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Reconstructing the tectonic architecture of the southern Altaids is of great importance to piece together the continental growth history of the Central Asian continent. In this paper, we address the subduction‐accretion process of the Paleo‐Tianshan Ocean, one branch of the South Tianshan Ocean, in the southern Altaids, through a detailed geological and geochemical investigation of the Wulanmoren Accretionary Complex (WAC). The WAC is composed of ophiolitic mélanges, ocean plate stratigraphy mélanges, and turbiditic coherent units. In this study, we present key geological, petrological, and geochemical evidence indicating back‐arc and ocean island affinity of the igneous rocks of the WAC. Zircon U‐Pb dates of these rocks ages range between 380.2 ± 1.3 and 302.0 ± 5.3 Ma. The sedimentary matrix units of the mélanges were deposited in the Early Devonian (∼405 Ma) to the Late Triassic (∼222 Ma), rather than Silurian strata as previously thought. However, the ages of some detrital zircons in the sedimentary matrix are Precambrian, pointing to a complex evolution involving multiple ocean island terrains and island arcs of different ages that accreted from the mid‐Paleozoic to the Early Mesozoic. Plain Language Summary: Well‐exposed rock outcrops of the Wulanmoren Accretionary Complex (WAC) offer an ideal opportunity to solve the enigma of the evolutionary history of the Paleo‐Tianshan Ocean (PTO) of Central Asia. We report field observations, geochemistry, and geochronology of the WAC in the southern Altaids, pointing to multiple tectonic settings of ages spanning from the Early Devonian (∼405 Ma) to the Late Triassic (∼222 Ma). These reconstructions suggest closure time of the PTO occurred post‐Triassic. Based on detrital zircons provenance analysis, we propose a multi‐island ocean model to explain the tectonic evolution of the PTO in the time period studied. Key Points: The Wulanmoren Accretionary Complex was composed of ophiolitic mélanges, ocean plate stratigraphy mélanges, and coherent unitsThe Late Paleozoic MORB‐like and OIB‐type basalts, and ∼222 Ma coherent units indicate closure of the Paleo‐Tianshan Ocean occurred post‐TriassicThe southern Paleo‐Asian Ocean was an archipelago with several subduction systems which is similar to the modern southwest Pacific [ABSTRACT FROM AUTHOR]

This paper presents new zircon U–Pb ages and Hf isotope data, and whole‐rock major and trace element geochemical data of Permian igneous rocks from the eastern Songnen Massif (SM) and the western Jiamusi Massif (JM), NE China, to constrain their tectonic evolution. Zircon U–Pb dating indicates that Permian magmatism within the eastern SM can be subdivided into two stages: early Permian (ca. 293 Ma) and middle to late Permian (272–257 Ma). The early Permian igneous rocks comprise a bimodal association of rhyolites, basaltic andesites, and gabbros. The middle to late Permian igneous rocks are dominated by gabbro–diorites, monzodiorites, quartz diorites, monzonites, quartz monzonites, granodiorites, monzogranites, syenogranites, and alkali feldspar granites, along with minor bodies of A‐type quartz trachytes. The Permian felsic magmas originated mainly from partial melting of a relatively juvenile lower crust, whereas the coeval mafic rocks were probably derived from partial melting of a relatively depleted lithospheric mantle that was modified by fossil subduction‐related fluids. The igneous rock associations and their geochemical features, together with data from coeval sedimentary and volcanosedimentary successions, indicate that Permian magmatism within the eastern Songnen and western Jiamusi massifs formed in an extensional environment, similar to a back‐arc setting, related to westward subduction of a Palaeo‐oceanic plate beneath the eastern margin of the Jiamusi Massif. We find no evidence for double‐sided subduction of the Mudanjiang oceanic plate during the Permian. [ABSTRACT FROM AUTHOR]

