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The Kochbulak gold deposit is situated on the northern slope of the Kurama range of eastern Uzbekistan and is one of the largest Tellurium-rich epithermal gold deposits in the world. Based on a detailed field and petrological investigation, three stages of mineralization can be classified, including, from early to late, quartz–pyrite vein stage, quartz–telluride–sulfide–sulphosalt–native gold stage, and pyrite–chalcopyrite vein stage. Abundant tellurides, including tellurobismuthite, rucklidgeite, tetradymite, altaite, volynskite, and hessite, have been well recognized in the second (main) mineralization stage. Based on the mineral assemblages and petrogenetic occurrence, the sequence of tellurides in the second mineralization stage can be approximately identified as altaite+calaverite+native tellurium, calaverite+native gold, Bi-telluride (e.g., tellurobismuthite and rucklidgeite)+petzite+native gold, Ag-Bi telluride (e.g., volynskite), and Ag-telluride (e.g., hessite)+native gold. By depicting the Log ƒ(Te2)-Log ƒ(S2) relationship diagram of the Kochbulak gold deposit under 250 °C and 200 °C, the Log ƒ(S2) value ranges from −14.7 to −8.6 and from −16.7 to −10.9, respectively, with Log ƒ(Te2) value varies from −12.3 to −7.8 under 250 °C and ranges from −13.8 to −11.2 under 200 °C. [ABSTRACT FROM AUTHOR]

Permian alkaline granitoids are widely distributed throughout the Tien Shan Orogen and adjacent region of the southern Central Asian Orogenic Belt. However, their petrogenesis and related tectonic setting remain equivocal. A detailed mineralogical, U-Pb zircon dating, in situ elemental and Sr-Nd-Hf isotopic studies of the uranium-rich Akkulen syenite intrusion in the Northern Tien Shan of Kyrgyzstan were undertaken to better understand its magmatic processes and geodynamic evolution. Four independent oxygen barometers have shown that the oxygen fugacity of the Akkulen syenitic magma evolved from initial low fO2 (2 (>NNO +1) during magma ascent and cooling; Apatite geochemical characteristics also indicate that the magma is relatively high F (2.9–5.1 wt.%), with low Cl (0.053–0.13 wt.%) and anhydrous (<4 wt %) contents. According to whole-rock geochemical data, the syenite samples have abnormally high U (38.5–57.1 ppm) and Th (96.2–137 ppm) concentrations, we suggest that high F content and moderate oxygen fugacity are beneficial for uranium enrichment. Zircon grains from a syenite sample yielded a weighted 206Pb/238U age of 283.5 ± 2.6 Ma. The intrusion has an A-type granite affinity with high alkali (Na2O + K2O) contents and Fe/(Fe+Mg) ratios, high LREE/HREE (~5), and low Sr, Ba, and Eu contents. They have negative εNd(t) (−5.2 to −3.6) values with Mesoproterozoic two-stage model ages (T DM2 = 1.35–1.47 Ga), and variable εHf(t) values (−4.6 to +2.4) with Mesoproterozoic two-stage model ages (T DM2 = 1. 2–1.59 Ga), which suggest these rock derivations from the relatively old crustal with minor contribution from juvenile crustal melts. In comparison with regional available dataset, we propose that the alkaline Permian granitoids in Kyrgyz Northern Tien Shan may have been originated from large-scale partial melting of Mesoproterozoic metamorphic basement with minor juvenile crustal material in a post-extensional setting. In contrast, the Early Permian granitoid magmatism in the Tarim Craton may have been caused by the partial melting of Neoproterozoic basement rocks associated with Permian mantle plume activities. [ABSTRACT FROM AUTHOR]

Elucidating metal transport agents is the key to understanding the genesis of deposits and tracking the locations of concealed orebodies. Here, we integrate H-O-S-Cu isotopic data from the shear-zone-hosted Lingyun Cu deposit, China, as a means to fingerprint metal transport agents. Sulfide mineralization can be divided into early and late stages, which consist of chalcopyrite + bornite + quartz veins and chalcopyrite + bornite + ankerite veinlets, respectively. Both δ18Ofluid and δD values of fluid inclusions hosted by quartz (δ18Ofluid: 0.5‰ to 9.9‰, δD: –103.9‰ to –60.1‰) and δ65Cu values of sulfides (–1.85‰ to +0.39‰) from the early stage progressively decrease from the southeastern to northwestern portions of the Lingyun deposit, whereas sulfide δ34S simultaneously shifts toward heavier values (–14.4‰ to 5.0‰). The δ34S and δ65Cu values of sulfides from the late stage have restricted ranges from –11.2‰ to –9.3‰ and –0.30‰ to 0.05‰, respectively. The possibilities of meteoric water addition, water-rock interaction, inter-mineral Cu partitioning, diffusion, and oxidation could be ruled out as reasons for having caused systematic H-O-S-Cu isotope variations. Vapor-liquid separation resulted in preferential incorporation of light Cu, H, and O isotopes into the vapor phase. The decrease in oxygen fugacity in the fluids resulted in a shift toward heavier δ34S values as fluid flowed outward. Vapor-phases are the dominant transport agents for Cu in the Lingyun deposit, which may be widely applicable to shear-zone-hosted deposits. The direction of progressively increasing δ65Cu, δD, and δ18O values and decreasing δ34S values allows identification of potential locations of concealed orebodies. [ABSTRACT FROM AUTHOR]

