[S-GL22] Geochronology and Isotope Geology

[SGL22-P06] Preliminary archeointensity results of silver slags from the Iwami silver deposit, Shimane

*Kengo Kataoka¹, Kazuo Kawasaki¹ (1.University of Toyama)

Archeological artifacts are often used to determine the ancient geomagnetic field intensities. These archeointensity data are important for determining temporal changes in the geomagnetic field and estimating the past geodynamo and the evolution of the Earth’s deep interior. These data are also essential to construct local reference curves of the geomagnetic field, which are used to date archeological remains and artifacts. Most archeointensities have been measured on young volcanic rocks or baked samples such as ceramics and kiln floors. Slag, a waste material produced in furnaces, can be a good recorder of the geomagnetic field intensity since the slag likely acquires a thermal remanent magnetization after removing the melt from the furnace. However, only a few archeointensity studies have been reported for slags. Archeointensity results are reported for silver slags from an archeometallurgical site in the Iwami silver deposit, Shimane. Based on thermomagnetic analysis, hysteresis loop measurements and stepwise isothermal remanent magnetization experiments, the main magnetic mineral of the slags is single to pseudosingle domain titanomagnetite. Although two types of remanent intensity decay trends were observed during thermal demagnetization, the analyses isolated a stable remanent magnetization. Archeointensities were determined using the Thellier method, and the observed intensities show good agreement with a reference archeointensity curve in Japan. The results indicate that silver slags can be a good candidate for determining the archeointensity and dating archeometallurgical sites. Silver slags are more widely available than other archeological remains and artifacts and, therefore, should be considered for application in different regions and time periods.