The Late Permian to Triassic Hongseong-Odesan Collision Belt in South Korea, and Its Tectonic Correlation with China and Japan

Abstract

We propose a new correlation of Middle Triassic (ca. 230 Ma) eclogites from the Hongseong area of the southwest Gyeonggi Massif, South Korea, with the Dabie-Sulu collision belt of China. Late Permian (ca. 257 Ma) mangerites that intrude the Odesan area in the eastern part of the Gyeonggi Massif show geochemical characteristics of collisional tectonic settings, implying that the Hongseong collision belt extends to the Odesan area. In the Higo terrain of southernmost Japan, sapphirine-bearing granulites and related high-temperature metamorphic rocks reveal ca. 245 Ma ultrahigh-temperature (UHT) metamorphic conditions. This metamorphism is well matched with the 245 ± 10 Ma UHT metamorphism estimated for spinel granulite in the Odesan area, suggesting that the Dabie-Sulu collision zone continues through the Hongseong-Odesan belt into the Higo area and that Paleozoic subduction complexes in southwest Japan represent an eastern extension of the Dabie-Sulu collision belt. The Paleozoic subduction complexes in Japan continue further to the Yanji belt, a Carboniferous and Permian subduction complex along the northeastern boundary of the North China block. These data indicate that Phanerozoic subduction along the margin of the North China block and the collision between the North and South China blocks contributed to formation of the Dabie-Sulu-Hongseong-Odesan-Higo-Yanji belt. P-T estimations reveal that there was a decrease in geothermal gradients and an increase of exhumation rates from east to west along the belt during collision. These gradients resulted in preservation of UHT metamorphism in the Odesan area in Korea and the Higo area in Japan, high-pressure (HP) metamorphism in the Hongseong belt, and ultra high-pressure (UHP) metamorphism in the Dabie-Sulu belt.