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Post‐collisional magmatism contains important clues for understanding the reworking and growth of continental crust, as well as lithospheric delamination and orogenic collapse. Early Devonian magmatism has been identified in the North Qilian Orogenic Belt (NQOB). This paper reports an integrated study of petrology, whole‐rock geochemistry, Sm‐Nd isotope and zircon U‐Pb dating, as well as Lu‐Hf isotopic data, for two Early Devonian intrusive plutons. The Yongchang and Chijin granites yield zircon U‐Pb ages of 394–407 Ma and 414 Ma, respectively. Both of them are characterized by weakly peraluminous to metaluminous without typical aluminium‐rich minerals, LREE‐enriched patterns with negative Eu anomalies and a negative correlation between P2O5 and SiO2 contents, consistent with geochemical features of I‐type granitoids. Zircons from the studied granites display negative to weak positive εHf(t) values (–5.7 to 2.1), which agree well with those of negative εNd(t) values (−6.4 to −2.9) for the whole‐rock samples, indicating that they were derived from the partial melting of Mesoproterozoic crust. Furthermore, low Sr/Y ratios (1.13–21.28) and high zircon saturation temperatures (745°C to 839°C, with the majority being >800°C) demonstrated a relatively shallow depth level below the garnet stability field and an additional heat source. Taken together, the Early Devonian granitic magmatism could have been produced by the partial melting of ancient crustal materials heated by mantle‐derived magmas at high‐temperature and low‐pressure conditions during post‐collisional extensional collapse. The data obtained in this study, when viewed in conjunction with previous studies, provides more information about the tectonic processes that followed the closure of the North Qilian Ocean. The tectonic transition from continental collision to post‐collisional delamination could be constrained to ∼430 Ma, which is provided by the sudden decrease of Sr/Y and La/Yb ratios and an increase in zircon εHf(t) values for granitoids. A two‐stage tectonic evolution model from continental collision to post‐collisional extensional collapse for the NQOB includes (a) continental collision and crustal thickening during ca. 455–430 Ma, characterized by granulite‐facies metamorphism and widespread low‐Mg adakitic magmatism; (b) post‐collisional delamination of thickened continental crust and extensional collapse of orogen during ca. 430–390 Ma, provided by coeval high‐Mg adakitic magmatism, A‐type granites and I‐type granitoids with low Sr‐Y ratios. [ABSTRACT FROM AUTHOR]

Xiazhuang uranium ore field, located in the southern part of the Nanling Metallogenic Belt, is considered one of the largest granite‐related U regions in South China. In this paper, we contribute new apatite fission track data and thermal history modeling to constrain the exhumation history and evaluate preservation potential of the Xiazhuang Uranium ore field. Nine Triassic outcrop granite samples collected from different locations of Xiazhuang Uranium ore field yield AFT ages ranging from 43 to 24 Ma with similar mean confined fission track lengths ranging from 11.8 ± 2.0 to 12.9 ± 1.9 μm and Dpar values between 1.01 and 1.51 μm. The robustness time‐temperature reconstructions of samples from the hanging wall of Huangpi fault show that the Xiazhuang Uranium ore field experienced a time of monotonous and slow cooling starting from middle Paleocene to middle Miocene (∼60–10 Ma), followed by relatively rapid exhumation in the late Miocene (∼10–5 Ma) and nearly thermal stability in the Pliocene–Quaternary (∼5–0 Ma). The amount of exhumation after U mineralization since the Middle Paleogene was estimated as ∼4.3 ± 1.8 km according to the integrated thermal history model. Previous studies indicate that the ore‐forming ages of U deposits in the Xiazhuang ore field are mainly before Middle Paleocene and the mineralization depths are more than 4.4 ± 1.2 km. Therefore, the exhumation history since middle Paleocene plays important roles in the preservation of the Xiazhuang Uranium ore field. [ABSTRACT FROM AUTHOR]

The Jitang metamorphic complex is key to studying the tectonic evolution of the Northern Lancangjiang zone. Through structural‐lithological mapping, structural analysis and laboratory testing, the composition of the Jitang metamorphic complex was determined. The macro‐ and microstructural analyses of the ductile detachment shear zone (Guoxuepu ductile shear zone, 2–4 km wide) between the metamorphic complex and the overlying sedimentary cap show that the shear sense of the ductile shear zones is top‐to‐the‐southeast. The presence of various deformation features and quartz C‐axis electron backscatter diffraction (EBSD) fabric analysis suggests multiple deformation events occurring at different temperatures. The average stress is 25.68 MPa, with the strain rates (έ) ranging from 9.77×10–14 s–1 to 6.52×10–16 s‐1. The finite strain of the Guoxuepu ductile shear zone indicates an elongated strain pattern. The average kinematic vorticity of the Guoxuepu ductile shear zone is 0.88, implying that the shear zone is dominated by simple shear. The muscovite selected from the protomylonite samples in the Guoxuepu ductile shear zone yields a 40Ar‐39Ar age of 60.09 ± 0.38 Ma. It is suggested that, coeval with the initial Indo–Eurasian collision, the development of strike‐slip faults led to a weak and unstable crust, upwelling of lower crust magma, then induced the detachment of the Jitang metamorphic complex in the Eocene. [ABSTRACT FROM AUTHOR]

As an important part of the early Mesozoic granites in the South Qinling tectonic belt (SQTB), the Guangtoushan pluton provides a material basis for research on the composition of magma sources and the effects of peritectic assemblage entrainment (PAE) on the changes in the granite composition. As shown by the results of LA‐ICP‐MS zircon U‐Pb dating, the Guangtoushan pluton was emplaced during the Late Triassic (214–212 Ma) and was formed in the post‐collision stage between the SQTB and the Yangtze plate. The collected samples had high SiO2 content and low Cr and Ni contents, indicating that the magmas did not undergo significant crust‐mantle mixing during their evolution. The Guangtoushan granitoids were distributed along the trend line of magmatic fractional crystallization in the F–An–Or diagram. This result, combined with the relatively homogeneous Sr‐Nd isotopic composition, implies that the Guangtoushan pluton underwent slight assimilation and contamination. As can be inferred from the comparison between the compositions of the Guangtoushan granitoids and various fluid‐absent experimental melts, the magma sources of the Guangtoushan granitoids contain a variety of materials, such as graywackes, pyroclastic graywackes, and pelites and are not derived from lower crustal mafic rocks. The correlation between the maficity and the major and trace elements further indicates that the strongly peraluminous granitoids from the Guangtoushan pluton was formed by the partial melting of biotite‐bearing crustal rocks and its magmatic evolution was accompanied by the entrainment of clinopyroxenes and accessory minerals. [ABSTRACT FROM AUTHOR]

Gneisses with anatectic characteristics from the Liansan island in the Sulu UHPM (ultra‐high pressure metamorphic) belt were studied for petrography, titanite U‐Pb dating and mineral geochemistry. Three origins of garnets are distinguished: metamorphic garnet, peritectic garnet and anatectic garnet, which are formed in the stages of peak metamorphism, retrograde anatexis and melt crystallization, respectively. The euhedral titanite has a high content of REE and high Th/U ratios, which is interpreted as indicating that it was newly‐formed from an anatectic melt. The LA‐ICP‐MS titanite U‐Pb dating yields 214–217 Ma ages for the titanite (melt) crystallization. The distribution of trace elements varies in response to the different host minerals at different stages. At the peak metamorphic stage, Y and HREE are mainly hosted by garnet, Ba and Rb by phengite, Sr, Nb, Ta, Pb, Th, U and LREE by allanite and Y, U and HREE by zircon. During partial melting, Y, Pb, Th, U and REE are released into the melt, which causes a dramatic decline of these element contents in the retrograde minerals. Finally, titanite absorbs most of the Nb, U, LREE and HREE from the melt. Therefore, the different stages of metamorphism have different mineral assemblages, which host different trace elements. [ABSTRACT FROM AUTHOR]

The Susong complex zone is a relatively low‐grade metamorphic unit located in the southern part of the Dabie orogen and preserves a variety of metasedimentary rocks, mostly with epidote–amphibolite facies. However, their depositional age, provenance and tectonic setting of sedimentary protolith remain controversial due to the lack of fossils, precise dating and integrated geochemical investigation. This study has conducted whole‐rock elemental, and zircon U‐Pb SHRIMP dating and Lu‐Hf isotope analyses on three types of representative metasedimentary rocks including garnet‐bearing mica‐quartz schist, graphite‐muscovite‐quartz schist and dolomitic marble from the Susong complex zone. The U‐Pb SHRIMP dating data indicate that the sedimentary protolith of these rocks have the maximum depositional ages of less than 840–750 Ma and have various sedimentary provenances. In combination with zircon Lu‐Hf isotope compositions, the provenance of the metasedimentary rocks in the region is for the first time documented to be mainly derived from four groups of magmatic rocks formed at ∼2.5 Ga, ∼2.0 Ga, ∼1.4 Ga and ∼0.8 Ga in response to four episodes of igneous activity in the northeastern margin of the Yangtze Block. The conventional geothermobarometry combined with rare metamorphic zircon ages indicate that the studied rocks underwent the Late Triassic continental subduction‐related metamorphism with peak epidote–amphibolite facies conditions at P = 0.34–0.91 GPa and T = 427–532°C. In addition, results of the elemental contents (i.e., La, Ce, Th and ΣREE) and ratios (i.e., Eu/Eu* and LaN/YbN) suggest that the protoliths of the metasedimentary rocks were mainly shales, wackes and limestones, most probably related to the Rodinia supercontinent rifting along the northern margin of the Yangtze Block during the Neoproterozoic. [ABSTRACT FROM AUTHOR]

Whether a Neoarchean basement existing in the Songnen massif is currently debated. Identification of Archean magmatism from the Songnen Massif is helpful to resolve this issue. Here, we report newly discovered Neoarchean Shanquan pluton in the Western Songnen Massif. These Neoarchean Shanquan pluton are mainly composed of granites that are exposed near the town of Shanquan in Heilongjiang Province. LA‐ICP‐MS zircon U‐Pb dating reveals that the sample 2015TW1 has an upper intercept age of 2801 ± 69 Ma and a weighted mean age of 2708 ± 18 Ma, while samples LJ27QY1 and LJ27QY2 have upper intercept ages of 2677 ± 57 Ma and 2653 ± 18 Ma, and weighted mean ages of 2649 ± 10 Ma and 2653 ± 15 Ma, respectively. This indicates that these granites were formed at ~2.7 Ga. Most of the ~2.7 Ga zircons have older TDM2 ages of 2762–3326 Ma with positive εHf(t) values ranging from 0 to 6.4, while a few of the zircons have negative εHf(t) values ranging from −8.1 to −11.5 and older TDM2 ages varying from 3158 to 3264 Ma. The zircon Hf isotopes indicate that Paleo‐Mesoarchean crusts might once existed in the Songnen Massif, and the studied Neoarchean magmas were principally derived from partial melting of these Paleo‐Mesoarchean ancient crust. Based on the geochronological spectrum of magmatic and detrital zircons, the Songnen, Erguna, Jiamusi, Bureya massifs may have a common basement prior to the Neoproterozoic and may even be linked with the Triam Craton. [ABSTRACT FROM AUTHOR]

