Abstract:

The Kungeyite plutons, outcropped in Qingeli River in Qinghe County of southern margin of Altay orogenic belt are mainly hornblende biotite tonalite, which were determined for LA-ICP-MS zircon U-Pb ages. The result shows that the zircon ²⁰⁶Pb/²³⁸U weighted average age is (403.4±7.4) Ma (MSWD=1.07), indicating the plutons were formed at Early Devonian. The SiO_² contents range from 52.39% to 71.89% and σ from 0.68 to 1.53, A/CNK from 0.76 to 1.06, indicating that the plutons are midK calcalkaline, metaluminousweakly peraluminous rocks. In addition, the plutons are enrichment in LILE (Cs, Rb, Th, U) and LREE, obvious negative anomaly in HFSE (Nb, Ta, Hf, Ti), HREE and Eu (δEu=0.56-0.86), thus resembling granitoid rocks formed in islandarc. Combined with the data of southern margin of Altay, the Kunge yite plutons were generated by partial melting of the lower crust underplayed by mafic magma of the mantle in a continental arc setting of active continental margin, and occurred magma mixing and differentiation.

Key words: hornblende biotite tonalitel LA-ICP-MS zircon U-Pb dating, Kungeyite plutonlQingeli River, AltaylXinjiang