The Korean Peninsula mainly comprises the Paleoproterozoic Gwanmo, Nangnim, Gyeonggi, and Yeongnam massifs from north to south. The Paleoproterozoic basement is rarely exposed in the Paleozoic Taebaeksan basin, which is located in the northeastern part of the Okcheon belt between the Gyeonggi and Yeongnam massifs. One of the most important issues in the tectonic interpretation of the Korean Peninsula is whether Paleoproterozoic rocks in the Taebaeksan basin have an affinity with those in the Gyeonggi or Yeongnam massifs. To solve this problem, we focused on the petrogenesis of the Imgye gabbroic diorite, Jungbongsan granite, and Jangsan quartzite in the Imgye area of the Taebaeksan basin. The Imgye gabbroic diorite shows mafic to intermediate compositions with slightly enriched LREEs compared to HREEs, slightly positive Rb, K, and Pb anomalies, and negative Ta, Nb, and P anomalies. The Imgye gabbroic diorite formed in a volcanic arc tectonic setting. The geochemical compositions of the Jungbongsan granite show enriched LREEs compared to HREEs with negative Eu anomalies, and reveal strong positive Rb, Th, K, and Pb anomalies with negative Ba, Ta, Nb, Sr, P, Eu, and Ti anomalies. This Jungbongsan granite also formed in an arc tectonic setting like the Imgye gabbroic diorite. LA-ICP-MS zircon age dating of the Imgye gabbroic diorite gives an intrusion age of 1948 ± 21 Ma, whereas SHRIMP U–Pb zircon age dating on the Jungbongsan granite yields an emplacement age of 1873 ± 14 Ma. The ε_Hf(t) values of the Imgye gabbroic diorite are from 3.5 to 9.7, whereas those of the Jungbongsan granite are from −2.9 to 0.6. These data imply that the Imgye gabbroic diorite formed from a depleted mantle in the arc tectonic environment, whereas the Jungbongsan granite formed by reworking pre-existing crust material in the arc environment. The detrital zircons in the Jangsan quartzite show ages ranging from 3.06 to 1.85 Ga, with a peak concentration of ca. 2.5 Ga. Previous studies have suggested that the northern Gyeonggi and Nangnim massifs underwent collision-related magmatism and metamorphism at ca. 1.93–1.90 Ga, and then post-collisional magmatism and metamorphism at ca. 1.89–1.83 Ga, whereas the southern Gyeonggi massif underwent subduction-related magmatism and metamorphism at ca. 1.94–1.92 Ga, and then post-collision-related magmatism and metamorphism at ca. 1.84–1.78 Ga. By contrast, subduction-related events were recognized in the northern Yeongnam massif at ca 2.02–1.96 Ga and 1.90–1.85 Ga. This work, combined with the previous studies, suggests that the Paleoproterozoic basement in the Imgye area of the Taebaeksan basin can be correlated with the Paleoproterozoic basement of the northern Yeongnam massif rather than with those of the Nangnim and Gyeonggi massifs.

영남육괴 서부 광주광역시-장성군과 화순-보성군일대에 분포하는 고원생대 다이아텍사이트 혼성암에 대한 저어콘 U-Pb 연령측정을 토대로 영남육괴 고원생대 퇴적기원 변성암 모암의 퇴적시기에 대해 검토하였다. 광주광역시-장성군 일대에 분포하는 다이아텍사이트 혼성암의 저어콘 상속핵 연령은 약 2478 Ma의 연령 피크가 두드러지며 퇴적시기 상한은 약 2085 Ma로 추정된다. 이와 달리 화순-보성군 일대에 분포하는 다이아텍사이트 혼성암에서는 약 2506 Ma, 2338 Ma, 2205 Ma, 1985 Ma, 1945 Ma의 다양한 저어콘 상속핵 연령 피크가 나타나며 퇴적시기 상한은 약 1971 Ma로 추정된다. 두 지역 모두에서 퇴적시기 하한은 저어콘 외연부가 지시하는 변성연대를 토대로 1880 Ma 내외로 제한된다. 광주광역시-장성군지역에 분포하는 다이아텍사이트 혼성암의 모암은 퇴적시기와 저어콘 연령 특성이 율리층군, 원남층군 등 영남육괴 동부에 분포하는 고원생대 지층들과 유사하며 서로 대비될 가능성이 있다. 반면 화순-보성군 일대에 분포하는 다이아텍사이트 혼성암 모암의 퇴적시기는 영남육괴 동부에 분포하는 고원생대 지층들보다 후기에 해당하며 저어콘 연령 특성 역시 구별된다. 이는 영남육괴 서부 일부 지역에 기존에 논의되지 않았던 새로운 고원생대 지층의 분포 가능성을 의미한다.

The Gyeonggi Massif is one of the major Precambrian basements in the Korean Peninsula where Paleoproterozoic orthogneiss and paragneiss were widely exposed. In this study, newly identified Rhyacian to Orosirian meta‐igneous rocks from the northwestern Gyeonggi Massif (Soyeonpyeongdo and Ganghwado areas) were investigated to elucidate their petrogenesis and tectonic implications based on zircon U–Pb–Hf isotopic data and whole‐rock geochemistry. The garnet‐bearing amphibole granite gneiss and biotite granite gneiss in the Soyeonpyeongdo area emplaced at ca. 2.06 Ga and 1.88 Ga, respectively, whereas the tonalite gneiss in the Ganghwado area formed at ca. 1.93 Ga. The 2.06 Ga garnet‐amphibole granite gneiss shows both I‐type and A ₂ ‐type features enriched in LILE and depleted in Nb–Ta, indicating generation in an arc‐related extensional regime. The 1.93 Ga tonalitic gneiss exhibits adakitic characteristics, negative εHf(t) values (−8.2 to −4.9), and thickened crustal signatures (42–74 km), which are consistent with derivation from Archean mafic lower crust thickened during a regional syn‐collisional stage. The 1.88 Ga biotite granite gneiss displays metaluminous to weakly peraluminous I‐ and A2‐type features with slightly negative εHf(t) values (−1.7 to +0.6), implying formation in a post‐collisional extensional setting. These successive magmatic events (2.06–1.85 Ga) in the Gyeonggi Massif are temporally and geochemically comparable to the Rhyacian–Orosirian magmatism in the Liao–Ji Belt of the eastern North China Craton. Therefore, the northwestern Gyeonggi Massif recorded a Paleoproterozoic tectono‐magmatic evolution broadly comparable to that of the Liao–Ji Belt.