A study of the ore-forming age of the Hutouya deposit and its geological significance:Geochemistry and U-Pb zircon ages of biotite monzonitic granite in Qimantag, East Kunlun Mountains

The Hutouya Pb-Zn polymetallic ore deposit is located in Qimantag, East Kunlun Mountains.Intermediate-acid intru-sive rocks occur widely in this area, and are closely related to iron polymetallic mineralization.The ²⁰⁶Pb/²³⁸U weighted average age is 234.2±1.5 Ma, which was obtained by in-situ LA-ICP-MS zircon dating of biotite monzonitic granite that was closely related to mineralization and skarn.The results of geochemical analysis show that the biotite monzonitic granite is characterized by high Al₂O₃, K₂O and low TiO₂, Na₂O.The I-type granites are characterized by rich LREE, Rb, Th and some of HFSE, but poor Nb, Sr and Zr, and clear separation of LREE from HREE.In diagram of(Y+Nb)-Rb, all samples fall into post-collision granite area, and in R1-R2 diagram, all samples fall into the superimpositon of post-collision granite area and collision granite area, indicating that the gran-ites probably formed in a collision-post-collision structural phase.The Ⅵ belt of the Hutouya Pb-Zn polymetallic ore deposit expe-riended strong skarnization.The authors hold that the deposit has characteristics of skarn deposit, as shown by its ore fabric, gangue minerals, wall rock alteration, and it was formed at 234.2±1.5 Ma (Middle-Late Triassic).