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The Chinese Tianshan experienced large-scale transcurrent tectonics, synkinematic emplacement of ultramafic to felsic intrusions, and the formation of various mineral deposits during late Paleozoic accretionary orogenesis. The relationships among the spatial variation of deformation, the distribution of Permian orogenic Au and magmatic Ni-Cu sulfide deposits, and the kinematic evolution of crustal-scale shear zones, however, remain ambiguous. To address these ambiguities, the spatial variation in the degree of deformation in the Kanggur-Huangshan shear zone in the Chinese Tianshan was characterized using detailed structural measurements and zircon U-Pb and muscovite 40Ar/39Ar age data. The new structural data indicate that a prominent spatial variation exists in the style of deformation throughout the Kanggur-Huangshan shear zone; intense ductile deformation structures are dominant in the east, while brittle structures become progressively more dominant toward to the west. Zircon U-Pb and muscovite 40Ar/39Ar age data for syn- and postkinematic intrusions along the Kanggur-Huangshan shear zone indicate that dextral strike-slip shearing occurred between 279 Ma and 249 Ma. The spatial variation in the degree of deformation and exhumation along the Kanggur-Huangshan shear zone was potentially caused by regional differential uplift induced by the collision of the Tianshan and Beishan regions; this was likely responsible for the predominant occurrence of magmatic Ni-Cu sulfide deposits in the eastern portion of the Kanggur-Huangshan shear zone and orogenic Au deposits in the western portion. The identified spatio-temporal relationship between deformation and distribution of orogenic Au and magmatic Ni-Cu sulfide deposits is crucial to the future success of mineral exploration in the Central Asian orogenic belt.

Late Paleozoic large-scale transcurrent tectonics and synkinematic intrusions are prominent features in the Eastern Tianshan segment of the southwestern Central Asian Orogenic Belt. However, the spatial and temporal relationship between synkinematic intrusions and crustal-scale shear zones remains unclear. Here we report petrology, geochemistry, and geochronology of the Qiziltag pluton associated with the Kanggur-Huangshan Shear Zone (KHSZ) with a view to characterize the spatial and temporal relationship between synkinematic intrusions and large-scale transcurrent shearing. Field relations and zircon U-Pb ages indicate that the Qiziltag pluton was formed through two stages of magmatism, with earlier stage granitoids (gneissic biotite granite: 288.9 ± 1.9 Ma, biotite monzogranite: 291.5 ± 1.7 Ma, K-feldspar granite: 287.9 ± 3.1 Ma), and later stage bimodal intrusions (biotite quartz monzonite: 278.5 ± 1.8 Ma, gabbro: 278.1 ± 2.3 Ma). The earlier stage granitoids are high-K calc-alkaline, enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs; e.g., Rb, Th, and U), and depleted in high field strength elements (HFSEs; e.g., Nb, Ta, and Ti). Combined with their depleted isotopic compositions (εNd(t) = +6.29 to +7.48) and juvenile model ages (TDM2 = 450–610 Ma), we infer that the granitoids were derived from juvenile lower crust in a post-collisional tectonic transition (from compression to extension). The structural and temporal features indicate that the earlier stage (ca. 290 Ma) granitoids formed prior to the regional large-scale dextral strike slip. The later stage bimodal intrusions are dominated by biotite quartz monzonite as the felsic member and gabbro as the mafic component. The biotite quartz monzonite is high-K calc-alkaline with enriched LREEs and LILEs (e.g., Rb, Th, and U), and depleted HFSEs (e.g., Nb, Ta, and Ti), whereas the gabbro is subalkalic with depleted LREEs and HFSEs (e.g., Nb and Ta), resembling normal mid-ocean ridge basalt features. The bimodal intrusions show similar isotopic compositions (εNd(t) = +6.41 to +6.72 and εHf(t) = +9.55 to + 13.85 for biotite quartz monzonite; εNd(t) = +9.13 to +9.69 and εHf(t) = +4.80 to +14.07 for gabbro). These features suggest that the later stage (ca. 280 Ma) bimodal intrusions were derived from partial melting of depleted mantle and anatectic melting of lower crust materials induced by synchronous underplating of basaltic magma in a post-collisional extension. The structural features of the bimodal intrusions indicate that the later stage (ca. 280 Ma) magmatism was coeval with the development of the KHSZ. In conjunction with spatial and temporal evolution of magmatism and sedimentary records of Eastern Tianshan, we infer that transition between the northward closure of the North Tianshan Ocean and subsequent collision between the Central Tianshan Massif and the Qoltag Arc belt occurred at ca. 300 Ma.

