Rb/Sr Age of Leucogranitic Rocks in the Samcheog Area

삼척지역(三陟地域)에 분포(分布)하는 우백질화강암류(優白質花崗巖類)의 Rb/Sr 연령(年齡)에 관(關)한 연구(硏究)

The purpose of this study is to clarify geological age of leucogranitic rocks in the Samcheog area. Petrographical and geochronological features of leucogranitic rock are as follows; (1) These rocks in the area can be classified into two rock types: Moogho leucogranite gneiss and Yimwon leucogranite. (2) These rocks intruded into Precambrian metasediments and are overlain by Paleozoic sedimentary rocks. (3) These rocks are distinctly showing slight foliation and containing garnet and sillimanite which produced by assimilation and contamination. (4) Rb/Sr whole rock age of these rocks indicates an isochron of $2088{\pm}8.5$ m.y. with the initial $^{87}Sr/^{86}Sr$ ratio of $0.7108{\pm}0.0007$.