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[Display omitted] • Five ore-forming stages are recognized in the Yechangping porphyry-type orebodies. • Fluid characteristics suggest that Yechangping is a Dabie-type porphyry Mo deposit. • The process of fluid immiscibility, boiling, and mixing cause the mineralization. • Magmatic-hydrothermal system of Yechangping deposit extends to depths of 10 km. Dabie-type porphyry Mo deposits have recently emerged as a distinct subtype of porphyry Mo deposits, but questions remain about the magmatic-hydrothermal fluid evolution in the formation of this type of deposit. Here, well-developed fluid inclusions in quartz phenocrysts, unidirectional solidification textures (UST), and quartz veins in the Yechangping porphyry Mo-W deposit, Qinling Orogen, completely record the magmatic-hydrothermal mineralization process. The characteristics and evolution of the ore-forming fluid in this deposit are investigated through petrography, microthermometry, and laser Raman spectroscopy analysis of fluid inclusions at different stages in order to improve our understanding of the fluid evolution in the genesis of Dabie-type porphyry Mo deposit. The mineralization process in the porphyry-type orebody can be divided into three periods and five stages: (1) magmatic period, including quartz phenocrysts (stage 1); (2) magmatic-hydrothermal transition period, including UST (stage 2); (3) hydrothermal period, including quartz ± K-feldspar veins (stage 3), quartz-molybdenite veins (stage 4), and calcite ± quartz veins (stage 5), where stage 4 is the main ore-forming stage. The fluid inclusions in quartz and calcite can be recognized as pure CO 2 (PC type), CO 2 -H 2 O (C type), daughter minerals-bearing (S type), and H 2 O (WV type and WL type) inclusions. Ore-forming fluid is initially high temperature, high salinity, and CO 2 -rich, belonging to the H 2 O-CO 2 -NaCl (±KCl) system suggested by the fluid inclusions identified in UST. The estimated lithostatic pressures of stage 1 range from 284–362 MPa, corresponding to depths of 10.3 to 13.2 km, which are consistent with the formation depth of the underlying magma chamber. The presence of UST in stage 2 indicates that the magma was saturated with fluid. Due to the fluctuating pressure (123–260 MPa) in UST of stage 2, fluid immiscibility happened soon after the fluid exsolution and is inferred to occur between the CO 2 -rich and aqueous phases. Then, the fluid boiling and mixing occurred in stages 3 and 4, respectively. The estimated pressures of stage 4, which represent the main mineralization stage, range from 45–175 MPa, corresponding to depths of 4.6–6.4 km. The immiscibility of CO 2, along with the fluid mixing-induced cooling and dilution, caused an increase in p H and a decrease in oxygen fugacity, which serves as a crucial mechanism for Mo mineralization at the Yechangping deposit. Stage 5 is characterized by low temperature (185–309 °C) and low salinity (2.9–8.7 wt% NaCl equiv.). The primary high temperature, high salinity, CO 2 -rich fluids, and relatively deep ore-forming depth suggest that the Yechangping deposit is a typical example of a Dabie-type porphyry deposit. The characteristics of fluids and the variation in estimated depth at each stage record the evolutionary process of a magmatic-hydrothermal system extending to depths of nearly 10 km in the Yechangping deposit. [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] • Five types of tourmaline have been identified in the Donggebei Mo deposit. • The tourmalines belong to alkali group, changing from shorl to dravite. • The δ11B values imply magmatic-hydrothermal fluid origin. • Chemical variations of tourmaline trace the ore-forming processes. Tourmaline is a chemically and mechanically stable mineral that commonly occurs in hydrothermal mineral systems, and has been used to trace the mineralization processes of many genetic types of ore deposits. Here we apply tourmaline chemistry and isotopic composition to trace the genesis of a porphyry Mo system for the first time. Tourmaline is widespread in the Donggebi Mo deposit in East Tianshan, NW China, where it occurs in five distinct associations: type PG disseminated in the porphyritic granite, TS as hydrothermal tourmalite in the country rocks (strata), V1 in quartz-molybdenite vein, V2 in quartz-polymetallic sulfide vein, and V3 quartz-calcite-fluorite vein. All the tourmaline types belong to the alkali group, with the V3 being schorl and the other types being dravite and schorl. The PG-type tourmalines partly inherit the features of the porphyritic granite, and are rich in F, Na, Al and Sc, and poor in Fe, Mg, Ca, Sr, Ba, Pb, V and Mo compared to the other types. They have low Fe3+ concentrations and low Fe3+/(Fe3++Fe2+) ratios, suggesting a reducing fluid system. They also display weaker Eu-depletion (with an average (Eu/Eu*) N value of 0.96) than the porphyritic granite, and are considered to be the products of interaction of the reducing fluids and the granites. The average (Eu/Eu*) N values of tourmalines decrease from 6.66 of type V1, 5.65 of type V2, to 4.80 of type V3, indicating that the fluids became progressively less reducing along with sulfide precipitation. The δ11B values of the tourmalines range between −15.9 ‰ and −12.5 ‰, resembling those of S-type granites or clastic sediment-sourced hydrothermal fluids. The tourmaline grains in our study do not display any remarkable δ11B variation from the cores to rims, indicating that the δ11B values of the fluids and their source were relatively constant. