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The Bengal Basin is a well‐known foreland basin that archives the tectonic evolution of the Himalayan and Indo‐Burman Ranges (IBR). The Dupi Tila Formation is the youngest among the stratigraphic successions of the Bengal Basin, which witnessed the last phase of the Himalayan uplift. However, there is still controversy regarding sediment provenances since the Himalayan and IBR are in the late Neogene exhumation stage. In this study, the petrographical and geochemical compositions of the Dupi Tila sandstones from the Lalmai Anticline of the Bengal Basin are examined to infer the source rocks, tectonic settings, palaeoclimate and weathering intensity in provenance areas. The detrital modes and geochemical discriminations, as well as Chondrite‐normalized rare earth elements patterns with enrichment in light rare earth elements and nearly flat heavy rare earth elements and negative Eu anomalies (average Eu/Eu* = 0.77) indicate dominantly felsic source rocks. The geochemical data also suggest that these source rocks in provenance areas were influenced by weak to moderate chemical weathering (chemical index of alteration: 65.64–75.62) and multiple recycling under warm and humid to semi‐humid climatic conditions. The detrital zircon ages show three dominant peaks at ca. 100, 500 and 1000 Ma with minor 1700 Ma. The amount of young zircon grains (<120 Ma) is noticeably higher (~18%) in this Lalmai outcrop compared to the Dupi Tila samples from the Sylhet Trough and Chittagong‐Tripura Fold Belt. Results from integrated zircon geochronology and geochemistry indicate that the detritus are likely derived from a recycled orogen provenance related mainly to active continental margin setting with subordinate influence from passive setting. Therefore, the regionally extensive Himalayan Orogen appears to be the primary sediment source, with additional mixing from the IBR and recycled sediments originating from the Gangdese batholith of the Trans‐Himalaya. [ABSTRACT FROM AUTHOR]

There are several different models for the origin of syenites, but the role of magma mixing in the formation of syenites remains unclear. The Wulingshan alkaline complex in the northern North China Craton consists mainly of porphyritic syenite and syenite with abundant enclaves. These enclaves may provide new insights into the petrogenesis of syenites. We obtained zircon U–Pb age, mineral chemistry, whole‐rock major and trace elements, and Sr–Nd isotopic data for the enclaves and their host rocks to constrain the petrogenesis and identify the role of magma mixing during the formation of the different syenites in the Wulingshan alkaline complex. The results of zircon U–Pb dating indicate that the enclaves and host rocks crystallized contemporaneously at ca. 133 Ma. The enclaves contain abundant clinopyroxene, amphibole, and biotite, and their average Nb/Ta (18.46) and Th/Ce (0.04) ratios are similar to those of the mantle. The enclaves have relatively high Fe2O3T, MgO, and CaO contents, and their SiO2 contents are equivalent to those of intermediate rocks, indicating that they formed by mixing the mafic and felsic magmas to some extent. The different mineral assemblages, major and trace elements and isotopic compositions of the enclaves in the porphyritic syenite and syenite indicate that they are two batches of parental magma with different properties derived from the mantle. The porphyritic syenite and syenite have high SiO2 and low Fe2O3T, MgO, and CaO contents, as well as low V, Cr, Co, and Ni contents. These major and trace element characteristics of the host rocks require the involvement of crustal components. The Sr–Nd isotopic compositions of the enclaves and the host syenitoids plot on a mixing curve between enriched lithospheric mantle and lower crust, indicating that these rocks are the products of magma mixing and crust–mantle interaction. Considering the contact relationships, the geochemistry data, and the mixing model presented in the paper, we propose that the upwelling of the hot asthenosphere heated the overlying enriched lithospheric mantle and triggered low‐degree partial melting. The alkalic mafic magmas derived from enriched mantle sources were mixed with felsic magmas generated by partial melting of the lower (or upper) crust to form the different syenites. [ABSTRACT FROM AUTHOR]

The genesis of intermediate intrusions is highly controversial, and one of the hot topics is whether they represent frozen melts or cumulates in the evolution of magmatic systems. Distinguishing accumulation from crystallization melt differentiated along the liquid line of descent is the key issue. The Paleoproterozoic intermediate intrusions in southern North China Craton provide an excellent case to decipher this issue. Multiple lines of evidence, including mineral textures, geochemistry as well as alphaMELTS modeling, indicate disequilibrium between whole‐rock and minerals, with melt extraction occurring at temperatures of 760°–820°C and with 10–40 wt.% of trapped melts. Effective water storage, revealed by amphibole and clinopyroxene hygrometers, plays a crucial role in promoting crystal‐melt segregation in pluton‐sized reservoirs in the upper crust. This study demonstrates that the accumulation in intermediate magmas can be identified even without evident complementary initial and extracted melts and provides deep insights into the genesis of intermediate continental crust. Plain Language Summary: The genesis of intermediate rocks has long been controversial since they are analogs of the average composition of continental upper crust. The key topic is whether intermediate rocks represent frozen melts of intermediate magmas or crystal residues after melt extraction in the evolution of felsic magmatic systems. Here we carried out a comprehensive study on the Paleoproterozoic intermediate intrusions in the southern North China Craton, which is considered to have recorded the process of crystal accumulation and melt segregation in the shallow crust. Upon mineral texture, geochronologic, whole‐rock and mineral geochemical, and thermodynamic investigation, we propose that crystal accumulation and crystal‐melt segregation processes can be identified in intermediate magmas with the melt extraction temperatures and proportions of trapped melts recorded by zircon trace elements. Amphibole and clinopyroxene hygrometers revealed high water content of the melts, which likely decreased the viscosity of melts and facilitated effective cumulate‐melt segregation. This study provides a powerful reference to see through the accumulation in intermediate magmas, record the processes of crystal‐melt segregation, and definitively resolve the debate concerning the genesis of intermediate intrusions. Key Points: Crystal accumulation in intermediate magmas can be identified by mineral texture and geochemistryThe effective water storage system in the reservoirs is key to promoting crystal‐melt segregationCrystal‐melt segregation and accumulation are fundamental processes to form evolved continental upper crust [ABSTRACT FROM AUTHOR]

