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Zhaxikang is one large Sb–Pb–Zn–Ag deposit located in the North Himalaya of southern Tibet. To date, the genesis of this deposit still remains controversial. Here, we present new pyrite Fe and sphalerite Zn isotopic data for the first three stages of mineralization, Fe–Zn isotopic data for Mn–Fe carbonate that formed during the first two stages of mineralization, and Zn isotopic data for the slate wall rocks of the Jurassic Ridang Formation to discuss the genesis of the Zhaxikang deposit. The overall δ 56 Fe and δ 66 Zn values range from −0.80‰ to 0.43‰ and from −0.03‰ to 0.38‰, respectively. The δ 56 Fe values of Mn–Fe carbonates are lighter than those of associated pyrite in six mineral pairs, indicating that the iron carbonates are preferentially enriched in light Fe isotopes relative to pyrite. The sphalerite has lighter δ 66 Zn values than associated Mn–Fe carbonates in three mineral pairs. The δ 56 Fe values of pyrite that formed during the first three stages of mineralization gradually increase from stage 1 (−0.33‰ to −0.09‰) through stage 2 (−0.30‰ to 0.19‰) to stage 3 (0.16‰–0.43‰). In comparison, the sphalerite that formed during these stages has δ 66 Zn values that gradually decrease from stage 1 (0.16‰–0.35‰) through stage 2 (0.09‰–0.23‰) to stage 3 (−0.03‰ to 0.22‰). These data, in conjunction with the observations of hand specimens and thin sections, suggest that the deposit was overprinted by a second pulse of mineralization. This overprint would account for these Fe–Zn isotopic variations as well as the kinetic Rayleigh fractionation that occurred during mineralization. The temporally increasing δ 56 Fe and decreasing δ 66 Zn values recorded in the deposit are also coincident with an increase in alteration, again supporting the existence of two pulses of mineralization. The δ 56 Fe values of the first pulse of ore-forming fluid were calculated using theoretical equations, yielding values of −0.54‰ to −0.34‰ that overlap with those of submarine hydrothermal solutions (−1‰ to 0‰). However, the δ 56 Fe values of the stage 3 pyrite are heavier than those of typical submarine hydrothermal solutions, which suggests that the second pulse of mineralization was probably derived from a magmatic hydrothermal fluid. In addition, the second pulse of ore-forming fluid has brought some Fe and taken away parts of Zn, which results the lighter δ 66 Zn values of sphalerite and heavier δ 56 Fe values of pyrite from the second pulse of mineralization. Overall, the Zhaxikang deposit records two pulses of mineralization, and the overprint by the second pulse of mineralization causes the lighter δ 66 Zn values and heavier δ 56 Fe values of modified samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • SEDE genesis is most plausible for the first episode of mineralization in the Zhaxikang and Keyue deposits. • A genetic relationship must exist between the Zhaxikang and Keyue deposits. • The Zhaxikang and Keyue deposits have the same metal origins and experience similar ore formation and ore-forming fluid evolution. • Zn–Cd isotopes have the potential to apply in ore deposit research and mineral exploration. The Keyue Sb–Pb–Zn–Ag deposit is a medium-sized deposit near the super-large Zhaxikang Sb–Pb–Zn–Ag deposit within the North Himalayan Metallogenic Belt (NHMB). These two deposits, separated only by a regional NS-trending normal fault with strike-slip properties, have similar ore-forming elements and mineral associations, ore characteristics, ore paragenetic sequence, wall rocks, and H–O–S–Pb isotopic and fluid inclusion characteristics. Herein, we establish Zn–Cd isotopic connections between these two proximal ore deposits. As a means to draw comparisons, we conducted Zn–Cd isotopic research of the Keyue deposit to compare it with that of the Zhaxikang deposit. Both the δ66Zn and δ 114/110Cd values of sphalerite from the Keyue deposit display a temporally decreasing trend from stage 2 (δ66Zn: 0.15‰–0.58‰, average value = 0.29‰; δ 114/110Cd: –0.23‰ to 0.38‰, average value = 0.05‰) to stage 3 (δ66Zn: –0.28‰ to 0.12‰, average value = –0.06‰; δ 114/110Cd: –0.38‰ to –0.32‰, average value = –0.35‰), which was also found in the Zhaxikang deposit. A simple three-phase separation distillation models this temporally decreasing trend, which resulted from the Zn–Cd isotopic fractionation that is most likely related to vapor–liquid-solid dynamics of ore-forming fluid. This distillation model was further augmented by the general geochemical characteristics and fluid inclusion data. A congruence among several geological and geochemical evidence points to the genetic relationships between these two ore deposits that have the same metal origins and experience similar ore formation processes. A three-phase separation model has been established to imitate this evolution, which reveals substantial exploration potential for Zn–Cd at depths below 4100 m within the Zhaxikang orefield. In summary, Zn–Cd isotopes have the potential to trace metal sources, monitor fluid evolution, constrain ore formation, and provide insights into mineral exploration. [ABSTRACT FROM AUTHOR]