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The Jiamusi‐Khanka Massif is an important tectonic unit of the Central Asian Orogenic Belt in North‐east China. Its Late Palaeozoic tectonic properties and the timing of assembly have restricted the understanding of the tectonic evolution process at the eastern segment of the Central Asian Orogenic Belt for a long time. Based on the study of clastic rock petrology and zircon U–Pb chronology of the Early Permian Erlongshan Formation in Mishan, it is clear that the zircon age of the Early Permian Erlongshan Formation in Mishan is mainly Late Palaeozoic, with a major age peak at 300 ± 3 Ma and secondary age peaks at 356 ± 7 Ma and 475 ± 10 Ma. The provenance mainly comes from the magmatic arc source area, and Early Palaeozoic (500–420 Ma) detrital zircons mainly come from the south‐east margin of Jiamusi Massif, Late Palaeozoic (400–270 Ma) detrital zircons mainly come from the eastern margin of Jiamusi Massif and the northern margin of Khanka Massif. Among them, detrital zircons of a special age group 330–310 Ma come from the north of Khanka Massif, while 490–470 Ma detrital zircons which are common in the Early‐Middle Permian strata of Khanka Massif come from Jiamusi Massif. Combined with the evidence of petrology and palaeontology, this paper believes that the Early Permian Jiamusi Massif and Khanka Massif should be a unified Massif, that is, Jiamusi‐Khanka Massif. [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 Central Asian Orogenic Belt (CAOB) is the largest accretionary orogenic belt in the world and its formation involved a complicated process of arc–continent collision. Large‐scale Mesozoic volcanic activity in the Great Xing'an Range (GXAR) in northeastern China, which constitutes part of the eastern CAOB, has received much recent research attention. However, the petrogenesis and formation mechanism of the late Mesozoic igneous rocks remain enigmatic. This paper investigates the geochronology, petrogenesis, and formation mechanism of late Mesozoic magmatic rocks in the Kelihe area of the GXAR based on zircon U–Pb dating, petrology, and geochemistry. Late Mesozoic magmatism in the Kelihe area occurred during the Late Jurassic (165–155 Ma) and Early Cretaceous (130–120 Ma). These igneous rocks generated by this magmatism are characterized by high SiO2 (69.97–75.49 wt%) and low MgO (0.11–0.68 wt%), Cr (10–30 ppm), Co (0.2–2.6 ppm), and Ni (0.5–1.6 ppm) contents. Trace elements show enrichment in Rb, Th, U, Zr, and K, and depletion in Ba, P, Nb, and Ti. These features indicate that the rocks were derived from partial melting of the crust. Furthermore, the rhyolites have high Na2O (5.02–5.44 wt%) and K2O (3.94–4.88 wt%) contents, similar to those of melts formed by the partial melting of basaltic crust. Combining the present results with the findings of previous studies, it is inferred that the Mesozoic igneous rocks formed in a post‐collisional extensional setting related to lithospheric thinning and asthenospheric upwelling after the closure of the Mongol–Okhotsk Ocean. [ABSTRACT FROM AUTHOR]

Devonian is a critical period for reversal of arc polarity and transition of continental margins from passive to active settings in the northern margin of the North China Block (NCB). However, the evolution processes during this period are still poorly constrained due to limited distributions of Devonian magmatism and sedimentary records in the NCB. In this paper, we present new zircon U–Pb geochronological, whole‐rock geochemical and Sr–Nd–Hf isotopic data of some recently identified Devonian volcanic rocks from the Jiefangyingzi area in the northeastern margin of the NCB. The Jiefangyingzi volcanic rocks display a bimodal composition and consist predominantly of amphibolite (meta‐basaltic andesite) and meta‐rhyolite and rhyolitic tuff with minor meta‐andesite. New SHRIMP and LA‐ICP‐MS zircon U–Pb dating results show that the volcanic rocks erupted during the early‐middle Devonian period (397–389 Ma). Geochemical and Sr–Nd–Hf isotopic data indicate that the mafic‐intermediate components were mainly derived from an enriched lithospheric mantle source, and the parental magma experienced fractional crystallization during magma ascent. The felsic rocks were mainly originated by partial melting of ancient lower continental crust, with mixing of some mantle‐derived mafic magmas. The occurrence of Devonian bimodal volcanic rocks, combined with the Devonian alkaline magmatic belt, suggesting that the northern margin of the NCB was a post‐collisional extension environment during the early‐middle Devonian period. In addition, the Sr–Nd–Hf isotopic results of the Devonian felsic volcanic rocks suggest that the Jiefangyingzi area is located in the North China Craton (NCC) rather than the Bainaimiao arc belt, and the orogen‐craton boundary between the northern NCC and Central Asian Orogenic Belt (CAOB) is located in some areas north to the Jiefangyingzi area. [ABSTRACT FROM AUTHOR]

The Yinggen‐Ejinaqi Basin (YEB) is located in the central‐southern part of the Central Asian Orogenic Belt (CAOB). Tectonically, the basin is situated at the intersection between the eastern and western CAOB, where Late Palaeozoic strata were well exposed. Hence, it offers a great opportunity to study the deep strata of the eastern CAOB. In this paper, based on extensive studies of Upper Palaeozoic field outcrops and reanalysis of associated geochemical and geochronological data in previous research, the local stratigraphic correlation is established, and the tectonic evolution, sedimentary filling, sedimentary characteristics, and petroleum system of the YEB are discussed. It is revealed that: (a) The filling characteristics of the Upper Palaeozoic strata in YEB are closely related to the closure of the Paleo‐Asian Ocean (PAO). YEB underwent subduction‐related compression during the initial extensional phase of the fore‐arc basin from the Viséan to the Serpukhovian (late Early Carboniferous). During the Bashkirian–Sakmarian interval (Late Carboniferous to Early Permian), it was in subduction‐related fore‐arc and postarc rifting phases. During the Artinskian–Capitanian (Early‐Middle Permian) times, it was in an intracontinental rifting‐depression phase. During the Wuchapingian (Late Permian), it was in an intracontinental compressional phase. Tectonostratigraphy, tectonic evolution, and hydrocarbon potential assessments of the study area show that the Zhusileng Hangwula‐Tost Ul tectonic zone (ZHTUTZ) and southwestern part of Querrshan‐Atasbogd tectonic zone (QATZ) are identified as the main prospective areas for the exploration in the YEB. (b) According to the tectonostratigraphic analysis, tectonic evolution and hydrocarbon system of Carboniferous–Permian in the YEB, the YEB has similar attributes to the basin province in western CAOB (e.g., Santanghu and Junggar basins) and eastern CAOB (Erlian, Songliao Basin). To explore commercial oil and gas in the deeper strata (Carboniferous–Permian) of the eastern CAOB basins, further tectonostratigraphic analyses and comprehensive assessment on hydrocarbon potentials are necessitated in the near future. [ABSTRACT FROM AUTHOR]

