The Gwangcheon intrusive rocks occur in the Hongseong collision belt of South Korea, which is thought to represent the eastern extension of the Dabie-Sulu collision zone of China. The central part of the Gwangcheon intrusive complex consists of orthopyroxene-bearing monzonite (mangerite), and the marginal part is composed of syenite. North of the Gwangcheon mangerite, the post-collisional (233±2Ma) Haemi biotite granite contains syenite enclaves. SHRIMP U-Pb zircon analysis yields ages of 232±3Ma for the mangerite and 230±3Ma for a syenite enclave within the Haemi biotite granite. The mangerite-syenite complex and syenite enclaves exhibit a shoshonitic affinity, with a total alkalinity (Na2O+K2O) of 7.38-9.64wt.%, high K2O, Mg#, Ba, Sr, Cr, Ni, and LREE contents, and insignificant negative Eu anomalies. Geochemical data indicate that the mangerite-syenite intrusion and the syenite enclaves are post-collisional igneous rocks formed by the partial melting of an enriched lithospheric mantle. The heat for this melting was derived from asthenospheric upwelling following oceanic slab break-off. The SHRIMP age data suggest that both the Gwangcheon intrusives and the syenite enclaves formed after the Triassic continental collision of the North and South China blocks in Korea.
|Number of pages||18|
|Publication status||Published - 2010|
- Post-collisional magmatism
- Shoshonitic affinity
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