The Shaquanzi Fe–Cu deposit is an important Fe (–Cu) deposit in the Yamansu Fe mineralization belt, Eastern Tianshan. Five-stage (Stage I to V) hydrothermal alteration/mineralization have been recognized: The early skarn (Stage I) and late skarn (Stage II) stages are featured by extensive garnet and amphibole alteration, respectively. Magnetite mineralization stage (Stage III) is associated with pervasive K + Fe ± Ca alteration, forming magnetite, mushketovite, K-feldspar, epidote, magnetite, pyrite and quartz. Chalcopyrite mineralization stage (Stage IV) has an ore mineral assemblage of chalcopyrite, bornite, acicular hematite and sphalerite, accompanied with broad epidote + chlorite + calcite alteration. The late veins stage (Stage V) occurs mainly as epidote + calcite veins crosscutting the host rocks and earlier-stage minerals.

Stage I hydrothermal fluids have high temperatures (> 600 °C), medium-high salinities, with magmatic δ¹⁸O_fluid = + 6‰ to + 11.7‰. Stage III ore-forming fluids are medium-high-temperature (ca. 470–570 °C) with medium salinity. Stage III minerals were formed under δD_fluid = − 45.7‰ to − 24.3‰, δ¹⁸O_fluid = + 5.8‰ to + 9.1‰ and δ³⁴S_fluid = − 1.7‰ to + 4.7‰, indicative of magmatic fluids mixed with minor seawater. In contrast, Stage IV fluids have low temperatures (ca. 160 °C), medium-low salinities and are Ca-rich, with isotopic compositions reflecting basinal brine mixed with meteoric water (δ¹³C_fluid = − 6.6‰ to − 2.3‰; δ¹⁸O_fluid = − 3.3‰ to + 2.8‰ and δ³⁴S_fluid ≥ + 24.8‰).

The Shaquanzi diorite (zircon U–Pb age: 298 ± 5 Ma) is broadly coeval with previous Re–Os ages of the Shaquanzi magnetite and pyrite (303 ± 12 Ma and 295 ± 7 Ma, respectively), indicating that the Shaquanzi Fe–Cu metallogeny may have been genetically linked to the regional magmatic–hydrothermal activities led by the Yamansu arc-backarc basin inversion. Features of hydrothermal alterations, mineral assemblages, ore-forming fluids and tectonic setting all suggest that the Shaquanzi Fe–Cu deposit is an IOCG-like deposit, similar to those in the Cenozoic Central Andes.