This paper reports in situ U–Pb ages and Hf isotopic data on detrital zircons from Palaeozoic strata in central‐eastern Jilin Province, NE China, with the aim of constraining the timing of final closure of the Paleo‐Asian Ocean and the tectonic evolution of the eastern segment of the Central Asian Orogenic Belt (CAOB). Zircons from Middle to Late Permian Fanjiatun and Yangjiagou formations in central Jilin Province are characterized by four major groups of age populations (2.5–2.3 Ga, 1.9–1.7 Ga, 1.3–1.0 Ga, and Late Palaeozoic ages). The Paleo‐Mesoproterozoic and Cambrian zircons have positive εHf(t) values, suggesting that the source was mainly locally derived from the CAOB, whereas a lesser amount of Archean zircons with positive εHf(t) values, indicating that source from the North China Craton (NCC). The Phanerozoic zircons have both positive and negative εHf(t) values indicates that material from bidirectional provenances in the CAOB and the NCC. However, Late Permian Kaishantun Formation in eastern Jilin Province contain a single group of Phanerozoic zircons with positive εHf(t) values, distinct from known igneous zircons in the NCC, suggesting a local source. These observations, along with the results of previous studies on Middle–Late Permian igneous rocks in Jilin Province, indicate that the eastern segment of the Paleo‐Asian Ocean underwent the initial closure in central Jilin Province during the Middle Permian and the final closure in eastern Jilin Province in the Late Permian–Early Triassic. The detrital zircon geochronological data clearly record two stages of tectonic evolution and the scissor‐like closure model of the Paleo‐Asian Ocean in the eastern segment of the CAOB. [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 southern West Junggar terrane in the south‐western Central Asian Orogenic Belt (CAOB) is mainly composed of accretionary complexes and characterized by widespread outcrops of ophiolitic mélanges in the Barleik, Mayile, and Tangbale (BMT) areas, representing the site of consumption of the Junggar–Balkhash Ocean. However, due to a lack of comprehensive synthesis of the ophiolitic mélanges, the early evolution of the Junggar–Balkhash Ocean remains poorly understood. This paper first focuses on the little‐known Barleik ophiolitic blocks and associated pillow basalts and then integrates the Barleik, Mayile, and Tangbale ophiolitic mélanges into one model. Mineral and whole‐rock chemistry suggests that the Barleik ophiolitic blocks, including serpentinized dunite, clinopyroxenite, and gabbro, show supra‐subduction zone (SSZ) affinities, as indicated by high Cr# values (76–78) in spinels and strong depletion in Nb, Ta, Zr, and Hf, whereas the Barleik pillow basalts are alkaline and have high TiO2 contents (2.82–3.42 wt.%) and Nb–Ta enrichment, similar to ocean‐island basalt (OIB) lavas. Combined with published chronological and chemical data from ophiolites, metamorphic rocks, and arc plutons, we propose that the BMT Ediacaran to middle Cambrian ophiolitic gabbros were formed in a SSZ environment, implying a single Mariana‐type arc system within the Junggar–Balkhash Ocean, which was coeval with an Andean‐type arc system in the Kyrgyz North Tianshan, supporting an archipelagic model for the south‐western CAOB. By contrast, the BMT OIB‐type basalts are early Silurian in age, much younger than the SSZ‐type ophiolites, and can be interpreted as relicts of seamounts. Thus, a model involving the Ediacaran to Ordovician intra‐oceanic subduction and late Silurian to Early Devonian seamount accretion is helpful for clarifying the different components of the accretionary complexes in the southern West Junggar terrane. [ABSTRACT FROM AUTHOR]

The Carboniferous tectonic history of the northern West Junggar of NW China is of key importance for understanding the tectonics of the Altaids. This paper presents a systematic study of the emplacement of the E'min ophiolite, the ages of turbidites, and a stitching granite dike in order to constrain the late Carboniferous oceanic evolution of northern West Junggar. Our field investigation reveals that the Tarbagatay subduction–accretion complex formed by imbrication of turbidites and ophiolitic slices in the Western Tarbagatay Mountain, which is considered as the forearc of the Saur arc in northern West Junggar. Field relationships and zircon geochronology suggest that the emplacement of the E'min ophiolite was later than the minimum time of deposition of hanging wall turbidites, which have a zircon age of 324 Ma, and must be earlier than the crystallization time of a 311‐Ma stitching granite dike that intruded the younger turbidites. The turbidites become younger from north to south, with minimum deposition ages varying from 324 to 309 Ma. The 311‐Ma dike has an adakitic affinity suggesting that it may have formed by magma melted from a subduction slab wedge and from accreted material at ~310 Ma. Therefore, we propose an accretionary arc setting for the Saur arc, with southward migration of the trench and magma front. The 311‐Ma dike has a high Al enrichment and arc‐related geochemical signature suggesting that it was generated by melting of accreted trench sediments. This may indicate that subduction of the Saur arc may have lasted to at least the late Carboniferous. The development of such arc accretion suggests that the formation of the southern Altaids was fundamentally similar to that of accretionary orogens in the western Pacific. [ABSTRACT FROM AUTHOR]

Structural evolution of the Paleoproterozoic Jiao‐Liao‐Ji orogenic belt in eastern North China Craton has been a subject of extensive study in the past decades. Studies of the characteristics of the crustal structure during orogenesis are essential to the understanding of the formation and evolution of the orogenic belt. In this paper, we present detailed studies of deformed amphibolites in the southern part of the orogenic belt to illustrate the changes of deformation conditions and variation of deformation mechanisms during the orogenic processes. Based on differences in structural characteristics of foliations, amphibolites from the Paleoproterozoic South Liaohe Group at Caohekou–Jiguanshan area are subdivided into four types (massive, weak‐gneissic, moderate‐gneissic, and strong‐gneissic). Our study shows that the different characteristics in microstructures, rock fabrics, and deformation mechanisms of the amphibolites were resulted from varying temperatures and pressures in relation to the tectonic deformation. The widely distributed massive amphibolites (P = 0.39 GPa, T = 639°C) display no or weak deformation, which is inferred to represent steady‐state crystallization. Weak‐gneissic amphibolites (P = 0.52 GPa, T = 753°C) were resulted from stress‐controlled grain growth. Amphiboles in such rocks show obvious (100) LPOs but minor evidence for crystal plastic deformation. Evidences for crystal plastic deformation of amphibole grains are common in moderate‐gneissic amphibolites (P = 0.61 GPa, T = 771°C). The amphibole grains have strong (100) and (001) LPOs. Dislocation slip is considered as the main deformation mechanism of the amphibole grains in the rocks. Both subgrains and mechanical twins of amphiboles from strong‐gneissic amphibolites (P = 0.77 GPa, T = 686°C) are long‐columnar shaped and show the same orientation as their host crystals. They are resulted from reactivation of (100)(001) slip system controlled by dynamic recrystallization, twinning, and twinning nucleation recrystallization. The evident pressure difference from 0.39 to 0.77 GPa during the formation of the various types of amphibolites may be related to the tectonic thickening during contractional orogenesis. [ABSTRACT FROM AUTHOR]

