Zircon U-Pb geochronology, geochemistry and mineralization significance of Hailiute highly fractionated granites in the Southern Da Hinggan Mountains.

There were multiple episodes of magmatism in the Southern Da Hinggan Mountains during the Late Jurassic to Early Cretaceous, and an in-depth study of the petrogenesis and evolutionary process is of great geological significance to reveal the Mesozoic geodynamic background and mineralization. In this paper, LA-ICP-MS zircon U-Pb dating and whole-rock geochemistry for medium-grained adamellite, fine-grained adamellite and granite peg-matite in Hailiute area were carried out. The zircon ²⁰⁶Pb/²³⁸U weighted average ages of the medium-grained adam-ellite, fine-grained adamellite and granite pegmatite are 142.0 ± 0.7 Ma, 141.2 ± 1.1 Ma and 139.7 ± 2.4 Ma respectively, belonging to the Early Cretaceous. They have high SiO₂ and total alkali contents, and their A/CNK value is 1.01 ~ 1.18, with an average value of 1.09, which is weak peraluminous. They are characterized by enrichment of large ion lithophile elements such as Rb, Th and K and depletion of high field strength elements including Ba, Sr, P and Ti, with extremely negative Eu anomalies (δEu = 0.012~0.040). The Zr+Nb+Ce+Y value of them is between 38. 25x10^-6 and 258. 2x10^-6, less than 350x10^-6. The zircon saturation temperature of them is 723X1 to 778X1. The primary muscovite and alkaline-mafic minerals Eire not found among them. The magma experienced the fractional crystallization of plagioclase and K-feldspar during its evolution. The Zr/Hf, La/Ta and La/Nb of them are lower than the range of normal granite, however Nb/Ta and Y/Ho of them are in the area of normal granite. The parameters of tetrad effect of rare earth element (TE_1,3) of them is between 1.18 and 1.34, greater than 1.1. In conclusion, the Hailiute granite belongs to early Cretaceous highly differentiated I-type granite. It has weak interaction between melt and fluid in the process of crystallization differentiation, which can promote the formation of tungsten, tin and rare metals minerals. [ABSTRACT FROM AUTHOR]