시료의 6개 점 분석 자료로부터 얻은 저어콘의 2 0 6 Pb/ 2 3 8 U 가중평균 연령은 170±2 Ma (2σ, MSWD=2.2)이다. 이 연령은 "화강암 거력"이 쥬라기 화강암의 일부이며, 빙하기원이 아님을 말해준다. Abstract: A "granite boulder", ~70 cm in size, was reported from the Geumgang Limestone, and has been considered as a glaciogenic dropstone. Since this interpretation has enormous implications for unraveling the evolution history of the Ogcheon Metamorphic Belt, we re-examined the contact relationship and structure of the "granite boulder", and estimated its emplacement

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... age based upon SHRIMP U-Pb zircon dating. The weighted mean 2 0 6 Pb/ 2 3 8 U age pooled from 6 spot analyses of two specimens is 170±2 Ma (2σ, MSWD=2.2). This zircon age suggests that the "granite boulder" in the Geumgang Limestone is a part of Jurassic granite, rather than a glaciogenic dropstone.