Using high‐precision zircon U‐Pb ID‐TIMS geochronology, tuffs from the Chang 9 shale and the Chang 7 shale were dated. The tuff in the Chang 9 shale is 241.47 ± 0.17 Ma, which falls between the top tuff age of 241.06 ± 0.12 Ma and the bottom tuff age of 241.558 ± 0.093 Ma in the Chang 7 shale. These reveal that the Chang 9 and Chang 7 shales are contemporaneous, belonging to the Ladinian stage of the Middle Triassic. This insight expands the region of the main source rock of Chang 7 to the northeast and will inform the search for the deep Chang 9 shale petroleum system, increasing the scope for exploring the Chang 7 shale system in northern Shaanxi. The research results clarify the relationship between the two sets of shale in the Yanchang Formation and redefine the distribution range of the Chang 7 shale in the Ordos Basin. At the same time, it shows that there is a cross‐layer problem in the stratigraphic division of the Yanchang Formation in different regions, the high‐precision U‐Pb dating technology providing a reference for the fine stratigraphic correlation of other continental basins in the world. [ABSTRACT FROM AUTHOR]

The Nanyuan Formation contains information related to the Mesozoic tectonic transformation. In this study, three representative profiles were surveyed from the Nanyuan Formation, and multiple analyses were conducted. Zircon U‐Pb dating yielded their ages as approximately 158–146 Ma. The volcanic rocks are enriched in Rb, Th, U, K, and Pb and depleted in Nb, Ta, P, and Ti, implying their affinity for I‐type granites. The εNd(t) values (–8.3 to −6.0), (87Sr/86Sr)i values (0.7077–0.7094) of the volcanic rock, and εHf(t) values (–8.71 to 0.12) of the Mesozoic zircons suggest that the Nanyuan Formation magma originated in the lower crust with the involvement of depleted mantle materials. The parent rocks of the rhyolitic and dacitic volcanic rocks formed by partial melting of basement rocks in South China and the andesitic volcanic rocks were derived from partial melting of the metasomatites generated by slab‐mantle interaction. The fractional crystallization also played an important role in later stage. Discrimination diagrams of the volcanic rocks indicated that they formed in a volcanic arc environment. Combined with previous data, the Nanyuan Formation recorded subduction of the Paleo‐Pacific Plate before regional tectonic transformation. The compressive stress field endured until the end of the Late Jurassic. [ABSTRACT FROM AUTHOR]

We investigated the meta‐gabbronorites in Liangcheng and used detailed petrography, geochemistry, zircon geochronological and in‐situ Hf isotopic studies to clarify their formation and metamorphic ages, petrogenesis, tectonic setting and provide constraints on the tectonic evolution of Khondalite Belt (KB). The zircon U‐Pb dating results show that the meta‐gabbronorites crystallized at ~1.94 Ga and were metamorphosed at ~1.91–1.89 Ga. They can be subdivided into the low‐Mg and high‐Mg groups. The low‐Mg meta‐gabbronorites contain relatively lower MgO and higher SiO2 contents than high‐Mg meta‐gabbronorites. They are enriched in light rare earth elements and large ion lithophile elements, depleted in high field strength elements, and exhibit positive (high‐Mg meta‐gabbronorites) and negative (low‐Mg meta‐gabbronorites) Sr and Eu anomalies. The zircon in‐situ εHf(t) of meta‐gabbronorites is 0.07–4.12, with Hf model ages (TDM) of 2169–2400 Ma. The meta‐gabbronorites in Liangcheng originated from the asthenospheric mantle and experienced fractional crystallization of olivine, orthopyroxene, clinopyroxene, and plagioclase. They were contaminated by the crustal rocks (mainly khondalite series) during ascent, especially for low‐Mg gabbronorites. The ridge subduction is the most plausible tectonic setting for meta‐gabbronorites, indicating the eastern segment of KB was in a ridge subduction setting at ~1.94 Ga following an orogenic thickening event during a prolonged orogenic process. [ABSTRACT FROM AUTHOR]

It is generally believed that the lithospheric mantle and the mantle transition zone are important carbon reservoirs. However, the location of carbon storage in Earth's interior and the reasons for carbon enrichment remain unclear. In this study, we report CO2‐rich olivine‐hosted melt inclusions in the mantle xenoliths of late Cenozoic basalts from the Penglai area, Hainan Province, which may shed some light on the carbon enrichment process in the lithospheric mantle. We also present a detailed petrological and geochemical investigation of the late Cenozoic basalts and mantle xenoliths from northern Hainan Island. The collected samples of late Cenozoic Hainan Island basalts belong to both alkaline and subalkaline series, showing fractionated REE patterns with high (La/Yb)N values of 3.52–11.77, which are typical for OIB. Based on Al‐in‐olivine thermometry, the temperatures estimated for the mantle xenoliths can be divided into two groups. One group has temperatures of less than 1050°C, and the other group has temperature ranging from 1050°C to 1282°C. Clinopyroxene (La/Yb)N–Ti/Eu and clinopyroxene Ca/Al–Mg# diagrams indicate that the mantle peridotite experienced metasomatism from both silicate and carbonate melts. Melt inclusions in the olivine of mantle xenoliths include (1) CO2 bubble–rich melt inclusions; (2) multiphase melt inclusions (glass + CO2 bubble + daughter minerals); (3) pure glass melt inclusions. Magnesite is a daughter mineral in the olivine‐hosted melt inclusions, which could be interpreted as a secondary mineral formed by the interactions of CO2‐rich fluids with an olivine host, due to post‐entrapment effects. The glasses in olivine‐hosted melt inclusions have high SiO2 contents (60.21–77.72 wt%). Our results suggest that a considerable amount of CO2‐rich melt inclusions are captured in the lithospheric mantle during metasomatism. The lithospheric mantle can therefore act as is a 'carbon trap', with much CO2 being absorbed by the lithospheric mantle in this way. [ABSTRACT FROM AUTHOR]

Haitaite‐(La), (La, Ce)(U4+, U6+, Fe2+)(Fe3+, Al)2(Ti, Fe2+, Fe3+)18O38, is a new member of the crichtonite group. It is named after the Haita Village in the Miyi County of Sichuan Province, China, where the mineral was discovered. The mineral occurs as black opaque centimeter‐sized aggregates in the external contact zone between the Neoproterozoic (∼800 Ma) alkali feldspar granite and the Mesoproterozoic (∼1700 Ma) micaschist. In the studied sample, haitaite‐(La) is associated with other minerals, including ilmenite, magnetite, rutile, zircon, brannerite and uraninite. The new mineral is a black, metallic phase and has a Mohs hardness of 6, with a density of 4.99 g/cm3 (calculated) and 5.03 g/cm3 (measured). Haitaite‐(La) is opaque in transmitted light and grayish‐white under reflected light, with a reflectivity between 22.5% and 16.42% in the 400–700 nm band (SiC, in the air). The compositions of the mineral were measured by EPMA, the U4+/U6+ ratio was determined by X‐ray photoelectron spectroscopy and the Fe2+/Fe3+ ratio was determined by Mössbauer spectroscopy. Haitaite‐(La) is trigonal, belongs to and has unit‐cell parameters a = 10.3678(5) Å, c = 20.8390(11) Å, V = 1939.9(2) Å3, Z = 3. The crystalline structure is composed of octahedra with 9 layers of close‐packed octahedra (M1, M3, M4, M5), tetrahedra (M2) and contains large 12‐coordinated M0 sites. [ABSTRACT FROM AUTHOR]

A comprehensive study of zircon U‐Pb geochronology, in situ Hf isotopes, whole‐rock major and trace element geochemistry, and Nd isotopes was carried out for two Early Jurassic two‐mica granites (Longtang and Menglong) in the southern part of the Tengchong terrane, which is in the northern part of the larger Sibumasu terrane. We assess the origin of the granites and explore their possible genetic relationship to the Paleo‐Tethyan regime. LA‐ICP‐MS zircon U‐Pb dating shows that they were simultaneously emplaced in the Early Jurassic (ca. 199 Ma). They have SiO2 contents of 69.7–75.1 wt% and are mainly strongly peraluminous with alumina saturation index (ASI) values ranging from 1.06 to 1.46. They show similar Mg# (0.29–0.42) to experimental partial melts of metasedimentary rocks under continental pressure‐temperature (P‐T) conditions. They are enriched in light rare earth elements (LREEs) relative to heavy rare earth elements (HREEs), with moderately negative Eu anomalies and flat HREEs patterns. They show negative εNd(t) values (–9.0 to –12.4) and εHf(t) values (–8.0 to –9.1). Elemental and isotopic data suggest that they most likely to formed by muscovite‐dehydration melting of a metapelitic source at lower temperatures in the range of 700°C to 750°C. The granites might represent a post‐collisional tectonic setting response to Paleo‐Tethyan regime. [ABSTRACT FROM AUTHOR]

The Yusishan deposit is a newly found leptynite‐type niobium and tantalum (Nb‐Ta) deposit, which is located in the Eastern Altun of Gansu Province. The leptynite of the Neoproterozoic Aoyougou Formation occurs more than 10 km long and 3 km wide. In this paper, we carried out a detailed study of the leptynite and related mineralization. The U‐Pb dating of zircon reveals ages of 831 ± 5 Ma and 790 ± 5 Ma for the unmineralized leptynite and 491 ± 4 Ma and 455 ± 4 Ma for the mineralized leptynite. The petrographic and geochemical evidence identified the protolith of the leptynite as alkaline volcanic rocks that erupted during Neoproterozoic at ca. 830 Ma. At ca. 490 Ma, the tectono‐magmatic and metamorphic event triggered remobilization and enrichment of Nb‐Ta as well as other critical metals (REE, Zr, Hf etc) with the formation of industry orebodies in the leptynite strata. The Yushishan deposit presents many similarities with the alkaline volcanic rocks related rare metal deposits in the south Qinling of China and the Brochman, Toogni and Southern Peak Range deposits in Australian. We therefore propose that the Yushishan deposit is a new type (sub‐type) of Nb‐Ta deposit and termed as leptynite type that represents the metamorphic counterpart of the alkaline volcanic rocks related rare metal deposits. [ABSTRACT FROM AUTHOR]

