Abstract
The upper Permian Takatsuki Formation in the Ultra-Tamba Zone, presumed to be forearc basin sediments. The mode of occurrence and geochemistry of greenstones from the base part of the Takatsuki Formation were studied. These greenstones are composed of pillow basalt, pillow breccia and hyaloclastite. The mode of occurrence of greenstones which adhere to sandstone of the Takatsuki Formation in Kawakubo area surely indicates in-situ greenstones, as the "basaltic dike" intruded into the boundary between the greenstones and the unconsolidated terrigenous clastic sediments and in which hyaloclastite is intercalated with black shale. Geochemical features suggest that the greenstones are similar to mafic lava at a volcanic arc. We infer that the eruption of the greenstones resulted from igneous activity in the island-arc (volcanicarc) area.
