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http://dx.doi.org/10.7854/JPSK.2011.20.4.231

SHRIMP Age Datings and Volcanism Times of the Igneous Rocks in the Cheolwon Basin, Korea  

Hwang, Sang-Koo (Department of Earth and Environmental Science, Andong National University)
An, Yu-Mi (Department of Earth and Environmental Science, Andong National University)
Yi, Kee-Wook (Korea Basic Science Institute)
Publication Information
The Journal of the Petrological Society of Korea / v.20, no.4, 2011 , pp. 231-241 More about this Journal
Abstract
Cheolwon Group in the Cheolwon Basin, which lies northwest of the Gyeonggi massif, has been correlated to the Yucheon Group in the Gyeongsang Basin, but its ages and volcanic times are defined to be considerately earlier than the other one. In this study, SHRIMP zircon U-Pb ages were determined from the igneous rocks in the Cheolwon Basin. The mean ages from zircons are $115.0{\pm}1.1Ma$ in rhyolite, and $111.24{\pm}0.85Ma$ and $109.1{\pm}1.1Ma$ in granite porphyry. The minimum age is 113 Ma in the Jijangbong Tuff. Such age in the rhyolite define the intrusion time of ring dykes, suggesting a caldera collapse following eruption of the Dongmakgol Tuff. Such age in the Jijangbong Tuff represent latest volcanism as postcaldera in the basin. The volcanic rocks in the basin were erupted during late Aptian, and are correlated to the Sindong Group in the Gyeongsang Basin. The plutonism in the basin occurred during $111.24{\pm}0.85Ma{\sim}109.1{\pm}1.1Ma$, following the volcanism. The age distribution of the analyzed zircons in the Jijangbong Tuff indicates the presence of foreign zircons derived from protoliths, regarding a wide span of zircon ages from Cretaceous to Jurassic, Triassic, early and late Protozoic, and Archean. The Archean age suggests the possible presence of the Archean protoliths with such age, which have not been exposed on the surface. The age distribution with wide span suggests that its vent is located in an area that several strata with different ages piled up and intercepted with some intrusives.
Keywords
Cheolwon Group; SHRIMP U-Pb age; Rhyolite; Granite porphyry; Jijangbong Tuff; Foreign zircon;
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Times Cited By KSCI : 2  (Citation Analysis)
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