Subduction system in the Qilian orogenic belt experienced the variability of an active continental arc in space and time related to the subduction of the Proto‐Tethys Ocean. Zircon U–Pb geochronology and whole‐rock chemical and Sr–Nd isotopic data of mafic to intermediate dykes in the western part of the Central Qilian belt (WCQB) are used to track magma provenance from compositionally variable reservoirs in the sub‐arc mantle and constrain the magmatic evolution of the rear‐arc at 450–445 Ma. Petrological, whole‐rock chemical and zircon U–Pb dating results reveal that the studied dykes mainly comprise calc‐alkaline lamprophyre (CAL), high Mg# andesitic porphyrite (HMA) and high FeO hornblende gabbro (HFG) with crystallization ages of 447, 453 and 448 Ma, respectively. Among them, CAL and HMA have affinities in high‐K calc‐alkaline suites, high REE contents (∑REE = 131.1–202.3 ppm) with high LaN/YbN values (6.77–17.99), enriched in large‐ion lithophile elements (LILE, e.g., Rb and U), and depleted in high‐field‐strength elements (HFSE, e.g., Nb, Ta, and Ti). They also have high Th/La (0.20–0.46), Th/Nb (0.67–1.64) and Th/Yb (3.88–14.11) ratios, and relatively high whole‐rock initial 87Sr/86Sr ratios (0.707469–0.708493) and εNd(t) values (−4.7 to −3.1). Whereas, HFG is affinities in medium to high‐K calc‐alkaline suites, and has moderate rare earth elements (∑REE = 70.1–112.5 ppm) with flat REE patterns (LaN/YbN = 2.12–3.05) and exhibits enriched LILE, and Sr–Nd isotopes ((87Sr/86Sr)i = 0.713496–0.729216, εNd(t) = −2.93 to +2.04). Such typical "continental" geochemical features of the different K‐rich dykes do not result from crustal assimilation but reflect an enriched mantle source resulting from their mantle heterogeneity due to recycling of different subducted sediments. The temporal evolution of the geochemical characteristics of mafic‐intermediate dykes is consistent with an extension setting triggered by removing the thickened arc crust root in the WCQB. [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 abundant petroleum reserves have been found in the Urho Formation in the past few years in western Mahu Slope, Junggar Basin. A great deal of studies has been carried out regarding tectonic evolution, sequence stratigraphy, reservoir prediction, and mechanism in the Urho Formation. However, little is known concerning the depositional evolution and associated controlling factors in the Upper Urho Formation. In this study, thin sections, cores, wireline logs, and seismic volumes are utilized to identify and describe sedimentary facies/microfacies, analyse mineral components and micro characteristics of microfacies, predict facies/microfacies distributions, and reveal depositional evolution and associated controlling factors. The results indicate the identification of eight sedimentary microfacies and the evolution of fan delta systems in Upper Urho Formation. In addition, depositional evolution of fan delta systems from bottom to top in Upper Urho Formation is characterized by retrogradation during lacustrine transgression period. The controlling factors, including tectonic activities along northwestern thrust fold belt and lacustrine fluctuations together exert influences over depositional evolution of regressive fan delta systems in Upper Urho Formation. [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]

To understand the crustal growth of the Qinling orogenic belt and the Mesozoic continental interaction between the North China and Yangtze blocks, it is critical to study the South Qinling accretionary complex belt, which is an important part of the Qinling orogen. Based on detailed zircon U–Pb geochronology and Hf isotopic compositional analyses of the Madao complex, this study presents constraints on the migmatization and tectonic evolution of the South Qinling orogenic belt during the Mesozoic. Zircons from leucosome samples of migmatites were found to have weak oscillatory zoning, and one sample yielded a weighted mean age that reflects the time at which the regional tectono‐thermal event initiated the anatexis (210–217 ± 2 Ma). The Hf isotopic compositions indicate that the Madao migmatites were derived from the ancient middle–Late Palaeoproterozoic crust. Zircons from mesosome samples of the migmatites that varied in age from the Palaeozoic to Neoproterozoic exhibited core‐rim textures with magmatic cores (256–1,329 Ma), indicating that they were derived from multiple sources with sedimentary protoliths. Of the 55 analysis spots on the overgrowth rims that yielded 206Pb/238U ages of 200–233 Ma, 40 analyses yielded a weighted age of 211.5 ± 1.0 Ma, indicating the time of anatexis due to the regional tectono‐thermal event. Combined with previously reported Mesozoic data from the South Qinling belt, these results suggest that the migmatites were probably controlled by post‐orogenic extension driven by Mesozoic orogenesis and a prolonged melting episode (from ~200 to 233 Ma). This study reinforces the interpretation that the continental crust in the South Qinling belt may have experienced complex interactions with asthenospheric mantle material during the Mesozoic. [ABSTRACT FROM AUTHOR]

West Junggar is an important part of the Central Asian Orogenic Belt, which is the evolutionary product of the Palaeo‐Asian Ocean (PAO). In this area, sporadically distributed ophiolitic mélanges and associated Palaeozoic stratal succession provided research materials revealing the reduction and closure of the PAO. Based on the systematically reviewed Ordovician strata in the northern West Junggar, we find that the Lower Ordovician is mainly composed of ultramafic and mafic rocks of ophiolitic mélanges, the Middle Ordovician is made up of island arc volcanic rocks and pelagic sedimentary rocks from the ophiolitic mélanges, and the Upper Ordovician consists of coarse volcaniclastic turbidites. The geochemical characteristics of the Middle Ordovician radiolarian‐bearing siliceous rocks show that these deposits formed in a limited oceanic basin controlled by terrestrial sources, and that the basin‐filling succession began with the occurrence of the Upper Ordovician proximal turbidites. The above shows that the Ordovician PAO underwent an evolutionary process from oceanic basin to limited oceanic basin and to marginal sea in northern West Junggar, and constrains the age of the ocean–continent transformation to the Middle–Late Ordovician transition, with northern West Junggar entering the evolutionary stage of marginal sea in the Late Ordovician. [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]