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Xiaoqinling area is widespread of the ∼2.3 Ga Xiaohe granitic plutons. • The REE patterns and Sr/Y and δEu values of granites vary with source depth of magmas. • The Xiaohe granite is A-type granite emplaced in an extensional setting. • The Xiaohe granite was intruded by the ∼1.8 Ga granite. The early Paleoproterozic is generally considered as a worldwide tectonic quiescent period. It is unusual that widespread early Paleoproterozoic magmatism has been identified in the North China Craton (NCC), especially in the Xiaoqinling Terrane at the southern NCC. The Xiaohe granite occurs along the southern margin of the Xiaoqinling Terrane and intrudes the lower portion of the Taihua Supergroup (gneisses). Previous data suggest the emplacement time of the Xiaohe granite ranging from the early to late Paleoproterozoic, leaving a controversy over 500 Ma. To accurately constrain the age, genesis and tectonic setting of the Xiao granite, we have carried out a comprehensive study and here present new petrographical, geochronological, and isotope and element geochemical data. It is confirmed that the Xiaohe granite is dominated by the ca. 2.3-Ga monzogranite and locally intruded by the Guijiayu granites at 1.82 ± 0.05 Ga. Three samples from the Xiaohe granite yield consistent zircon U − Pb ages of ca. 2.3 Ga, and ɛ Hf (t) values showing mixing of juvenile and recycled continental crust sources. The Xiaohe granite are characterized by high SiO 2 (70.7–79.6 %) and high alkali (5.67–10.15 %), belong to calc-alkaline to shoshonite series and show weak peraluminous feature with A/CNK values around 1.1. Its geochemical characteristics are similar to those of A-type granites formed involcani arc or syn- to post-collision tectonic settings. Samples also display eastward decrease of Sr/Y, (La/Yb) N and δEu values, and weakening REE fractionation, indicating an eastward increase of plagioclase in residue during partial melting of the crust, and the magma sources become shallow eastwardly. Hence it is concluded that the Xiaohe granite was formed in a widespread granitic event associated with continental collision or terrane amalgamation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Taishanmiao was constructed by three pulses of magmatism at 125, 123 and 116 Ma. • The latest porphyritic syenogranite induced Mo mineralization at Zhuyuangou. • The highly fractionated I-type granite results from partial melting of ancient crust. • Small porphyry can concentrate Mo from batholith and then effectively deposit it. The Qinling Orogen is well known for its huge Mo resource. The porphyry Mo deposits are associated with small granite porphyries, albeit great batholiths accommodate limited Mo mineralization. In this study, detailed geochemical, isotopic, and geochronological studies were carried out to constrain the petrogenesis of the Taishanmiao batholith and time framework of magmatism and associated Mo mineralization at Zhuyuangou. Zircon geochronology reveals gradually decreasing emplacement ages, from 124.8 ± 1.0 Ma for the medium- to coarse-grained syenogranite, through 122.8 ± 1.4 Ma for fine- to medium-grained syenogranite, to 115.1 ± 0.95 Ma for porphyritic syenogranite. The last two phases hosted the Zhuyuangou Mo mineralization with a molybdenite Re-Os isochron age of 117.7 ± 1.0 Ma. Major and trace element features support highly fractionated I-type affinity for Taishanmiao. Zircon Lu-Hf isotopic studies yield ε Hf (t) values of −19.6 − -8, and two-stage Hf model ages (T DM2) of 1679–2408 Ma. It thus supports ancient continental crust, especially Taihua Supergroup and Xiong'er Group, as the primary source. Compared to the source rock, the low Mo concentrations of the batholith are attributed to the massive fluid flux that contributes to the formation of the Zhuyuangou and Donggou deposits. Small porphyries can effectively concentrate exsolved fluids and metal compared with great batholith. Their shallow emplacement depths result in greater temperature/pressure/composition gradient with the wall rocks, higher cooling rate, more fractures or even breccia, and fluid boiling and mixing, facilitating intensive hydrothermal alteration and mineralization. [ABSTRACT FROM AUTHOR]

[Display omitted] Western Tianshan along the southwestern Central Asian Orogenic Belt is well-endowed with epithermal and porphyry Au-Cu deposits. The Kuruer Cu-Au deposit, recently discovered in the eastern part of Western Tianshan, represents a transition from a high-sulfidation epithermal to a porphyry system. In this contribution, we explored the capacity of chalcopyrite to record direct mineralization time and fluids evolution in the Kuruer deposit, by presenting Re-Os isotopic data and the concentration range of 16 trace elements obtained through LA-ICP-MS. The chalcopyrite Re-Os isochron age of 256 ± 12 Ma (MSWD = 2.6) is comparable within error with the U–Pb age of the ore-causative albite porphyry which demonstrates a Permian porphyry-epithermal system instead of the previously proposed Carboniferous epithermal mineralization. The initial 187Os/188Os ratio of 0.81 ± 0.17 for chalcopyrite implies mixing between crust and mantle. Both pyrite and chalcopyrite can host trace elements in considerable amounts, where pyrite primarily hosted Co, As, Au, V, and Bi, but chalcopyrite concentrated more Zn, Cd, In, Sn, Sb, Mo. The study also highlighted systematic variation of trace element concentrations and Cd/Zn ratios in chalcopyrite and pyrite that can be powerful indicators of fluid phase separation and fluid mixing with meteoric water. [ABSTRACT FROM AUTHOR]