Objective The recent discovery of the Hongchuan Cu−Ni deposit in the North Qilian Orogenic Belt represents a significant breakthrough in mineral exploration. Uncertainties in the formation age, petrogenesis, and magmatic source of the ore−bearing intrusions hinder a comprehensive understanding of the deposit′s mineralization mechanisms.

Methods Therefore, this study integrates petrological, whole−rock geochemical, zircon U−Pb geochronological, and Hf isotopic analyses to characterize these intrusions.

Results The ore−bearing rock in the Hongchuan Cu−Ni deposit predominantly comprises strongly serpentinized peridotite and biotite amphibolite, and the main ore−bearing lithology is strongly serpentinized peridotite. Geochemical analyses reveal features, including low SiO₂(39.13%~46.35%) and high MgO(13.69%~27.47%) contents, high Mg^# values (68.28~79.91). The distribution curve of rare earth elements shows flat characteristics, and trace elements Nb, P, and Ti are deficient. Zircon U−Pb dating, conducted via LA−ICP−MS on zircons from the plagioclase−bearing peridotite, yielded a weighted mean ²⁰⁶Pb/²³⁸U age of 486.9 ± 5.9 Ma, with zircon ε_Hf(t) values ranging from −0.19 to 7.12.

Conclusions Integrating geological data with regional geological context suggests a genesis within an island arc environment. The magma source is proposed to have originated from a depleted mantle that was influenced by fluid alteration and subduction processes, with less than 10% contamination of lower crustal materials during magma emplacement.