The gold mineralization of the North China Craton (NCC) is characterized by regional heterogeneous distribution. Such a feature is mainly reflected by the spatial dispersity and local concentration, as well as multiperiods of gold‐forming events. Gold deposits are principally converged in the Jiaodong, Xiaoqinling‐Xiong'er Mountain, Jidong, Liaodong, and Taihang Mountain regions. The northern margin of the NCC is strongly enriched in Au, Mo, and Cu elements, whereas its southern and eastern margins trend to show significant enrichment of Au–Mo and Au, respectively. Among them, the early period of Mesozoic mineralization is Au–Mo–Pb–Zn combination, the peak is Au, and the late period is Au–Ag combination. The Early Cretaceous is the main gold metallogenic epoch of the NCC followed by the Middle–Late Triassic and Jurassic. Generally, gold mineralization time of the Xiaoqinling‐Xiong'er Mountain and Taihang Mountain is a little earlier than those of Jiaodong gold deposits; some of Jidong (Jinchangyu, Yuerya, and Niuxinshan) and the Liaodong (Baiyun and Maoling) gold deposits were formed in the Triassic–Jurassic. Overall, the uneven distribution of gold deposits in the NCC is generally controlled by the tectonic evolution and interaction of the regional geological blocks, the hydrothermal alteration and gold activation in the metamorphic basement, and the Mesozoic magma activity. In the Middle Jurassic and before, the tectonic evolution of the NCC was mainly influenced by the Central Asian Orogenic Belt and the Qinling Orogenic Belt. Tectonic system transition from extrusion to extension, locally developed mantle upwelling and lithospheric thinning, as well as a series of Middle Triassic–Jurassic magmatic activities, and even the presence of alkaline rocks along the east–west direction occurred on the northern margin of the NCC, which generated a series of Au–Mo deposits. This is the first craton destruction and gold mineralization event that occurred in the northern margin of the NCC after its formation. In the Cretaceous and after, the geological evolution of the NCC was mainly controlled by the ancient Pacific Plate. The NCC was subjected to extensive lithospheric thinning, which in turn led to a more large‐scale gold mineralization. In addition, it is found that these ore‐forming materials sourced from the metamorphic rock are not entirely dependent on the gold content but also affected by one or more geological processes, which activate and extract gold from the wall rock and upgrade it in suitable tectonic environments. The influence of granitoids and intermediate–basic dikes in these gold deposits seems like a "hot machine," which is the source of metallogenic hydrothermal fluid, and it is also a possible source of some ore‐forming minerals. [ABSTRACT FROM AUTHOR]

The Mulei Depression is a secondary structural unit in the south‐eastern part of the Junggar Basin in the Central Asian Orogenic Belt. As in other parts of the Junggar Basin, it experienced large‐scale volcanic activity in the Carboniferous. However, due to the seismic data, quality of this area is poor, and the drilling data is less early, the Carboniferous volcanic activity is difficult to identify and explain. In the case of minimal well information available, we identify the volcanoes of the Upper Carboniferous Bashan Formation of the Mulei Depression and clarify its distribution characteristics. Through frequency decomposition and a reconstruction of seismic data, the seismic reflection characteristics of the ancient volcanic cone become prominent and easy to identify, and even the period of some stacked volcanic cones can be divided. According to the geological model put forward, the seismic reflection characteristics of the ancient volcanic cone and its surrounding volcanic rocks are clarified. The volcanic cones are characterized by mound‐clutter and weak‐blank amplitude reflection. The internal clutter mainly have resulted from rapid changes in lithology and complex secondary faults. Away from the crater direction, the energy of a seismic event is gradually enhanced, and the volcanic sediments from other sources will be superimposed above the previously formed volcanoes. It is found that the volcanic channel with a short‐axis continuous illusion is often developed at the bottom. The volcanic channel which can be identified in seismic mainly affects the development of large volcanoes. Finally, 27 volcanic cones and seven volcanic channels were identified via establishing the three‐dimensional (3D) model of the volcano and the amplitude of the root mean square of seismic data after reconstruction, as well as interpreting deep faults. The volcanic development in the Mulei Depression has the characteristics of an NE spread along deep faults and northern more than southern. [ABSTRACT FROM AUTHOR]

The nature of the Precambrian basement in the Cathaysia Block of South China is controversial, which inhibits our understanding of the pre‐Devonian tectonic evolution of the region. In this study, a suite of amphibolites and marbles in northern Fujian area located in the north of the Cathaysia Block were subjected to LA–ICP–MS U–Pb zircon geochronological and geochemical analyses. Results show that the protolith of the amphibolite formed after ca. 459 Ma, and its metamorphism happened at ca. 429 Ma. The protolith of the marble was deposited after ca. 518 Ma, and its metamorphic age is ca. 437 Ma. The amphibolites are divided into two groups based on geochemical data. Group 1 has an OIB‐like feature that might have formed in an environment characterized by oceanic islands and seamounts. Magmas associated with Group 1 were derived from an enriched mantle source with OIB characteristics. The protolith of Group 2 shows IAB feature that formed in an island arc environment. Marbles are interpreted to represent metamorphosed marine carbonate rocks. Integration of geochronological and geochemical study indicates that the marble and amphibolite should be an early Palaeozoic oceanic island–seamount association. It suggests the Cathaysia Block underwent oceanic subduction during collisional orogenesis in the early Palaeozoic. This subduction is thought to have initiated prior to ca. 437 Ma. The U–Pb zircon ages of younger intrusive granites indicate that final amalgamation occurred before ca. 392 Ma. During this process, east and west Wuyi were amalgamated to form the unified Cathaysia Block. Thus, it suggests that there was no unified pre‐Devonian basement in the Cathaysia Block. The pre‐Devonian tectonic setting of the Cathaysia Block was an accretionary orogeny. [ABSTRACT FROM AUTHOR]

