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Graphical abstract Highlights: • The Arqiale deposit is a distal skarn Zn-Pb deposit. • Regional magmatism and mineralization age are consistent at ca. 340 Ma. • S-Pb isotope compositions suggests the ore-forming materials were derived from a magmatic source. • There is significant potential for skarn Zn-Pb deposits associated with Late Paleozoic magmatic intrusions in Western Tianshan. Abstract The Arqiale deposit, located in the southern Yili Block of Western Tianshan, Xinjiang, China, is a newly discovered large Zn-Pb deposit with a resource of approximately 10 million tons ore grading 9.65% Zn+Pb, and a certain amount of Cu and Ag. The Zn-Pb orebodies are tabular and lentoid in shape, developed along SW-striking and NW-dipping interlayer structures between the Lower Carboniferous Akeshake (mainly carbonate rocks) and Dahalajunshan (mainly volcanic rocks) formations. Garnet and pyroxene-rich skarn, formed in the early (prograde) stage of skarnization, occurs only locally as lenses within skarn bodies enriched in actinolite, tremolite, ilvaite, biotite, epidote, chlorite, calcite, quartz and fluorite, which were formed in the retrograde stage. Metallic minerals comprise sphalerite, galena, chalcopyrite, pyrite, and hematite. They mainly occur as disseminations, patches and massive ores, replacing retrograde skarn minerals and crosscut by later stage quartz and calcite veinlets. There is a general trend of increasing Cu contents and decreasing Zn/Pb ratios from the upper and south portion to the lower and north portion of the orebody. Rb-Sr dating of seven sphalerite samples yielded an isochron age of 339.5 ± 2.7 Ma, which is almost identical to the 341.8 ± 2.5 Ma age obtained from Sm-Nd dating of eight actinolite samples. Furthermore, zircon U-Pb dating yielded an age of 343 ± 6 Ma for a gabbro-diorite stock that is located about 600 m south of the Zn-Pb orebody. The age data indicate that the mineralization and retrograde skarnization were contemporaneous, and they are likely related to a magmatic intrusion of similar age which may be linked to the gabbro-diorite stock. Thus, although the direct causative intrusion has not been identified, the Arqiale deposit can be classified as a distal skarn deposit. The δ34S V-CDT values of 26 ore sulfide samples range from −7.1‰ to +1.3‰ with an average of −1.5‰. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of 25 ore sulfide samples range from 18.266 to 18.880, 15.577 to 15.668 and 38.068 to 38.720, respectively, which are similar to the Early Carboniferous intrusions of the Wusun Range and partly overlap with the volcanic rocks of the Dahalajunshan Formation, and are different from the carbonate rocks of the Akeshake Formation. Based on these data, we propose that the Arqiale deposit formed from magmatic-hydrothermal fluids emanated from a concealed magmatic intrusion which may be located beneath the northern and deep part of the deposit. Much of the metals and sulfur may have been derived from the magmatic intrusions, although some of them may have also been extracted from the volcanic rocks underlying the deposit. The results of this study indicate that there is a great potential of finding more skarn Zn-Pb mineralization in Western Tianshan, where numerous Early Carboniferous arc-related intrusions with similar ages as the Arqiale deposit, in relation to the subduction of the Southern Tianshan Oceanic plate underneath the Yili-Central Tianshan Block, were emplaced into or beneath carbonate rocks. [ABSTRACT FROM AUTHOR]

[Display omitted] • Skarn Zn-Pb metallogeny in the Tianshan is related to the Late Paleozoic subduction of the Paleo-Asian Ocean. • The ore-forming materials were mainly derived from magmatic source, and partly from country rocks. • A genetic model of skarn Zn-Pb metallogenesis related to the Paleozoic oceanic slab subduction in the Tianshan is established. The Tianshan orogenesis was initiated as a dynamic response to the subduction of several branches of the Paleo-Asian Ocean (PAO) and formed a significant polymetallic metallogenic belt in the western Central Asia. Skarn-related Zn-Pb deposits occupies an essential position in Zn-Pb mineral resources of the Tianshan, but its genesis remains ambiguous, and its economic importance is substantially undervalued. Here, we present a comprehensive overview of the spatiotemporal distribution, geological characteristics, geochemical characteristics of causative intrusions, fluid inclusion geochemistry, H-O-C-S-Pb isotopic systematics to constrain the tectonic setting, source and metallogenic mechanism of skarn Zn-Pb deposits in the Tianshan. Our study suggests that the 380–320 Ma and 350–300 Ma skarn type Zn-Pb mineralization occurred in the Tianshan is temporally and genetically related to the Late Paleozoic subduction of the PAO. The skarn type Zn-Pb resources are primarily hosted by distal skarns, with causative intrusions characterized by calc-alkaline to high-K calc-alkaline, peraluminous, and oxidized rock series that originated from partial melting of depleted mantle wedge and metasomatized by subducted sediment or sediment-derived melts. The hydrothermal fluids that enriched with ore-forming elements were mainly released from the causative intrusions and channeled along interlayer fracture structures within the host rocks, where Zn-Pb mineralization took place due to fluid-rock interaction and fluid mixing. Finally, the mineralization model established in this study may be used to evaluate similar skarn Zn-Pb mineralization systems elsewhere in the Tianshan. [ABSTRACT FROM AUTHOR]