The Huangshandong Ni–Cu sulfide deposit, located in the Kangguer–Jing’erquan ductile shear zone, belongs to the Jueluotage island arc belt in Eastern Tianshan of the Central Asian Orogenic Belt. The Huangshandong mafic–ultramafic pluton, which has a fusiform shape, is believed to have intruded strongly foliated Late Carboniferous volcanic rocks during the development of the regional ductile shear zone. Some orebodies in the deposit show intense ductile deformation. Among them, the No. 17 orebody is entirely controlled and hosted by the ductile shear zone. Host rocks and ores from this orebody show intense deformation and alteration, and could be called ore mylonites. Furthermore, numerous anastomosing veinlets can be observed in copper-rich carbonate-sulfide veins in the ductile shear zone. Geological field investigation and ore petrography studies indicate that sulfide ores at Huangshandong are composed of three types: undeformed magmatic ores, deformed magmatic ores, and hydrothermal overprinted ores. Magmatic ores with net fabrics remain unaltered and undeformed, and sulfide minerals in them show only brittle fractures. Silicate and sulfide minerals in deformed magmatic ores are characterized by intense deformation fabrics. Examples for such fabrics are kink bands, wavy extinction of uralite, domino structure of phlogopite, and elongated grains of pyrrhotite and pentlandite. Hydrothermal overprinted ores are characterized by strong deformation, flattened grains, and recrystallization of pyrrhotite; moreover, annealing of pyrrhotite is frequently observed. Pyrrhotite, pentlandite, and chalcopyrite in hydrothermal overprinted ores have high Ni and Co concentrations in pyrrhotite, a higher Ni concentration in pentlandite, and high Ag and Cd concentrations, respectively. We attribute Ni and Co in fluid-overprinted ores mainly to the alteration of olivine, and the dissolution of primary chalcopyrite is the likely source of copper in chalcopyrite-rich hydrothermal overprinted ores. During the intruding and cooling of the Huangshandong pluton, intense regional ductile shearing caused the ductile deformation of sulfide ores in the deposit, and subsequently, ore mylonites were formed. Gangue minerals in the deformed orebodies were crushed to fine-grained minerals and altered to serpentine, chlorite, and uralite. During these processes, fluid and ore elements were released and reacted with deformed rocks and ores, forming anastomosing veinlets on hydrothermal overprinted ores.

Triassic magmatism has been increasingly identified in the Eastern Tianshan and played a crucial role in the tectonic evolution of the Tianshan Orogenic Belt. The petrogenesis and geodynamic setting of the Triassic magmatism, however, are poorly constrained. In this study, we integrate new field and petrological observations, zircon U Pb ages and Hf isotopic compositions, and whole-rock geochemical data for the microgranular enclaves (MEs) and their host Triassic Tianhu granitoids to investigate their origin and the tectonic regime of the Eastern Tianshan during the Triassic. Based on zircon U Pb geochronology, the Tianhu granitoids and MEs have indistinguishable Early Triassic crystallization ages of 247.1 ± 1.8 Ma, 249.5 ± 2.0 Ma, and 251.0 ± 3.2 Ma. The MEs in the Tianhu granitoids are typically sub-rounded to ellipsoidal in shape. They contain abundant acicular apatite, plagioclase that has been partially resorbed, and megacrysts of feldspar and quartz. They are characterized by high Mg# (50–52), positive eHf(t) values of 3.41–5.83, and young one-stage Hf model ages, all of which are indicative of crystallization from mantle-derived melts. The host Tianhu granitoids, which belong to I-type granites, contain higher SiO2 contents (68.3–69.8 wt%) and lower Mg# (38.3–45.4) than the MEs, are metaluminous (A/CNK = 0.97–0.98), and are characterized by high eHf(t) values of 2.26–5.46 and young two-stage Hf model ages. These geochemical characteristics indicate that the Tianhu granitoids and the MEs likely formed through mixing between mafic and felsic magmas. The mafic magma was originally derived from partial melting of a depleted mantle source, and subsequently evolved via fractional crystallization and modification by the felsic magma. In contrast, the felsic magma was generated by partial melting of the juvenile continental lower crust. The Tianhu granitoids would likely form in an intracontinental extensional environment, in which upwelling of the asthenospheric mantle led to partial melting of the lithospheric mantle to form the mafic magmas. And the felsic magmas were produced by partial melting of the deep juvenile crust with a heat source either from the ascending mafic magmas or the upwelling asthenospheric mantle along the thinned orogenic lithosphere. In either case, there would be significant Triassic crust–mantle interaction in the Eastern Tianshan and its adjacent Beishan area. This interaction was responsible for the formation of widespread Triassic granites and related ore deposits in this intracontinental region.