Early Paleoproterozoic rocks occur sporadically in the Sulu ultrahigh‐pressure (UHP) belt. The tectonic affinity and evolution of these rocks are still disputed. Two magmatic events (Early Paleoproterozoic and Neoproterozoic) and two metamorphic events (Late Paleoproterozoic and Triassic) were revealed by the zircon U–Pb ages and trace elements from the Weihai gneisses, which provide a key clue to understand the evolution of the Sulu orogen. The Early Paleoproterozoic zircons occur as residual zircons or zircon‐inherited cores in the two gneisses. They generally show oscillation zoning and enriched HREE patterns. The weighted mean age of the upper intercept age of these zircons is ~2.46 Ga, suggesting that the protolith of the ancient gneisses formed at ~2.46 Ga. The Late Paleoproterozoic zircons occur as metamorphic zircon core or mantle domains in the two gneisses and a quartzite. They generally show planar zoning or no zoning, with relative lower Th/U ratios. These zircons yield metamorphic ages of 1.8–1.84 Ga, which are consistent with the age of the Paleoproterozoic ultrahigh‐temperature metamorphism of the northern Sulu orogenic belt. The Neoproterozoic zircons occur as magmatic cores or mantles in the zircon grains of the two gneisses and their wall rocks. They show typical oscillatory zoning and enriched HREE patterns, yielding magmatic ages of ca. 740–787 Ma. The Neoproterozoic igneous rocks are the dominant basement rocks in the Sulu orogenic belt. Triassic UHP metamorphism has been well studied in the Sulu orogenic belt. Two Triassic age groups were also recognized here: 228–229 and 208 Ma, respectively. The Triassic zircons occur as metamorphic rims of the two ancient gneisses and their wall rocks. These two age ranges correspond to the time of subduction and exhumation of the the South China Craton (SCC) during the Triassic orogeny. This study provides solid evidence that the Weihai ancient gneisses have a strong affinity with the Yangtze Block. The protoliths of them are Paleoproterozoic (ca. 2.46 Ga) magmatic rocks. They were subsequently suffered from ca. 1.8‐ to 1.84‐Ga metamorphism, new crustal materials overgrowth during ca. 740‐ to 787‐Ma magmatism, and then experienced Triassic continental deep subduction and exhumation process to build the Sulu orogenic belt. [ABSTRACT FROM AUTHOR]

The significant Late Mesozoic thinning of lithospheric mantle in eastern China caused the formation of many basins and intensive volcanism. Crust exhumation process is a crucial part of supracrust response of lithosphere destruction. It has been studied in order to constrain the model of Late Mesozoic thinning of lithospheric mantle. The Sulu orogenic belt and the Jiaobei Terrane underwent a substantial exhumation process in Early Cretaceous, and though many studies have been carried out to investigate its exhumation history, it is still lacking understanding. Extensional terrestrial domain of the Jiaolai Basin was formed along with the Early Cretaceous exhumation of the Jiaobei Terrane and the Sulu orogenic belt. It provides an ideal research object for studying the exhumation process of Jiaodong Peninsula in Early Cretaceous because of the continuous sedimentary record in the basin. In this study, we analysed detrital zircon geochronology of three sandstone samples from Early Cretaceous sediments in north‐eastern part of the Jiaolai Basin. Detrital zircon age spectrums indicate that zircon ages consist mainly of six clusters, and they comprise Neoarchean ages, Palaeoproterozoic ages, Neoproterozoic ages, Triassic ages, Jurassic ages, and Early Cretaceous ages. The study shows that the Jiaobei Terrane and the Sulu orogenic belt served as source areas that provided detrital materials for Early Cretaceous strata in the Jiaolai Basin. Our results, along with those of previous studies, suggest that Jiaobei Terrane and the Sulu orogenic belt in Jiaodong Peninsula had discrepant exhumation history in Early Cretaceous. [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 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 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 final closure of the Junggar–Balkhash Ocean resulted in the amalgamation of the circum‐Balkash–Junggar segments of the south‐western Central Asian Orogenic Belt, but the exact timing of its closure remains uncertain. Here, we use zircon U–Pb and whole‐rock chemical data for the adakitic rocks and fractionated I‐type granitoids in the Alashankou area of the southern West Junggar terrane (WJT) to investigate their petrogenesis and tectonic implications for the closure of the Junggar–Balkhash Ocean. The adakitic rocks were emplaced at 313–295 Ma and exhibit high Sr/Y ratios of 121–229. Their low MgO contents (0.91–2.09 wt%), Co, Cr, and Ni concentrations, initial 87Sr/86Sr ratios, and high εNd(t) values, indicate an origin from partial melting of juvenile lower crust under garnet‐amphibolite‐facies conditions triggered by basaltic underplating. By comparison, the fractionated I‐type granitic plutons (283–273 Ma) are weakly peraluminous and distinctive in terms of their low MgO contents (0.31–0.39 wt%) and strongly negative Nb, Ta, P, Eu, and Ti anomalies. These features, along with their higher initial 87Sr/86Sr ratios and lower εNd(t) values, suggest derivation by partial melting of a depleted mantle source and/or of newly underplated lower crust with crustal contamination. Given the Late Carboniferous depositional hiatus and post‐orogenic strike‐slip faulting and absence of post‐Devonian ophiolites and post‐Palaeozoic magmatic events in the WJT, the widespread occurrence of Late Carboniferous to Permian compositionally diverse granitoids (including the adakitic rocks, high‐Mg dioritic rocks, and I‐ and A‐type granitoids) and coeval mafic dykes can be best explained by a post‐collisional slab breakoff model. Together with other lines of geological evidence in the circum‐Balkash–Junggar area, we propose that the Junggar–Balkhash Ocean should have been closed at the beginning of the Late Carboniferous (~320 Ma), consistent with the closure time (~325–300 Ma) for regional major ocean basins. [ABSTRACT FROM AUTHOR]

The temporal–spatial framework of arc amalgamation is an important key for understanding the anatomy of orogenic collages, present and past. The Junggar‐Balkhash Ocean was a major branch of the southern Paleo‐Asian Ocean where several arcs were amalgamated. Among them, the Dananhu arc with its characteristic juvenile magmatism and lack of Precambrian basement is an efficient recorder of the evolutional history. From our U–Pb and Lu–Hf isotopic analyses of Devonian to Triassic sediments in the Dananhu arc and Permian sediments in the Yamansu‐Central Tianshan arc, we discovered two major changes in detrital zircon provenance of the Dananhu arc: (a) An increasing input of Precambrian ages from the Mongolia collage at 850, 1,850, and 2,500 Ma, together with Phanerozoic zircons ranging from 420 to 480 Ma with negative εHf(t) value since ca. 288 Ma; (b) the presence of the Yamansu‐Central Tianshan arclike Precambrian age cluster of 1,400–1,600 Ma around 243 Ma. In combination with regional tectonothermal events, these two changes correspond to the formation of the Harlik‐Dananhu composite arc in the latest Carboniferous–early Permian followed by its collision with the Yamansu‐Central Tianshan arc in the latest Permian–early Triassic, which marks the termination of the eastern Junggar‐Balkash Ocean. Analysis of the sedimentary successions within the intraoceanic arcs sheds light on the amalgamation history of the Central Asian Orogenic Belt. [ABSTRACT FROM AUTHOR]

