Tectonic and sedimentary evolution of the Korean peninsula: a review and new view

This review focuses on the tectonics and sedimentation of major sedimentary basins and orogenic belts (Late Proterozoic–Neogene) in the Korean peninsula. The Korean peninsula is part of the Amuria Plate and represents an important link between continental blocks of North and South China and the island arcs of Japan. The basement rocks, exposed in the Kyonggi and Yongnam massifs, consist of 2.7 to 1.1 Ga high-grade gneiss and schist. These massifs are separated by the Okchon Fold Belt which comprises metasedimentary rocks and bimodal meta-volcanic rocks. The stratigraphy of the Okchon Group is unclear at present. The Okchon Basin was probably initiated as an intraplate rift prior to the Late Proterozoic. The Hwanggangri Formation (clast-bearing phyllite) most likely represents deposition by subaqueous debris flows in slope environments of an enclosed basin. The stratigraphic relationship between the Okchon Group and the Choson Supergroup (Cambro-Ordovician) of the Taebaeksan Basin is poorly constrained. The Choson Supergroup unconformably overlies the Yongnam Massif and consists mainly of carbonate sequence that formed mostly in shallow marine and tidal environments, reflecting numerous sea-level fluctuations. The sequence is disconformably overlain by siliciclastic sequence of Pyongan Supergroup (Carboniferous–?Triassic) which formed most likely in shallow marine, deltaic, and fluvial environments. The Imjingang Belt is an east-trending fold and thrust zone and consists of metasedimentary rocks and volcaniclastics (Devonian–Carboniferous), underlain unconformably by Proterozoic basement rocks. Late Proterozoic amphibolites of oceanic affinity were metamorphosed at about 8–13 kbar and 630–740°C during the late Permian to the early Triassic. The south-vergent contraction and top-down-to-the-north normal faulting are suggestive of a suture belt between the North China Block (Sino-Korea Craton) and the South China Block (Yangtze Craton), an extension of Sulu Belt across the Yellow Sea. Entire peninsula experienced strong deformation and metamorphism during the suturing event, namely Songrim orogeny. During this orogenic event, the Kyonggi Massif (and the Okchon Basin) accreted to the Yongnam Massif (and Taebaeksan Basin) along the South Korean Tectonic Line running northeast–southwest. A series of northward-trending thrust formed along the boundary zone to the east (Kaktong and Kongsuwon thrusts and others). Piggyback basins locally developed along the thrust