Geochemistry and zircon U-Pb-Hf isotopic analysis of the Paleoproterozoic granitoids (ca. 1997–1967 Ma) in the northeastern Yeongnam Massif, central-eastern Korean Peninsula: Geological significance and metallogenic potential

Abstract

Paleoproterozoic granitoids of the Buncheon and Hongjesa suites, distributed in the central–eastern Korean Peninsula, were investigated to constrain their petrogenesis, tectonic setting, and metallogenic potential. The Buncheon granitoids exhibit porphyritic textures, whereas the Hongjesa granitoids are equigranular; both are composed mainly of alkali feldspar, plagioclase, microcline, quartz, biotite, and muscovite, with minor opaque minerals. Zircon U–Pb dating indicates that the Hongjesa granitoids crystallized earlier (ca. 1997–1971 Ma) than the Buncheon granitoids (ca. 1980–1967 Ma), implying temporally distinct magmatic pulses during the Early Orosirian. Whole-rock and zircon Lu–Hf isotopic compositions suggest derivation from reworked ancient continental crust within a subduction-related arc setting. These findings are consistent with previously documented Early Orosirian arc magmatism in the Korean Peninsula and coeval arc activity in the Japanese Islands, indicating that a magmatic arc belt developed across southeastern Northeast Asia during this period. Notably, the Orosirian arc magmatism in the southeastern part of the Korean Peninsula differs from the Orosirian orogeny-related magmatism in the eastern North China Craton suggesting that the southeastern part of the Korean Peninsula might be separated crustal units from the eastern North China Craton. While some samples exhibit elevated fluorine concentrations and moderate to strong magmatic differentiation, most granitoids display geochemical features characteristic of barren arc-related intrusions, suggesting limited metallogenic potential.