The Shanmen deposit, located in the Siping area of Jilin Province, is one of large‐scale silver deposits in Northeast (NE) China. Due to its high Ag grade, associated gold resources and special tectonic location, this deposit has important theoretical and ore‐prospecting significance. To present new data on the ore genesis, mineralization time and tectonic settings, the relationship between silver mineralization and intrusions in this deposit has been studied and some analyses have been carried out, including LA‐ICP‐MS zircon U‐Pb dating, whole‐rock major and trace element analysis and Sr‐Nd‐Pb isotope analysis of the granitoids associated with silver mineralization. Studies on deposit geology indicate that the ore‐hosting granodiorite and monzogranite have intimate genetic relationships with silver mineralization. LA‐ICP‐MS zircon U‐Pb dating results of the both intrusions are 167.6 ± 1.9 Ma and 167.0 ± 1.5 Ma, respectively, implying that the two intrusions and associated silver mineralization in the Shanmen deposit formed during the Middle Jurassic. Major element analytical data suggest that the two intrusions are high‐K calc–alkaline series I‐type granites and belong to metaluminous and peraluminous rocks. Both intrusions have similar REE characteristics with regard to the relative enrichment of LREEs, depletion of HREEs, obvious fractionation of LREEs and HREEs (ΣLREE/ΣHREE = 8.68–14.09, (La/Yb)N = 12.51–21.96), moderately negative Eu anomalies as well as weakly negative Ce anomalies (δEu = 0.56–0.71, δCe = 0.93–1.09). Moreover, the samples are generally enriched in LILEs and depleted in HFSEs. The rock assemblages and geochemical characteristics of granitoids in the Shanmen deposit suggest that they formed in an active continental margin associated with the Paleo‐Pacific plate subduction. The Sr‐Nd‐Pb isotope compositions show that both the granodiorite and monzogranite have low Sr initial ratios and high Sm/Nd initial ratios. The εNd(t) values and young Nd‐model ages are –3.2 to –1.7 and 990 Ma to 1110 Ma, respectively. Considering the Sr‐Nd isotope compositions, in conjunction with the relatively high 206Pb, 207Pb and 208Pb, alongside the relatively low 204Pb, it can be concluded that the Middle Jurassic intermediate‐acidic magma represented by the studied monzogranite and granodiorite in the Shanmen deposit, was derived from the partial melting of juvenile lower crust enriched in mantle‐derived materials and affected by the mixing of ancient crustal materials during the ascension and intrusion processes. [ABSTRACT FROM AUTHOR]

The late Paleozoic tectonic framework of the southeastern Central Asian Orogenic Belt is key to restricting the accretion orogeny between the Siberia Craton and the North China Craton. To clarify the framework, petrogenesis of early Permian intrusive rocks from southeastern Inner Mongolia was studied. Zircon U‐Pb dating for bojite and syenogranite from Ar‐Horqin indicate that they were emplaced at 288–285 Ma. Geochemical data reveal that the bojite is highly magnesian and low‐K to middle‐K calc‐alkaline, with E‐MORB‐type REE and IAB‐like trace element patterns. The syenogranite is a middle‐K calc‐alkaline fractionated A‐type granite and shows oceanic‐arc‐like trace element patterns, with depleted Sr‐Nd‐Hf isotopes, (87Sr/86Sr)I = 0.7032–0.7042, εNd(t) = +4.0 to +6.6 and zircon εHf(t) = +11.14 to +14.99. This suggests that the bojite was derived from lithospheric mantle metasomatized by subducted slab melt, while the syenogranite originated from very juvenile arc‐related lower crust. Usng data from coeval magmatic rocks from Linxi–Ar‐Horqin, the Ar‐Horqin intra‐oceanic arc was reconstructed, i.e., initial transition in 290–280 Ma and mature after 278 Ma. Combined with regional geological and geophysical materials in southeastern Inner Mongolia, an early Permian tectonic framework as 'one narrow ocean basin of the PAO', 'two continental marginal arcs on its northern and southern' and 'one intra‐oceanic arc in its southern' is proposed. [ABSTRACT FROM AUTHOR]

The Alxa Block is the westernmost part of the North China Craton (NCC), and is regarded as one of the basement components of the NCC. Its geological evolution is of great significance for the understanding of the NCC. However, the Precambrian basement of the Alxa Block is still poorly studied. In this study, we present new in situ LA‐ICP‐MS zircon U‐Pb and Lu‐Hf isotope data from the Diebusige Metamorphic Complex (DMC) which located in the eastern Alxa Block. Field and petrological studies show that the DMC consists mainly of metamorphic supracrustal rocks and minor metamorphic plutonic rocks and has experienced amphibolite‐granulite facies metamorphism. Zircon U‐Pb dating results suggested that the amphibolite sample yields a crystallization age of 2636 ± 14 Ma and metamorphic ages of 2517–2454 Ma and 1988–1952 Ma, proving the existence of exposed Archean rocks in the Langshan area and indicating that late Neoarchean to Paleoproterozoic metamorphic events existed in the Alxa Block. Two paragneiss samples show that the magmatic detrital zircons from the DMC yield 207Pb/206Pb ages ranging from 2.48 Ga to 2.10 Ga with two youngest peaks at 2.13 Ga and 2.16 Ga, respectively, and they were also overprinted by metamorphic events at 1.97–1.90 Ga and 1.89–1.79 Ga. Compilation of U‐Pb ages of magmatic detrital and metamorphic zircons suggested that the main part of the DMC may have been formed at 2.1–2.0 Ga. Zircon Lu‐Hf isotope data show that the source materials of the main part of the DMC were originated from the reworking of ancient Archean crust (3.45–2.78 Ga). The Hf isotope characteristics and the tectonothermal event records exhibit different evolution history with the Khondalite Belt and the Yinshan Block and the other basements of the Alxa Block, indicating that the Langshan was likely an independent terrain before the middle Paleoproterozoic and was subjected to the middle to late Paleoproterozoic tectonothermal events with the Khondalite Belt as a whole. [ABSTRACT FROM AUTHOR]

The adakites rocks are typically considered as direct diagnostic evidence for subduction and continental growth, as well as the important evidence to determine the location of the major oceanic basin and evolution history of lost oceanic basins, which are longstanding conundrums for understanding the tectonics of the Paleo‐Asian Ocean (PAO). As the processor of the Altaids, the PAO was a long‐lived ocean, and its multiple subductions led to substantial continental growth in the Central Asian continent. Here we report our newly discovered Paleozoic adakitic rocks (granite and dacite) developed in Jijitaizi in the Eastern Tianshan of the southern Altaids to address the above issues. The Jijitaizi granite and dacite contain high concentrations of Sr (203–343 ppm) and low concentrations of Y (3.00–6.36 ppm) and Yb (0.23–0.62 ppm), indicative of the adakitic affinity. Zircon U‐Pb dating results show that the adakitic rocks were formed in three episodes at 372.26 ± 1.51 Ma, 356.02 ± 1.11 Ma and 334.51 ± 0.68 Ma from the Late Devonian to Carboniferous. The rocks are depleted in Nb, P and Ti, and possess variable Mg# values (28.51–57.22), high Na2O/K2O ratios (1.39–4.94), as well as relatively depleted Hf isotopic compositions, all of which point to a subduction origin from slab melting. Our new finding with the date from the Jijitaizi complex (ca. 321 Ma) suggests continuing subduction of the Paleo‐Asian oceanic slab beneath the Central Tianshan from the Late Devonian to Carboniferous. Our work provides a solid line of key evidence demonstrating that continuous oceanic subduction of the major PAO evolved into its mature stage following subducting beneath the Central Tianshan from ca. 372 to 321 Ma. [ABSTRACT FROM AUTHOR]

The Upper Ediacaran microbial carbonates of the Tarim Basin are potential reservoir geobodies for future hydrocarbon exploration with rising interest in exploration for deeply‐buried reserves. However, little knowledge has been acquired on the types of microbial carbonates that are present, the properties of the reservoir and the pore evolution, hampering predictions of high‐quality reservoirs in these carbonates. Integrated with petrography and in‐situ U‐Pb dating geochronology analyses, this study aims to clarify the types of microbial carbonates present and to reconstruct the pore evolution processes of the potential reservoir rocks. The Upper Ediacaran microbial carbonates of the Tarim Basin can be divided into four types, based on their features in terms of different scales (macro‐ to micro‐): microbial laminite, stromatolite, spongiomicrobialite and microbial‐peloidal wackestone/mudstone. Petrophysical properties show that all these microbial carbonates have low porosity and very low permeability with poor connectivity. These carbonates were subject to long‐term and complex diagenetic processes, mainly consisting of dissolution, compaction, pervasive dolomitization, cementation and fracturing. The most important reservoir spaces are contributed by vugs and dissolution‐enlarged pores, which are likely to have been associated with the widespread uplift of the Aksu area in the terminal Ediacaran. In contrast, the cementation of the fine‐to‐medium crystalline dolomite greatly reduced the pre‐existing pores. Pore types are closely related to different microbial fabrics, which played an important role in the pore evolution of the microbial carbonates. [ABSTRACT FROM AUTHOR]

The Mesoproterozoic Baoban Group is the oldest basement in Hainan Island and has played an important role in Columbia (Nuna) supercontinent reconstructions. The Mesoproterozoic granitic intrusions in the Baoban Group are the most widely‐exposed Precambrian magmatic rocks and are the key to understanding the tectonic settings of Hainan Island and its relationship with the South China Block and the Columbia supercontinent. New LA‐ICP‐MS zircon U‐Pb dating on three mylonitic granite samples from the Tuwaishan and Baoban areas yield ages ranging from 1447 Ma to 1437 Ma, representing the absolute timing of the emplacement of the granitic intrusions. Combined with previously published geochronological data for rocks from the Baoban Group and regional mafic intrusions, it is concluded that the Baoban Group formed at 1460–1430 Ma, coeval with the emplacement of the granitic and mafic intrusions. New in‐situ zircon Lu‐Hf isotope analyses for the three mylonitic granite samples yielded positive ∊Hf(t) values, ranging from +0.49 to +8.27, with model ages (TDMC) ranging from 2181 Ma to 1687 Ma, suggesting that the granitic intrusions originated from a mixed source of Paleoproterozoic crust with juvenile crust. New zircon trace element data show characteristics of high Th/U values of 0.24–1.50, steep slopes from LREE to HREE and negative Pr, Eu anomalies with positive Ce, Sm anomalies, representing typical magmatic zircons formed in continental crust. Compared with available magmatic and detrital zircon ages from Precambrian rocks in the Cathaysia Block, Yangtze Block and western Laurentia, it is inferred that Hainan Island was separated from both the Cathaysia Block and the Yangtze Block, instead being connected with western Laurentia in the Columbia supercontinent. Considering the decreasing tendency of basin deposition time along the western margin of Laurentia, it is proposed that Hainan Island was located to the north or northwest of the Belt‐Purcell Supergroup, along the western margin of Laurentia, during the breakup of the Columbia supercontinent. [ABSTRACT FROM AUTHOR]

The Taishanmiao Au deposit is in the western part of the Ningshan–Zhenan ore field, in the South Qinling orogen. Based on geological and geochemical features, we propose that the Taishanmiao Au deposit is a magmatic‐hydrothermal type of deposit. All samples have high SiO2, K2O + Na2O contents and differentiation index values, low CaO, MgO, P2O5, and TiO2 contents, are enriched in high field‐strength elements, and depleted in large ion lithophile element. The stable isotope δ34S values of pyrite vary from 6.8%–7.8%, and the H‐O isotopic compositions of quartz from quartz‐pyrite veins indicate the ore‐forming fluid is a mixture of a small amount of magmatic‐hydrothermal solution and groundwater. Lead isotope ratios of pyrite and silicalite can show that the ore‐forming materials were derived from a mixed source containing mantle and crustal materials. At the same time, the LA‐ICP‐MS U‐Pb dating of monzogranite is 198.4 ± 4.2 Ma. Combined with the regional geological background, the intracontinental extension in the late collisional orogeny and large‐scale lithospheric thinning associated with mantle uplift may lead to large‐scale mineralisation in the region. [ABSTRACT FROM AUTHOR]

