K-Ar dating on granitic rocks from the Eonyang- and the northwestern part of Ulsan-quardrangle, Kyeongsang-nam-do, Korea

한국(韓國) 경상남도(慶尙南道) 언양도폭(彦陽圖幅) 및 북서부(北西部) 울산도폭(蔚山圖幅) 지역산(地域産) 화강암질암(花崗岩質岩)의 K-Ar 연대(年代)

The K-Ar age determined on six granitic rocks samples from the Eonyang- and the northwestern part of Ulsan-quardrangle, Kyeongsang-nam-do, Korea, ranges from $87{\times}10^6$ years to $58{\times}10^6$ years. Three of the samples belong to the upper Cretaceous ($87{\times}10^6-71{\times}10^6years$) and three to the late Cretaceous-early Tertiary ($63{\times}10^6-58{\times}10^6years$) in age. The early Tertiary ages are measured first on the "Younger Granites" in Korea. These two emplacement periods of granitic rocks are representative that the former is correlated to north Kyushu-Seto Inland belt ($95{\times}10^6-75{\times}10^6years$) and the later to Sanin-central Honshu belt ($65{\times}10^6-50{\times}10^6years$), in southwestern Japan.