The Wangjiadashan Cu–Au deposit is a vein‐type deposit controlled by the secondary faults of the Wushan Fault zone in the Suizao area of Hubei Province. Three hydrothermal stages are identified, namely, (I) barren quartz stage, (II) the quartz‐sulphide stage, and (III) quartz‐carbonate stage. Six types of fluid inclusions occur in quartz: (a) liquid‐rich aqueous fluid inclusions (L + V), (b) vapour‐rich aqueous‐carbonic fluid inclusions (V + L), (c) water‐rich aqueous‐carbonic fluid inclusions (L + V + CO2), (d) CO2‐rich aqueous‐carbonic fluid inclusions (V + L + CO2), (e) pure carbonic fluid inclusions (pure CO2), and (f) daughter mineral‐bearing multiphase inclusions (S‐type) with three subclasses (S1, S2, and S3 subtype). Two types of fluid inclusions occur in calcite: (a) liquid‐rich aqueous fluid inclusions (L + V) and (b) pure carbonic fluid inclusions (pure CO2). The S‐type fluid inclusions include halite (NaCl), calcite (CaCO3), and chalcopyrite (CuFeS2). The fluid system is composed of CO2–NaCl–H2O. The homogenization temperatures of the three stages are 295°C to 390°C, 245°C to 280°C, and 200°C to 241°C, with salinities of 7.3–19.8 wt% NaCl equiv. (except for several high values of 33.8 to 44.3 wt% NaCl equiv.), 7.7–13.7 wt% NaCl equiv., and 5.6–10.1 wt% NaCl equiv., respectively. Fluid immiscibility occurred in stage I that accounts for the high‐salinity fluids, but the dominant ore precipitation occurred afterward during temperature drop. In situ sulphur isotope analysis indicates a δ34S value around 0 (+1.1% to +2.2%) for the chalcopyrite, suggesting that the sulphur likely derived from the deep‐seated magma. Pyrites show δ34S values from −0.5‰ to +6.5‰ in stage II, from +0.7‰ to +6.6‰ in country rock of marble, but significantly higher from +12.8‰ to +21.7‰ in country rock of greenschist. These results indicate the sulphur for pyrite in stage II likely derived from the mixing of deep‐seated magma and country rocks. From stages I to II, a slightly increase of δD (from −86‰ and −73‰ to −59‰ and −56‰) and a decrease of δ18O (from 8.9‰ and 7.1‰ to 1.3‰ and 3.4‰) indicate that an increasing involvement of meteoric water. The carbon isotopes of fluid inclusions CO2 in quartz of stage I (−11.0‰ to −13.0‰) indicate a major magmatic or metamorphic carbon source mixed with minor sedimentary sourced carbon, but a major organic carbon source (−32.0‰ to −35.0‰) for stage II fluids. In conclusion, the Wangjiadashan Cu–Au deposit belongs to the orogenic type. [ABSTRACT FROM AUTHOR]

The Jiawula Ag–Pb–Zn deposit is located in the northern part of the Great Xing'an Range metallogenic belt within the eastern segment of the Central Asian Orogenic Belt. Here, we report results from muscovite 40Ar/39Ar geochronology and fluid inclusion study and formulate a vertical projection map of the ore grade in this deposit. The muscovite from the Jiawula deposit yields a plateau age of 133.27 ± 0.66 Ma and a 40Ar/39Ar isochron age of 131.88 ± 0.83 Ma. The muscovite 40Ar/39Ar data indicate a discrete second hydrothermal event postdating the mineralization, which we correlate with post‐collisional extension after the subduction direction of the Palaeo‐Pacific Plate changed. Low‐salinity aqueous fluid inclusions in quartz from the Jiawula deposit represent meteoric water or groundwater. Based on the fluid inclusion study, the fluids were trapped during cooling and decompression, which may have resulted in metal precipitation. We envisage that the copper precipitated from a high‐temperature fluid in the southern domain whereas lead, zinc, and silver precipitated at a lower temperature in the north. The spatial distribution of the ore‐forming elements, therefore, reflects the ore fluid migration‐cooling path from the south to north. [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]

Collision of the South and North China cratons was an important event in eastern Asia and contributed to the formation of the Central Orogenic Belt in China. While the timing of collision has been documented to the west (at the West Qinling Belt) and east (at the Dabie Mountains), little is known regarding the timing of collision in the middle sector of the collision zone. We present field, sedimentological, mineralogical, and geochemical data from the Late Permian Dalong Formation and Early Triassic Daye Formation (lower part) in the Western Hubei Trough which is located in the northern South China Craton. Based on sedimentary facies, SEM, and XRD data, we suggest that the Dalong Formation, which is mainly composed of chert and carbonaceous mudstone, was deposited in a deep shelf, and the lower part of the Daye Formation, which is mainly composed of mudstone and carbonate rocks, was deposited in a shallow shelf. Geochemical data imply that the source of the mudstone in these formations was the Qinling active continental margin of the North China Craton. These data support a scenario that the South and North China cratons may have collided by the end of the Late Wuchiapingian of Late Permian time at the southern margin of the East Qinling Belt. The collision event may have led to the formation of the Western Hubei Trough. [ABSTRACT FROM AUTHOR]

Early Neoproterozoic granites rarely outcrop in the Qilian Orogenic Belt (QOB) at the north‐eastern margin of the Qinghai–Tibet Plateau; however, they are vital to understanding the Precambrian evolution of the QOB. Thus, we present an integrated study, comprising petrology, geochronology, and whole‐rock geochemistry of two Early Neoproterozoic granitic plutons (Baihuagou and Yamacha plutons) in the eastern Qilian Block (QB). The results provide three key findings. First, their magma emplacement age is ca. 900 Ma (i.e., 918 Ma for Baihuagou and 910 Ma for Yamacha), and the two plutons have similar high‐K calc‐alkaline, strongly peraluminous characteristics, with slight enrichment in light rare earth elements; weak negative Eu anomalies; enrichment in large‐ion lithophile elements (e.g., K, Th, Ba, and Rb); strong depletion in Ti; and weak depletion in Nb, Ta, and, Sr. These characteristics indicate that the granites from these plutons are S‐type granites. Second, the two‐mica granite and gneissic granite samples may have been formed by partial melting of ancient crustal material (mainly psammitic rocks), with contributions from a meta‐igneous component, under high‐temperature and low‐pressure conditions. Third, new data from this study, combined with previously reported dates, indicate a continental margin arc setting for the QB during the Early Neoproterozoic (ca. 900 Ma). [ABSTRACT FROM AUTHOR]

