Upper Permian paleoclimate of the Sino-Korean block: an example from the Gohan Formation (Korea) in the eastern margin and a synthesis

Abstract

The Upper Permian Gohan Formation, a terrestrial stratum deposited in the foreland basin in central eastern Korea, provides information on the provenance, tectonic setting, and paleoclimatic conditions of the eastern margin of the Sino-Korean block (SKB) composed of the North China craton and the Korean Peninsula. Geochemical composition of Gohan mudrocks suggests that the source rocks consisted of a mixture of intermediate−mafic igneous rocks and some sedimentary rocks. The source terrain was situated in an Andean-type active continental margin setting. In the clay mineral composition, kaolinite predominates in the lower section, illite in the middle, and illite and chlorite in the upper section. Such upsection changes are consistent with the upward decrease of chemical weathering index, which indicates that the climatic conditions of Late Permian time changed from hot and humid to semi-arid, and to arid conditions with time, due to progressive increasing altitude of the coastal mountain range. The synthesis of paleoclimatic conditions in the Upper Permian SKB indicates that a dry climate prevailed over the entire SKB. The cause of the dry climate is interpreted as orographic effect due to the high topography formed by collision tectonics in the northern margin and subduction tectonics in the eastern margin.