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Porphyry copper deposits are economically significant sources of Cu and Mo, formed when metal-rich fluids precipitate at shallow levels, exsolving from underlying magmatic reservoirs at depth. However, the origin and evolution of these metal-rich fluids, whether through episodic enrichment from multiple pulses or a single continuous fluid-release event, remain a subject of controversy. To gain deeper insights into these processes, data on cathodoluminescence (CL) imaging, in situ trace elements, and Sr isotopes of newly discovered scheelite (Sch 1, Sch 2, and Sch 3) found in three generations of vein types within the giant Qulong porphyry Cu-Mo mineralization system are presented. The anhedral Sch 1 occurs in quartz + magnetite + anhydrite + chalcopyrite veins, exhibiting no obvious zoning in the CL image. These scheelite samples show high concentrations of Mo, Nb, Ta, and 87Sr/86Sr ratios ranging from 0.70688 to 0.71109. Moreover, they demonstrate enriched rare earth elements (REE) and negative Eu anomalies in the chondrite-normalized pattern, indicative of their formation in relatively oxidized metal-rich fluids during the early high-temperature alteration stage. Among the discovered scheelite varieties, the most volumetrically significant is the subhedral Sch2, which occurs in veins composed of quartz + pyrite + chalcopyrite. In its central region (Sch 2a), Cu-rich cores are dispersed, surrounded by an oscillatory Cu-poor mantle and rim (Sch 2b and 2c), as observed in the CL image. When compared to Sch 1, Sch 2 exhibits lower levels of REE, Nb, Ta, Mo, and 87Sr/86Sr ratios (ranging from 0.70502 to 0.70578), but higher Cu concentration and positive Eu anomalies. The gradual decrease in Cu content from the core to rim in Sch2, along with its rim's intergrowth with sulfide, suggests the precipitation of Cu during the second pulse of fluids. Euhedral Sch 3 is found in relatively moderate-temperature mineral assemblages within quartz + galena + sphalerite + molybdenite veins. It displays an oscillatory pattern with a Mo-rich core (Sch 3a), an extremely Mo-rich mantle (Sch 3b), and a Mo-poor rim (Sch 3c) in the CL image. Sch 3 shows lower REE, Cu, and Pb contents but variable Mo concentrations in different domains while consistently recording 87Sr/86Sr ratios ranging from 0.70498 to 0.70542. These characteristics indicate the precipitation process of Mo and Pb during the third pulse of fluid evolution. The observed shift in mineral assemblages, metal contents, and Sr isotopic components from Sch 1 to Sch 3 reflects the occurrence of different fluid pulses within a cooling porphyry Cu-Mo mineralization system. Overall, the three generations of scheelite found at the Qulong porphyry Cu-Mo deposit indicate the occurrence of multiple pulsed flows of magmatic fluids, revealing a more complex fluid evolution for porphyry Cu deposits than previously recognized. Notably, Sch 1 exhibits relatively high 87Sr/86Sr ratios, similar to the post-ore mafic porphyries, which are higher compared to Sch 2 and Sch 3, showing 87Sr/86Sr ratios similar to the pre- and syn-ore host granite and porphyry. This result implies that mafic magma has significantly contributed to the formation of the first pulse of magmatic fluids, whereas synore granitic magma contributed to the ore fluids responsible for forming the veins containing Sch 2 and Sch 3 in the later stage. Therefore, we propose that volatiles from mafic magma, injected into the porphyry metallogenic system, play a crucial role in the formation of porphyry Cu deposits. Additionally, for the first time, the presence of Cu-Mo-W metal endowment in the porphyry Cu deposits of the Gangdese magmatic belt is identified, providing valuable new insights into the metallogeny of porphyry Cu deposits and offering promising opportunities for tungsten exploration in the collision zone. [ABSTRACT FROM AUTHOR]

Relatively little attention has been given to variations in ore‐forming metal sources of Pb–Zn polymetallic deposits hosted in or near the Linzizong volcanic rocks from the eastern to western Gangdese belt. Based on the S and Pb isotopic data of typical Pb–Zn polymetallic deposits from the eastern to western Gangdese, the ore‐forming sources are discerned. The δ34SV‐CDT values of the typical Pb–Zn polymetallic deposits in the Gangdese metallogenic belt have a relatively large range of −11.6‰ to 6.0‰, different from those of the porphyry Cu ± Mo ± Au deposits (mainly vary from −2.0‰ to 1.0‰) in the Gangdese metallogenic belt, indicating that the sulphur in the ore‐forming fluid of Pb–Zn polymetallic deposits was dominantly of magmatic origin, but also influenced by strata nearby. The Nuocang and Beina deposits in the western Gangdese have a predominantly upper crustal source of Pb (average values: 207Pb/204Pb = 15.705, 208Pb/204Pb = 39.102), while the Narusongduo and Dexin deposits in the central Gangdese and the Leqingla and Xingaguo deposits in the eastern Gangdese are characterized by a mixed source in which Pb was derived from both the subducted slab and the ancient Lhasa basement. From the eastern to western Gangdese, Pb isotopic data show a gradually increasing scale of crustal materials from the Lhasa terrane basement. Combined with the geochemical data of the ore‐related intrusions and Linzizong volcanic rocks from the six deposits, or nearby, we proposed that the heterogeneity of Lhasa terrane crust resulted in more ancient Lhasa basement components contributing to ore‐forming sources from the eastern to western Gangdese. Moreover, relatively higher contents of Au, Ag elements could be identified in the Linzizong volcanic rocks of the western Gangdese than those of in the central and eastern Gangdese. Therefore, in addition to finding the cryptoexplosive breccia, epithermal, skarn, hydrothermal vein‐type Pb–Zn polymetallic deposits, there is exploration potential for epithermal Au–Ag deposits associated with the Linzizong volcanic rocks, western Gangdese. [ABSTRACT FROM AUTHOR]