The Tianshan Belt, which lies in the southwest part of Central Asian Orogenic Belt (CAOB), is characterized by abundant ophiolites or ophiolitic mélanges, which are indicators of the existence of oceanic basin can be used for tracking the tectonic evolutionary history of the orogen. The Bindaban (BD) ophiolitic mélange is located in the Central Tianshan Belt, northwest China, which comprises mainly gabbros, diabases, basalts, basaltic lavas (greenschist), and cherts. This paper presents new zircon geochronology, whole‐rock major and trace elements, and Sr, Nd isotope data for mafic rocks in the BD ophiolitic mélanges. In the eastern part of BD ophiolitic mélanges, one normal (N)‐MORB‐type basalt has a U–Pb zircon age of 265.2 ± 1.8 Ma, and one enriched‐MORB‐type dolorite in the western part of BD ophiolitic mélanges has an age of 425.4 ± 3.9 Ma, respectively, indicating either an existing ocean basin from continental rifting to normal oceanic spreading with a long time span from late Silurian to Permain, or two separate ocean basins that formed in late Permian and late Silurian during the Paleo‐Tianshan Ocean evolution. In particular, the 265.2 ± 1.8 Ma age of N‐MORB‐type basalt from BD ophiolitic mélange suggests the youngest oceanic basin (late Permian) existed in southwest CAOB, which reveals that Paleo‐Asian Ocean might last to late Permian, therefore finally closed in or after the late Permian in the North Tianshan area. [ABSTRACT FROM AUTHOR]

The Suolong gold deposit is in the eastern part of the Min‐Li metallogenic belt within the West Qinling Orogen. It is hosted in Lower Permian sandstone and siltstone. The gold mineralization is fault‐ and joint‐controlled. Four hydrothermal stages of mineralization, including the sulphide‐quartz stage, the arsenian pyrite‐quartz stage, the polymetallic sulphide‐quartz‐carbonate stage and the sulphide‐carbonate stage, were identified. Here we report results from fluid inclusion studies and C‐H‐O‐S‐Pb isotopes to get insight into the characteristics of mineralization and ore genesis. Fluid inclusion results indicate that the ore‐forming temperatures and salinities were in the range from 135 to 419°C and 0.18 to 15.27 wt.%, respectively. The δ34S values of pyrite, arsenopyrite and pyrrhotite varied in the 5.3‰–11.4‰ range, suggesting that sulphur originated from stratum sulphur. Lead isotopic compositions of sulphide (206Pb/204Pb = 18.344–18.418, 207Pb/204Pb = 15.628–15.701, 208Pb/204Pb = 38.508–38.743) indicate an upper crust source for Pb. The δ18OH2O‐SMOW and δDSMOW values range from 1.01‰ to 10.31‰ and −116.0‰ to −29.2‰, respectively, indicating that metamorphic water was the source of ore‐forming fluids. The δ13CPDB values (−11.4 to −2.1‰) show that the carbon in the ore‐forming fluids originated predominantly from a deep source. Our data suggest that the Suolong gold deposit is an orogenic gold deposit related to the subduction of an oceanic plate along the Mianlue belt. [ABSTRACT FROM AUTHOR]

The Dabie Orogen constitutes the eastern part of the Qinling‐Tongbai‐Hong'an‐Dabie orogenic belt, however, whether it has involved into the early Palaeozoic subduction–related event as well‐recorded in the western part is still in debate. This study provides new petrological, geochronological and geochemical data for the Beilou and Mafan plutons in the Dabie‐Hong'an orogens. The Beilou pluton is dominated by granite, some of which have been strongly deformed to form mylonites. The Beilou pluton was emplaced at ca. 490 and ca. 450 Ma, whereas the Mafan pluton was emplaced at 450–430 Ma. The whole‐rock major‐ and trace‐element analyses results indicate that both plutons are depleted in high‐field‐strength elements and heavy rare earth elements. The Beilou pluton also has positive whole‐rock εNd(t) values and generally positive zircon εHf(t) values, whereas all but one of the Mafan pluton samples yield positive whole‐rock εNd(t) and consistently positive zircon εHf(t) values. All of the samples have low (87Sr/86Sr)i ratios. These data indicate that these plutons are formed from magmas generated by the partial melting of metasomatized mantle wedge material with minor additions of crustal materials, representing arc magmatic rocks associated with subduction. Detailed detrital zircon dating of flysch sequences of the Foziling Group within the Dabie Orogen indicates that the early Palaeozoic magmatic rocks had once been distributed in the whole Orogen, although only the Beilou pluton now is exposed in the western Dabie Orogen. [ABSTRACT FROM AUTHOR]

