Optically stimulated luminescence dating using the quartz inclusion method of earthenware from the Nam Tok Khao Pang archaeological site, Kanchanaburi, Thailand

Abstract

The Nam Tok Khao Pang archaeological site, located in Tha Sao subdistrict, Sai Yok district, Kanchanaburi province, Thailand, is a limestone cave where numerous artifacts, including black-burnished earthenware fragments with in-curving rims, out-curving rims, and carinated bodies, have been discovered. Mineralogical and microstructural analyses using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) identified quartz (SiO₂) as the dominant mineral phase within a partially sintered silicate matrix. The absence of vitrification and the presence of mineral impurities indicate that the earthenware was fired at temperatures between 900°C and 1000°C. To determine the age of these ceramics, optically stimulated luminescence (OSL) dating was conducted on three black-burnished earthenware fragments using the quartz inclusion method and the single aliquot regeneration (SAR) protocol. Annual dose rates were estimated from uranium (U), thorium (Th), and potassium (K) concentrations measured by laser ablation–inductively coupled plasma mass spectrometry (LA-ICP-MS). The individual OSL ages obtained were 3.591 ± 0.63 ka, 3.479 ± 0.74 ka, and 3.717 ± 0.73 ka, yielding an average age of approximately 3.59 ± 0.34 ka. This places the artifacts within the Late Neolithic to Middle–Late Bronze Age period. These findings are consistent with the typological characteristics of the earthenware and align with radiocarbon dates obtained from charcoal collected from black-burnished earthenware vessels at the Ban Kao site, which also fall within the Late Neolithic period. This correlation supports the chronological framework of prehistoric settlement in the region and highlights the reliability of OSL dating for ceramic artifacts in tropical archaeological contexts.