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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 Jiapigou gold ore belt is located in the northeastern corner of the wedge‐shaped North China Craton and is hosted by Neoarchean basement gneiss and amphibolite, along with late Palaeozoic and Mesozoic granitoids. In this paper, whole‐rock major and trace element geochemistry together with zircon U–Pb ages and Lu–Hf isotope compositions are reported for Late Permian to Triassic igneous rocks from the gold belt. The dominant population of zircons in all these rocks shows oscillatory growth zoning in CL images, and relatively high Th/U ratios (0.10–5.23) that are indicative of a magmatic origin. Zircon U–Pb data indicate that the igneous rocks formed during two major phases: ca. 252 Ma and ca. 230–213 Ma. Geochemically, the Late Permian (ca. 252 Ma) diorites are high‐K calc‐alkaline in composition and low total Fe2O3, MgO, and CaO contents, and represented by enrichment in LILEs relative to HFSEs and HREEs, all of which are indicative of a postcollision high‐K calc‐alkaline granite affinity. In contrast, the Late Triassic (ca. 230–213 Ma) igneous rocks are mainly quartz syenite porphyries, felsites, and granodiorites, and are variable medium‐ to high‐K calc‐alkaline series and exhibit a negative Eu anomaly with A‐type affinities, indicating an extensional environment. In addition, in situ Hf isotopic analyses of zircons from four dated samples reveal that they have εHf(t) values of −3.0 to +2.2, with two‐stage model (TDM2) ages range from 964 to 1,210 Ma, indicating that they probably originated from the partial melting of a dominantly Mesoproterozoic to Neoproterozoic crustal source. On the basis of the geochemical data and regional geological investigations, we further propose that the Jiapigou gold ore belt in the Late Permian was formed in a postcollisional tectonic setting, whereas an extensional tectonic setting in the Late Triassic that caused lithospheric thinning during a postorogenic event. [ABSTRACT FROM AUTHOR]

During the Late Ordovician, abundant siliceous rocks interlayered with K‐bentonites were widely distributed in the Wufeng Formation in the north‐western part of the Sichuan Basin, South China. In order to analyse the material provenance, redox condition, sedimentary environment, and their formation, here we present mineralogical and geochemical investigations on siliceous rocks samples collected from three sections. The presence of massive radiolarian tests, high Si/Si + Al + Fe + Ca ratios (0.87–0.99) and Al–Fe–Mn diagram plotting at nonhydrothermal area, reflects that the deposition of the siliceous rocks was simultaneous, effected by biogenic and terrigenous origin. The TiO2–Zr, La/Th–Hf, and La/Yb‐∑REE bivariate diagrams indicate that the provenance of Late Ordovician siliceous rocks was primarily from felsic igneous rocks. According to the palaeoredox indicators (V/(V + Ni), V/Cr, V/Sc, U/Th, and Ni/Co) and the size of framboidal pyrite, it is considered that the water column conditions of the Late Ordovician siliceous rocks were likely to be anoxic in all three sections. The application of parameters for relatively immobile elements allowed us to establish a continental margin for most samples from the three sections. Finally, we propose that the deposition of siliceous rocks was related to the accretion of the Cathaysia Block to the Yangtze Block. During the Late Ordovician, huge amounts of volcanic ash were released by intensified volcanic eruptions and fell into the ocean, triggering the proliferation of radiolarians. The abundant radiolarians and the persistent continental detritus constituted the major components of siliceous rocks in the Upper Yangtze Block. [ABSTRACT FROM AUTHOR]

In this study, we present new U–Pb zircon ages and whole‐rock major and trace element data for the late Carboniferous–Middle Jurassic intrusive rocks in the Helong area, NE China. These data constrain the timing of tectonic transition from the Paleo‐Asian oceanic regime to the circum‐Pacific regime. U–Pb zircon dating indicates that the late Carboniferous–Middle Jurassic magmatic events in the Helong area can be subdivided into late Carboniferous, middle Permian, Early–Middle Triassic, Late Triassic, Early Jurassic, and early Middle Jurassic. The late Carboniferous granodiorites and middle Permian monzogranites belong to the calc‐alkaline series and have an affinity to I‐type granitoids, suggesting that they formed in a typical Andean‐type continental arc setting due to the southward subduction of the Paleo‐Asian oceanic plate beneath the NCC. The Middle Triassic granodiorites and monzogranites in the Helong area exhibit an affinity to adakitic rocks with their parental magma derived by the partial melting of thickened lower continental crust. The Late Triassic I‐type monzogranites and coeval ultramafic–mafic rocks constitute a bimodal igneous rock association, together with coeval A‐type granites and rhyolites, signifying an extensional environment. Combined with the absence of 240‐ to 225‐Ma sedimentation, the study area experienced a change from Early–Middle Triassic compression to Late Triassic extension related to the final closure of the Paleo‐Asian Ocean. The Early–early Middle Jurassic gabbros, diorites, granodiorites, and monzogranites are calc‐alkaline in nature and enriched in LREE and LILE but depleted in HREE and HFSE. Combined with the spatial variations in K contents of Early Jurassic igneous rocks in NE China from the continental margin to intracontinental region, and the presence of an Early Jurassic accretionary complex, we suggest that Early–early Middle Jurassic magmatism in the Helong area formed in an active continental margin setting related to the subduction of the Paleo‐Pacific Plate beneath Eurasia. We conclude that the tectonic transition from the Paleo‐Asian oceanic regime to the circum‐Pacific regime occurred in the Late Triassic–Early Jurassic. [ABSTRACT FROM AUTHOR]