The Yuhaixi Mo(Cu) deposit is a new discovery in the eastern section of the Dananhu-Tousuquan island arc, Eastern Tianshan. However, the genesis of the Yuhaixi Mo(Cu) deposit is still not fully understood. The Yuhaixi intrusion is composed of monzonitic granites, diorites, granites, and gabbro dikes, among which disseminated or veinlet Mo and Cu mineralization is mainly hosted by the monzonitic granites. The LA-ICP-MS zircon U-Pb dating yields emplacement ages of 359.4 ± 1.6 Ma for the monzonitic granite, 298.8 ± 1.8 Ma for the diorite, and 307.0 ± 2.3 Ma for the granite. The Re-Os dating of molybdenite hosted by monzonitic granite yields a well-constrained 187Re-187Os isochron age of 354.1 ± 6.8 Ma (MSWD = 1.7) with a weighted average age of 344.5 ± 3.1 Ma. The Mo mineralization is closely associated with the Yuhaixi monzonitic granite. The Yuhaixi monzonitic granite rocks are characterized by high silica (SiO2 > 70 wt.%), low MgO (0.23–0.36), Ni, Cr contents, and they are enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs: e.g., K, Ba, Pb and Sr), and depleted in heavy rare earth elements (HREEs) and high field-strength elements (HFSEs: e.g., Nb, Ta and Ti). They are weak peraluminous and have high εHf(t) (11.37–17.59) and εNd(t) (1.36–7.75) values, and varied initial 87Sr/86Sr (0.7037–0.7128) values. The Yuhaixi post-ore granites exhibit similar geochemical and isotopic signatures to the Yuhaixi monzonitic granite. These characteristics suggest that the Yuhaixi felsic rocks are likely sourced from the partial melting of the juvenile lower crust. The Yuhaixi diorite has low SiO2, and K2O contents, relatively high Na2O, MgO (Mg# = 45–53) contents, and depletions in HFSE (e.g., Nb, Ta, and Ti). These geochemical features, coupled with isotopic data such as low initial 87Sr/86Sr (≤0.7043), high εNd(t) (2.5 to 3.0) and εHf(t) (≥11.6) values, and young Hf model ages, suggest that their parental magmas possibly originated from the partial melting of the depleted lithospheric mantle that was metasomatized by hydrous melts or fluids from the subducting oceanic plate. Integrating our new results with previous works on the Dananhu-Tousuquan island arc belt, we suggest that the Yuhaixi Mo(Cu)deposit is likely sourced from the juvenile lower crust, which was formed in an arc setting, where the bipolar subduction of the North Tianshan oceanic slab forms the Dananhu Tousuquan belt to the north and the Aqishan-Yamansu belt to the south. The eastern section of the Dananhu-Tousuquan island arc is a promising target for late Paleozoic porphyry Mo(Cu) deposits. [ABSTRACT FROM AUTHOR]

In the Yili terrane at Awulale mountain, most shoshonitic lavas are related to post-collision extension and were extruded during the Late Carboniferous to Early Permian (310–280 Ma). Herein, we evaluate a small-volume occurrence of shoshonitic magmas in the southern Yili terrane formed c. 346 Ma ago. The high MgO (Mg#) and positive Hf isotope values of the shoshonitic magmas indicate the input of juvenile mantle-derived material. Still, their high Ba–Sr signatures were likely inherited from the partial melting of previously metasomatized lithospheric mantle. We argue the shoshonitic magmatic activity recorded a syn-subduction extensional history in the Yili terrane. This interpretation is consistent with the magmatic records from Early Carboniferous A-type granite and magnesian andesite found in the Zhaosu–Adentao–Dahalajunshan area of the southern Yili terrane. Combined with the geological development in this area, we propose that the emergence of the shoshonitic rocks records either the retreat of the trench or the rollback of the Junggar oceanic slab that occurred at or before the 346.1 ± 3.1 Ma age of the rocks. [ABSTRACT FROM AUTHOR]