The depositional environment and sediment provenance of the third member of Palaeogene Shahejie Formation (Es3) in the Nanpu Sag of the Bohai Bay Basin, eastern China, are reconstructed by analysing trace element and rare earth element (REE), and the formation mechanism of organic‐matter‐rich shales of the same member is also evaluated. These results show that the terrigenous detrital supply in the Nanpu Sag was relatively sufficient during the Es3 interval, and the total REE contents range from 148.23 to 319.28 ppm, close to or higher than that of the upper crust. The Sr concentrations are 214.22–525.54 ppm and the Sr/Ba ratios are 0.31–0.74, which represent the coexistence of fresh, brackish, and saline waters during the Es3 interval. The V/(V + Ni) ratios of 0.71–0.82, Th/U ratios of 0.82–4.05, and positive δCe anomaly confirm that the water column was suboxic condition, with moderate stratification during the Es3 interval. Comparison of REE behaviours suggests that the Es3 sediments were primarily derived from Yanshanian granites at the Yanshanian fold belt at the active continental margin. The development of organic‐matter‐rich shales in the Es3 member in the Nanpu Sag was closely related to major palaeoenvironmental and palaeogeographical variations in that time, which can be summarized: (a) suitable palaeosalinity as well as sufficient nutrients in water column contributed to the boom of various planktonic algae, improving the production efficiency of aquatic organic matter; (b) suboxic water column slowed down the degradation of oxygen‐sensitive materials during the burial process, enhancing the preservation efficiency of aquatic organic matter. [ABSTRACT FROM AUTHOR]

The geochemical differences of magmatic rocks can be influenced by melt source and magmatic processes, including partial melting, fractional crystallization and magma mixing. New whole‐rock geochemical analyses, zircon U–Pb ages and Hf‐isotope data on granitoids from the Qingshanbao complex in the Longshoushan belt highlight a significant Late Ordovician–Early Silurian magmatic episode during the collision between the Alxa and Qilian‐Qaidam blocks, in which magma mixing was a fundamental process. The Qingshanbao complex comprises K‐feldspar granite, granodiorite and diorite emplaced coevally from 442 to 433 Ma. They exhibit peraluminous to metaluminous I‐type features, are enriched in large‐ion lithophile elements (LILEs) and light rare earth elements (LREEs) and depleted in high‐field‐strength elements (HFSEs). Chondrite‐normalized REE patterns are fractionated (LaN/YbN = 10.2–34.9) with weakly negative Eu anomalies (Eu/Eu* = 0.66–0.94). The 176Lu/177Hf zircon two‐stage model ages (TDM2) and the εHf(t) on zircons extracted from the K‐feldspar granite (1613–2,316 Ma, εHf(t) = −14.4 to −3.0) and granodiorite (1640–2015 Ma, εHf(t) = −9.6 to −3.6) suggest they were formed by the mixing of melts produced by the melting of Mesoproterozoic crustal materials, most likely meta‐basic rocks from the Longshoushan Group, and to a lesser extent mantle materials. In contrast, zircons in the diorite yield TDM2 ages ranging from 964 to 1767 Ma and εHf(t) values of −5.5 to 7.1, implying melting of depleted mantle rocks with subordinate participation of lower crust materials. We suggest that the Qingshanbao complex was emplaced when the North Qilian area was in a transitional stage from a compressional to an extensional environment as early as approximately 442 Ma. [ABSTRACT FROM AUTHOR]

