Presentation Information
[T14-O-11]Non-destructive provenance analysis of Shimanto Belt sandstone used in the tombstones of the Tosa domain lords based on pXRF, magnetic susceptibility, and PCA
*Wataru TANIKAWA1,2, Yoshichika Mochizuki2, Shota Takagi3, Takahiro Suzuki4, Osamu Tadai4, Tetsuya Yamamoto5 (1. Japan Agency for Marine-Earth Science and Technology, 2. Kochi University, 3. Kochi Castle Museum of History, 4. Marine Works Japan, LTD., 5. Kuroshio Town Board of Education)
Keywords:
Yamauchi family cemetery,sandstone,provenance estimation,portable XRF,magnetic susceptibility
The provenance of stone materials used in large tombstones and stone monuments provides information on regional geological resources and on the social and technological systems that supported quarrying, transport, and construction. Because cultural heritage stone structures cannot usually be sampled destructively, provenance evaluation must rely on non-destructive analyses combined with historical records. This study examines sandstone daimyo tombstones at the Yamauchi family cemetery in Kochi City, a National Historic Site, using portable X-ray fluorescence (pXRF), magnetic susceptibility, and principal component analysis (PCA).
Most daimyo tombstones in the cemetery are made of white to gray sandstone. Historical records indicate that sandstone for Lord VIII was procured from Higashimorogi, that for Lord XI from Higashimorogi and Kodono, and that for Lord XVI from Karyogo, but exact quarry locations remain uncertain. We conducted field surveys and interviews in Higashimorogi and Kodono in southern Kochi City and in Karyogo, Nahari Town, including Namura-no-hana, Suzumegamori, the Nomoto family property, and the Karyogo coast.
Magnetic susceptibility was measured at more than 40 points for each tombstone, associated structure, quarry-candidate outcrop, boulder, and local stone monument. pXRF analysis was performed using a MESA-800 instrument, and elemental concentrations were estimated from calibration curves based on 20 GSJ geochemical reference materials. Because tombstones could only be measured on natural surfaces, selected collected samples were analyzed on both natural and sawn surfaces to evaluate surface effects. Eight pXRF-derived elements (Mg, Si, K, Ca, Ti, Fe, Rb, and Sr) and magnetic susceptibility were standardized and compared using Rb-Sr plots, magnetic susceptibility-Fe/Ti plots, and PCA.
Most sandstone daimyo tombstones have magnetic susceptibility values of (0.17-0.21) x 10^-3 SI, overlapping with sandstone samples from Higashimorogi and Kodono. In contrast, the Lord XVI tombstone shows much lower values of (0.05-0.07) x 10^-3 SI, similar to sandstone and stone structures from Karyogo. The Rb-Sr plot separates the southern Kochi City sandstone group from the Karyogo sandstone group, with the Lord XVI tombstone plotting close to the Karyogo samples. The magnetic susceptibility-Fe/Ti plot shows the same tendency: Karyogo-related samples are characterized by lower magnetic susceptibility and lower Fe/Ti ratios. PCA also separates the Lord XVI tombstone from most other sandstone tombstones, mainly along variables related to Rb, K, and Si. In contrast, most other daimyo tombstones form a broad cluster associated with Sr and magnetic susceptibility, showing affinity with sandstones from Higashimorogi and Kodono. The Lord XI tombstone provides a component-level example: the main monument is similar to samples from the Nomoto family property in Kodono, whereas the lower base stone plots closer to Higashimorogi samples, suggesting that different stone sources may have been selected within a single tomb complex.
These results are broadly consistent with historical records for Lords VIII, XI, and XVI. They further suggest that many sandstone tombstones from Lords III to XIV were probably made using sandstone resources from southern Kochi City, whereas the Lord XVI tombstone represents an exception and was likely made from Karyogo sandstone. Although pXRF alone cannot establish one-to-one correspondence among closely related sandstone sources, integrating Rb-Sr and Fe/Ti relationships, magnetic susceptibility, PCA, macroscopic observations, and historical information improves the reliability of non-destructive provenance estimation. This study provides a geological basis for reconsidering stone procurement for early modern Tosa daimyo tombstones made of Shimanto Belt sandstone in relation to local resources, transport infrastructure, and funerary practices.
Ref.: Mochizuki (2023) Bull. Kochi Castle Mus. Hist., 5, 1-18.
Most daimyo tombstones in the cemetery are made of white to gray sandstone. Historical records indicate that sandstone for Lord VIII was procured from Higashimorogi, that for Lord XI from Higashimorogi and Kodono, and that for Lord XVI from Karyogo, but exact quarry locations remain uncertain. We conducted field surveys and interviews in Higashimorogi and Kodono in southern Kochi City and in Karyogo, Nahari Town, including Namura-no-hana, Suzumegamori, the Nomoto family property, and the Karyogo coast.
Magnetic susceptibility was measured at more than 40 points for each tombstone, associated structure, quarry-candidate outcrop, boulder, and local stone monument. pXRF analysis was performed using a MESA-800 instrument, and elemental concentrations were estimated from calibration curves based on 20 GSJ geochemical reference materials. Because tombstones could only be measured on natural surfaces, selected collected samples were analyzed on both natural and sawn surfaces to evaluate surface effects. Eight pXRF-derived elements (Mg, Si, K, Ca, Ti, Fe, Rb, and Sr) and magnetic susceptibility were standardized and compared using Rb-Sr plots, magnetic susceptibility-Fe/Ti plots, and PCA.
Most sandstone daimyo tombstones have magnetic susceptibility values of (0.17-0.21) x 10^-3 SI, overlapping with sandstone samples from Higashimorogi and Kodono. In contrast, the Lord XVI tombstone shows much lower values of (0.05-0.07) x 10^-3 SI, similar to sandstone and stone structures from Karyogo. The Rb-Sr plot separates the southern Kochi City sandstone group from the Karyogo sandstone group, with the Lord XVI tombstone plotting close to the Karyogo samples. The magnetic susceptibility-Fe/Ti plot shows the same tendency: Karyogo-related samples are characterized by lower magnetic susceptibility and lower Fe/Ti ratios. PCA also separates the Lord XVI tombstone from most other sandstone tombstones, mainly along variables related to Rb, K, and Si. In contrast, most other daimyo tombstones form a broad cluster associated with Sr and magnetic susceptibility, showing affinity with sandstones from Higashimorogi and Kodono. The Lord XI tombstone provides a component-level example: the main monument is similar to samples from the Nomoto family property in Kodono, whereas the lower base stone plots closer to Higashimorogi samples, suggesting that different stone sources may have been selected within a single tomb complex.
These results are broadly consistent with historical records for Lords VIII, XI, and XVI. They further suggest that many sandstone tombstones from Lords III to XIV were probably made using sandstone resources from southern Kochi City, whereas the Lord XVI tombstone represents an exception and was likely made from Karyogo sandstone. Although pXRF alone cannot establish one-to-one correspondence among closely related sandstone sources, integrating Rb-Sr and Fe/Ti relationships, magnetic susceptibility, PCA, macroscopic observations, and historical information improves the reliability of non-destructive provenance estimation. This study provides a geological basis for reconsidering stone procurement for early modern Tosa daimyo tombstones made of Shimanto Belt sandstone in relation to local resources, transport infrastructure, and funerary practices.
Ref.: Mochizuki (2023) Bull. Kochi Castle Mus. Hist., 5, 1-18.
Comment
To browse or post comments, you must log in.Log in