Ore-forming processes of the Ketelegaole Cu-W polymetallic deposit, East Kunlun Orogenic Belt, China: Constraints from textures, trace elements, and sulfur isotopes of pyrite, pyrrhotite and sphalerite

• Sphalerite shows strong enrichment in the critical metals Cd and In. • Sulfur was mainly from magma, influenced by fluid boiling with minor wall rock contributions. • Fluid boiling and meteoric water influx controlled sulfide S isotopes and trace elements. The Ketelegaole Cu-W polymetallic deposit (1.11 Mt at 0.50% Cu, 0.50% WO 3 , 1.22% Pb, and 3.60% Zn) is situated in the Qimantagh area, eastern East Kunlun Orogenic Belt. As the first systematic study of this deposit, we integrate field geology with LA-ICP-MS trace element analysis and sulfur isotopes of sulfides from different mineralization stages, supplemented by regional comparisons. These results provide initial constraints on its genetic type, mineralization processes, and fluid evolution. LA-ICP-MS trace element data of sulfides indicate that Po1 is enriched in Co and Ni with high Co/Ni ratios, suggesting a high-temperature origin. Co, Ni, and Bi decrease from Py1 to Py3 suggest a cooling trend in the ore-forming fluid, possibly due to increased meteoric water influx. Py1 and Py3 exhibit As and Cu enrichment but Co and Ni depletion, along with low Co/Ni, Tl/Cu, high As/Sb (>20) ratios, and elevated Ag/Co (>0.01), indicating vigorous fluid boiling during this stage. Sphalerite is enriched in Fe, Mn, Co, In, and Sn, but depletion in Ga and Ge. The Ga/In (0.001 ∼ 0.05) and Zn/Cd (155 ∼ 223) ratios, combined with Fe/Zn geothermometry (255 ∼ 380 °C, avg. 322 °C), confirm that the Ketelegaole Cu-W polymetallic deposit formed in a high-temperature hydrothermal system. LA-ICP-MS sulfur isotope data reveal the majority of sulfides (Po1, Po2, Py1, Py3, Sp) display a narrow δ 34 S range (−0.14 ‰ to 4.12 ‰, n = 29), consistent with magmatic sulfur signatures. Early sulfides from the pyrite stage (Py1, Po2) show moderately negative δ 34 S values (Py1: −6.4 to − 6.2 ‰, n = 4; Po2: −5.9 to 0.6 %, n = 8), interpreted as resulting from vigorous fluid boiling. Conversely, late sulfides from the pyrite stage (Py3) show the slightly enriched δ 34 S values are attributed to potential mixing with diagenetic sulfur derived from wall rocks. The δ 34 S values of sphalerite (Sp = 0.4 ∼ 3.5 ‰, n = 17) from the Pb-Zn sulfide stage clearly reflect remarkable magmatic sulfur source. Combined geological and geochemical evidence conclusively classifies the Ketelegaole deposit as a skarn-type deposit.