Tectonic elements with South China affinity in the Korean Peninsula: New Early Jurassic palaeomagnetic data

Early Jurassic sandstones and shales were collected at 14 sites from the Kimpo area in the western part of the Korean Peninsula for a palaeomagnetic study. A characteristic remanent magnetization component, which passes the fold test, was isolated from seven sites. This characteristic component is interpreted to be of primary Early Jurassic origin because the folding age is Middle-Late Jurassic. The primary directions, together with previously reported ones, provide a mean direction (D = 38.1°, I = 39.7°,α₉₅ = 3.8°, 11 sites) and a palaeomagnetic pole (54.1° N, 230.2° E, A₉₅ = 4.1°) for the Kimpo area. This palaeomagnetic pole shows good agreement with the coeval poles for the South China Block and is significantly removed from that for the North China Block, suggesting that the Kimpo area has been part of the South China Block since at least Early Jurassic times. The Kimpo area constitutes a part of the lmjingang Belt which is palaeontologically allocated to the South China Block in its origin, while all Precambrian tectonic blocks that compose the basement of the Korean Peninsula are interpreted to be of North China origin. We conclude that the Imjingang Belt, including the Kimpo area, is a tectonic extension of the South China Block on the Korean Peninsula. The South China elements were obducted onto the North China Block at the site of the present Korean Peninsula during the collision event of the North and South China Blocks, and hence the Korean Peninsula is composed of areas with both North and South China affinities.