Petrographic Study on Mylonitic Granite in the Unbong-Ayoung Area

운봉(雲峰)-아영(阿英) 지역(地域)에서 나타나는 압쇄상화강암(壓碎狀花崗岩)에 대(對)한 암석기재학적(岩石記載學的) 연구(硏究)

The characteristic features of mylonitic granite in the Unbong-Ayoung area is as follow; (1) Mylonitic granite is a shearing product from porphyritic granite of Namweon Granites. (2) This rock megascopically shows foliated texture, and their modal compositions according to classification of dynamically metamorphosed rock are correspond to blastomylonite. (3) This rock generated by dextral strike slip movement at deep level. (4) The geochronological data of hornblendes from this rock undertaken by $^{40}Ar/^{89}Ar$ method are 191Ma to 195Ma. (5) The geochronological data of this rock suggests that Namweon Granites might be a product of intrusion and crystallization at the late Triassic or the Jurassic.