Geochemical characteristics, formation age and tectonic environment of the Mankeyidingsayi rocks in the Wuxilike area of Altay

The Wuxilike area of Altay is located in Siberian Altay terrigenous mobile belt and the Altay Paleozoic plutonic magmatic arc, where granite is widely distributed. By LA-ICP-MS zircon U-Pb dating and geochemical analysis, the authors studied the age and tectonic environment of the Makeyidingshayi granite body. The LA-ICP-MS zircon U-Pb age of the medium-fine grained muscovite adamellite of Mankeyidingsayi granite body in southern Wuxilike area is 217.9±2.3Ma, showing that the granite body was emplaced in the early Late Triassic of the early-Mesozoic. The rocks have high SiO₂ (70.86%~74.32%) and Al₂O₃ (14.51%~14.96%), low P₂O5 (0.24%~0.33%) and MgO+FeO (0.39%~1.25%) content, high alkali (K₂O+Na₂O=8.07%~8.29%), and low CaO/Na₂O (0.13~0.30, ≤0.3) ratio. These characteristics indicate that the granite body belongs to high-K calc-alkaline peraluminous rocks, with the typical features of S-type granites. In combination with the work and the results from previous comprehensive analysis, the authors infer that the granite body was formed in an intercontinental (inland) environment, related to the mantle plume. The granite body was mainly derived from partial melting of argillaceous sediments in the crust, and during the partial melting process, residuals of calcium-rich plagioclase, ilmenite and other minerals were preserved.