The Huangshandong Ni–Cu sulfide deposit is the largest magmatic sulfide deposit in the Huangshan–Jing’erquan mafic–ultramafic belt in the Eastern Tianshan; it was overprinted by post-magmatic hydrothermal fluids, and metamorphosed and deformed as a result of regional ductile shearing. Ore-forming elements were remobilized as a result of post-magmatic hydrothermal fluid flow, but the extent of this remobilization is still unclear. In this contribution, detailed mineralogical–textural characteristics of silicates and base-metal sulfides in different types of ores in the Huangshandong Ni–Cu sulfide deposit were integrated with spatially resolved trace-element compositions of olivine, serpentine, pyrrhotite, pentlandite, and chalcopyrite to identify the metals that were mobilized, the scale and quantity of metal remobilization, and the phases into which the mobilized metals were incorporated. Based on varying degrees of serpentine and talc alteration, three different types of ores are identified – weakly serpentinized magmatic ores, which are most representative of the primary magmatic mineralization, strongly serpentinized and deformed ores, and talc-altered ores. The cracks consisting of serpentine and magnetite in weakly serpentinized magmatic ores caused by the expansion of olivine during serpentinization; this, serpentine is enriched in ore-forming metals (e.g., Ni, Co, Cu) relative to olivine. The expansion cracks extend from olivine to sulfides also enriched in ore-forming metals, suggesting that some metals were mobilized from olivine during serpentinization. Based on the higher Ni content of secondary pyrrhotite compared to primary pyrrhotite, it is suggested that base-metal sulfides in the primary, weakly serpentinized ores were dissolved and reprecipitated in the strongly serpentinized and deformed ores from metal-rich fluids that interacted with olivine.

The Tianshan is one of the largest gold provinces on Earth and hosts several giant gold deposits, while most giant gold deposits are distributed in the western and central segments of the Tianshan (i.e., the Western Tianshan) but not in Chinese Tianshan. Thus, the differences for metallogenesis of gold deposits between the Western and Chinese Tianshan attract intensive interest but remain ambiguous. Here we present sericite 40Ar/39Ar ages and S–Pb isotope compositions of pyrite from the Kanggur gold deposit, the largest shear zone-related gold deposit in the Chinese Tianshan. By integrating new sericite 40Ar/39Ar plateau ages (262.71 ± 2.95 Ma and 263.40 ± 2.94 Ma) with previous geochronological results, three peaks in gold mineralization are identified for the entire Tianshan: an early peak at ca. 330 Ma during which time subduction–accretion-related porphyry-type and orogenic gold deposits formed, a middle peak at ca. 290 Ma during which time post-collisional magmatism-related orogenic gold deposits formed in a collisional compressional to post-collisional extensional environment, and a late peak at ca. 260 Ma during which time strike–slip shear zone-related orogenic gold deposits formed in a post-collisional extensional environment. The sulfur (δ34SV-CDT of −1.0 to +2.5‰ for pyrite from ores and −1.9 to +2.6‰ for pyrite from wall rocks) and lead (18.199–18.231 for 206Pb/204Pb, 15.585–15.624 for 207Pb/204Pb, 38.104–38.229 for 208Pb/204Pb for pyrite from ores, and 18.176–18.244 for 206Pb/204Pb, 15.583–15.611 for 207Pb/204Pb, 38.090–38.205 for 208Pb/204Pb for pyrite from wall rocks) isotope compositions of pyrite indicate that the metals in gold deposits throughout the Tianshan were sourced from different reservoirs. In the Western Tianshan, the ore-forming metals for the deposits southwest of longitude 70°E were mainly sourced from upper crustal reservoirs, whereas those east of longitude 70°E were mainly sourced from lower crustal reservoirs. In the Chinese Tianshan, however, the ore-forming metals were dominantly sourced from lower crustal and/or mantle reservoirs. These different reservoirs were likely responsible for the distinct characteristics of the gold deposits located in the Western and Chinese Tianshan.

