Precise radiocarbon dating of charred materials on potsherds by means of their characterization

1. 陶片上焦化物质的稳定同位素研究大部分陶片上焦化物质表现为典型的陆源，δ - 13c值约为-26 / mil。该样品与考古观察结果吻合较好。δ - 13c值较高的样品可能受到低碳氮比海源和δ - 15n分馏的影响。少量样品的δ - 13c值与放射性碳测年一致，表明炭化物质来源于谷子等C4植物。日本北海道和东北北部地区出土的陶器碎片炭化物质的放射性碳定年研究表明，样品的δ - 13c值中等（约为-24 / mil），碳氮比较高，其放射性碳年龄比预期的要早。海洋哺乳动物不可能是这种烧焦物质的来源，而化石燃料，例如泥炭，可能是这种物质的来源。烧焦材料的表征：对烧焦材料进行了c - ms和FT-IR测量，但这些都不成功。样品中挥发物的提取和化学前处理有待改进。另一方面，稳定同位素的测定将成为估计陶器炭化物质来源的一个很好的工具。

1. Stable isotope research of charred materials on potsherdsMost of charred materials on potsherds showed typical land source, about -26 per mil of delta-13C value. Such sample was in good agreement with archaeological observation. Samples with higher delta-13C value might be affected by marine source of a low C/N ratio and fractionated delta-15N. Few sample showed much higher delta-13C value with coincide radiocarbon date, indicating that the charred material was derived from C4 plant such as millet.2. Radiocarbon dating of charred material on potsherds excavated in northern part of Japanese archipelagoSamples excavated in Hokkaido Island and northern Tohoku region often show moderate delta-13C value (ca. -24 per mil) and high C/N ratio with older radiocarbon age than expected. Marine mammals cannot be the source of such charred material, while usage of fossil fuel, peat for instance, might be likely.3. Characterization of charred materialGC-MS and FT-IR measurement were carried out on charred materials, however these were not successful. The extraction of volatiles from sample and chemical pretreatment should be improved. On the other hand, stable isotope measurement will be a good tool for estimation of the source of charred materials on pottery.