CHARACTERISTICS OF BAORILAJINWULA RIEBECKITE GRANITE IN INNER MONGOLIA

The Baorilajinwola riebeckite granite body, located in the eastern flank of the middle section of Daxing'an Mountains, was formed in the late stage of Early Cretaceous or later. The rock body contains rich SiO₂ (71.63%-77.35%) and alkaline minerals (ALK=4.94%-9.17%), with poor Al, Mg and Ca. The total amount of rare earth elements (∑REE) in the riebeckite granite body is high. In the rock body, the ∑REE of riebeckite moyite is 271.77×10^-6-701.77×10^-6, and the ∑REE of monzonitic granite is 2938×10^-6-6933.2×10^-6. The ratio of LREE/HREE is from 1.63 to 7.49 (mostly between 2 and 5). The REE pattern diagram shows V-shaped curves inclining to the right, suggesting that the fractionation between LREE and HREE is not ideal. The δEu is quite low (0.016-0.035), showing an evident negative Eu anomaly. The riebeckite granite in the region is formed in anorogenic setting, which is located inside the plate and relatively steady.