Abstract
A mass of granite, which is covered unconformably by the Silurian-Devonian Yokokurayama Formation, is discovered in the Yokokurayama Lenticular Body of the Kurosegawa Tectonic Zone of Mt. Yokokura, Kochi Prefecture, and is named the Yokokurayama Granite. It is composed generally of medium-grained, hornblende-biotite granodiorite with some coarse-grained, pegmatitic varieties. It is characterized by 1) reddish potassium feldspar, 2) low grade of or almost devoid of mylonitization, and 3) zoned plagioclase. It is distinguished clearly from granites of the Mitaki Igneous Rocks. Many of the pebbles, grains and fragments of granite found in the Silurian sequence are identified with the granites of the Yokokurayama Granite.
