空知-エゾ帯の"未分離日高累層群"から高圧変成鉱物の発見

抄録

High P/T metamorphic minerals are found from a Late Cretaceous accretionary complex (Ganpi-yama Complex) separately occurring within a serpentinite mass in the Kamuikotan Zone of the Sorachi-Yezo Belt, Hokkaido. The complex was previously referred to as the "undivided Hidaka Supergroup". The Yon-no-sawa Unit, a major member of the complex, is composed of deformed alternation of siliciclastic sandstone and mudstone, greenstones and chert. Sodic pyroxenes coexisting with quartz are found from greenstone, and metamorphic aragonite from sandstone and greenstone. The finding of these high P/T metamorphic minerals suggests that the Ganpi-yama Complex has, at least, a metamorphic affinity to the Kamuikotan Zone. An exact tectonostratigraphic correlation of the complex, however, is still open to the argument.