The Beina Pb–Zn–(Ag) deposit is a newly discovered deposit situated in the southern Lhasa terrane, Tibet. LA‐ICP‐MS U–Pb dating for the ore‐bearing rhyolite porphyry indicates that it was emplaced at 64.6 Ma. The Beina rhyolite porphyry displays high SiO2 (74.31–76.52 wt%), K2O + Na2O (6.99–8.05 wt%), and A/CNK (0.97–1.33), similar to the peraluminous S‐type granites related to Pb–Zn–(Ag) mineralization in the central Lhasa terrane. The Beina rhyolite porphyry is strongly depleted in Nb, Ta, Ti, P, Sr, and Ba, enriched in Rb, K, Th, U, and Pb, enriched in light rare earth elements (LREEs), slightly depleted in heavy rare earth elements (HREEs) (LaN/YbN = 6.52–9.28), and has moderate negative Eu anomalies (δEu = 0.38–0.48), showing an arc affinity. It also shows high CaO/Na2O ratios (0.21–0.73), low Rb/Ba (0.30–0.46), and Rb/Sr ratios (1.17–4.01), indicating that it was mainly derived from partial melting of a clay‐poor, plagioclase‐rich metapsammitic source. The samples have relatively high 87Sr/86Sr(i) (0.7084–0.7092) and Pb isotopes (206Pb/204Pb = 18.61–18.74, 207Pb/204Pb = 15.65–15.68, 208Pb/204Pb = 38.99–39.14) and low εNd(t) (−8.6 to −7.2) and εHf(t) (−8.6 to −4.8) values, yielding ancient two‐stage Nd model ages (1,459–1,569 Ma) and two‐stage Hf model ages (1,433–1,684 Ma), respectively. The Beina rhyolite porphyry was formed at relatively high temperatures (average 817°C) according to zircon saturation thermometer. These results reveal that Beina rhyolite porphyry was generated by partial melting of ancient crustal materials (dominated by metapsammite) heated by mantle‐derived magma during rollback of the Neo‐Tethyan oceanic slab. In addition, our research suggests that both I‐ and S‐type granites related to Pb–Zn mineralization are believed to exist in the Lhasa terrane. Similar to the central Lhasa terrane, the middle segment of the southern Lhasa terrane (83°E–87°E) is also an ancient block, large‐scaled silicic volcanic rocks of the Linzizong Group, and coeval plutons are widely exposed and several Pb–Zn deposits have recently been discovered in the Nuocang–Chazi area. All these facts indicate that there is a great potential for prospecting of intrusions‐related Pb–Zn deposits in the middle segment of the southern Lhasa terrane. [ABSTRACT FROM AUTHOR]

An integrated study using cathodoluminescence (CL) images, U–Pb geochronology, and Hf isotopic characterization of zircons was performed on migmatites from the Yuka terrane to provide insights into the timing and nature of the protoliths, metamorphism, and partial melting of these rocks. Zircon grains separated from the migmatites have three distinct domains. Residual zircon cores in samples YKT01 and YKT02 exhibit oscillatory zoning, high Th/U ratios (0.10–0.79), steep heavy rare earth element (HREE) patterns, and mean ages of 936 ± 5 Ma and 927 ± 11 Ma, respectively, indicating that they are igneous in origin and record Neoproterozoic magmatism during the Grenvillian Orogeny. CL‐grey cores record an ultrahigh‐pressure (UHP) peak metamorphism age of 435 ± 5 Ma and have low Th/U and 176Lu/177Hf ratios, weak negative Eu anomalies, and relatively flat HREE patterns. The CL‐bright rims have steep HREE patterns with lower middle rare earth element (MREE) concentrations but higher HREE concentrations compared with the metamorphic cores and a weighted average age of 422 ± 4 Ma, which records the timing of melt crystallization. The migmatites incorporate garnet relicts coexisting with fluid inclusions and hydrous minerals like peritectic phengite and peritectic large anhedral poikilitic tourmaline in the leucosomes. Peak temperatures are less than 750°C, suggesting that the anatectic melts may be derived from melting of felsic gneiss in the presence of water. The timing of melt crystallization is ca. 13 Ma later than UHP metamorphism, indicating that the partial melting took place during the exhumation stage. The metamorphic zircon cores have higher 176Hf/177Hf(t) ratios than the residual magmatic cores, which provides powerful evidence for the generation of the metamorphic zircons through the incorporation of internal high Hf minerals other than zircon in a closed system. Anatectic rims with lower 176Hf/177Hf(t) ratios but higher 176Lu/177Hf ratios than metamorphic cores suggest that the main formation mechanism is dissolution‐reprecipitation of pre‐existing zircons. In conclusion, the elevated 176Hf/177Hf(t), TDM2 age and decreasing 176Lu/177Hf(t) ratios in the metamorphic and anatectic domains imply that the new zircons in some migmatites and granites may not reflect the Hf isotope compositions of their source rocks, accounting for the variable Hf isotope compositions in S‐type granites. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Jiru porphyry copper deposit was formed by two magmatic-hydrothermal events. [•] Early event was caused by 48.6Ma monzogranite formed in syncollision setting. [•] Late event resulted from 16Ma monzogranite porphyry in postcollisional setting. [ABSTRACT FROM AUTHOR]