Granitic gneiss (orthogneiss) and Himalayan leucogranite are widely distributed in the Himalayan orogen, but whether or not the granitic gneiss made a contribution to the Himalayan leucogranite remains unclear. In this study, we present the petrological, geochronological and geochemical results for orthogneisses and leucogranites from the Zhada area, Western Himalayas. Zhada orthogneiss is composed mainly of quartz, plagioclase, K‐feldspar, biotite and muscovite, with accessory zircon and apatite. Orthogneiss zircon cathodoluminescence (CL) images show that most grains contain a core with oscillatory zoning, which indicates an igneous origin. Sensitive high‐resolution ion microprobe (SHRIMP) U‐Pb dating of the zircon cores in the orthogneiss shows a weighted 206Pb/238U age of 515 ± 4 Ma (early Paleozoic), with spongelike zircon rims of 17.9 ± 0.5 Ma (Miocene). Zhada leucogranite shows 206Pb/238U ages ranging from 19.0 ± 0.4 Ma to 12.4 ± 0.2 Ma, the weighted average age being 16.2 ± 0.4 Ma. The leucogranites have a low Ca content (<1 wt%), FeOt content (<1 wt%), Rb content (67.0–402 ppm), Sr content (<56.6 ppm), Ba content (3.35–238 ppm) and Rb/Sr ratio (0.5–14.7), which are similar to the geochemical characteristics of the Himalayan leucogranite derived from muscovite dehydration partial melting of metasediments and representative of most Himalayan leucogranites. The highly variable Na2O + K2O (4.33 wt%–9.13 wt%), Al2O3 (8.44 wt%–13.51 wt%), ∑REE (40.2–191.0 ppm), Rb (67.0–402 ppm) and Nb (8.23–26.4 ppm) contents, 87Sr/86Sr(t) ratios (0.7445–0.8605) and εNd(t) values (–3.6 to –8.2) indicate that the leucogranite is derived from a heterogenetic source. The nonradiogenic Nd isotope values of the studied Zhada leucogranite and orthogneiss range from –8.2 to –3.6 and from –8.7 to –4.1, respectively. Therefore, the general mixing equation was used to perform the Sr and Nd isotope mixing calculations. The results indicate that the heterogenetic source was the Tethyan Himalayan Sequence (THS)/Higher Himalayan Crystalline (HHC) metasediments and Zhada orthogneiss. The Zhada area experienced crustal anatexis during the Miocene and the heterogenetic source of the orthogneiss and metasediment may have experienced crustal anatexis controlled by muscovite dehydration. The Zhada leucogranite inherited not only the geochemical characteristics of the Himalayan metasediment (muscovite dehydration melting), but also the trace elements and Sr‐Nd isotopic characteristics of the Zhada orthogneiss. These results indicate that the Paleozoic Zhada orthogneiss was involved in crustal anatexis at 17.9 ± 0.5 Ma (Miocene) and that the muscovite dehydration of the metasediments in the heterogenetic source produced fluid, which may have caused the orthogneiss solidus lines to decline, triggering a partial melting of the Zhada orthogneiss. It is therefore proposed that Himalayan leucogranite is a crust‐derived granite rather than a S‐type granite, as previously hypothesized. [ABSTRACT FROM AUTHOR]

The latest Cretaceous magmatic activity in the eastern segment of the Lhasa terrane provides important insights for tracking the magma source and geodynamic setting of the eastern Gangdese batholith, eastward of eastern Himalayan Syntaxis. Detailed petrological, geochemical and geochronological studies of the intrusive rocks (monzodiorites and granodiorites) of the eastern Gangdese batholith are presented with monzodiorites and granodiorites giving zircon U–Pb crystallization dates of 70–66 Ma and 71–66 Ma with εHf(t) values of –4.8 to +6.2 and –1.9 to +5.3, respectively. These rocks are metaluminous to weakly peraluminous I‐type granites showing geochemically arc‐related features of enrichment in LREEs and some LILEs, e.g., Rb, Th, and U, and depletion in HREEs and some HFSEs, e.g., Nb, Ta, and Ti. The rocks are interpreted to be derived from partial melting of mantle material and juvenile crust, respectively, which are proposed to be triggered by Neo‐Tethyan slab rollback during northward subduction, with both experiencing ancient crustal contamination. The studied intrusive rocks formed in a transitional geodynamic setting caused by Neo‐Tethyan oceanic flat subduction to slab rollback beneath the eastern Gangdese belt during the latest Cretaceous. [ABSTRACT FROM AUTHOR]

The Aqishan lead‐zinc deposit, located in the Jueluotag metallogenic belt of eastern Tianshan, Xinjiang, Northwest China, has a stratiform occurrence in the marine volcanic tuff of the Yamansu Formation. The ore body has a typical double‐layer structure, having a stratified, stratoid, lenticular upper part and a veined, stockwork‐like lower part. The occurrence of the upper orebody is consistent with that of the volcanic tuff wall rock. The ore minerals are mainly chalcopyrite, pyrite, sphalerite, galena and magnetite, the altered minerals mainly being silicified, such as sericite, chlorite, epidote, garnet. The garnetized skarn, being stratiform and stratoid, is closely related to the upper part of the orebody. Geological observations show that the limestone in the ore‐bearing Yamansu Formation is not marbleized and skarnized. Spatially, it is associated with the ferromanganese deposits in the marine volcanic rocks of the Yamansu Formation. These geological features reflect the likelihood that the Aqishan lead‐zinc deposit is a hydrothermal exhalation sedimentary deposit. The results from the EPMA show that the garnet is mainly composed of grossular–andradite series, contents being in a range of 34.791–37.8% SiO2, 32.493–34.274% CaO, 8.454–27.275% FeO, 0.012–15.293% Al2O3, 0.351–1.413% MnO, and lower values of 0.013–1.057% TiO2. The content of SiO2 vs. CaO and FeO vs. Al2O3 has a significant positive correlation. The results of ICP‐MS analysis for the garnet show that the REE pattern is oblique to right in general. The total amount of rare earth elements is relatively low, ΣREE = 71.045–826.52 ppm, which is relatively enriched for LREE and depleted for HREE. LREE/HREE = 8.66–4157.75, LaN/YbN = 23.51–984.34, with obvious positive Eu and Ce anomalies (δEu = 2.27–76.15, δCe = 0.94–1.85). This result is similar to the REE characteristics of ore‐bearing rhyolite volcanic rocks, showing that the garnet was formed in an oxidizing environment and affected by clear hydrothermal activity. The U‐Pb isotopic dating of garnet by fs‐LA‐HR‐ICP‐MS gives an age of 316.3 ± 4.4 Ma (MSWD = 1.4), which is consistent with the formation time of the Yamansu Formation. According to the study of deposit characteristics and geochemical characteristics, this study concludes that the Aqishan lead‐zinc deposit is a hydrothermal exhalation sedimentary deposit, the garnet being caused by hydrothermal exhalative sedimentation. [ABSTRACT FROM AUTHOR]

The Chaihulanzi area in eastern Inner Mongolia is tectonically situated on the northern margin of the North China Craton (NCC). The main Precambrian lithologies of the area have been referred to the Archean Jianping Group meta‐supracrustal sequences. Based on field observations, petrographic, whole‐rock geochemical, and zircon U‐Pb geochronological results, a magmatic origin for the units is proposed. Our results show that the Chaihulanzi gneisses are mainly of granitic, dioritic and granodioritic compositions, and show typical magmatic rock textures and mineral assemblages. The dioritic and granodioritic gneisses show Na‐rich tonalite–trondhjemite–granodiorite (TTG)‐like affinity with zircon U‐Pb dates of ca. 2.57–2.59 Ga, representing a juvenile continental growth for the northeastern NCC. The granitic gneiss is indeed potassic granite and yielded a zircon U‐Pb date of ∼2.50 Ga, which is contemporaneous with the Jining–Jiaoliao microblock collision (2.53–2.49 Ga), implying another crustal growth event. The well‐developed gneissosity in 2.57–2.59 Ga dioritic and granodioritic gneisses together with the 2.5 Ga potassic granite, which crosscuts the gneissosity implies a 2.57–2.50 Ga (mainly 2.53–2.51 Ga) collisional orogeny, probably related to the Jining–Jiaoliao microblock collision. Our new geology and chronological results provide new evidence for the early Precambrian tectonic evolution of the NCC. [ABSTRACT FROM AUTHOR]

The western segment of the Main Tianshan shear zone (MTSZ) branches into three major dextral strike‐slip shear zones in the Borohoro Ranges, northwestern China. Mylonitic rocks within these zones exhibit vertical foliations, subhorizontal lineations, and dextral kinematics. The microstructures and CPO patterns of calcite and quartz in the tectonites suggest shearing at temperatures of 200°C to 500°C or above. The amount of dextral displacement along the zones is less than 100 km. LA‐ICP‐MS U‐Pb dating of zircons from some pre‐kinematic granites gave ages of 364–325 Ma and 316 Ma, and zircons from a syn‐kinematic leucogranite gave an age of 291 Ma. We propose that dextral shearing along the MTSZ started in the earliest Permian. Our data indicate that collision between the Yili and Junggar plates might have finished before 325 Ma or 316 Ma, with a tectonic transformation from 325 Ma to 300 Ma, resulting in intracontinental transpression from 300 Ma or 291 Ma. We suggest that the formation of the Kazakhstan orocline (KO) took place in two stages, with the early stage of bending driven by convergence related to oblique subduction, and the late stage possibly associated with lateral disarticulation as a result of the dextral strike‐slip shear zones. [ABSTRACT FROM AUTHOR]

The Dongjun Pb‐Zn‐Ag deposit in the northern part of the Great Xing'an Range (NE China) consists of quartz‐sulfide vein‐type and breccia‐type mineralization, related to granite porphyry. Hydrothermal alteration is well‐developed and includes potassic‐silicic‐sericitic alteration, phyllic alteration and propylitic alteration. Three stages of mineralization are recognized on the basis of field evidence and petrographic observation, demarcated by assemblages of quartz‐pyrite‐arsenopyrite (early stage), quartz‐polymetallic sulfide (intermediate stage) and quartz‐carbonate‐pyrite (late stage). Zircon LA‐ICP‐MS U‐Pb dating indicates that the granite porphyry was emplaced at 146.7 ± 1.2 Ma (Late Jurassic). Microthermometry and laser Raman spectroscopy shows that ore minerals were deposited in conditions of intermediate temperatures (175–359°C), low salinity (0.5–9.3 wt% NaCl eqv.) and low density (0.60–0.91 g/cm3). Ore‐forming fluids were derived largely from magmatic hydrothermal processes, with late‐stage addition of meteoric water, belonging to a H2O‐NaCl‐CO2 ± CH4 system. The δ34SV‐CDT values range from 0.75‰ to 4.70‰. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values of the ore minerals are in the ranges of 18.240–18.371, 15.542–15.570, and 38.100–38.178, respectively. Data for the S and Pb isotopic systems indicate that the ore‐forming metals and sulfur were derived from Mesozoic magma. Based on the geological characteristics and geochemical signatures documented in this study, we conclude that the Dongjun deposit is a mesothermal magmatic hydrothermal vein‐type Pb‐Zn‐Ag deposit controlled by fractures and related to granite porphyry, in response to Late Jurassic tectonic–magmatic–hydrothermal activity. We further conclude that fluid immiscibility, fluid mixing and fluid‐rock interactions were the dominant mechanisms for deposition of the ore‐forming materials. [ABSTRACT FROM AUTHOR]