The return of widespread banded iron formation (BIF) deposition during the Neoproterozoic Era after a more than one-billion-year hiatus appears to be a hallmark of the Neoproterozoic, and may be indicative of critical changes in the Earth’s environmental and tectonic conditions. However, consensus on the Fe sources and origin of Neoproterozoic iron formations (NIFs) remains elusive. Here we present new petrographic and geochemical data from the newly discovered Shalong NIF from the Central Tianshan block in order to constrain the iron source and elucidate the origin and depositional conditions of the NIF. The major and trace element composition of the Shalong NIF indicates that it is a relatively pure chemical sediment with a low detrital input. Rare earth elements and Y patterns (REY) exhibit seawater-like signature such as depletion in light REEs (LREEs) and enrichment in heavy REEs (HREEs). The weak positive Eu anomalies (Eu/Eu∗ = 1.11–1.31) and consistent chondritic Y/Ho ratios of 25 to 29 (average 26) suggest a predominant influx of low-temperature hydrothermal fluids. The geochemistry of the Shalong NIF also supports a predominant hydrothermal iron source characterized by low-temperature hydrothermal fluids. The lack of negative Ce anomalies, as well as weak positive Eu anomalies, and positive and variable δ56Fe values (−0.09‰ to +1.28‰) in the Shalong NIF indicates partial Fe2+ oxidation in a relatively large dissolved iron marine basin under oxygen-limited conditions. The Shalong NIF deposition likely took place on the slope of an extensional oceanic basin in a low energy environment. The Shalong NIF has a close association with metamorphized- bimodal volcanic rocks and predominant hydrothermal iron source. Combined with no sign for any glacial influence and depositional age prior to the global Sturtian glaciations, we suggest that the Shalong NIF is a non-glaciogenic Neoproterozoic iron formation in association with volcanic and hydrothermal activity. Our results, in conjunction with previous studies, suggest that glacial events are not essential or necessary for the origin of all the NIFs. Instead, hydrothermal activity seems to be a more important controlling factor for the build-up of ferruginous basins and subsequent iron oxidation events in the Neoproterozoic leading to the sudden recurrence of NIFs.

The Dajingou gold deposit is one of the typical gold deposits in the Quruqtagh metamorphic terrane, north of the Tarim Craton. The deposit mainly comprises gold-bearing quartz veins hosted in Precambrian metamorphic rocks and structurally controlled by the subsidiary faults and ductile shear zone. To determine the age of gold mineralization in the Dajingou deposit, a single sericite 40Ar/39Ar age of 829.4 ± 4.8 Ma (MSWD = 0.57) and hydrothermal zircon weighted average U–Pb ages (812 ± 15 Ma, MSWD = 3.2) from auriferous quartz veins were obtained in this study, indicating that mineralization occurred in the mid-Neoproterozoic (ca. 0.83 Ga), corresponding to regional metamorphism of the Tarim Craton, termed the Tarim orogeny. The Dajingou deposit is the first Precambrian gold deposit identified in North Xinjiang, NW China. The δ18O and δD of quartz ranges from 14.7‰ to 15.9‰ and −104‰ to −75‰, respectively; the calculated δ18OH2O of the fluids ranges from 0.9‰ to 5.0‰. This suggests that the ore-forming fluids in the Dajingou gold deposit were derived from dehydration of metamorphic rocks during regional metamorphism, with a subsequent input of meteoric water. Based on its similarities with typical orogenic gold deposits, the Dajingou deposit is proposed to be an orogenic gold deposit formed during the mid-Neoproterozoic Tarim orogeny in the Tarim Craton.

Metadiabase sills are extensively distributed in the Astingbulake region in the central Quruqtagh block of the NE Tarim Craton. Here we report laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U–Pb ages and Hf isotopes, as well as whole rock elemental and Sr–Nd isotopic data for these Mesoproterozoic sills. Zircons from one of the mafic sills yield an emplacement age of 1470 ± 9 Ma (95% confidence, MSWD = 3.2, n = 23) Ma. Despite the greenschist-amphibolite facies metamorphism, most of the immobile elements provide important clues for the petrogenesis and tectonic settings of these rocks. Except for their variable fluid mobile-element contents, all the studied samples show enrichment in incompatible trace elements with no obvious Nb–Ta depletion, similar to the features of continental flood basalts and ocean island basalts (OIB). Combined with their relative higher 87Sr/86Sr (t) ratios (0.70666 to 0.70784), negative ɛNd(t) (−4.30 to −3.96) and ɛHf (t) (−5.49 to −1.13) values, we propose that the protolithic magmas were derived from the high degree partial melting of enriched continental lithospheric mantle within continental rifting settings. The ∼1.5 Ga diabase sills from North Tarim corresponded to the major episode of mafic magmatism during Early Mesoproterozoic time identified from other crustal fragments of Laurentia, Siberia, Greater Congo and South China, and probably belong to one of the three major large igneous provinces associated with the breakup of the Mesoproterozoic Columbia supercontinent. Our data provide important constraints on the configuration of the Tarim Craton within the Columbia supercontinent

