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The newly discovered giant Dahutang W–Cu–Mo deposit in the central part of the Jiangnan Orogen hosts an estimated resource of 1.1 million tons (Mt) of WO 3 , plus a proven resource of 0.65 Mt Cu and 0.08 Mt Mo. The Dahutang deposit is temporally and spatially associated with the Late Mesozoic S-type granites emplaced into the Neoproterozoic Jiuling granodiorite batholith and the Shuangqiaoshan Group. Based on petrographic observations, eight hydrothermal alteration/mineralization stages have been recognized, comprising pegmatitic (Stage I), potassic alteration (Stage II), albite alteration (Stage III), greisenization and main mineralization (Stage IV), polymetallic sulfide mineralization (Stage V), late scheelite mineralization (Stage VI), carbonate alteration (Stage VII) and supergene alteration (Stage VIII). Stage IV can be further divided into the early greisenization (Stage IV-A), the main wolframite mineralization (Stage IV-B) and the main scheelite mineralization (Stage IV-C). Fluid inclusion and H–O isotope analyses on nine Stage IV to VII ore/gangue minerals (wolframite, cassiterite, scheelite, sphalerite, fluorapatite, fluorite, quartz, calcite and chlorite) suggest the presence of an early W and a late Cu–Mo ore-forming fluid system. The early ore-forming fluids belong to a medium to high temperature (200°–420 °C), low salinity H 2 O–NaCl–CaCl 2 system. This primary magmatic-hydrothermal fluid (δ 18 O fluid  = 5.4 to 8.8‰ and δD = −102 to −75‰) was likely exsolved from the Late Jurassic granites at Dahutang. Wolframite and scheelite coexist closely with fluorapatite and fluorite, respectively, indicating that the volatile-rich fluids at Dahutang were also rich in tungsten, fluorine and phosphorous. Tungsten was likely transported as tungstate species (e.g., WO 4 2− and HWO 4 − ), oxygen fluorine complexes (e.g., [WO 2 F 4 ] 2− , [WO 3 F 2 ] 2− ) and phosphorous heteropolytungstate (e.g., [P(W 12 O 40 )] 3− ) in the fluids. Fluorapatite and wolframite may have precipitated first when the temperature dropped from 400° to 320 °C (along with pH increase) at an estimated depth of 7.8 km. This was likely followed by the extensive scheelite mineralization (with fluorite precipitation) that formed huge disseminated/veinlet-type W orebodies when the temperature further dropped to 200 °C (along with pH increase). After the W mineralization, extensive Cu–Mo polymetallic mineralization and the associated sericite-chlorite alterations may have formed by the granite porphyry and/or muscovite granite emplacement. The late ore-forming fluids belong to a medium to high temperature (200°–360 °C), low salinity H 2 O–NaCl–CaCl 2 system. Molybdenum was likely transported mainly as Mo complexes (e.g., H 2 MoO 4 /MoO 4 2− ), and copper as Cu–Cl complexes. Molybdenite and chalcopyrite may have begun to precipitate when the fluids ascended and the temperature dropped to 330 °C. Meteoric water incursion may have then occurred (δ 18 O fluid  = 1.9–6.9‰ and δD = −99 to −68‰) and further cooled the fluid system to 250 °C, forming large Cu–Mo orebodies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zircon U-Pb ages record two phases of granitic magmatism of 159 and 145 Ma. • Molybdenum and W are enriched in porphyry by prolonged fractionation and high f O2. • Scheelite petrography and compositions reflect mechanisms of Mo-W mineralization. • Porphyry-skarn Mo-W systems may be controlled by magmatic sources and wall rocks. Eastern Qinling Orogen is the largest Mo province in the world, hosting nine giant Mo deposits. Four giant Mo deposits contain economic W mineralization, while the mechanism of W mineralization remains unclear. The Yechangping deposit is a representative porphyry-skarn Mo-W deposit, with four paragenetic stages of prograde skarn, retrograde skarn, polymetallic sulfides and carbonate stage. Magmatism at Yechangping includes early barren monzogranite porphyry at 159.0 ± 1.5 Ma and late ore-related granite porphyry at ca. 145 Ma, and the latter porphyry shows a higher magmatic fractionation than the early barren monzogranite porphyry. Both barren and ore-related porphyries have similar high magma oxidation states, which may efficiently extract Mo during partial melting and hinder subsequent molybdenite crystallization until the porphyry-skarn Mo mineralization. Three types of scheelites are distinguished by their texture, paragenetic relationship and geochemistry, including Sch-1a in the retrograde skarn stage, and Sch-1b and Sch-2 in the polymetallic sulfides stage. Scheelite displays decreasing MoO 3 contents from 7.01–51.59 % in Sch-1a, through 3.15–17.51 % in Sch-1b, to 0–1.51 % in Sch-2. The decreasing MoO 3 contents in scheelite are attributed to the transformation of dominant Mo-bearing phases, i.e., from retrograde