The Zhunuo porphyry Cu deposit (2.9 Mt Cu @ 0.48%) in the Gangdese belt, southern Xizang, represents a key Miocene post-collisional system. This study integrates textural, major-, and trace-element analyses of pyrite from distinct alteration zones to unravel its hydrothermal evolution and metal precipitation mechanisms. Our study identifies four distinct pyrite types (Py1-Py4) that record sequential hydrothermal stages: main-stage Py2-Py3 formed at 354 ± 48 to 372 ± 43 °C (based on Se thermometry), corresponding to A and B vein formation, respectively, and late-stage Py4 crystallized at 231 ± 30 °C, coinciding with D-vein development. LA-ICP-MS data revealed pyrite contains diverse trace elements with concentrations mostly below 1000 ppm, showing distinct distribution patterns among different pyrite types (Py1-Py4). Elemental correlations revealed coupled behaviors (e.g., Au-As, Zn-Cd positive correlations; Mo-Sc negative correlation). Tellurium variability (7–82 ppm) records dynamic fO₂ fluctuations during system cooling. A comparative analysis of pyrite from the regional deposits (Xiongcun, Tiegelongnan, Bada, and Xiquheqiao) highlighted discriminative geochemical signatures: Zhunuo pyrite was enriched in Co-Bi-Ag-Pb (galena inclusions); Tiegelongnan exhibited the highest Cu but low Au-As; Xiquheqiao had the highest Au-As coupling; and Bada showed epithermal-type As enrichment. Partial Least Squares Discriminant Analysis (PLS-DA) identified Cu, As, and Bi as key discriminators for deposit types (VIP > 0.8), with post-collisional systems (Zhunuo and Xiquheqiao) showing intermediate Cu-Bi and elevated As versus arc-related deposits. This study establishes pyrite trace-element proxies (e.g., Se/Te, Co/Ni, and As-Bi-Pb) for reconstructing hydrothermal fluid evolution and proposes mineral-chemical indicators (Cu-As-Bi) to distinguish porphyry-epithermal systems in the Qinghai-Tibet Plateau. The results underscore pyrite’s utility in decoding metallogenic processes and exploration targeting in collisional settings.

The peripheries of rare-metal metallogenic systems frequently host skarn-type or hydrothermal vein-type Pb-Zn deposits, though their genetic connections with parental systems remain debated. The newly identified Gariatong W-Mo polymetallic metallogenic system in the Lhasa Terrane displays well-defined Nb-Ta-Rb, Mo-W, W-Mo, W-Bi, and Pb-Zn-Ag metallogenic zoning, establishing it as an exemplary site for investigating genetic relationships between Pb-Zn and rare-metal mineralization. This investigation targets skarn-type Pb-Zn deposits spatially associated with rare-metal orebodies at Gariatong, utilizing integrated analytical approaches, including in situ LA-ICP-MS trace-element analysis of sulfides, sulfur isotope geochemistry, and LA-ICP-MS elemental mapping of sphalerite, to constrain metal sources, characterize fluid evolution, and establish genetic correlations with the rare-metal system. Key findings include the following: (1) sphalerite shows enrichment in Fe, Mn, Co, and Cd, while pyrite contains elevated As, Pb, Co, Cu, and Mn. Fe, Cd, and Mn primarily occur as solid solutions or nanoparticles, whereas As and Pb exist as micro-inclusions. (2) Sphalerite Zn/Cd ratios (73.6–184) and Co-Ni-As ternary diagrams confirm a magmatic–hydrothermal skarn origin. (3) Mineralization occurred under moderate-temperature, mildly oxidized conditions, as constrained by sphalerite Fe contents and mineral assemblages. Sulfur isotope compositions (δ³⁴S = −1.0‰ to 3.2‰; mean: 1.9‰) indicate a magmatic sulfur source. This study reveals that the Nb-Ta-Rb mineralization, quartz-vein- and greisen-type W-Mo deposits, and skarn-type Pb-Zn orebodies—all genetically associated with highly fractionated granites—constitute an integrated magmatic–hydrothermal system with vertical (depth-related) zoning relative to the granitic intrusion. These results provide critical constraints for understanding rare-metal–Pb-Zn genetic associations and suggest that Pb-Zn mineralization may serve as a key exploration indicator for rare metals in the Lhasa Terrane.

The Late Cretaceous to Paleocene magmatic evolution along the southern margin of the Lhasa Terrane records a critical transition from oceanic subduction to continental collision, yet its western segment remains underexplored. This study presents integrated petrographic, zircon U–Pb geochronological, zircon Hf isotopic, whole-rock geochemical, and Sr–Nd isotopic data for three distinct phases of intermediate to felsic intrusions from the Qiuwo area in the western segment of the southern Lhasa terrane. The results reveal three distinct magmatic pulses: an early granodiorite emplaced at 89.9 ± 0.75 Ma, followed by a diorite crystallizing at 68.6 ± 0.56 Ma, and a late-stage granodiorite forming at 56.75 ± 0.43 Ma. All three rock units are metaluminous to weakly peraluminous (A/CNK < 1.1), sodic (Na₂O > 3.2 wt.%), and dominated by amphibole, with zircon saturation temperatures of 737–786 °C, consistent with I-type granitoid affinity. All units are metaluminous (A/CNK = 0.92–1.00), calc-alkaline to high-K calc-alkaline, and enriched in LILE (K, Th, Rb) while depleted in HFSE (Nb, Ta, P, Ti), with moderate ΣREE (81–130 ppm), elevated (La/Yb)_N (9.3–15.8), and negative Eu anomalies (δEu = 0.70–0.89). The early granodiorite is Na-rich (Na₂O/K₂O = 1.6), whereas the Paleocene granodiorite shows elevated K₂O (3.2 wt.%) and reduced Na₂O/K₂O (~1.0), reflecting progressive crustal thickening and increasing magmatic differentiation. Zr and Hf are relatively enriched, and Sr/Y ratios decrease from 39 to 21, consistent with evolving magmatic conditions from deeper crustal melting in the Late Cretaceous to shallower, more evolved sources in the Paleocene. Zircon Hf isotopes reveal consistently positive εHf(t) values (+10.4 to +4.9), indicating derivation from juvenile basaltic lower crust. Sr–Nd isotopic data further demonstrate a systematic evolution: εNd(t) decreases from +2.7 to −0.1, while (⁸⁷Sr/⁸⁶Sr)_i increases from 0.7044 to 0.7055, reflecting progressive incorporation of ancient crustal components into the magma source from the early Late Cretaceous to the Paleocene. These findings indicate that the Qiuwo intrusions formed by partial melting of a juvenile basaltic lower crust, with increasing crustal contamination during ascent and emplacement. The temporal progression of magmatism—spanning the waning stages of Neo-Tethyan subduction to the initial India–Eurasia collision (~55 Ma)—supports a model in which slab breakoff and lithospheric delamination triggered decompression melting of the lower crust, while assimilation of older crustal materials intensified as the continental collision progressed. This work provides key geochemical evidence for the transition from arc to post-collisional magmatism in the western Gangdese belt and refines the timing and mechanism of crustal growth in southern Tibet.