This research paper investigates the diagenetic age, geochemical characteristics, and tectonic setting of granite in the Bairiqili area, contributing to our understanding of the Paleo- Tethys Ocean’s tectonic evolution in East Kunlun. We conducted a comprehensive study of the petrology, zircon U- Pb dating, Lu—Hf isotopic analysis, and whole- rock geochemistry of moyite samples. Our zircon U- Pb dating indicates the granite formed during the Early Devonian, specifically at 408.9 ± 0.9 Ma. The granite exhibits high levels of SiO2 and K2O but low MgO, enriched in large ion lithophile elements such as Rb, K, and Ba, and depleted in high field strength elements including P, Nb, Ti, and Zr, classifying it as a peraluminous to quasi- aluminous rock. The trace elements reveal a marked negative Eu anomaly, while the rare earth element distribution presents a distinct ‘seagull’ pattern, characteristic of A- type granites. The calculated εHf(t) values range from -5. 52 to 3. 53, suggesting a predominantly crustal origin for the source materials. According to the tectonic discrimination diagrams, the studied granite is identified as A2- type, which typically forms in post- collisional extensional environments. When correlating these findings with regional magmatic activity, we infer that the East Kunlun orogenic belt was likely in a collision—extension phase during the late Silurian and had transitioned fully into an extensional regime by the Early Devonian.