Mineralogy, geochemistry, and genesis of stones of arhat statuettes unearthed in Naju, Korea: geoarchaeological implications

초록

High-fidelity data on the chemical compositions and mineral phases were obtained to delve into the geoarchaeological significance underlying the stones of the arhat statuettes excavated in Naju, Korea. Quantitative chemical and mineralogical analyses were performed using calibration curves and Rietveld-based methods, respectively. Light and electron probe microscopy and colorimetric analyses were also employed to provide complementary information regarding the materials. The stones of statuettes were identified as ash tuffs with a rhyolitic composition. The findings of amorphous iron-oxide phase filling voids in laminated reddish layers were crucial in describing the formation of the layered texture prevailing on the stones. In addition, the different abundances of two distinctive pairs of illite-feldspars and kaolinite-micas in a hydrothermal system revealed the existence of contrasting pathways in the weathering processes of volcanic ashes in terms of temperature and fluid pH. By mediating iron content and the pairs of minerals, the color of powder samples allowed the texture and hydrothermal environment to be tied within a single system. Finally, a comprehensive geological model comprising rock-forming processes and the surrounding environment could be established. The model based on multilayered scientific investigations would make significant contribution to conservation science by providing the significance of elucidating the provenance of the source rock of the arhat statuettes.

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