2018 Volume 69 Issue 1 Pages 47-79
Whole-rock major and trace geochemical analyses of igneous rocks and igneous-origin rocks from the 1:200,000, Hiroo Quadrangle and related area have been carried out to confirm geotectonic attribution and correlation. Studied samples are; 1) Okutokachi Amphibolite, 2) Rekifune Volcanic Rocks, 3) dolerite dike in the Okawa Formation (Middle Miocene), 4) greenstone in the Toyokoro area (originated from Nikoro Group, Tokoro Belt), 5) granitic gravels in the Toyonigawa Formation (Middle Late Miocene), 6) Nupinai Granite in the Hidaka Metamorphic Belt, 7) mafic volcanic gravels in the Nakanogawa Group, Hidaka Belt (Paleocene–Eocene), 8) greenstone from the Daimaruyama Greenstone body in the Nakanogawa Group, 9) granitic gravel in the Erimo Formation (Utaro Conglomerate: Late Oligocene), and 10) acidic tuff in the Sakashita Formation, Nakanogawa Group, Hidaka Belt. Obtained data are important as the scientific bases of the 1:200,000, Hiroo Quadrangle (2nd edition), and valuable information for future researches. Based on the analytical results, geotectonic attribution, origin and tectonics of the studied samples are preliminary discussed.