We present new zircon U–Pb ages, geochemical data on the Late Palaeozoic volcanic rocks of the Suji and Dahongshan formations, which are exposed in the Plate Marginal Orogenic Belt along the northern margin of the North China Craton. Our aim is to constrain the petrogenesis, tectonic setting of volcanic rocks, and to address the late stage tectonic evolution of the Paleo‐Asian Ocean. Lithologically, the Suji and Dahongshan formations present the main rock association with basaltic andesite, andesite, dacite, rhyolite, and tuff. New zircon U–Pb dating results suggest that the volcanic rocks formed during 280–261 Ma and 277–267 Ma, respectively. Geochemically, these volcanic rocks belong to the low‐K tholeiitic to high‐K calc‐alkaline series and are characterized by highly enriched light rare earth elements, K, Rb, Ba; depleted Nb, Ta, Ti; and highly negative Eu anomalies, very similar to that of the continental arc magmatism. These data, together with geological field investigations, suggest that the Early Permian volcanic rocks from Suji and Dahongshan formations were related to southward flat subduction of the Paleo‐Asian Ocean beneath the northern margin of the North China Craton. Therefore, these volcanic rocks were interpreted as Andean‐style continental margin arc magmatism. This also indicates that the final collision between the North China Craton and the Siberian Craton did not occur until the Early Permian. [ABSTRACT FROM AUTHOR]

The evolution correlation between the North China Craton (NCC) and the Indian Shield (IND) is very important for plate reconstruction. Recently, more and more research results show that the NCC and IND had been pieced together in the Paleoproterozoic. In order to analyse the correlation between the NCC and IND, we use the latest gravity and magnetic data to study deep geophysical characteristics of the NCC and IND respectively, and we also use a two‐dimensional discrete wavelet transform method to discuss the division scheme of the basement tectonic unit in the Paleoproterozoic at the point of gravity and magnetic field. On the basis of gravity and magnetic anomalies, the NCC is divided into the Eastern Block, Western Block, and the Trans‐North China Orogen, which are further divided into the secondary tectonic zones and blocks. The IND is divided into the Southern Block, the Northern Block, and the Central Indian Tectonic Zone, and they also are further divided into secondary tectonic zones and ancient cratons. On the basis of that, according to the four Paleoproterozoic plate assemblage schemes proposed by predecessors, we compared the geophysical characteristics and the correlation through the regional gravity and magnetic anomalies between the two continents. The results show that the faults and tectonic boundaries in the Trans‐North China Orogen of the NCC correspond well to those in the Central Indian Tectonic Zone of IND. Moreover, the gravitational and magnetic anomalies in the Eastern Block of the NCC are quite similar to those in the Southern Block of IND, which shows that the NCC and IND might have been pieced together during the Paleoproterozoic. The geophysical result that verifies the correlation between the NCC and IND based on gravity and magnetic fields provides the evidence for Paleoproterozoic plate reconstruction and constrains the assembling patterns between the NCC and the IND. [ABSTRACT FROM AUTHOR]

The high‐pressure Heilongjiang Complex belongs to a Jurassic accretionary complex in Yilan area, NE China. The complex is located in the junction of three orogenic systems in the NE Asia: the E‐W‐striking Central Asian Orogenic Belt (CAOB), the N‐S‐striking Paleo‐Pacific system, and the ENE‐WSW‐striking Mongol‐Okhotsk system. Thus, a detailed tectono‐metamorphic analysis coupled with accurate radiometric dating of the Heilongjiang Complex provided in this study represent important evidence for understanding the complex interactions between the three orogenic systems in the Late‐Palaeozoic to Mesozoic. New structural and microstructural data combined with the strain analysis highlight the presence of three distinct deformation events affecting the high‐pressure Heilongjiang Complex. The first deformation event D1 is related to development of blueschist facies prolate to plane strain fabrics that were subsequently reworked by the blueschist‐amphibolite facies event D2 that transposed all previous structures by the main west‐dipping schistosity. This planar fabric was folded by upright F3 folds and heterogeneously reworked by greenschist facies E‐W‐striking vertical cleavage during large scale N‐S shortening. Each deformation event was related to specific strain fabrics and metamorphic conditions highlighting dynamic evolution of the subduction complex during burial, exhumation, and final shortening. The first D1 event is related to westward directed prograde constrictional flow and progressive dismembering of competent mafic, ultramafic layers, and quartzites in highly stretched meta‐sedimentary matrix. This mélange was folded by recumbent detachment folds resulting in emplacement of the exhumed unit progressively reaching amphibolite facies conditions atop of W‐WSW‐dipping channel. This event is associated with dominant flattening implying increasing mechanical coupling between the colliding Songliao and Jiamusi blocks. Subsequently, the accreted subduction complex was reworked during N‐S‐directed horizontal shortening. This event was associated with an important post‐buckle flattening of fold limbs and rotation of competent blocks with inherited D1 and D2 strain ellipsoids along F3 fold axes. Our new 40Ar‐39Ar plateau ages on muscovite and phengite (173–177 Ma), together with previous radiometric data, are interpreted as reflecting exhumation of subduction channel during the blueschist‐amphibolite facies event while the N‐S shortening (D3) probably operated in Late Jurassic as indicated by some previously published cooling ages (~140–160 Ma). The westward‐oriented subduction and exhumation fabrics of the high‐pressure Heilongjiang accretionary complex followed by N‐S‐directed upright folding are interpreted to reflect transition from E‐W Pacific subduction regime to N‐S‐directed shortening related to the closure of the Mongol‐Okhotsk Ocean. [ABSTRACT FROM AUTHOR]

