Zircon U-Pb Age of Monzonite Granite from Abag Banner in Inner Mongolia and Its Tectonic Significance

Through detailed field investigation and test analysis, it's found that the granite in Hazhanhua area, north of Abag Banner in Inner Mongolia has the geochemical characteristics of high silicon, aluminum and alkali, but poor calcium and magnesium. It has low content of total rare earth, with relative enrichment of light rare earth and loss of heavy rare earth elements, as well as a moderate negative Eu anomaly. It riches in Rb, Th, U and othter large ion lithophile elements, but it is strongly loss in high field strength elements, such as Nb, P and Ti. The high Sr content and low Rb/Sr ratio show that the magma was sourced from strong enrichment mantle, which was formed in volcanic arc environment, displaying the characteristics of TTG rock series. The LA-ICP-MS zircon U-Pb dating shows that this monzonite granite was emplaced in Late Devonian, with an age of (367.5+1.9) Ma.