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Evidences of the presence of old continental basement in Cheju volcanic Island, South Korea, revealed by radiometric ages and Nd-Sr isotopes of granitic rocks

Title
Evidences of the presence of old continental basement in Cheju volcanic Island, South Korea, revealed by radiometric ages and Nd-Sr isotopes of granitic rocks
Authors
Kim K.H.Tanaka T.Suzuki K.Nagao K.Park E.J.
Ewha Authors
김규한
SCOPUS Author ID
김규한scopusscopus
Issue Date
2002
Journal Title
Geochemical Journal
ISSN
0016-7002JCR Link
Citation
vol. 36, no. 5, pp. 421 - 441
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
Major and trace element and Nd-Sr isotopic data are presented on the granitic rocks known as a basement in the Cheju volcanic island, together with CHIME age data on prophyritic hornblende-biotite granite xenolith from the Byeoldobong area. The CHIME ages from zircon and allanite grains of porphyritic hornblende-biotite granite were determined to be 169 ± 29 Ma and 183 ± 40 Ma, respectively, which are corresponding to a Jurassic age. It is concordant with a K-Ar age of 172.4 ± 5.2 Ma of a biotite granite in the same area, which is comparable to the Daebo granite in the Korean peninsula. Granitic xenoliths from the Byeoldobong area have Nd-Sr isotopic compositions (initial ratio (143Nd/ 144Nd)i = 0.51156∼0.51158, εNd = -19∼-14 and (87Sr/86Sr)i = 0.7156∼0.7164, εSr = 101∼179) which are close to those of Jurassic Daebo granite (εNd = -21∼-14, εSr = 104∼171). On the other hand, the micrographic granite from the drilling core in the Hadeokcheon area gives initial ratio (143Nd/144Nd)i = 0.51218 and (87Sr/86Sr)i = 0.7077), which are comparable to the Cretaceous Bulguksa granite ranging from 0.51184 to 0.51268 in 143Nd/144Nd and 0.7055 to 0.7167 in 87Sr/86Sr. The TNd DM model ages of 1.0 to 1.7 Ga from the Mesozoic granitic plutons in the Cheju island suggest that the source materials of the plutons in the island have evolved since mid-Proterozoic time as those of the peninsula. In combination with the basement geology and petrochemistry, Nd-Sr isotopes, and radiometric and model ages of granitic rocks, our results imply that the Okchon zone is continuously extended to the Cheju volcanic Island of the southeastern end of the continental margin of the Eurasian plate.
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사범대학 > 과학교육과 > Journal papers
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