The Jiamusi Block is an important tectonic unit in the Chinese segment of the CAOB. Its eastern margin became an active continental margin in the period of Late Carboniferous. However, the tectonic affinity of this section has not been resolved yet. The Early Permian andesites within the Erlongshan Formation in the eastern Jiamusi Block provide a critical record for the active continental margin setting. Precise LA‐ICP‐MS U–Pb zircon dating on four andesite samples gave ages of 280 ± 3 Ma, 282 ± 3 Ma, 286 ± 4, and 284 ± 2 Ma, respectively, defining an Early Permian age for the crystallization of the andesites. The andesites have medium‐K and calc‐alkaline compositions, with variable SiO2 (54.70–57.46 wt%), TiO2 (0.87–1.12 wt%), TFe2O3 (6.52–8.13 wt%), MgO (2.62–3.33 wt%), Al2O3 (15.96–17.83 wt%), Na2O (3.28–4.10 wt%), and K2O (1.16–1.95 wt%) contents. They are relatively enriched in LREEs ((La/Yb)N = 5.0–7.1) and LILEs (e.g., Ba, Th, Sr, and U), deleted in HREEs and HFSEs (e.g., Nb, Ta, Zr, and Y) and have weak or no Eu anomalies (Eu/Eu* = 0.87–1.02). These geochemical features indicate that the andesites within the Erlongshan Formation originated from an active continental margin setting, and their magma source was produced by partial melting of a mantle material that had been metasomatized by subduction‐related melts and subsequently underwent the removal of mafic minerals and accumulation of plagioclase. Integrated with previous studies on the igneous and sedimentary rocks, we thus propose that the Jiamusi Block was in an active continental margin setting in the period of the Late Carboniferous to Early Permian (310–280 Ma), and it is more likely related to the subduction of the Mongol‐Okhotsk Ocean. [ABSTRACT FROM AUTHOR]

The Sadaigoumen Mo deposit is a typical porphyry‐type deposit which is located in the northern margin of the North China Craton (NCC), China. Mineralization of the deposit mainly occurs as finely disseminated within the host granites. To get a better understanding of the ore‐forming process of the deposit and the genetic link between mineralization and host igneous rocks, we report LA‐ICP‐MS zircon U–Pb and whole‐rock major and trace elements data from the magmatic rocks which are exposed in the mining area. LA‐ICP‐MS U–Pb analyses yield weighed mean ages of 239.5 ± 0.58 Ma for alkali‐feldspar granites and 1872.8 ± 5.1 Ma for porphyritic granodiorite. The porphyritic granodiorite, which was previously considered to be part of the Hongqiyingzi Group, is redefined as Palaeoproterozoic highly fractionated I‐type granites: (1) They have high contents of SiO2 (69.57–72.21 wt.%) and Al2O3 (13.24–13.90 wt.%) and high Na2O + K2O (up to 7.1 wt.%) and FeOT/MgO values (6.7 to 7.7), and (2) significant depletion of Eu, Sr, Ba, P, and Ti elements; (3) compared with typical A‐type granites, they have lower Ga (around 20.5 ppm) and 10000 × Ga/Al values (around 2.8); the Triassic alkali‐feldspar granite samples also show highly fractionated I‐type geochemical signatures with high Na2O + K2O (8.40–8.50 wt.%), FeO*/MgO (12.67–13.49), and Ga/Al (2.58–2.81) ratios. The higher ∑REE values (>199.69 ppm) and depletions of Nb, Ta, and Ba make it different from typical A‐type granites. By comparative analysis of geochemical data, we believed that the ca. 1872.8 Ma porphyritic granodiorite formed in a tectonic environment resembling that of magmatic arc granites and the ca. 239.5 Ma alkali‐feldspar granite formed in syn‐collisional settings which is related to closure of Palaeo‐Asian Ocean. Our new data, combined with previous studies, allow us to speculate that the Triassic alkali‐feldspar granite is directly related to the Mo mineralization in this area. [ABSTRACT FROM AUTHOR]

We present zircon U–Pb and Hf isotopic and whole‐rock geochemical data for late Paleozoic igneous rocks in the central Great Xing'an Range, northeast China, to constrain the late Paleozoic amalgamation history of the united Xing'an–Erguna and Songnen–Zhangguangcai Range massifs. Based on zircon U–Pb dating, we ascertain three main stages of magmatic events: Late Devonian (381–364 Ma), early Carboniferous (360–341 Ma), and late early Carboniferous–early Permian (328–271 Ma). Late Devonian rhyolites originated from partial melting of Meso‐proterozoic accreted lower crust. The crust‐derived rhyolites and coeval mantle‐derived basalts constitute a bimodal volcanic association in the west. Early Carboniferous igneous rocks include syenogranites, monzogranites, gabbro diorites, and gabbros. The granitoids are derived from partial melting of Meso‐proterozoic accreted lower crust. The gabbros and gabbro diorites show the spatial variation in zircon εHf(t) values (−0.53 to +0.84 in the east and +12.3 to +13.5 in the west), which imply that they were mainly derived from metasomatized mantle wedge and asthenosphere mantle, respectively. These characteristics indicate that northwest‐towards high‐angle subduction of the Paleo‐Asian Ocean plate beneath the united Xing'an–Erguna Massif induced arc magmatism in the east and back‐arc magmatism (similar to back‐arc rift) in the west during the Late Devonian to early Carboniferous. Late early Carboniferous–early Permian sub‐alkaline and alkaline igneous rocks are characterized by multiple sources, such as the depleted mantle, juvenile lower crust, and thickening lower crust. Their temporal variations in geochemical characteristics imply that the central Great Xing'an Range was situated under a transitional setting from syn‐collisional to post‐collisional during the late early Carboniferous to early Permian. Using the combined insight from lithofacies palaeogeography and regional magmatisms, we suggest amalgamation of the united Xing'an–Erguna and Songnen–Zhangguangcai Range massifs occurred during the late early Carboniferous to late Carboniferous. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]