The Tulaergen magmatic Ni–Cu deposit is related to mafic‐ultramafic rocks of the Central Asian Orogenic Belt. The ore‐host rocks are lherzolite and websterite and the major ore types are net‐textured and sparsely disseminated ores. The disseminated ores host high‐Fo (82–85) olivine and hornblende with low‐Al contents, high‐rare earth element (REE) abundances and negative Eu anomalies. The net‐textured mineralized lherzolite contains low‐Fo (74–82) olivine and high‐Al hornblende, the latter characterized by low REE concentrations and no Eu anomaly. The contrasting composition of olivine and hornblende suggests two stages of magmatism. In situ analysis of pentlandite, chalcopyrite and pyrrhotite shows that platinum‐group elements contents in sulphides are low. Contrasting Ni, Co, Se, Ag, Cd, and Pb contents in sulphides from net‐textured and in disseminated ores also supports two pulses of magmas, each with a distinct chemical composition. High‐Mg basaltic magma characterized the first stage, followed by a second‐stage less basic magma with a high H2O content. Whole‐rock Sr and Nd isotopic signatures suggest that about 4–6% crustal materials were added to the depleted mantle source. The fractional crystallization of olivine and crustal contamination play important roles in sulphur segregation at Tulaergen based on sulphur content at sulphide saturation modelling. Injection of magma enriched in H2O further enhanced sulphide aggregation and deposit forming. It is proposed that two pulses of magma injections occurred at the Tulaergen deposit, with the products of the first pulse settling at the base, and of the second one with dense mineralization laying at the top of the deposit. [ABSTRACT FROM AUTHOR]

Numerous granitoid suites exposed in the Qilian orogen, NE Tibetan Plateau preserve important records of the tectonic evolution of this orogen. Here we present zircon U–Pb, zircon rare earth elements (REEs), and whole‐rock geochemical and Sr–Nd–Hf isotopic data on Niuxinshan granitoids in the North Qilian orogen, with a view to constrain their petrogenesis and timing of emplacement, as well as to gain new insights into the Early Palaeozoic tectonic evolution of the Qilian orogen. Zircon U–Pb data show multiple concordant ages of ~517, 455–425, 397–389, and 351–319 Ma for syenogranite, and ages of ~758 and 724 Ma together with some scattered Early Mesozoic discordant ages for porphyritic granite, suggesting episodic magmatism from Neoproterozoic to Early Mesozoic. Zircon ∑REEs range from 276.43 to 4,582.32 ppm, and are characterized by depletion of light REEs (LREEs) and enrichment heavy REEs (HREEs) with negative Eu anomalies, indicating a mixture of magmatic and hydrothermal zircons. Whole‐rock geochemical data show similar variation of LREEs, large‐ion lithophile elements (LILEs), HREEs, and high‐field‐strength elements (HFSEs) with zircon REEs, with Eu, Ba, P, and Ti negative anomalies and Rb, U, and Pb positive anomalies. Based on their formation ages, two groups of granitoids are identified. Group I rocks (Early Palaeozoic) are represented by I‐type granites whereas Group II rocks (Early Mesozoic) are of S‐type. Whole‐rock Sr–Nd–Hf isotopes display (87Sr/86Sr)i ratios of 0.707085–0.709591, εNd(t) values of −5.3 to −2.3, εHf(t) values of −2.2 to 0, and two‐stage model (Nd and Hf) ages of 1.6–1.4 Ga for Group I rocks, and of 0.728156–0.734113, −9.4 to −9.3, −10.6 to −6.9, and 2.1–1.9 Ga for Group II rocks. Accordingly, we infer that the magma for Group I was sourced from the partial melting of basaltic protoliths in the mafic lower crust and underwent fractional crystallization. Group II was derived from metasedimentary protoliths through reworking of ancient Palaeoproterozoic crustal components. Integrating the results from this study with those from previous studies on Niuxinshan granitoids, we argue that the southward subduction model of the North Qilian Ocean beneath the Qilian Block during the Early Palaeozoic might be a more reasonable scenario. However, the Early Mesozoic magmatic event reported here remains equivocal in the North Qilian orogen. [ABSTRACT FROM AUTHOR]

