Chemical Compositions of Obsidian in Japan -An Approach to Archaeological Provenience Studies

本文从化学成分(常量元素和微量元素浓度)入手，对日本地质源黑岩的特征进行了研究，为考古学鉴定来源提供了科学依据。采用仪器中子活化分析(INAA)对北海道、本州、冲绳和九州北部50个地点的370个黑岩样品中的15种微量元素进行了测定。采用完全无损的能量色散X射线荧光(EDXRF)分析方法测定了主要成分。在以12种微量元素浓度为变量的多元分析(因子分析、聚类分析)的基础上，将370个地质源黑铁矿样品归类为产地的地质露头，用中子活化分析测得的12种微量元素的浓度作为“指纹”，将这些样品与黑铁矿的地质来源进行匹配。因此，对日本不同史前时期(震前时期和柔门期)的黑铁矿文物进行了聚类分析，并对50个地点的地质来源黑铁矿进行了聚类分析。黑铁矿文物的来源已经成功实现。

This report presents the research results of the characterization of geological source obsidian in Japan on the basis of the chemical compositions (concentrations of major and trace elements) as a scientific approach to the archaeological studies in the identification of provenience.Instrumental neutron activation analysis (INAA) was used to determine 15 trace elements in 370 samples of obsidian from geological outcrops of 50 localities in Hokkaido, Honshu, Okinawa, and northern Kyushu.The principal constituent elements were determined by the energy dispersive X-ray fluorescence (EDXRF) analysis, which is entirely nondestructive method. Thus, the samples of obsidian from geological sources and artifacts were mounted on the sample stage without any processing.On the basis of the multivariate analyses, (factor analysis, cluster analysis) using concentrations of 12 trace elements as variables 370 samples of geological source obsidian have been classified into the geological outcrops of localities.The concentrations of 12 trace elements measured in obsidian artifacts by INAA can be used as "fingerprint" to match the artifacts to geological sources of obsidian. Thus, the cluster analysis of each of obsidian artifacts from various sites of Prehistoric age (the Preceramic period and the Jomon period) in Japan together with the geological source obsidian of 50 localities was carried out. The sourcing of the obsidian artifacts has been achieved successfully.