Sr and Nd isotopic compositions of late Paleozoic Youngju and Andong granites in the northeastern Yeongnam Massif, Korea.

Mesozoic episodic magmatism in South Korea and its tectonic implication

“…Sphenes from the hornblende biotite granite have concordant U‐Pb ages: a 206 Pb*/ 238 U age of 169.4 ± 1.6 Ma and a 207 Pb*/ 235 U age of 168.3 ± 4.3 Ma. Lee et al [1999] reported a Rb‐Sr whole rock age of 267 ± 27 Ma for the batholith, which is much older than our U‐Pb sphene ages. The Rb‐Sr whole rock age may suffer the same problem as in the Andong batholith.…”

“…Sphenes from the hornblende biotite granodiorite have slightly discordant U-Pb ages that agree within error: a 206 Pb*/ 238 U age of 185.0 ± 1.7 Ma and a 207 Pb*/ 235 U age of 188.5 ± 5.7 Ma. Lee et al [1999] reported a Rb-Sr whole rock age of 361 ± 41 Ma for the Andong batholith, which is much older than our U-Pb sphene age. A close inspection of the original data of indicates that the total variation of seven 87 Rb/ 86 Sr data is very narrow (0.1 -0.9) and five out of seven data cluster within 0.1 -0.15, suggesting that Rb-Sr system of the Andong granite can be easily affected by contamination of country rocks with high Rb/Sr and 87 Sr/ 86 Sr ratios.…”

“…A close inspection of the original data of indicates that the total variation of seven 87 Rb/ 86 Sr data is very narrow (0.1 -0.9) and five out of seven data cluster within 0.1 -0.15, suggesting that Rb-Sr system of the Andong granite can be easily affected by contamination of country rocks with high Rb/Sr and 87 Sr/ 86 Sr ratios. Therefore we think the whole rock age of Lee et al [1999] [1995] reported a Rb-Sr whole rock age of 341 ± 105 Ma for the granite, which is much older than our U-Pb sphene ages. Field observations indicate that the Jeomchon granite intruded the Carboniferous sedimentary rocks (the Pyeongan Supergroup) and is nonconformably overlain by the Triassic sedimentary rocks (the Daedong Supergroup) [Bak, 1974;Choi et al, 1993;Hwang, 1998].…”

“…A close inspection of the original data of Lee et al [1999] indicates that the total variation of seven 87 Rb/ 86 Sr data is very narrow (0.1–0.9) and five out of seven data cluster within 0.1–0.15, suggesting that Rb‐Sr system of the Andong granite can be easily affected by contamination of country rocks with high Rb/Sr and 87 Sr/ 86 Sr ratios. Therefore we think the whole rock age of Lee et al [1999] is a fictitious one.…”

Sr Isotopic Composition of Apatite from the Yeongju and Andong Granites: Isotopic Distinction between the Two Granites and Location of the Boundary

“…영주화강암과 안동화강암은 영남육괴의 북동부지역 에 위치한 비교적 큰 규모의 저반이며, 생성시기 Sagong et al, 2005;Park et al, 2006;Yoon et al, 2014), 마그마의 생성환경과 분 화 (Lee and Lee, 1991;Jwa, 1997;Lee et al, 1998Lee et al, , 1999Hwang et al, 1999Hwang et al, , 2000Hwang et al, , 2002aHwang et al, , 2002b, 그리고 정치 깊이 (Cho and Kwon, 1994;Hong, 2001) 등에 대해 여러 연구가 수행되어 왔다. 각섬석 지압계를 이용한 연구결과에 따르면 영주화강 암과 안동 화강암은 남한에 분포하는 현생 화강암체 들 중에서 가장 깊은 정치압력(각각 7.9 kb, 7.5 kb)을 보이며 (Hong, 2001), 두 암체의 사이에 대규모의 전 단대가 지나가고 있다.…”