of both quartz arenite and sublitharenite. Sandstones from Sop Nam, Ban Kut Kaen, and Wat Pa Don Ku are identified as litharenite. Geochemical ratios (SiO₂/Al₂O₃ and Fe₂O₃/K₂O) further classify the samples into Fe-sandstone, quartz arenite, litharenite, sublitharenite, arkose, wacke, Fe-siltstone, and siltstone. Trace element analysis (Rb/Sr) indicates geochemical similarities between sandstone sources from Ban Ruea and Wat Pa Don Ku, consistent with the Phu Kradung Formation, while distinct signatures were observed in samples from Tham Phra Kho Khat and the Phra Wihan Formation. These results contribute to understanding ancient resource utilization and inform cultural heritage conservation within Khon Kaen Geopark.