Geochronology and Geochemistry of Intrusive Rocks of Xiaojianshan Gold Deposit in the East Tianshan Mountains and Its Geological Significance

The Xiaojianshan gold depost is located in the Kanggurtag gold belt of the East Tianshan mountains, but the relationship between the mineralization and the intrusive rocks in the mining area is not clear. Based on the systematic study of petrography, petrogeochemistry and chronology, the results show that Xiaojianshan granite is dominated by adamellite, with SiO₂ concentrations of 66.30%-68.31%, Al₂O₃ of 16.65%-18.28%, K₂O of 3.25%-4.00%, Na₂O of 2.38%-3.46%, and K₂O/Na₂O (0.94-1.68) with an average value of 1.41, belonging to peraluminous high-K cale-alkaline series. The granite is enriched in the light rare earth elements ((La/Yb)_N values of 7.68-9.04) and LILEs like Rb and K, but is relatively depleted in the high field strength elements (Ta, Th, U, Nb and Ti). This granite has negligible Eu anomalies (δEu=1.02-1.25) and weak negative Ce anomaly (δCe=0.79-0.86). In the Nb-Y diagram, the samples all fall into the area of the volcanic arc-syncollisional granite; In the Rb-(Y+Nb) diagram, the samples fall into the area of volcanic arc granite; LA-ICP-MS zircon U-Pb dating shows that granite age is 257.0±2.3 Ma and formed in Late Permian and concordance with the extrusion strike slip structure and metallogenic time of the Kanggur gold belt. The Zr/Hf (31.90-37.60) and Nb/Ta (4.96-11.28) values of the samples show the characteristics of the partial melting of the crust, therefore, the granite is the partial melting product of the tectonic compression of the deep crust, and the emplacement process is closely related to gold mineralization.