For magmatic rocks, it is often found that zircon 206Pb/238U and 207Pb/235U ratios continuously plot on the concordia line with a relatively large age span for the same sample, which gives rise to large dating errors or even unrealistic dating results. As the trace element concentrations of zircon can reflect its equilibrated magma characteristics, they can be used to determine whether all the analytical spots on the zircons selected to calculate the weighted mean age are cogenetic and formed in a single magma chamber. This work utilizes the results of zircon trace element concentrations and U‐Pb isotopic analyses to explore the screening of reasonable U‐Pb ages, which can be used to determine a more accurate intrusion crystallization age. The late Mesozoic Huayuangong granitic pluton complex, which is located in the Lower Yangtze region, eastern China, was selected for a case study. The Huayuangong pluton comprises the central intrusion and the marginal intrusion. Two samples from the marginal intrusion yielded consistent zircon weighted mean 206Pb/238U ages of 124.6 ± 2.0 Ma and 125.9 ± 1.6 Ma. These analytical spots also exhibit Zr/Hf and Th/U ratios concordant with the evolution of a single magma, from which the dated zircons crystallized. However, for the central intrusion, the analytical spots on zircons from two samples all show a continuous distribution on the concordia line with a relatively large age span. For each sample from the central intrusion, the zircon Zr/Hf ratios do not conform to a single magma evolutionary trend, but rather can be divided into two groups. We propose that zircon Zr/Hf ratios can provide a new constraint on U‐Pb zircon dating and zircon Th/U ratios can also be used as a supplementary indicator to constrain zircon dating and determine the origins of the zircons and whether magma mixing has occurred. By screening zircon analytical spots using these two indicators, the two samples from the central intrusion of the Huayuangong pluton produce results of 122.8 ± 4.3 Ma and 122.9 ± 2.2 Ma, which are consistent with the field observations that the central intrusion is slightly younger than the marginal intrusion. [ABSTRACT FROM AUTHOR]

During the Late Cretaceous in the Eastern Mediterranean, the northern branch of the southern Neotethys was closed by multiple northward subductions. Of these, the most northerly located subduction created the Baskil continental arc at around 82–84 Ma. The more southerly and intra‐oceanic subduction, on the other hand, produced an arc‐basin system, the Yüksekova Complex, as early as the late Cenomanian–early Turonian. The abundant and relatively well‐studied basaltic rocks of this complex were intruded by dykes, sills and small stocks of felsic–intermediate rocks, not previously studied in detail. The intrusives collected from five different localities in the Elazığ region of eastern Turkey are all subalkaline, with low Nb/Y values. Most of them have been chemically classified as rhyodacites/dacites, whereas a small number appear to be andesites. In normal mid‐ocean‐ridge basalt (N‐MORB)‐normalised plots, the intrusives are characterised by relative enrichments in Th and La over Nb, Zr, Hf, Ti and high field strength elements (HREEs), indicating their derivation from a subduction‐modified source. While their relatively high, positive εNd(i) values (+6.4 and +7.2) might suggest a depleted mantle source for their ultimate origin, somewhat radiogenic Pb values indicate a sedimentary contribution to the source of the rocks. The overall geochemical characteristics indicate their generation in an oceanic arc setting. The zircon U‐Pb Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) data obtained from five felsic‐intermediate rock samples yielded intrusion dates of 80–88 Ma. This suggests that the Elazığ oceanic arc‐related intrusives are slightly younger than those of the Yüksekova arc‐basin system, but coeval with the Baskil continental arc. However, the felsic–intermediate intrusives show different geochemical characteristics (oceanic arc‐type, with a lack of crustal contamination) to those of the Baskil continental arc. This indicates that these two igneous systems are unrelated and likely developed in different tectonic settings. This, in turn, supports a geodynamic model in which the northern strand of the southern Neotethys was consumed by multiple northward subductions. [ABSTRACT FROM AUTHOR]

Seamount accretion is one of the most significant accretionary orogenic processes in the Central Asian Orogenic Belt, but there are few paleo‐seamounts reported from and debate on the tectonic evolution of the Junggar Ocean still exists. In this study, we present geochronological, mineralogical, geochemical and isotopic data for basalts from the Chagantaolegai ophiolitic mélanges in Junggar. Zircon U‐Pb dating on one basalt yielded a weighted mean 206Pb/238U age of 469 ± 7 Ma, which suggests that it formed in the Middle Ordovician. All rock samples belong to alkaline basalt and show similar geochemical characteristics, displaying high TiO2 (∼3 wt%), (La/Yb)N (17.6–19.0), ΣREE (232–289 ppm) and enrichment in Nb and Ta, which implies an ocean island basalt (OIB) affinity. Based upon positive εNd(t) (+4.16 to +4.23), ΔNb (0.20–0.22) and low initial 87Sr/86Sr (0.70425 to 0.70452) and Zr/Nb (3.35–3.57), we suggest that the Chagantaolegai OIB samples were likely derived from a fertile mantle source related to plume. The OIB rock assemblage, chert and marble in the southern part of the Chagantaolegai ophiolitic mélange indicates that a Middle Ordovician seamount was accreted to the Boshchekul‐Chingiz arc due to the northward subduction of the Junggar‐Balkhash Ocean. [ABSTRACT FROM AUTHOR]

Late Paleozoic volcanic rocks are well exposed in the Yining Block, NW China, and are predominately composed of andesites, rhyolites and volcaniclastics as well as minor basalts. Study of the petrology, whole‐rock geochemistry and zircon U‐Pb dating for the Early Carboniferous alkaline basalts from Wusun Mountain, western Yining Block, constrains their petrogenesis and tectonic evolution. The alkaline basalts consist mainly of plagioclases, mostly albite and labradorite, as well as clinopyroxenes and olivines; zircon U‐Pb dating indicates their formation at ca. 350 Ma. Geochemically, the basaltic samples have low SiO2 contents, and high TiO2, Al2O3 and alkaline contents, coupled with high Na2O/K2O ratios, displaying an alkaline basalt affinity. They show remarkable LILE enrichment and HFSE depletion. Meantime, these samples have relatively high TFe2O3, MgO, and Mg# values as well as Ni and Cr, relatively high Sm/Yb and U/Th, suggesting origination from a mantle source metasomatized by slab fluids. They formed in a transitional tectonic setting from arc to intraplate, showing a typical affinity of back‐arc basin basalts. The alkaline basalts were likely generated in a nascent back‐arc extension setting resulting from slab rollback of the southern Tianshan oceanic lithosphere. A bi‐directional subduction model seems more reasonable for the evolution of the southern Tianshan Ocean. These new data will provide a new tectonic model for Late Paleozoic tectonic evolution of the western Yining Block. [ABSTRACT FROM AUTHOR]

The Yaojialing deposit is the first large‐scale Zn–Au–Cu polymetallic skarn deposit located in the Shatanjiao ore field of the Tongling area in the Middle–Lower Yangtze belt. It has distinct metallogenic characteristics and is clearly different from the known skarn Cu–Au deposits in the Tongling area and the Middle–Lower Yangtze belt. Previous studies of the Yaojialing deposit have included rock geochemistry, alteration and mineralization characteristics, as well as metallogenesis and metallogenic models. However, there are still numerous problems concerning the coexistence of multiple elements, metallogenetic specialization of the magma and the metallogenic model. In this study, using the latest production exploration work on the deposit, we investigated the Yaojialing deposit including its geological characteristics, petrography, LA–ICP MS zircon U–Pb dating and whole rock geochemistry. Two kinds of magmatic rocks have been distinguished for the first time in the deposit, amongst which the granodiorite porphyry exposed on the surface of the mining area, which is the host rock of the veined lead–zinc ore body, is the wall‐rock intrusion; and the deep concealed quartz monzonite porphyry is the causative intrusion, the distribution of orebodies and wall‐rock alteration characteristics showing regular zoning around the quartz monzonite porphyry. The 206Pb/238U weighted average age of the granodiorite porphyry is 140.2 ± 1.0 Ma (MSWD = 0.85, n = 13) by LA–ICP MS zircon U–Pb dating, while the quartz monzonite porphyry is 138.9 ± 1.2 Ma (MSWD = 0.60, n = 16), which is consistent with petrographic evidence. The geochemical characteristics show that the quartz monzonite porphyry is a high‐K calc‐alkaline series peraluminous rock. The trace element characteristics show that the quartz monzonite porphyry is enriched in LILE such as K, Rb, Sr, Ba and LREE, yet depleted in HFSE such as Nb, Ta, P and Ti. The Yaojialing deposit shows the mineralization characteristics of proximal skarn and distal skarn, having the common characteristics of 'multi‐storey' and 'Trinity' metallogenic models. [ABSTRACT FROM AUTHOR]

The Feidong district is located in the southern segment of the Tan–Lu fault zone that separates the South China Block (NCB) from the North China Craton (NCC). We report zircon U‐Pb geochronology and Hf isotope data, as well as whole‐rock geochemistry for Xishanyi granodiorite and Jianshan granite in the Feidong district. Zircon U‐Pb dating results show that the emplacement ages of the Xishanyi and Jianshan intrusions are 124 ± 3 Ma and 130 ± 1 Ma respectively, coeval with magmatic events linked to large‐scale lithospheric thinning in eastern China. The whole‐rock geochemistry of the Xishanyi and Jianshan intrusions demonstrate that they are peraluminous, high potassium calc‐alkaline I‐type granites with adakitic characteristics. Both intrusions underwent weak crustal assimilation during emplacement. The in situ zircon ∊Hf(t) values of the Xishanyi granodiorites range from –26.4 to –21.8, with TDM2 model ages of 2552 to 2841 Ma. The in situ zircon ∊Hf(t) values of the Jianshan granite are from –27.5 to –23.0 with TDM2 model ages of 2632 to 2904 Ma. The peak age of inherited zircon grains from the Xishanyi granodiorite and the Jianshan granite were ∼2.07 Ga and ∼1.94 Ga, respectively. After compared with the regional magmatism, we suggest that both the Xishanyi and Jianshan granitoid intrusions were derived from partial melting of the NCC lower crust. [ABSTRACT FROM AUTHOR]

