청양 대박리 유적 출토 흑요석 석기의 재질 분석

Material analysis and geoarchaeological interpretation were carried on the obsidian artifact collected at Daebak-ri site, Cheongyang County, Korea. First of all, the provenance was very different from the geological background of this area that is mainly composed of granite gneiss formed in Precambrian. Magnetic susceptibility was evaluated in the range of 0.214 to 0.347 ( 10-3 SI unit). From the SEM images, it was also shown that the obsidian was typical of glass rock, which has the property of the rapid cooling of magma, but other remarkable structure or phenocryst mineral was not investigated. The results from the geochemical analysis indicated that a large quantity of rhyolite was measured. Therefore the obsidian was judged to be produced at a similar stage of the evolution process of felsic elements and magma. In addition,there was a possibility of the magnetite-deficient solid solution, because Fe was partially concentrated from quantitative surface analysis. Comparing with the other obsidians from prehistoric sites in the middle Korean Peninsula, Mt. Baekdu, and Kyusu of Japan, it is finally concluded that the rock type of Daebak-ri obsidian differed from the obsidians of Mt. Baekdu and Kyusu, but the contents and mobility of major elements were similarly represented with those of obsidians from the middle Korean Peninsula.