Numerous copper—polymetallic deposits are distributed in the border region between China and Mongolia. The Shiertolgai Cu—Mo deposit, located in Darhan Mumingan United Banner, Inner Mongolia, has undergone multiple exploration campaigns since its discovery, providing preliminary insights into the geological characteristics of the deposit. Methods: In this paper, based on detailed field geological work, systematic sampling of malachitized and unmineralized granodiorite from the Shiertaolegai mining area was carried out for analyses of major and trace elements, zircon U- Pb dating, and Hf isotopes.Results: The granodiorites exhibit high Si, Al, and K major element compositions, are relatively enriched in large ion lithophile elements (LILE) such as Rb, Ba, and K, and show depletions in high field strength elements (HFSE) including Nb, Ta, and Ti, indicating typical arc magmatic affinities. In addition, the zircon εHf(t) values of the granodiorites range from +4. 5 to +11. 3 and +7. 5 to +10. 6, with corresponding two- stage Hf model ages (TDM2) of 1028~589 Ma and 831~631 Ma, respectively, suggesting that the parent magmas were products of island arc magmatism. Conclusions: Based on regional tectonic studies, the authors propose that the Early Permian granites in the Mandula region were formed in a southward subduction setting of the Paleo- Asian Ocean.