Geochemistry of REEs and reconstruction of structural formula of Baba-Nazar garnet index, Takab, W.Azarbayedjan, Iran

The Baba-Nazar garnet deposit mineralized in hornfelsic body is located 80 km of NE of Takab town, Western- Azarbayedjan province. Ten samples from coarse-grained garnets of various colors were selected for major elements analysis by XRF and nine of these samples were analyzed for trace elements by ICP-OES. The presence of hornfels and carbonates in the contact with Doran granite intrusion indicates a skarn contact metamorphism garnet deposit in the area. Garnet crystals of 1-2 cm size are observed in anhedral to subhedral form of mainly deep green color. They show isotropic and high relief features in polarized light associated with abundant fractures. Major element analysis indicates that the Baba-Nazar Garnet consists of andradite-grossularite groups but in three samples the pyrope content is exceptionally higher than that of the grossular. The presence of grossular and andradite is revealed by XRD analysis. All the garnet minerals with different colors indicate enrichment of Zr, U, Y, Ti and V and depletion of Ba, Hf, Nb, Ta, Sc, Co and Th. REE's elements normalized to chondrites, in garnet with various colors garnet indicate enrichment of LREE's compared to HREE's and weak positive europium and positive cerium anomaly.