Caledonian orogeny is another important tectonic event in South China Block after the breakup of the Rodinia supercontinent. With a view to constrain the tectonic evolution and proto–basin in South China, this paper reports the geochemical and zircon U‐Pb dating data of the Ordovician strata in central Hunan, South China. Geochemical features and paleocurrent directions suggest that the lower Ordovician deposited in a passive continental margin basin with a provenance of quartzose components and showing an affinity with the Yangtze Block. U‐Pb age data for 260 detrital zircons from upper Ordovician identify three major age populations as: 900–1200 Ma, 1400–1800 Ma and 2400–2700 Ma. The detrital zircon age spectrum as well as the paleocurrent directions suggest that upper Ordovician deposited in a foreland basin and showing a close affinity with the Cathaysia Block. It is also suggest that the lower Ordovician continuously accepted the mineral from the Yangtze Block, whereas the provenance of the upper Ordovician sedimentary basin changed from the Yangtze Block to the Cathaysia Block. This change implies a tectonic movement, which caused the transformation of the proto–basin in the Hunan area in SCB from passive continental margin basin to foreland basin probably took place during late Ordovician. This fact also demonstrate that the Caledonian orogeny in South China Block began no later than 453 Ma, and a new crustal evolution model is proposed. [ABSTRACT FROM AUTHOR]

Limited Devonian magmatic record in northern West Junggar leads to contrasting models on its tectonic evolution. In this study, we conducted LA‐ICP‐MS U‐Pb dating on detrital zircons of two sandstones from the Hebukesaier Formation in the Shaerbuerti Mountains. Detrital zircons with oscillatory zoning are characterized by high Th/U (> 0.3) and low La/Yb (< 0.15), indicating their magmatic origin. The youngest zircon ages of two samples are 402 ± 2 Ma and 406 ± 2 Ma, respectively, suggesting that the Hebukesaier Formation was deposited at the Early Devonian. Detrital zircon age patterns show single peaks (at ca. 424 Ma, n = 157), which indicates that these clastics were likely proximal accumulation after short distance transportation. Provenance of the Hebukesaier Formation was the Xiemisitai and Shaerbuerti Mountains. Detrital zircon ages range from 481 Ma to 395 Ma, which indicates that there was relatively continuous Early Paleozoic magmatism in the Xiemisitai and Shaerbuerti Mountains since the Early Ordovician. Age spectrums of sampled detrital zircons are distinct from those of Lower Devonian strata either in southern West Junggar or in East Junggar, which implies for individual tectonic evolution of northern West Junggar. We favor that Lower Devonian Hebukesaier Formation was developed in a fore–arc setting due to the northward subduction of the Junggar–Balkhash Ocean. [ABSTRACT FROM AUTHOR]

The Berere HTHP Complex belt in Maevatanana area of north–central Madagascar formed in the ∼ 2.5 Ga orogeny and underwent high temperature (up to 1050°C) and high pressure (up to 11.5 kbar) granulite facies metamorphism. Then a widespread anatexis took place and numerous widely distributed felsic leucosomes formed. The majority of these leucosomes are parallel to the schistosity of the complex or are present as stockworks, as thin layers, or as lenses at different scales in the host rocks. Here, we report new petrographic data, zircon LA‐ICP‐MS U‐Pb ages, and Lu–Hf isotopic data for felsic leucosomes within this complex. Anatexis, as identified by the petrological study of felsic leucosomes in the field and in thin sections, involved initial ternary feldspar exsolving to produce antiperthite and a quartz + plagioclase ± K‐feldspar + sericite mineral assemblage around feldspar grain boundaries. Dissolution is apparent along muscovite grain boundaries, and residual sericite is present around the margins of feldspar and quartz, all suggesting that anatexis was driven by reactions involving muscovite. Zircon U–Pb dating indicates that the felsic leucosomes within the complex formed at 2467–2369 Ma. The majority of samples have positive ∊Hf(t) values, although a few have negative values, suggesting their formation from magmas predominantly sourced from the depleted mantle, possibly with the involvement of minor amounts of crustal materials. Two‐stage Hf model ages and ∊Hf(t) values for these samples are consistent with those for gneisses of the basement, indicating that the felsic leucosomes were formed by the anatexis of gneisses and both of their protolith formed during the formation of continental crust in Meso‐Neoarchean (ca. 3.1–2.7 Ga). As such, the crystallization age of the felsic leucosome (∼2.4 Ga) represents the timing of regional anatexis and a change to post‐orogenic tectonism. And this anatexis is also corresponds to the thermal event in Dharwar craton in India which has a pronounced similar Precambrian geology with Madagascar, providing an important constraints on the correlation of the two continental fragments. [ABSTRACT FROM AUTHOR]

Post‐collisional volcanic rocks of Mesozoic age occur in the regions adjacent to Gerze, part of the southern Qiangtang Terrane of northern Tibet, China. Geochronological, geochemical, and whole‐rock Sr‐Nd isotopic analyses were performed on the volcanic rocks to better characterize their emplacement age and models for their origin. Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) U‐Pb zircon analyses yielded consistent ages ranging from 123.1±0.94 Ma to 124.5±0.89 Ma for six volcanic rocks from the study area. The intermediate volcanic rocks belong to the alkaline and sub‐alkaline magma series in terms of K2O+Na2O contents (5.9%–9.0%), and to the shoshonitic and calc‐alkaline series on the basis of their high K2O contents (1.4%–3.3%). The Gerze volcanic rocks are characterized by the enrichment of light rare earth elements [(La/Yb)N=34.9–49.5] and large–ion lithophile elements (e.g., Rb, Ba, Th, U, K, Pb, and Sr), slightly negative Eu anomalies (Eu/Eu*=0.19–0.24), and negative anomalies in high field strength elements (e.g., Nb, Ta, Hf and Ti), relative to primitive mantle. The samples show slightly elevated (87Sr/86Sr)i values that range from 0.7049 to 0.7057, and low ∊Nd(t) values from –0.89 to –2.89. These results suggest that the volcanic rocks studied derived from a compositionally heterogeneous mantle source and that their parent magmas were basaltic. The more mafic, parental magmas to the Gerze volcanic rocks likely underwent fractional crystallization of clinopyroxene, hornblende, biotite, and potassium feldspar, during ascent, with little to no crustal contamination, prior to their eruption/emplacement. While these volcanic rocks exhibit geochemical signatures typical of magmas formed in a destructive plate‐margin setting, it is plausible that their mantle source might also have acquired such characteristics in an earlier episode of subduction. [ABSTRACT FROM AUTHOR]

The metasedimentary Lujiapuzi Formation crops out along the northeastern margin of the North China Craton, close to the Yan‐Liao Rift. The age and tectonic setting of the formation, and its relationship with the Yan‐Liao Rift are currently unclear. Here we present detrital zircon U‐Pb ages, and Hf isotopic and geochemical data for the Lujiapuzi Formation to constrain the timing of deposition, the provenance of the formation, and the regional stratigraphy relationship. Zircon U‐Pb dating constrains the timing of deposition of the Lujiapuzi Formation to younger than 1780 Ma, and indicates that most grains were sourced from the Longgang Block and the Paleoproterozoic Liao‐Ji Belt. Detailed field investigations and a correlation of the regional stratigraphy reveal that much of the Lujiapuzi Formation is equivalent to the Tuanshanzi Formation in the Yan‐Liao Rift; the lower section may represent the earliest sediments deposited within the Fanhe Basin. Based on these results and the findings of previous studies, we suggest that the base of the Changcheng System has an age of 1.80 Ga. Zircon Hf isotopic data indicate that the main period of crustal growth along the northeastern margin of the North China Craton occurred at 3.2–2.5 Ga, with a peak at 2.9–2.7 Ga. [ABSTRACT FROM AUTHOR]

