Cretaceous to Early Tertiary Granites and Magma Mixing in South Korea : Their Spatio-temporal Variations and Tectonic Implications (Multiple Slab Window Model)

Based on the petrologic and age data of the Cretaceous to early Tertiary granites in south Korea, we propose a new tectonic model reflecting their temporal and spatial variations. A number of petrographic and geochemical studies on the granites suggest that they originated from the magma formed by subduction of oceanic crust in continental margin and were emplaced in epizone. The MMEs with various shapes and sizes, which were produced due to the magma mixing caused by the injection of mafic magma from mantle during the crystallization of the granitic magma, are observed in the granites. The distributions of the MMEs and ages of the granites show a distinctive spatio-temporal distribution pattern. The distribution pattern can be explained by a multiple slab window model related to the ridge subduction of Izanagi-Pacific plates during the Late Cretaceous.