LA-ICP-MS zircon U-Pb geochronology, element geochemistry and petrogenesis of the andesites in the eastern Taerbieke gold deposit of the western Tianshan region
西天山东塔尔别克金矿区安山岩LA-ICP-MS锆石U-Pb年代学、元素地球化学与岩石成因

The eastern Taerbieke gold deposit is geographically located to the south of the Axi gold deposit in the Tulasu basin, western Tianshan, and tectonically occurs in the western section of the Early Paleozoic Borohoro island arc between the Junggar plate to the north and the Yili-central Tianshan micro-plate to the south. The eastern Taerbieke andesites are geochemically similar to high-Mg andesite, e.g., high SiO2 (58.94%~63.85%) and MgO contents (3.75%~6.59%), Mg# values (58~69), and Cr (94.2×10-6~241×10-6) and Ni (54.5×10-6~126×10-6) contents, and low FeOT/MgO ratios. Except for slight low Sr contents (235×10-6~696×10-6), they are also geochemically similar to adakites, e.g., high Al2O3 (15.39%~16.65 %), high Sr/Y(23.8~48.1) ratios, no significant Eu anomalies and clear depletion in Nb, Ta and Ti. LA-ICP-MS U-Pb age data suggest that the eastern Taerbieke andesites were generated in the Early Carboniferous (347.2±1.6Ma). The enrichment in large ion lithophile elements (e.g. Rb, Th and U) and depletion in high field strength elements (e.g. Nb, Ta and Ti), and higher light rare earth element contents relative to heavy rare earth elements for the andesites, suggest that they are similar to island arc rocks. We suggest that the eastern Taerbieke andesites were possibly generated by the interaction between mantle and melts derived by partial melting of subducting sediments and altered oceanic crust during the subduction of Late Paleozoic northern Tianshan Ocean. The interaction between mantle and melts possibly played an important role in generating Au mineralization.