The Tianshan Orogen (TO) is one of the largest typical accretionary orogenic belts in the world. Of which, the late Paleozoic was a critical era to understand the tectonic and geodynamic transition from accretion to collision. However, the late Paleozoic tectonic evolutionary history, especially for the time of the ocean‐continent transition, is still debated although the origin and tectonic settings for the Paleozoic volcanic, felsic igneous magmatism in TO and reginal geology have been done in the last decades. In contrast, the researches on the mafic dykes in TO was not systematically carried out till now. Reginal‐scale mafic dykes are commonly regarded as the products created in a extensional setting, and used to identify the major tectonic events such as rifting and continental break‐up and further trace the mantle natures and geodynamic mechanism (Halls, 1982; Bleeker and Ernst, 2006; Li et al., 2008; Ernst et al., 2010; Srivastava, 2011; Hou, 2012; Peng, 2015; Peng et al., 2019). There are widespread late Paleozoic mafic dykes beside the huge of intermediate‐acid igneous rocks in the TO, being an idea object to reveal the extensional events, tectonic evolution and the mantle nature and geodynamic processes. We present the ICP‐MS in situ zircon U–Pb dating, Lu‐Hf and whole‐rock Sr‐Nd isotopes as well as the geochemistry data for these mafic dykes to better constraint their petrogenesis and mantle nature. New zircon U‐Pb dating for 12 samples from the representative basic dykes and basalts yield three distinct stages of ∼332 Ma, 316–302 Ma and 288–282 Ma, respectively. In which, the first stage of mafic dykes is mainly occurred in both East Tianshan Orogen (ETO) and West Tianshan Orogen (WTO), and composed of dolerite with minor basalts. The second stage of mafic dyke also can be found in both ETO and WTO. However, in contrast to the first stage of mafic dykes, they have relatively variable rock types from the dolerite/or gabbros to gabbroic diorite. The third stage of mafic dykes are slightly intermediate in composition, and chiefly consist of andesitic‐basaltic dolerite with some diorites. They are widely developed not only in both ETO and WTO, but also in the Beishan area to the east of the ETO, indicating a large‐scale mafic magmatism in Tianshan and adjacent areas. Geochemically, first stage of mafic dykes is characterized by low SiO2 content of 47.23–47.09 wt% in ETO and 48.69–51.31 wt% in WTO with the variable Mg# values varying from 48.24 to 60.8 in ETO and from 54.26 to 59.14 in WTO. They evolved towards Fe‐depletion along the calc‐alkaline trend. Some of dykes display a slightly negative Sr anomalies and minor negative Eu anomalies (δEu=0.84–0.96), indicating a calc‐alkaline series with a the clinopyroxene‐ and plagioclase‐dominated fractionation. While, those sharing the positive Eu and Sr anomalies are most likely indicative of some degree of plagioclase accumulation. All mafic dykes have relative higher and variable LREE {(La/Yb)N=1.61–9.39} as well as LILEs (Rb, Ba and K) and depletion in HFSE with evident peak of Pb and valley of Nb. They show coherent zircon Hf and whole rock Sr‐Nd‐Pb isotopic composition, with a low (206Pb/204Pb)i (18.79) and variable (87Sr/86Sr)i (0.7033–0.7060) and positive variable ∊Nd(t) from 3.69 to 10.14 and ∊Hf(t) from 3.24 to 13.09. In addition, these mafic dykes have high Zr/Nb (13.6–48.6, average 30.9), and low La/Nb (2.1–5.1, average 3.2) ratios, showing a similarity to those of MORB mantle melts (Zr/Nb=30, La/Nb=1.07) (Sun and McDonough, 1989) rather than OIB asthenospheric mantle melts (Zr/Nb=5.3, La/Nd=0.77, Sun and McDonough, 1989). Their higher Zr/Y (2.5–6.8, average 4.0) and Nb/Y (0.1–0.5, average 0.2) ratios further suggest that they were derived from partial melting of a depleted lithospheric mantle (Bradshaw and Eugene, 1993; Condie, 2005). However, their Nb/La (0.20–0.49, average 0.35), Nb/U (3.3–17.8, average 8.6) and Ce/Pb (1.1–11.8, average 6.84) ratios are very low, much close to those of the continental crust (Nb/La=0.4, Nb/U=6.15, Ce/Pb=3.9, Rudnick and Gao, 2003), indicating crustal contamination (Xia and Li, 2014). All geochemistry and isotope composition favor that they were derived from a heterogeneous mantle source mixed by both depleted lithosphere mantle and EMI, and then experienced crustal contamination during the magma ascending. Second stage of mafic dykes have variable SiO2 content of 46.71–54.92 wt% in ETO and 48.53–52.59 wt% in WTO and variable Mg# values from 45.94 to 55.74 in ETO and from 27.04 to 53.64 in WTO and FeOT/MgO values higher than 1 (1.75–2.33 in ETO, 1.71–5.35 in WTO), showing a calc‐alkaline series in ETO and tholeiitic series in WTO associated with a certain extent magmatic evolution. However, many of the chemical and Sr‐Nd‐Hf isotopic features are in accord with those of first stage of mafic dykes. They are characterized by the right deviation REE pattern with slightly high LREE, moderate fraction between LREE and HREE {(La/Yb)N =2.55–7.52} and Eu (δEu =0.85–1.10) anomalies as well as the enrichment in LILEs (Rb, Ba and K) and poor HFSEs with obvious depletion of Nb and peak of Pb. Furthermore, they, just like first stage mafic dyke, have relatively depleted zircon Hf and whole rock Nd isotopic composition with a higher ∊Nd(t) (2.68–9.73) and ∊Hf(t) (2.55–15.46) but variable (87Sr/86Sr)i of 0.7036–0.7157 and high (206Pb/204Pb)i of 19.26‐19.78. They also display a higher Zr/Nb (10.3‐50.7, average 22.3), La/Nb (1.1‐3.7, average 2.51), Zr/Y (2.4–10.3, average 5.3) and Nb/Y (0.05–0.5, average 0.3) as well as low Nb/La (0.27–0.91, average 0.46), slightly high Nb/U (4.59–26.80, average 13.28) and Ce/Pb (2.21–16.94, average 7.71) ratios. All geochemistry and isotopic composition suggest they have a mantle source similar to those of first stage of mafic dykes, and originated from partial melting of a heterogeneous mixing source composed of the depleted lithosphere mantle and EMII. The third stage of mafic dykes, like the second stage of mafic dyke, have variable SiO2 ranging from 46.39 to 52.69 wt% in ETO and 49.62 to 54.68 wt% in Beishan area, and belong to a calc‐alkaline series. They have moderate Mg# values from 41.86 to 55.24 in ETO and from 41.7 to 55.28 in Beishan area, and exhibit negative Sr anomalies and medium negative or slight positive Eu anomalies (Eu/Eu=0.56–1.08), indicating plagioclase‐dominated fractionation during magma evolution. They are enriched in LILEs and LREE {(La/Yb)N = 3.16–6.38} and depleted in HFSEs with the valleys of Nb and Ti and a peak of Pb. They have narrow (87Sr/86Sr)i (0.7040 to 0.7050) and low (206Pb/204Pb)i (18.41). Their eNd(t) values are positive and variable, ranging from 5.36 to 10.36. While, their eHf(t) range from −7.13 to 18.33. Furthermore, like early mafic dykes, they are also characterized by the higher Zr/Nb (13.0‐29.8, average 20.57), La/Nb (1.0‐3.4, average 2.35), Zr/Y (3.2–6.8, average 4.8) and Nb/Y (0.1–0.4, average 0.3) as well as low Nb/La (0.29–1.00, average 0.50), Nb/U (3.21–17.53, average 7.92) and Ce/Pb (1.73–10.79, average 6.75) ratios. All suggest they were derived from a source inherited from early heterogeneous depleted lithosphere mantle involved in EMI and subjected crustal contamination during magma ascending. In summary, the late Paleozoic mafic dykes widely developed in the TO can be subdivided three distinct stages of mafic magmatism, and shear the consistent rock associations, petrogeochemistry and isotopic compositions. Three stages of mafic dykes are relatively enriched in LREE, LILEs and depleted in HFSEs with the valleys of Nb and Ti and a peak of Pb and slightly fractionation between LREE and HREE. They are coherently characterized by positive and variable ∊Nd(t) and ∊Hf(t) values, low (206Pb/204Pb)i and variable (87Sr/86Sr)i isotope ratios. Furthermore, they have higher Zr/Nb, La/Nb, Zr/Y and Nb/Y and low Nb/La, Nb/U and Ce/Pb ratios. All suggest that these late Paleozoic mafic dykes were mainly originated from a long‐lived unitary heterogeneous lithospheric mantle mixed by EMI and possible minor MEII and experienced varying degrees crustal contamination during the magma ascending. Consequently, based our new geochemical and Sr‐Nd‐Pb‐Hf isotopic data and combined with the previous studies on the reginal geology and widespread late Paleozoic post‐collisional magmatism (Xu et al., 2013; Xia et al., 2004, 2013), it can be proposed that the arc‐microcontinents collision in the TO started at least before the early late Carboniferous (Serpukhovian), and the mafic dykes with three distinct stages of ∼332 Ma, 316–302 Ma and 288–282 Ma were generated in a lithosphere extensional settings after arc‐microcontinents collision from late Carboniferous to early Permian. [ABSTRACT FROM AUTHOR]

The Tianshan Orogen (TO) is one of the largest typical accretionary orogenic belts in the world. Of which, the late Paleozoic was a critical era to understand the tectonic and geodynamic transition from accretion to collision. However, the late Paleozoic tectonic evolutionary history, especially for the time of the ocean‐continent transition, is still debated although the origin and tectonic settings for the Paleozoic volcanic, felsic igneous magmatism in TO and reginal geology have been done in the last decades. In contrast, the researches on the mafic dykes in TO was not systematically carried out till now. Reginal‐scale mafic dykes are commonly regarded as the products created in a extensional setting, and used to identify the major tectonic events such as rifting and continental break‐up and further trace the mantle natures and geodynamic mechanism (Halls, 1982; Bleeker and Ernst, 2006; Li et al., 2008; Ernst et al., 2010; Srivastava, 2011; Hou, 2012; Peng, 2015; Peng et al., 2019). There are widespread late Paleozoic mafic dykes beside the huge of intermediate‐acid igneous rocks in the TO, being an idea object to reveal the extensional events, tectonic evolution and the mantle nature and geodynamic processes. We present the ICP‐MS in situ zircon U–Pb dating, Lu‐Hf and whole‐rock Sr‐Nd isotopes as well as the geochemistry data for these mafic dykes to better constraint their petrogenesis and mantle nature. New zircon U‐Pb dating for 12 samples from the representative basic dykes and basalts yield three distinct stages of ∼332 Ma, 316–302 Ma and 288–282 Ma, respectively. In which, the first stage of mafic dykes is mainly occurred in both East Tianshan Orogen (ETO) and West Tianshan Orogen (WTO), and composed of dolerite with minor basalts. The second stage of mafic dyke also can be found in both ETO and WTO. However, in contrast to the first stage of mafic dykes, they have relatively variable rock types from the dolerite/or gabbros to gabbroic diorite. The third stage of mafic dykes are slightly intermediate in composition, and chiefly consist of andesitic‐basaltic dolerite with some diorites. They are widely developed not only in both ETO and WTO, but also in the Beishan area to the east of the ETO, indicating a large‐scale mafic magmatism in Tianshan and adjacent areas. Geochemically, first stage of mafic dykes is characterized by low SiO2 content of 47.23–47.09 wt% in ETO and 48.69–51.31 wt% in WTO with the variable Mg# values varying from 48.24 to 60.8 in ETO and from 54.26 to 59.14 in WTO. They evolved towards Fe‐depletion along the calc‐alkaline trend. Some of dykes display a slightly negative Sr anomalies and minor negative Eu anomalies (δEu=0.84–0.96), indicating a calc‐alkaline series with a the clinopyroxene‐ and plagioclase‐dominated fractionation. While, those sharing the positive Eu and Sr anomalies are most likely indicative of some degree of plagioclase accumulation. All mafic dykes have relative higher and variable LREE {(La/Yb)N=1.61–9.39} as well as LILEs (Rb, Ba and K) and depletion in HFSE with evident peak of Pb and valley of Nb. They show coherent zircon Hf and whole rock Sr‐Nd‐Pb isotopic composition, with a low (206Pb/204Pb)i (18.79) and variable (87Sr/86Sr)i (0.7033–0.7060) and positive variable ∊Nd(t) from 3.69 to 10.14 and ∊Hf(t) from 3.24 to 13.09. In addition, these mafic dykes have high Zr/Nb (13.6–48.6, average 30.9), and low La/Nb (2.1–5.1, average 3.2) ratios, showing a similarity to those of MORB mantle melts (Zr/Nb=30, La/Nb=1.07) (Sun and McDonough, 1989) rather than OIB asthenospheric mantle melts (Zr/Nb=5.3, La/Nd=0.77, Sun and McDonough, 1989). Their higher Zr/Y (2.5–6.8, average 4.0) and Nb/Y (0.1–0.5, average 0.2) ratios further suggest that they were derived from partial melting of a depleted lithospheric mantle (Bradshaw and Eugene, 1993; Condie, 2005). However, their Nb/La (0.20–0.49, average 0.35), Nb/U (3.3–17.8, average 8.6) and Ce/Pb (1.1–11.8, average 6.84) ratios are very low, much close to those of the continental crust (Nb/La=0.4, Nb/U=6.15, Ce/Pb=3.9, Rudnick and Gao, 2003), indicating crustal contamination (Xia and Li, 2014). All geochemistry and isotope composition favor that they were derived from a heterogeneous mantle source mixed by both depleted lithosphere mantle and EMI, and then experienced crustal contamination during the magma ascending. Second stage of mafic dykes have variable SiO2 content of 46.71–54.92 wt% in ETO and 48.53–52.59 wt% in WTO and variable Mg# values from 45.94 to 55.74 in ETO and from 27.04 to 53.64 in WTO and FeOT/MgO values higher than 1 (1.75–2.33 in ETO, 1.71–5.35 in WTO), showing a calc‐alkaline series in ETO and tholeiitic series in WTO associated with a certain extent magmatic evolution. However, many of the chemical and Sr‐Nd‐Hf isotopic features are in accord with those of first stage of mafic dykes. They are characterized by the right deviation REE pattern with slightly high LREE, moderate fraction between LREE and HREE {(La/Yb)N =2.55–7.52} and Eu (δEu =0.85–1.10) anomalies as well as the enrichment in LILEs (Rb, Ba and K) and poor HFSEs with obvious depletion of Nb and peak of Pb. Furthermore, they, just like first stage mafic dyke, have relatively depleted zircon Hf and whole rock Nd isotopic composition with a higher ∊Nd(t) (2.68–9.73) and ∊Hf(t) (2.55–15.46) but variable (87Sr/86Sr)i of 0.7036–0.7157 and high (206Pb/204Pb)i of 19.26‐19.78. They also display a higher Zr/Nb (10.3‐50.7, average 22.3), La/Nb (1.1‐3.7, average 2.51), Zr/Y (2.4–10.3, average 5.3) and Nb/Y (0.05–0.5, average 0.3) as well as low Nb/La (0.27–0.91, average 0.46), slightly high Nb/U (4.59–26.80, average 13.28) and Ce/Pb (2.21–16.94, average 7.71) ratios. All geochemistry and isotopic composition suggest they have a mantle source similar to those of first stage of mafic dykes, and originated from partial melting of a heterogeneous mixing source composed of the depleted lithosphere mantle and EMII. The third stage of mafic dykes, like the second stage of mafic dyke, have variable SiO2 ranging from 46.39 to 52.69 wt% in ETO and 49.62 to 54.68 wt% in Beishan area, and belong to a calc‐alkaline series. They have moderate Mg# values from 41.86 to 55.24 in ETO and from 41.7 to 55.28 in Beishan area, and exhibit negative Sr anomalies and medium negative or slight positive Eu anomalies (Eu/Eu=0.56–1.08), indicating plagioclase‐dominated fractionation during magma evolution. They are enriched in LILEs and LREE {(La/Yb)N = 3.16–6.38} and depleted in HFSEs with the valleys of Nb and Ti and a peak of Pb. They have narrow (87Sr/86Sr)i (0.7040 to 0.7050) and low (206Pb/204Pb)i (18.41). Their eNd(t) values are positive and variable, ranging from 5.36 to 10.36. While, their eHf(t) range from −7.13 to 18.33. Furthermore, like early mafic dykes, they are also characterized by the higher Zr/Nb (13.0‐29.8, average 20.57), La/Nb (1.0‐3.4, average 2.35), Zr/Y (3.2–6.8, average 4.8) and Nb/Y (0.1–0.4, average 0.3) as well as low Nb/La (0.29–1.00, average 0.50), Nb/U (3.21–17.53, average 7.92) and Ce/Pb (1.73–10.79, average 6.75) ratios. All suggest they were derived from a source inherited from early heterogeneous depleted lithosphere mantle involved in EMI and subjected crustal contamination during magma ascending. In summary, the late Paleozoic mafic dykes widely developed in the TO can be subdivided three distinct stages of mafic magmatism, and shear the consistent rock associations, petrogeochemistry and isotopic compositions. Three stages of mafic dykes are relatively enriched in LREE, LILEs and depleted in HFSEs with the valleys of Nb and Ti and a peak of Pb and slightly fractionation between LREE and HREE. They are coherently characterized by positive and variable ∊Nd(t) and ∊Hf(t) values, low (206Pb/204Pb)i and variable (87Sr/86Sr)i isotope ratios. Furthermore, they have higher Zr/Nb, La/Nb, Zr/Y and Nb/Y and low Nb/La, Nb/U and Ce/Pb ratios. All suggest that these late Paleozoic mafic dykes were mainly originated from a long‐lived unitary heterogeneous lithospheric mantle mixed by EMI and possible minor MEII and experienced varying degrees crustal contamination during the magma ascending. Consequently, based our new geochemical and Sr‐Nd‐Pb‐Hf isotopic data and combined with the previous studies on the reginal geology and widespread late Paleozoic post‐collisional magmatism (Xu et al., 2013; Xia et al., 2004, 2013), it can be proposed that the arc‐microcontinents collision in the TO started at least before the early late Carboniferous (Serpukhovian), and the mafic dykes with three distinct stages of ∼332 Ma, 316–302 Ma and 288–282 Ma were generated in a lithosphere extensional settings after arc‐microcontinents collision from late Carboniferous to early Permian. [ABSTRACT FROM AUTHOR]