Located between the Turpan-Hami, Junggar and Tarim blocks, the Central Tianshan zone is an important component of the Central Asian Orogenic Belt (CAOB) and crucial linkage between the Siberian, Kazakhstan, Junggar, Turpan-Hami and Tarim blocks. The Hongliujing granite associated with Nb–Ta mineralization in the Central Tianshan zone, dated at ca. 740 Ma using zircon LA-ICP-MS dating, is the first reported Neoproterozoic intrusion with a reliable and precise age in the Chinese Central Tianshan. The Hongliujing granite shares all the characteristics of A-type granites. It contains predominant alkali feldspar, and is characterized by high contents of SiO 2 , Na 2 O + K 2 O, K 2 O and high field strength elements (such as Nb, Ta, Zr, Ga and Y), and low contents of CaO, MgO, Ba and Sr, with high FeO t /(FeO t + MgO) and Ga/Al ratios typical of A-type granites. Based on the geochemistry and zircon Hf isotope data, we propose that the Hongliujing granite was most likely produced by partial melting of basic rocks in the lower crust which may have been derived from mantle magmas. The Hongliujing granite belongs to A1-type granites, which indicate a rifting formation environment, suggesting that like the Tarim Block, the Central Tianshan zone recorded Neoproterozoic rift-related igneous events related to the breakup of the Rodinia supercontinent. Our study verifies that not only the Tarim Block is related to the breakup of the Rodinia supercontinent, but also it is true for some key blocks in CAOB such as the Central Tianshan. Our new geochemical and geochronologic data also support and strengthen the notion that the Central Tianshan zone may be a part of the Tarim Block.

The Tarim block, one of the largest cratons in China, records an important part of the Proterozoic crustal evolution of the Earth. Many previous studies have focused on the Neoproterozoic magmatism and tectonic evolution of this block in relation to the break-up of Rodinia, although relatively little is known about its earlier tectono-magmatic history. In this article, we present detailed petrographic, geochronologic, whole-rock geochemical, and in situ zircon Hf isotope data for the pre-Neoproterozoic Xishankou granitoid pluton (XBP), one of several blue quartz-bearing granitoid intrusions well exposed in the Quruqtagh area, and discuss these intrusions in terms of their tectonic environment. Zircon LA-ICP-MS dating indicates that gneissic quartz diorite and granodiorite of the XBP crystallized at 1934 ± 13 and 1944 ± 19 Ma, respectively. Both underwent metamorphism essentially coeval with emplacement, a time that is compatible with the globally distributed 2.1–1.8 Ga crustal amalgamation during formatio...

The Baishitouquan (BST) pluton is a topaz- and amazonite-bearing leucogranite intrusion located in the Middle Tianshan orogen of Xinjiang, northwestern China. This pluton exhibits five lithological zones gradational from the bottom upwards: leucogranite (zone-a), amazonite-bearing granite (zone-b), amazonite granite (zone-c), topaz-bearing amazonite granite (zone-d) and topaz albite granite (zone-e). Contents of REE and other trace elements were analysed on major and accessory minerals, including quartz, plagioclase, K-feldspar, white micas, topaz, fluorite, garnet, zircon and monazite, separated from above five zones of the BST pluton. Chondrite-normalized REE patterns of minerals from zone-a to zone-e display clear convex tetrad effect, and the TE1,3 (quantification factor of tetrad effect) values of these minerals increases from zone-a to zone-e, except that a quartz sample from zone-b and zircon from zone-c exhibits W-type tetrad effect. Therefore, we conclude that REE tetrad features of the minerals, such as quartz, plagioclase, zircon, garnet and monazite, are inherited directly from the melt and have not significantly affected by both fractional crystallization and surface weathering. With progressing of magmatic differentiation, total REE contents decrease, Eu anomaly becomes more negative, whereas Nb/Ta, Zr/Hf and Y/Ho ratios decrease gradually from zone-a to zone-e with increasing TE1,3 values. Therefore, we suggest that F-rich magmatic fluid–melt interaction above its solidus may leave the residual silicate melt with the features of very low contents of all REE, subchondritic Y/Ho, Zr/Hf and Nb/Ta values, and with an M-type tetrad pattern, including minerals crystallizing from it. Such a pattern is manifested by both whole-rock and separate minerals. Hydrothermal fluid–rock interaction played only a minor role to the convex tetrad effect of the minerals and their host rocks.