• The Aqishan deposit is a distal skarn Zn-Pb mineralization system. • Re-Os dating of pyrite and zircon U-Pb dating of granodiorite porphyry are consistent at ca. 306 Ma. • Ore-forming materials are mainly derived from magmatic source, some sulfur is sourced from country rocks. • There is significant potential for skarn Zn-Pb mineralization associated with Late Paleozoic magmatism in the Eastern Tianshan. The Aqishan deposit, located in the Eastern Tianshan, Xinjiang, China, is a newly discovered large-scale Zn-Pb deposit with a proven reserve of 1.94 Mt Pb and Zn metal at an average grade of 1.05%. The Zn-Pb orebodies are tabular and lentoid in shape, developed within skarnized carbonates and calcareous volcanoclastic rocks of the Yamansu Formation. The skarn mineral assemblages are characterized by abundant garnet, epidote, chlorite, actinolite, calcite and quartz, with minor amounts of pyroxene. Metallic minerals, comprising sphalerite, galena, chalcopyrite, pyrite, pyrrhotite and arsenopyrite, mainly occur as disseminations and irregular patches within the skarn. Re-Os dating of five syn-ore stage pyrite samples yielded an isochron age of 301 ± 13 Ma, which is in agreement with the 306 ± 2.8 Ma age obtained from the granodiorite porphyry occurring at southeast part of the Aqishan Zn-Pb deposit. The ε Hf (t) values of zircon from the granodiorite porphyry vary from + 9.62 to + 14.69, suggesting a juvenile crust source. The δ 34 S V-CDT values of 22 sulfide samples range from −11.6‰ to −2.76‰, with an average of −5.08‰. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of 9 sulfide samples range from 18.102 to 18.336, 15.539 to 15.655, and 37.929 to 38.479, respectively, which are similar to the Carboniferous grantoids of the Aqishan area and partly overlap with the volcanoclastic rocks of the Yamansu Formation. Based on these data, we propose that the Aqishan deposit formed from magmatic-hydrothermal fluids that emanated from the granodiorite porphyry. Much of the metals were derived from the magmatic intrusions with minor contributions from the volcanoclastic rocks, whereas the sulfur may have been mainly extracted from the country rocks with slight contributions from a magmatic source. The close genetic relationships between the Carboniferous magmatism and skarn type Zn-Pb mineralization in the Aqishan area as well as other deposits in the region suggests a great potential of finding more analogous deposits in the Eastern Tianshan, where carbonates or calcareous volcanoclastic rocks and plutons that related to the subduction of the Northern Tianshan Oceanic slab beneath the Yili-Central Tianshan Terrane during Late Paleozoic are well-developed. [ABSTRACT FROM AUTHOR]

• The Zn-Pb mineralization age of the Caixiashan deposit is 337.2 ± 5.7 Ma. • Reduced sulfur of multiple sources may involve a possible input of magmatic sulfur. • Ore metals are mainly sourced from wall rocks and Carboniferous felsic intrusions. • It is a distal high-temperature carbonate replacement deposit related to intrusions. The Caixiashan Zn-Pb deposit is the largest carbonate-hosted Zn-Pb deposit in Eastern Tianshan, NW China. The deposit comprises the No. Ⅰ, Ⅱ, III and IV ore zones with a proven reserve of 131 Mt ore at 3.95% Pb + Zn. The orebodies generally occur as irregular lenses and pods in altered carbonate rocks of the Mesoproterozoic Kawabulake Group near faults. The mineralization is characterized by massive, disseminated and vein/veinlet sulfides including pyrite, pyrrhotite, sphalerite and galena with minor arsenopyrite and chalcopyrite, as well as sulfosalt minerals of Ag, As, Sb and Pb. The mineralization is associated with tremolite, chlorite, silica and carbonate alterations. Rb-Sr isotopic dating of sphalerite and pyrrhotite yields an isochron age of 337.2 ± 5.7 Ma, which is interpreted as the mineralization age. Zircon U-Pb dating reveals that stocks of diorite, quartz diorite, K-feldspar granite and monzonitic granite that occur in the deposit area were emplaced at 348.2 ± 3.7 Ma, 351.9 ± 3.5 Ma, 333.6 ± 3.6 Ma and 330.0 ± 3.6 Ma, respectively. These age data suggest that the mineralization is coeval with Carboniferous granitic magmatism. The δ34S V-CDT values of sulfides (excluding the syn-sedimentary pyrite) range from −2.42‰ to 19.1‰, suggesting that the reduced sulfur was mainly derived from thermal sulfate reduction (TSR) of seawater-derived sulfates in the marine sedimentary basement rocks and minor contribution by replacement of syn-sedimentary pyrite, as well as a possible input of magmatic sulfur. The Pb isotopic compositions of sulfides, with 206Pb/204Pb ranging from 17.074 to 17.361, 207Pb/204Pb from 15.422 to 15.614, and 208Pb/204Pb from 36.685 to 37.303, partly overlap with those of basement rocks of the Mesoproterozoic Kawabulake Group and the Carboniferous intrusions, suggesting that the ore metals were derived from both the basement and Carboniferous magmatism. On the basis of the spatio-temporal relations between hydrothermal alterations/mineralization and Carboniferous magmatism, we conclude that the Caixiashan Zn-Pb deposit is a high-temperature carbonate replacement deposit related to concealed granitic intrusions, which were formed in an arc environment related to the subduction of the South Tianshan Ocean plate beneath the Central Tianshan massif during the Carboniferous time. The results of this study indicate that there is a great potential of finding more large-scale Zn-Pb deposits similar to Caixiashan in Eastern Tianshan. [ABSTRACT FROM AUTHOR]