skarn stage powellite to polymetallic sulfides stage molybdenite. We suggest that the Mo-W mineralization is triggered by the decreasing oxygen fugacity, p H, and temperature, supported by thermodynamic modeling. In addition, the precipitation of fluorite and destabilization of fluorine complexes may have also promoted the Mo-W mineralization. Zircon Hf isotopes yielded ε Hf (t) values of −14.9 to −7.5 and T DM2 ages of 1671–2147 Ma, indicating that Yechangping porphyries were primarily sourced from the ancient basement of the Huaxiong Block, with additional contribution from the North Qinling Accretionary Belt. Skarn W mineralization in the southern part of Huaxiong Block may be controlled by both magmatic fertility and carbonate wall-rocks. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hydrothermal titanite associated with Au mineralization was formed at 130.8 ± 0.63 Ma. • The early Cretaceous Au mineralization overprinted the Triassic and late Jurassic Mo-Pb mineralization in Huangshui'an. • The gold precipitation mechanisms are sulfidation, collection-redissolution by LMCE melt, and changes in f Te 2 and f S 2. Huangshui'an deposit, situated in the Xiong'ershan area of Qinling orogenic belt (QOB) in China, is a globally rare carbonatite-type molybdenum polymetallic deposit that contains economic Mo, Au, Pb, and REE mineralization. The molybdenite Re-Os ages (Ca. 213.5–209.2 Ma) indicates that Huangshui'an Mo mineralization formed at Late Triassic. However, it is still unclear whether the Au mineralization is related to carbonatite dykes, and the formation age and genesis mechanism of Au mineralization remain poorly understood at Huangshui'an. This paper presents a comprehensive investigation of the Au mineralization events at the Huangshui'an deposit, including geology, mineralogy, and geochronology. The aim is to provide insights into its formation and mineralization processes and offer a broader understanding of regional Au metallogeny. Based on petrographic investigations, four stages are identified in the Au mineralization as follows: (I) quartz-K-feldspar stage; (II) quartz-pyrite-gold stage, including (IIA) pyrite-native gold sub-stage and (IIB) gold-tellurite-bismuthide sub-stage; (III) quartz-pyrite-polymetallic sulphide-oxide stage; and (IV) calcite-quartz-chlorite stage. The LA-ICP-MS titanite U-Pb dating yields a weighted mean age of 130.8 ± 0.63 Ma which determined that the Au mineralization at Huangshui'an was in the Early Cretaceous and was an independent mineralization event, which may be related to the lithosphere's destructive effect on the North China Craton (NCC). Combined with mineralography by automatic quantitative mineral analysis and testing system (TIMA), we consider that tellurium-bismuth minerals are closely associated with Au mineralization. The sulfur and tellurium fugacity of the ore-forming fluids in each stage were calculated using metal sulfide-oxides and tellurium-bismuth minerals. It was concluded that the precipitation of Au in the Huangshui'an deposit was mainly due to the combined effects of sulfidation, gold collection-redissolution by the low-melting point chalcophile elements (LMCE) melts, and the variation of sulfur fugacity and tellurium fugacity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mo isotopes variation in both the two Mo deposits may be controlled by Rayleigh and equilibrium fractionation. • The Taihua Soupergroup and the Xiong'er Group would be the main contributor of Mo metal for the Paleoproterozoic Mo mineralization. • The mantle with light isotopically Mo involved into the Mo Paleoproterozoic mineralization in Qinling orogenic belt. Longmendian and the Zhaiwa are the two oldest Mo deposits in the Qinling orogenic belt, China, which is one of the most important Mo provinces in the world with numerous and diverse types of Mo deposits that experienced multistaged mineralization. Here we investigated Mo isotope compositions in molybdenite and rocks from the Longmendian and the Zhaiwa Paleoproterozoic Mo deposits to link Mo isotopes to the sources of Mo metal. The significant Mo isotope variation in the Longmendian and the Zhaiwa Mo deposits (δ98Mo = −0.51‰ to + 1.01‰ and −0.37‰ to +0.53‰, respectively, relative to NIST-3134) may be controlled by Rayleigh and equilibrium fractionation. The different distributions of Mo isotope compositions of molybdenite in the two deposits may be caused by the physiochemical differences in ore-forming systems. The high Mo content of the Taihua Supergroup and the Xiong'er Group, combined mean values of Mo isotopes between molybdenite and whole rocks suggested that the two stratigraphic units would be the main contributor of Mo for the Paleoproterozoic Mo mineralization that mixed with small proportions of isotopically lower values of the mantle. [ABSTRACT FROM AUTHOR]