한반도의 117-84 Ma 염기성 및 중성 화성암류의 높은 Ti/V 비율과 Zr 함량은 이들이 판내부 환경에서 형성되었음을 지시하며 한반도의 117-84 Ma 산성 화성암류는 I 혹은 A2 화강암 유형의 성분을 보여준다. 이러한 미량원소 특징은 북중국판과 남중국판의 백악기 화성암류의 미량원소 특징과 매우 유사하며 이는 한반도의 117-84 Ma 백악기 화성암류가 북중국판과 남중국판의 백악기 화성암류와 같이 고태평양판의 후퇴작용에 기인한 인장력에 의해 발생하였을 것으로 생각된다. 북동아시아에서 일어난 고태평양판의 후퇴작용에 의한 화성작용은 145-110 Ma에 북중국판 북동부에서 시작한 후 남동쪽으로 이동하여 117-84 Ma에는 한반도 지역에서 일어났다. 이에 반해 일본지역의 백악기 화성암류는 화산호 환경 하에서 형성되었으며 128 Ma부터 시작되었다. 이는 128 Ma에 고태평양판 섭입대가 태평양 방향으로 물러남에 따라 발생한 인장력에 의해 섭입 해양판이 한반도와 일본 사이에서 끊어진 후, 일본 하부로 섭입하는 해양판의 각도가 증가하면서 형성된 화산호 환경에서 화성활동이 일어났을 가능성을 지시한다. 이 후 약 66 Ma 경까지 일본 남서부에서 화산호 관련 화성활동의 연령은 북서쪽으로 가면서 젊어진다. 이는 해양판의 섭입각도의 감소에 의해 일어났을 것으로 생각되며 이러한 변화는 80 Ma 이후 경상분지를 포함한 한반도 남동부 경계 지역에서 섭입 관련된 화성작용을 일으켰을 가능성이 있다.

Jurassic dioritic to granitic igneous rocks extensively intrude into the southern Korean Peninsula, including the Yuseong area located at the boundary between the southern margin of the Gyeonggi Massif and the northern margin of the Okcheon Belt. In this study, the petrogenesis and sources of Jurassic igneous rocks in the Yuseong area were investigated. The U–Pb zircon age data from the Jurassic plutonic rocks in the Yuseong area give two igneous ages, ca. 178–177 Ma and 169–168 Ma, indicating that two stages of igneous activity occurred in the Yuseong area during the Jurassic. The geochemical characteristics of Jurassic diorites indicate that they originated from enriched mid-ocean ridge basalt (E-MORB; Nb/Yb = 5.63–7.27; Zr/Yb = 118–156). The enriched Th/Yb ratios (5.5–8.0) in the diorites imply that they experienced crustal contamination during magma ascent. The Jurassic granitoids in the Yuseong area are divided into I- and S-type granites. The Jurassic I-type granitoids may have formed via the partial melting of mafic rocks with mixtures of 10–40% pelite-derived melt, while the S-type granites originated from felsic pelite. The Jurassic diorites have low Nb/Th ratios with depletion of the Nb and Ta components, indicating that they formed in a volcanic arc tectonic environment. On the other hand, the Jurassic granitoids show two different tectonic environments: a volcanic arc, and a syncollisional environment. The granites with syncollisional character are S-type granites, and may give incorrect information about tectonic setting because of the changes in the trace elements of the S-type granite due to fractional crystallization. Early Jurassic (200–190 Ma) igneous rocks are distributed only in the southeastern Korean Peninsula, including the Yeongnam Massif; Jurassic igneous rocks formed at ca. 190–180 Ma occur mainly in the Okcheon Belt and southern Gyeonggi Massif, which includes the Yuseong area. Middle Jurassic igneous rocks widely intruded from the Okcheon Belt, through the Gyeonggi and Nangrim massifs in the Korean Peninsula, to the Liaoning area in the North China Craton at 180–160 Ma. This distribution pattern of the Jurassic granitoids suggests that flat subduction started after 180 Ma in Northeast Asia.

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.

Cretaceous volcanic and volcaniclastic rocks are sporadically distributed around the Ganghwa Strait in the Incheon-Gimpo area in the western Korean Peninsula. While their existence was documented by several public geological maps, these rock units have remained largely neglected in scientific research. To foster further research, the zircon U-Pb age and whole-rock geochemical analysis results on these Cretaceous volcanic rocks acquired during the recent geological mapping have been made publicly available through an open-access database. The Cretaceous rocks in the Incheon-Gimpo area, mostly found as isolated bodies forming small islands, exhibit diverse lithologies including tuff, dacite, andesite, and tuffaceous conglomerate-mudstone. Geochemical analyses reveal a predominance of calc-alkaline, dacitic compositions, with subordinate andesitic or rhyolitic rock bodies occurring locally in the marginal parts. Zircon U-Pb ages of tuff and dacite samples range from 112 to 108 Ma, corresponding to the Albian stage of the Cretaceous. In contrast, age dating results of a tuffaceous sandstone sample suggest post-108 Ma deposition, indicating that the several-hundred-meter-thick volcaniclastic successions in the middle part of the study area may represent late-stage basin-fill deposits, rather than syn-volcanic as previously interpreted. The tectonostratigraphic evolution of this area is presumed to be closely linked to the Cretaceous basins with contemporaneous volcanic activities, developed along the western Gyeonggi Massif, namely the Cheorwon, Tando-Namyang, and Cheonsuman Basins.