Laser ablation–inductively coupled plasma–mass spectrometry zircon U–Pb ages indicate that the Shaziling pluton in the Jiuyishan area, Ningyuan County, Hunan Province crystallised at 151.9 ± 1.1 to 154.1 ± 1.2 Ma, indicating that it was emplaced during the Late Jurassic. The Shaziling pluton is metaluminous to peraluminous (A/CNK = 0.93–1.09), and has high silica and alkali contents, low Ca and Mg contents, and K2O/Na2O and FeO*/MgO ratios of 1.37–2.65 (mean = 1.80) and 5.43–15.33 (mean = 7.14), respectively. The total rare earth element (REE) content varies from 186.75 to 413.17 ppm, and the pluton is enriched in light REEs and shows negative Eu anomalies (0.095–0.224). It is enriched in the large‐ion lithophile elements Rb and Th, and depleted in Ni, Cr, Eu, Ti, V, P, and Sr. The pluton yields Ga/Al ratios of 245–582 ppm (mean = 350 ppm) and Zr + Nb + Ce + Y contents of 256.8–630.7 ppm (mean = 441.95 ppm), similar to A‐type granites. The Shaziling pluton has a high initial 87Sr/86Sr ratio (Sri = 0.71603–0.71817), and low εNd(t) (−6.8 to −7.4) and εHf(t) (4.8 to −14.2) values. The granitic magmas were produced by partial melting of crustal material, along with a mantle contribution. The Nd and Hf model ages are 1546–1498 and 1756–1061 Ma, respectively, suggesting that the source rocks separated from the mantle reservoir during the Mesoproterozoic. The Shaziling pluton was formed in an intracontinental extensional environment related to subduction. [ABSTRACT FROM AUTHOR]

Granitoids and their mafic microgranular enclaves (MMEs) provide important insights into magmatic activity and tectonic evolution associated with accretionary orogens. Here we investigate the origin of Middle Triassic granodiorites and MMEs in the central segment of the eastern Kunlun Orogen (EKLO) in NW China, which is an important region to evaluate the history of closure of the Paleo–Tethys, through zircon U–Pb geochronology, major and trace element geochemistry, and Sr–Nd–Hf isotopes. Zircon U–Pb ages indicate the coeval formation of granodiorites and their MMEs during the Anisian (ca. 245 Ma). The granodiorites are calc‐alkaline and metaluminous with high SiO2 contents and Mg# values. They are characterized by enrichment of LREEs and LILEs, and depletion of Nb, Ta, and Ti. Their Sr–Nd –Hf isotopic compositions indicate that the magmas were derived from enriched mantle and Paleoproterozoic basement. The monzodioritic‐dioritic MMEs exhibit low SiO2 contents and high Al2O3 and MgO with high Mg# values, enrichment in LREEs and LILEs, and depletion in HFSEs with negative Nb, Ta, Ti, and P. In contrast, the gabbroic MMEs show higher Mg# values and Cr contents. Both types of MMEs have Sr–Nd–Hf isotopic compositions similar to the host granodiorites, and originated from mixing of lower crust‐ and enriched mantle‐derived magmas. The mantle‐derived sources were metasomatized by slab‐derived melts. The Middle Permian to Middle Triassic magmatism, metamorphism, sedimentation, and tectonics in the EKLO suggest northward subduction of the Paleo–Tethys Ocean as represented by the A'nyemaqen Ocean. The magma mixing that generated the Anisian granodiorites and MMEs was likely associated with slab break‐off of the Paleo–Tethys Ocean. The formation of the Anisian magmatic rocks in the EKLO suggest that the cessation of subduction of the Paleo–Tethys Ocean and onset of collision took place during the late stage of Middle Triassic. [ABSTRACT FROM AUTHOR]

