Characteristics and Genesis of Garnet from Loufan District, Shanxi Province

Garnets from Loufan district, Shanxi Province, are widely distributed through the layers——Lüliang group metamorphic rocks, which formed from metamorphism of mudstone and sandstone. In order to find out the interrelations between garnet and the metamorphic conditions, EPMA and the mineral assemblage geothermometry are adopted. The results show that from the north to the south of the research area, the amounts of CaO and MnO in garnets decrease, while that of FeO and MgO increase. This regular variation is controlled by the metamorphic conditions, especially the pressure, which can be explained by different cation radiuses in the octahedral coordination site of garnet lattice under different pressure.