The article focuses on a study related to the distribution of Baoligaomiao Formation in the Zhanlantun Area, Mongolia and discusses their sedimentary age. It includes information on the presence of Angara biological fossils in the formation. It also includes information on the results of zircon uranium-lead dating.

The Weiquan Ag–polymetallic deposit is located on the southern margin of the Central Asian Orogenic Belt and in the western segment of the Aqishan–Yamansu arc belt in East Tianshan, northwestern China. Its orebodies, controlled by faults, occur in the lower Carboniferous volcano‐sedimentary rocks of the Yamansu Formation as irregular veins and lenses. Four stages of mineralization have been recognized on the basis of mineral assemblages, ore fabrics, and crosscutting relationships among the ore veins. Stage I is the skarn stage (garnet + pyroxene), Stage II is the retrograde alteration stage (epidote + chlorite + magnetite ± hematite ± actinolite ± quartz), Stage III is the sulfide stage (Ag and Bi minerals + pyrite + chalcopyrite + galena + sphalerite + quartz ± calcite ± tetrahedrite), and Stage IV is the carbonate stage (quartz + calcite ± pyrite). Skarnization, silicification, carbonatization, epidotization, chloritization, sericitization, and actinolitization are the principal types of hydrothermal alteration. LA–ICP–MS U–Pb dating yielded ages of 326.5±4.5 and 298.5±1.5 Ma for zircons from the tuff and diorite porphyry, respectively. Given that the tuff is wall rock and that the orebodies are cut by a late diorite porphyry dike, the ages of the tuff and the diorite porphyry provide lower and upper time limits on the age of ore formation. The δ13C values of the calcite samples range from −2.5‰ to 2.3‰, the δ18OH2O and δDV‐SMOW values of the sulfide stage (Stage III) vary from 1.1‰ to 5.2‰ and −111.7‰ to −66.1‰, respectively, and the δ13C, δ18OH2O and δDV‐SMOW values of calcite in one Stage IV sample are 1.5‰, −0.3‰, and −115.6‰, respectively. Carbon, hydrogen, and oxygen isotopic compositions indicate that the ore‐forming fluids evolved gradually from magmatic to meteoric sources. The δ34SV‐CDT values of the sulfides have a large range from −6.9‰ to 1.4‰, with an average of −2.2‰, indicating a magmatic source, possibly with sedimentary contributions. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of the sulfides are 17.9848–18.2785, 15.5188–15.6536, and 37.8125–38.4650, respectively, and one whole‐rock sample at Weiquan yields 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of 18.2060, 15.5674, and 38.0511, respectively. Lead isotopic systems suggest that the ore‐forming materials of the Weiquan deposit were derived from a mixed source involving mantle and crustal components. Based on geological features, zircon U–Pb dating, and C–H–O–S–Pb isotopic data, it can be concluded that the Weiquan polymetallic deposit is a skarn type that formed in a tectonic setting spanning a period from subduction to post‐collision. The ore materials were sourced from magmatic ore‐forming fluids that mixed with components derived from host rocks during their ascent, and a gradual mixing with meteoric water took place in the later stages. [ABSTRACT FROM AUTHOR]

Magma mingling has been identified within the continental margin of southeastern China. This study focuses on the relationship between mafic and felsic igneous rocks in composite dikes and plutons in this area, and uses this relationship to examine the tectonic and geodynamic implications of the mingling of mafic and felsic magmas. Mafic magmatic enclaves (MMEs) show complex relationships with the hosting Xiaocuo granite in Fujian area, including lenticular to rounded porphyritic microgranular enclaves containing abundant felsic/mafic phenocrysts, elongate mafic enclaves, and back-veining of the felsic host granite into mafic enclaves. LA-ICP-MS zircon U-Pb analyses show crystallization of the granite and dioritic mafic magmatic enclave during ca. 132 and 116 Ma. The host granite and MMFs both show zircon growth during repeated thermal events at ∼210 Ma and 160-180 Ma. Samples from the magma mingling zone generally contain felsic-derived zircons with well-developed growth zoning and aspect ratios of 2-3, and mafic-derived zircons with no obvious oscillatory zoning and with higher aspect ratios of 5-10. However, these two groups of zircons show no obvious trace element or age differences. The Hf-isotope compositions show that the host granite and MMEs have similar εHf( t) values from negative to positive which suggest a mixed source from partial melting of the Meso-Neoproterozoic with involvement of enriched mantle-derived magmas or juvenile components. The lithologies, mineral associations, and geochemical characteristics of the mafic and felsic rocks in this study area indicate that both were intruded together, suggesting Early Cretaceous mantle-crustal interactions along the southeastern China continental margin. The Early Cretaceous magma mingling is correlated to subduction of Paleo-Pacific plate. [ABSTRACT FROM AUTHOR]

The article offers a study on a Late Carboniferous back-arc basin basalts from the Chengjisihanshan Formation in the southern West Junggar to determine its formation age and tectonic environment, magma source and petrogenesis. Topics include Laser ablation inductively coupled plasma mass spectrometry zircon U-Pb isotopic dating and in situ zircon Hf isotope analyses; and cocludes he discovery and confirmation of the Late Carboniferous tholeiites m the Chengjisihanshan Formation.

The article offers a study on zircon U-Pb dating of finegrained tonalite in the Jiefangyingzi area of Chifeng from Silurian Badangshan Formation in order to provide petrologic and chronologic constraints in the Jiefangyingzi area, Mongolia. Topics include collection of samples of tonalite for zircon Laser ablation inductively coupled plasma mass spectrometry U-Pb dating in the area; and conclude that there is a Precambrian basement beneath the Bainaimiao arc belt.

The article presents a study on the structural geology, petrology, chronology, and geochemistry of the Shirenshan gneiss in North Qinling Terrane (NQT), China. The study evaluates the zircon uranium-lead (U-Pb) dating, the magma sources and petrogenesis, and geodynamic regimes of the gneiss. Result shows that the gneiss features A-type granite, rock production through partial melting of amphibolites, and strong interaction between crust and mantle.

The article discusses the research on the termination time of the Large Igneous Province due to the eruption of Emeishan flood basalt volcanism at the Buotuo region in Sichuan Province, China. Topics include the analysis of Xuanwei Formation in China, the use of zircon uranium-lead (U-Pb) dating and hafnium isotopic for analyse of sedimentary tuff, and the geochemical and paleogeography analysis of sedimentary tuff.

The article discusses the research on the uranium-lead dating of cassiterite for geochronology of the mineralization process of Yangbin Porphyry tin deposits in Zhejiang, China. Topics include the relationship between granitic magmatism and tin mineralization, the potential for prospecting in the metallogenic belts in South China, and the use of laser ablation inductively coupled plasma mass spectrometry to analyse cassiterite.

The article discusses the uranium-lead (U-Pb) dating of uranium deposit discovered at the Northern Qinling Orogen, a tectonic belt in China. Topics include the mineralization of uranium during the Devonian period, the crystallization age of uraninite, and the use of laser ablation inductively coupled plasma mass spectrometry to analyse uranium deposit. A chart on the U-Pb isotopic dates of uraninite is presented.

The article discusses the research on the zircon uranium-lead dating of granites identified in Niukutou lead-zinc deposit at the Qaidam Basin in Qinghai Sheng, China. According to the author the research aims to provide data on prospecting in China. Topics include the lead-zinc polymetallic mineralization, the magma crystallization age, and the use of laser ablation inductively coupled plasma mass spectrometry to analyse rocks.