We undertook an integrated approach incorporating whole‐rock geochemistry and detrital zircon U‐Pb geochronology from Permian sedimentary rocks in the Solonker area of central Inner Mongolia, China with the aim of constraining the tectonic evolution of the eastern segment of the Central Asian Orogenic Belt. Geochemical analysis reveals a close relationship between the sedimentary and volcanic rock suites in the study region. Detrital zircons from seven samples collected from the Zhesi Formation yield U‐Pb ages that cluster around 309–275 Ma and 464–435 Ma, with two main age peaks of ~452 and ~288 Ma. However, additional detrital zircons with ages in the range of 2,634–543 Ma are sparse and with no obvious age peaks. The results suggest that the deposition of the Zhesi Formation occurred from the Middle to the Late Permian and from two major age provenances: the Precambrian basement of the North China Plate (~1,880 Ma and ~2,520 Ma) and the Paleozoic Southern orogenic belt along the northern margin of North China (~288 Ma and ~452 Ma). In this contribution, we suggest that the Zhesi Formation in the Solonker area formed in response to the Early to Middle Permian subduction tectonic setting of the Paleo‐Asian Ocean (PAO), probably formed in a forearc basin and that the final closure of the PAO occurred after the Late Permian. [ABSTRACT FROM AUTHOR]

The eastern Heilongjiang Province, NE China, is located in the eastern CAOB (Central Asian Orogenic Belt). Previous studies suggest that subduction of the Mudanjiang and Paleo‐Pacific oceans had been initiated in this area during the early Mesozoic. However, research on the Mesozoic volcanic rocks is insufficient, limiting our understanding of the relationship between magmatism and subduction process. To solve the problem, seven volcanic rocks in the Lesser Xing'an‐Zhangguangcai Range and the Jiamusi Block were collected for zircon U–Pb dating (SHRIMP) and whole‐rock geochemical analysis. Most samples from the Lesser Xing'an‐Zhangguangcai Range are Jurassic in age (189–178 Ma), including andesite, trachyandesite, trachydacite, and rhyolite. The andesitic to trachytic rocks were generated by magma mixing at an active continental margin, whereas the rhyolite is highly fractionated I‐type. All the samples from the Jiamusi Block and one basaltic andesite from the Lesser Xing'an Range are late Early Cretaceous in age (ca. 100 Ma) and were formed in a back‐arc extensional setting (roll‐back). Fractional crystallization was important in the generation of most Cretaceous rocks (basalt to trachydacite). However, magma mixing or crustal contamination was required to explain some andesites from the Jiamusi Block showing extremely low Cr, Ni, and Mg#. When integrated with the coeval blueschist‐facies metamorphism, the Early Jurassic volcanism indicates an active continental margin in the Lesser Xing'an‐Zhangguangcai Range due to the westward subduction of the Mudanjiang Ocean. After the closure of the Mudanjiang Ocean, two NE/NNE trending sinistral strike‐slip faults in NE China were triggered, accompanied by the slab roll‐back of the Paleo‐Pacific oceanic plate. The Jurassic continental arc and accretionary complexes in NE China were cut through by the two strike‐slip faults and bended to form small oroclines. At ca. 100 Ma, numerous accretionary complexes were accreted along the eastern margin of the CAOB, further forcing the retreat of trench and slab roll‐back. The late Early Cretaceous intra‐continental volcanism was generated in the Lesser Xing'an‐Zhangguangcai Range and Jiamusi Block during this roll‐back process. [ABSTRACT FROM AUTHOR]

