A review of Permian to Jurassic magmatism along the Korean Peninsula and the Japanese Islands: Tectonic interpretations and a key for paleogeographic reconstructions

Abstract

Late Paleozoic to Mesozoic granitoids occur extensively in East Asia. In this article, previously reported zircon U-Pb age data from the Korean Peninsula and the Japanese Islands are reviewed to examine the tectonic correlation of Permian to Jurassic granitoids between the Korean Peninsula and the Japanese Islands. Permian to Jurassic granitoids are widespread in the Korean Peninsula. In contrast, they are scarce in most parts of the Japanese Islands except the Hida Belt, Southwest Japan. The spatiotemporal distribution of the Permian to Jurassic granitoids in the Korean Peninsula shows the following pattern: ca. 280-215 Ma arc granitoids are found in the Gyeongsang Basin and Yeongnam Massif in the southeastern Korean Peninsula and in the Tumangang Belt, Kwanmo Massif, and Machollyong Belt in the northeastern Korean Peninsula, while ca. 235-225 Ma post-collisional granitoids occur mainly in the Gyeonggi Massif, Imjingang Belt, and Nangrim Massif. The distribution of the Jurassic arc-related granitoids in the Korean Peninsula and the Japanese Islands indicates the migration of the magmatic front from the trench side (ca. 200-190 Ma) to the inner continental side (ca. 170-160 Ma) due to the shallowing subduction angle. This was most likely induced by the buoyancy caused by the subduction of oceanic plateaus in the Early Jurassic, which are recognized in the Jurassic accretionary complex in Japan. Wide occurrence of later stage Jurassic magmatism (ca. 180-160 Ma) on the continental side of the Korean Peninsula indicates flat subduction. The arc igneous activity in the Hida Belt has two major phases of ca. 260-230 Ma and ca. 200-180 Ma, indicating that the Hida Belt may have been located in the continental arc that developed along the eastern margin of the Korean Peninsula from the Permian to Jurassic and may be a missing part between the continental arcs that developed in the southeastern and northeastern parts of the Korean Peninsula.