The Central Tianshan zone is located between the Turpan–Hami and Tarim blocks and played a pivotal role in crustal evolution and collisional tectonics of the southern Altaids (or the Central Asian orogenic belt). The Xingxingxia granodiorite in the eastern Central Tianshan is an Early Paleozoic (424.9 ± 5.8 Ma) intrusion. Petrography, geochemistry and Sr–Nd–Hf isotopes suggest that the Xingxingxia granodiorite was genetically related to a volcanic arc, emplaced above a subduction zone. Thus, the Central Tianshan zone was a magmatic arc above an early Paleozoic subduction zone of the Paleoasian ocean. We present LA-ICP-MS zircon U–Pb dating and Hf isotope determinations of Precambrian zircon grains trapped in the Xingxingxia granodiorite. Three populations of inherited zircons indicate that Neoproterozoic (809 ± 41 Ma; eHf(t) = 0.10–5.73), Mesoproterozoic (~ 1400 Ma; eHf(t) 8.71–10.05) and Paleoproterozoic (~ 1750 Ma; eHf(t) 0.11 and 4.80) tectonomagmatic events in the Central Tianshan zone, which are comparable with those in the Tarim block. Combined with a series of similar geological characteristics between these two blocks, it is suggested that the Central Tianshan zone might have been originally a part of the Tarim block, and was separated from it during the Early Paleozoic time due to pull-apart caused by southward subduction of the Northern Tianshan ocean, a branch of the Paleoasian ocean.

New Sr‐Nd‐O isotopic data are reported for the early Triassic (early Indosinian) Weiya quartz syenite from eastern Central Tianshan, northwestern China, with the aim of documenting its possible source(s), constraining its petrogenesis and discussing its tectonic implications. Whole-rock Rb‐Sr isochron of the Weiya quartz syenite rock yielded an age of 246.5 ± 4.8 Ma, which is well consistent with zircon SHRIMP U‐Pb age. Additionally, the rock exhibits positive e Nd (t) value (+1.36 to +1.66), medium Isr (0.7088 to 0.7090), “normal” δ 18 O value (6.9 to 8.1‰) and young Nd model ages (TDM = 0.88 to 0.91 Ga). Combined with their petrogaphic and geochemical characters, the Weiya quartz syenite is suggested to have been generated by partial melting of juvenile lower crust rocks at high temperature. The partial melting is attributed to intra-continental subduction, which resulted in thickening of the continental crust, delamination of the lithosphere root, underplating of mantle-derived magma and subsequent regional extension. Heat from underplated mantle magma caused melting of the overlying lower crustal rocks and consequent generattion of the quartz syenitic liquid. It is supposed that the intra-continental subduction was induced by tectonic conversion from the Paleo‐Asian subduction-collision system to the Paleo‐Thethys regime during the latest Permian or earliest Triassic in the eastern Tianshan.

The stratabound Tianhu iron deposit, with a reserve of 104 Mt at 42% Fe, is located in the eastern part of the Central Tianshan zone in the southern part of the Central Asian Orogenic Belt. The deposit hosts schist, quartzite, marble, amphibolite, and granitic gneiss belonging to the Tianhu Group. Laser ablation inductively coupled plasma mass spectrometry was used to perform zircon U–Pb geochronology, bulk-rock geochemistry, and in situ zircon Hf isotope analyses of the metavolcanic host rocks for constraining the timing and genesis of the Tianhu iron deposit. According to the newly determined age constraints of 452 ± 3 and 477 ± 4 Ma, the iron deposit was concluded to be Ordovician in age. Geochemistry and zircon Lu–Hf isotope analyses suggested that the host rocks of the deposit represent metamorphosed arc-type volcanic rocks generated by the partial melting of a lower crustal source. Combined with geological and ore petrographic characteristics, the Tianhu iron deposit is interpreted to be of volcano–sedimentary origin with enrichment during subsequent metamorphism. The early Palaeozoic marks a critical iron mineralization epoch in the Eastern Tianshan area. The results also support the model of the Central Tianshan area as a volcanic-arc during the early Palaeozoic, associated with the subduction of the Northern Tianshan Ocean.