The Early Palaeozoic granitoid rocks represent a volumetrical component of the eastern part of the Dananhu–Tousuquan island arc belt of the East Tianshan and preserve useful information about the tectonomagmatic history of this region. The Hongshi intrusion primarily consists of granodiorite, which intrudes the Ordovician–Silurian Daliugou Formation in the Kalatag area. Zircon U–Pb dating of magmatic zircons from the granodiorite was formed at 426.6 ± 2.3 Ma, suggesting that the intrusion was emplaced in the Middle Silurian. Geochemically, granodiorite belongs to the metaluminous calc‐alkaline I‐type granitoids associated with a narrow range of SiO2 concentration (63.53–67.71 wt.%), A/CNK values ranging from 1.01 to 1.12. They have high Ba, LREE, and LILE contents and low abundance of HREE and HFSE. These samples displayed MgO contents of 1.38–1.52 wt.%, resulting in low K2O/Na2O ratios of 0.11–0.33 and intermediate Mg# values of 29.03–37.31, with high Sr/Y, La/Yb, and Ba/Th ratios, positive εNd(t) (6.60 to 7.95) and εHf(t) (13.1–16.0), low (87Sr/86Sr)i (0.704113–0.704312), and low Nb/U and Ta/U ratios. These features indicated that the parental magma of the granodiorite was probably derived from a juvenile crust with no significant mantle component involvement. Based on the regional geology and geochemical evidence, the Hongshi granodiorite is considered to have formed in an arc setting, associated with the northward subduction of the young Kangguer Ocean slab beneath the Dananhu island arc. [ABSTRACT FROM AUTHOR]

The petrology, geochemistry, zircon U–Pb geochronology, and Hf isotopes of Duobagou diorite and Karatashtage diorite were studied to establish the evolution of Palaeozoic orogeny in the Dunhuang area in Western China. The weighted mean 206Pb/238U age of 448 ± 2 Ma in zircon grains from Duobagou diorite indicated an origin in the late Ordovician Period; age‐corrected εHf(t) values of −0.98 to +4.46 correspond to a two‐stage zircon Hf model age (TDM2) of 1,145 Ma to 1,477 Ma. Karatashtage diorite has a weighted mean 206Pb/238U age of 436 ± 3 Ma, indicating an origin in the early Silurian Period; age‐corrected εHf(t) values of −1.13 to +7.96 correspond to a two‐stage zircon Hf model age (TDM2) of 718 Ma to 1,301 Ma. These findings indicate that Duobagou and Karatashtage diorites were derived from ancient crust. Duobagou diorite has high levels of Al2O3 (15.76%~17.64%), MgO (2.18%~5.44%), Mg# (40~51), Na2O (2.78%~4.19%), Sr (466~1,160 ppm), and Ba (523~892 ppm), low levels of K2O (1.29%~3.13%) and TiO2 (0.64%~1.0%), variable levels of Cr (73.4~253 ppm) and Ni (42.2~98.8 ppm), and depleted HREEs. Karatashtage diorite is characterized by high levels of Al2O3 (16.33%~17.59%), MgO (4.15%~7.10%), Mg# (50~59), Na2O (3.39%~4.41%), Cr (73.4~253 ppm), Ni (42.2~98.8 ppm), Sr (466~1,160 ppm), and Ba (523~892 ppm), low levels of K2O (1.29%~3.13%) and TiO2 (0.64%~1.0%), and depleted HREEs. The Duobagou pluton and the Karatashtage pluton display arc signatures, suggesting that they were formed by the partial melting of a subducted slab under garnet–amphibolite facies in an active continental margin, and an interaction between melt and mantle materials during emplacement. Subduction of the oceanic plate in the Dunhuang terrane occurred during the Early Silurian Period (435–430 Ma), which is close to that of the Beishan orogenesis but later than the formation of the Hongliugou–Lapeiquan ophiolitic belt. We suggest that the Dunhuang terrane underwent an orogenic process related to the Palaeo‐Asian Ocean during the Early Palaeozoic Era, and that it belongs to the Central Asian Orogenic Belt (CAOB). [ABSTRACT FROM AUTHOR]

