Fission Track Ages and Uranium Contents of Obsidians

Abstract

The method of dating and measuring uranium concentrations of obsidians by fission tracks were applied to the characterization of obsidians from known volcanic sources in Japan. The sources which yield flake quality obsidians are Shirataki, Oketo, Tokachi, Akaigawa (Hokkaido), Fukaura, Itayama (Tohoku), Wadatoge, Kirigamine, Hakone, Kozushima (Chubu), Kumi (Oki), Himeshima, Koshidake, Yodohime, Furusato and Mifune (Kyushu). The fission track ages and uranium contents of obsidians from these sources are homogeneous within sources and heterogeneous between sources. Accordingly, the method of dating and measuring uranium concentrations of obsidians by fission tracks is expected successfully applicable to the identification of geologic sources of obsidian artifacts found from archaeological contexts.