神居古潭構造帯北部地域産砂クロム中のイリジウム系白金族元素異常
1995 年 45 巻 254 号 p. 401-408
詳細
1995 年 45 巻 254 号 p. 401-408
Platinum-group elements (PGE) in nonmagnetic panned-out detrital samples from the northern Kamuikotan ophi-olitic complex, Hokkaido, was examined by neutron activation method. Their Cl-chondrite normalized PGE patterns are similar to those of ophiolitic host rocks and chromitite. Positive correlation between the iridium and chromium contents imply that iridium-series-PGE anomalies are probably due to chromite-hosted platinum-group minerals. Averaged PGE concentration in the samples from the central Hokkaido (Do-ou) region is almost eight times higher than that from the northern Hokkaido (Do-hoku) region. Based on the chemical analyses and the estimated reserve of chromite, total amounts of PGE included within placer chromite grains are estimated to be 17 kg in the northern Hokkaido, and 245 kg in the central Hokkaido.