The Beishan area, located in the southernmost part of the Central Asia Orogenic Belt, is crucial for understanding the tectonic evolution associated with the closure of the Paleo‐Asian Ocean. One intermediate and two granitic plutons from the eastern Beishan area between Mingshui–Shibanjing–Xiaohuangshan (MSX) and Niujuanzi–Xichangjing (NX) ophiolitic belts, including Tongchangkou gabbroic diorite, Northern Tongchangkou and Sandaomingshui plutons, are dated at 426 ± 3, 408 ± 2, and 365 ± 2 Ma by SIMS U–Pb zircon analyses. The Middle Silurian Tongchangkou gabbroic diorites with medium‐K calc‐alkaline metaluminous characteristics represent volcanic arc rocks. The Early Devonian Northern Tongchangkou pluton, a highly evolved calc‐alkaline mylonitic monzogranite with low εNd(t), −3.5 and −2.4, and relatively low initial 87Sr/86Sr (0.707095 and 0.707249), was mainly derived from Mesoproterozoic mafic to intermediate igneous protolith and shows both volcanic arc and postcollisional characteristics. The Late Devonian Sandaomingshui pluton, a calc‐alkaline granite with slightly positive εNd(t), 0.6 and 0.9, and low (87Sr/86Sr)t, 0.705543 and 0.705851, is likely from a more depleted source and represents a volcanic arc granite. Combined with previous studies of Late Paleozoic granites, we find that the widely distributed Permian granites in Central Asia Orogenic Belt are absent between MSX and NX ophiolitic belts. Given the regional geology, we conclude that the back‐arc basin represented by the NX ophiolitic belt closed during Early Devonian and afterward, flat subduction of the oceanic basin represented by the MSX ophiolitic belt occurred. It also indicates that the oceanic crust was still being produced in the Paleo‐Asian Ocean during the early Carboniferous. [ABSTRACT FROM AUTHOR]

The Jinlongshan gold deposit, Shaanxi Province, is a large Carlin-type deposit in the Western Qinling Gold Province (WQGP) in the Qinling Orogenic Belt, Central China. In this study, we present new EPMA and LA-ICP-MS geochemical data on the Fe-S-As minerals at Jinlongshan, which consist mainly of pyrite, arsenian pyrite and arsenopyrite. Diagenetic pyrite (Py0) is preferentially hosted in the sedimentary rocks as rounded or framboidal aggregates. Three types of hydrothermal pyrite (Py1, Py2 and Py3) and two types of arsenopyrite (Apy1 and Apy2) were newly identified in the ores and wall-rocks: fine-grained Py1 and Apy1 were formed at the early mineralization stage; coarse-grained Py2 and Apy2 were formed at the middle mineralization stage; and Py3 with stibnite were formed at the late mineralization stage. Their trace elements differ in concentrations, associations and rim-core zonations, implying different genesis and crystallization processes. Py0 is As-poor (Au < 0.105 wt% and As < 0.094 wt%); Py1 and Py2 are Au-As-rich (Au = 1.9-113 ppm and As up to 7.270 wt%); Py3 is Au-As-poor (Au = 0.03-11.4 ppm and As < 0.56 wt%); and Apy1 and Apy2 show the highest Au concentration (up to 576 ppm). Co, Ni and As (±Se and Te) occur in pyrite as isomorphism, and Ag, Cu, Pb and Zn are distributed primarily as invisible or visible sulphide inclusions. The dominant state of Au in the hydrothermal Fe-S-As minerals at Jinlongshan is lattice bound Au+1, and possibly invisible Au0 nanoparticles, whereas in the diagenetic Py0, the dominant state is mainly Au0. By integrating the evidence from ore deposit geology, mineral morphology, internal structure and trace element geochemistry of the Au-bearing Fe-S-As minerals, it is concluded that the formation of the Jinlongshan Au deposit may have been related to the regional metallogenic episode at around 170 Ma in the WQGP, which was coeval with the regional tectonic transition from a collisional compression to a late- to post-collisional extension in the Qinling Orogen. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]