The South Tianshan Orogenic Belt (STOB) is situated in the southwest margin of the Central Asian Orogenic Belt and is characterized by the distribution of ophiolitic mélanges and metamorphic rocks. In this study, we focus on 5 ophiolitic mélanges with ocean island basalt (OIB) and aim to discuss the tectonic evolution of the South Tianshan Ocean. The Kynda, Kainar, Uchkel, Heiyingshan, and Guluogou ophiolitic mélanges in STOB mainly consist of metamorphic peridotite, gabbros, basaltic lavas (pillows), abyssal radiolarian cherts, and limestones. The basaltic rocks mainly occur as tectonic blocks within the mélanges. These basaltic rocks are characterized by LREE enrichment and HREE depletion, very weak or no Eu anomalies, and no obvious Nb, Ta, and Ti negative anomalies, positive εNd(t) values, relatively high initial 87Sr/86Sr ratios, and wide 206Pb/204Pb ratios, showing the signature of OIB. The OIB‐type rocks from Kynda, Kainar, and Guluogou are likely to be derived from garnet lherzolite by relatively high degrees of melting (10% to 20%). But the basaltic rocks of Uchkel and Heiyingshan formed at significantly lower degrees of partial melting (1% to 5%) of spinel and/or garnet lherzolite. The OIB‐type rocks in these ophiolitic mélanges are considered as accreted seamount fragments and may represent mantle plume‐related magmatism within the South Tianshan Ocean. In combination with previous work, we suggest an updated model, which is bidirectional oceanic subduction with seamounts accretion and subduction system, is suitable for Palaeozoic tectonic evolution of the South Tianshan Ocean. [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 Wei River Basin is located between the Qinling Orogenic Belt and the Ordos Block. It is an important seismic belt and part of the Silk Road in China. The development of the basin is the result of interaction between the Qinling Orogenic Belt and the Ordos Block. Based on the geomorphic features, sedimentary characteristics, and geophysical detection data, combined with the tectonic movement of the Qinling Orogenic Belt in the Cenozoic, this article considers that the Wei River Basin was formed by both the Qinling Orogenic Belt thrusting to the Ordos Block and the left‐lateral strike‐slipping of the margin fault in the Cenozoic. The combined actions of Indian Plate subduction and Pacific Plate subduction have caused the eastern section of the Wei River Basin to turn from east–west to northeast and the Ordos Block to undergo counterclockwise rotation. The analysis of the formation mechanism and evolutionary process of the Wei River Basin should be of great practical significance in the study of the seismicity of the Wei River Basin. [ABSTRACT FROM AUTHOR]

The Fe-Ti ore-bearing Shangzhuang mafic intrusion in the Yanshan Orogenic Belt, north of the North China Craton, is characterized by compositional layering with troctolite, noritic gabbro and gabbro from the bottom to the top. The intrusive complex formed through fractionation of Fe-, Ti- and Mg-rich mafic hydrous magma. Here, we present a systematic petrological and mineral data on the various rock types from this intrusion. The plagioclase laths exhibit Na-enriched rims with homogeneous cores and XAn content decreasing towards the margin, induced by sluggish coupled inter-diffusion of (Ca + Al) versus (Na + Si). The reactions also resulted in amphibole and orthopyroxene rims surrounding olivine. Subsolidus equilibrium is indicated by Fe-Ti oxide lamellae in pyroxenes. The H2O content of the primary magma is estimated to be less than 2.5 wt.%, and initial crystallization temperature in the magma chamber is estimated as approximately 884 °C at a pressure of 3.45 kbar. The formation of the parent magma was due to the thermal-chemical erosion through mantle upwelling, basaltic underplating and heat input from convection of deep asthenosphere mantle, widely associated with the large-scale Mesozoic lithospheric thinning beneath the North China Craton. Final emplacement of the Shangzhuang intrusion is related to the intra-continental extensional setting, at a depth of approximately 14.5 km, suggesting large-scale, post-emplacement uplift and exhumation of the Yanshan Orogenic Belt in the Late Jurassic and Early Cretaceous. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

East Asia suffered an important transformation from the Tethys to the Pacific tectonic domain during the early Mesozoic. Moreover, the South China Block (SCB) in East Asia has an obvious change from an Indosinian syn-orogenic compression to a post-orogenic extensional tectonic setting. The dynamic evolution of the SCB that caused this change is still unclear. Here, we combine the petrology and whole-rock geochemistry of the Daoxian mafic granulite xenoliths in basalts from South Hunan Province and the structural features of the Xuefengshan tectonic belt, to propose a late Triassic tectonic model in the central SCB. The Daoxian region is located in the eastern part of the Xuefengshan basement uplift belt. The Daoxian mafic granulite xenoliths, forming in the late Triassic, have high Mg# value, high MgO and low SiO2 contents. They have flat REE patterns with a positive Eu anomaly, enriched in Rb, Ba, and depleted in Th, U, Nb, Zr and Hf. These xenoliths are the product of pyroxene and plagioclase accumulation of the mafic melts. The mafic melts originated from the asthenosphere and then underplated to the bottom of the lower crust. In the Xuefengshan belt, it is observed that the unconformities during the Late Triassic changed from high-angle unconformity, through low-angle unconformity and para-unconformity, to conformity, from the central to western parts of the SCB. The detachment layer beneath the Xuefengshan belt displaying NW-trending thrusts cross-cuts the late Palaeozoic strata. We suggest that orogenic collapse happened beneath the central SCB during the Late Triassic, which was accompanied by lithospheric extension and asthenospheric upwelling. These dynamic processes induced different effects on the SCB. Beneath the central SCB, the mantle-derived melt underplated the lower crust, and subsequently influenced the deep crust. From central to western SCB, the regular westward change of the stratal unconformities is related to the weakening of the lithospheric extension. In the central and eastern SCB, the orogenic collapse and the subsequent asthenosphere upwelling could have contributed to the mantle disturbance to enhance the roll-back of the Palaeo-Pacific slab. Copyright © 2016 John Wiley & Sons, Ltd. [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]

The Qinling Orogen in central China preserves the records of a complex geological and tectonic history, and also carries abundant mineral resources. Previous investigations on the Qinling Orogen have identified that the final transition from the Palaeo-Tethys Ocean to a continental orogen occurred in the Triassic, although the timing of the oceanic closure and the tectonic affinity of the Triassic Qinling belt have been poorly constrained. In this contribution, we compile the palaeomagnetic data and geological evidence related to sedimentation, magmatism and mineral systems. The palaeomagnetic data show that the Palaeo-Tethys Ocean in the Qinling Orogen gradually closed westward during the Triassic, terminating in the beginning of the Jurassic. Triassic strata are widely developed in the Qinling Orogen and conformably overlie the Permian strata. They are composed of carbonates and siliciclastic rocks that were strongly deformed and weakly metamorphosed during the Late Triassic to Late Jurassic. The Triassic magmatic rocks are dominated by I-type granitoids, with subordinate S-type and alkaline granites and minor carbonatite dykes, with a clear northward transition in lithology and geochemical features from the Mian-Lue Suture. Different types of Triassic mineral systems have been reported from this region, including sedimentary-hosted epizonogenic hydrothermal Hg-Sb, Pb-Zn ± Ag, Au deposits, metamorphic hydrothermal lodes of Au, Ag-Pb-Zn, Mo-Au and Mo, magmatic hydrothermal systems including porphyry Mo, breccia pipe Au, and carbonatite-hosted Mo deposits. We infer that the Triassic Qinling Orogen witnessed synchronous oceanic plate subduction in the west and continental linkage in the east, with a transition from oceanic basin to continental orogen through gradual subduction-related consumption of the oceanic plate. The Palaeo-Tethys Ocean closed in a westward scissor-like fashion in the Triassic and continental collision and extensive crustal shortening in the Jurassic, following which post-collisional extension occurred in the Early Cretaceous. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]