Zircon U-Pb age and geochemistry of the Chuncheon granite in the north central Gyeonggi massif, Korea

초록

The Chuncheon granite in the north central Gyeonggi massif consists of white porphyritic biotite granite containing white alkali feldspar and quartz phenocrysts, and pink porphyritic biotite granite with pink alkali feldspars phenocryst. White porphyritic biotite granite and pink porphyritic biotite granite have 183.8 +/- 0.8 Ma and 167.5 +/- 0.3 Ma zircon U-Pb age, respectively. Whole-rock zircon saturation thermometer indicates that white porphyritic biotite granite and pink porphyritic biotite granite of the Chuncheon granite formed at ca. 788.9 degrees C (mean value) and 810.7 degrees C(mean value), respectively. Two lithologies show similar geochemical characteristics, which indicates that both white porphyritic biotite granite and pink porphyritic biotite granite formed from peraluminous magma originated from graywacke or S-type granitoid protolith with residual plagioclase via similar degree of partial melting through distinct melting events. The enriched values of large ion lithophile elements of Cs, Rb, Ba, and negative trough of Ta, Nb, P, Ti on the spider diagram suggest that the Chuncheon granite formed in subduction tectonic environment. There were continuous magma activities from 185 Ma to 167 Ma in the Chuncheon-Hwacheon area in the north-central Gyeonggi massif, Korea.

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