Review of the Mesozoic Iron Mineralization in South Korea. Journal of the Geological Society of Korea

In the Korean Peninsula, the Yangyang, Hongcheon, and Pocheon iron deposits have been considered as metasediment origin deposits formed during Precambrian. However, recently, Yangyang iron deposit was confirmed as an iron oxide-apatite (IOA)-type deposit formed at 216-212 Ma by hydrothermal fluid injection with brecciation along the ductile shear zone after the intrusion of syenite in post-collisional tectonic setting during Triassic (about 233-226 Ma). And, the Hongcheon Fe-REEs deposit and the Chuncheon Yonghwa Fe-Nb deposit were reported as igneous origin related to carbonatite. The mineralization ages of Hongcheon carbonatite and Yonghwa phoscorite-carbonatite complex were reported as 233-227 Ma and 195-193 Ma, respectively. The Pocheon iron deposit was interpreted as a skarn-type deposit of Ca, Mg, and Na-Ca types, which were developed by hydrothermal metasomatism of limestone and dolomite. Iron ore mostly occurred whitin Na-Ca and Mg skarns, and was locally overlapped with the copper mineralization during retrograde skarn stage. During the last stage of deformation around the mine, strike fault movement occurred, and the Myeongseongsan granite (about 112 Ma) injected along the fault causing iron mineralization. In the late Paleozoic/early Mesozoic Hongseong to Yangyang collision belt of the Gyeonggi Massif, Triassic (ca. 230 Ma) mangerite/symite formed from the magma generated from the mantle/lower crust during post-collisional stage. Subsequently, a unique mineralization fluid which contained a large amount of Fe-P components along with alkali components, induced IOA-type mineralization along with Na-Ca-K alterations. The Yangyang iron mineralization and Hongcheon-Yonghwa carbonatite mineralization are the first identified Triassic mineralizations in the Korean Peninsula and were related to mantle origin alkaline magma which can be induced in a typical post-collisional stage igneous activity after continental collision.