Petrological study on upper mantle xenoliths from Asan and Pyeongtaek area

Geochemical characteristics of spinel peridotite xenoliths, enclosed in Miocene volcanic rocks from Asan and Pyeongtaek, area, Korea, provide important clues for understanding the lithosphere composition, equilibrium temperature and pressure conditions, and depletion and enrichment processes of subcontinental lithospheric mantle beneath Asan and Pyeongtaek area. The spinel peridotite xenoliths with protogranular textures were accidentally trapped by the ascending magma. The spinel peridotite xenoliths from both areas originate from depths between 56 and 74 km, determined by heat flow data, O'Neill (1981) geobarometer, and Brey and Kohler (1990) geothermometer. The ranges of equilibrium temperature obtained from the investigated materials are about 987 1164 degrees C for Asan spinel peridotites and 937 1045 degrees C for Pyeongtaek spinel peridotites. Modeling using HREEs indicates that the mantle xenoliths from Asan and Pyeongtaek have been undergone 1 5% and 1 similar to 10% fractional melting, respectively. The LREE-enriched characteristics of the analyzed samples are considered to have been attributed to cryptic metasomatism. Sr and Nd isotope compositions of subcontinental lithospheric mantle beneath both areas are similar to those beneath East China and South Korea (Cheju Island and Boeun) rather than Japanese Island Arc.