The tectonic transition from oceanic subduction to continental collision is a fundamental process during orogenesis, yet the nature of such transition and associated deep geodynamic processes for the Tibetan Plateau are still controversial. The long‐lived magmatism of the Gangdese Belt of southern Tibet provides an excellent opportunity to study the tectonic transition from subduction of the Neo‐Tethys oceanic lithosphere to the continental collision between Indian and Asian plates. We present zircon U–Pb–Hf isotopes, whole‐rock geochemistry, and Sr–Nd isotopes for the intrusions from Maizhokunggar, southern Lhasa Terrane. The zircon U–Pb dating indicates that two episodes of magmatism occurred in the Maizhokunggar region, ca. 70 Ma diorites and ca. 60 Ma granitoids. The ca. 70 Ma diorites are medium‐K calc‐alkaline and characterized by pronounced high‐field‐strength element depletion and light rare earth element enrichment, similar to arc‐type rocks. They have homogeneous (87Sr/86Sr)i ratios (0.70378–0.70424) and εNd(t) values (+2.6 to +3.4), and εHf(t) (+5.9 to +13.0) with relatively young depleted mantle model ages (307–762 Ma), suggesting that they were generated from the juvenile mafic lower crust induced by the underplating of basaltic magmas from depleted mantle wedge. The ca. 60 Ma granitoids, Kajiacun (KJC) granodiorites, and Qulongxue (QLX) and Bangdacun (BDC) monzogranites are high‐K series and metaluminous to weakly peraluminous. The KJC granodiorites with high Sr/Y ratios (25–43) are adakitic and were likely derived from partial melting of a thickened lower crust. The BDC monzogranites have more evolved Sr–Nd–Hf isotopes and older Nd–Hf model ages than the QLX monzogranites. These geochemical variations were mainly controlled by the fractionation crystallization with assimilation of ancient crustal materials. We propose that at ca. 70 Ma, the subduction of the Neo‐Tethys oceanic slab triggered the partial melting of the juvenile lower crust and formed the diorites with arc affinity, and then the initial collision (>60 Ma) between the Indian and Asian plates caused locally thickened lower crust, resulting in adakitic granodiorites. Our study sheds light on the lithospheric scale magma evolution from the deep mantle to the shallow crust during the critical geodynamic transition to collision, and early uplift. [ABSTRACT FROM AUTHOR]

The Zangalou Cu deposit lies in the Sabzevar volcanic‐plutonic zone, northeastern Iran. The deposit is hosted by the middle Eocene volcanic‐sedimentary sequences and it has been affected by propylitic, carbonate, sericitic, and minor argillic alterations. The volcanics have features typical of calc‐alkaline and metaluminous magmas and are plotted in the continental volcanic arc region. Zircon U–Pb dating of the andesite porphyry yield ages of 41.2 and 38.4 Ma (Bartonian). Ore mineralization occurs as stratabound with open‐space filling, dissemination, veinlet, and replacement textures in mineralized conglomerate, andesite porphyry, and trachyandesite host rocks. Cu content in Zangalou deposit vary from 1,234 g/t to 6.24% which mostly occurred as chalcocite mineral. Fluid inclusion data of mineralization‐related calcites indicate medium salinities (12.8–16.6 wt.% NaCl equivalents) and a wide range of temperatures (154–295°C) and show evidence of fluid cooling trend during the ore formation. The δ13C (between 19.3 and −2.8‰) and δ18OSMOW (between 24.8 and 25.34‰) values of ore‐related calcites suggests a contribution of sedimentary organic matter and marine carbonates as the source of carbon in the ore‐forming fluid. High positive δ34S values (27.8–33.47‰) suggest that the source of sulphur is related to sedimentary country rocks. Mineralization is lithologically and structurally controlled and it is epigenetic. According to geological, petrological, alteration, mineralization textures and geometry of deposit, fluid inclusion, and isotopic studies, the Zangalou deposit is similar to manto‐type deposits. [ABSTRACT FROM AUTHOR]

Here we report the first set of thallium (Tl) isotope data in alkaline rocks from the North China Craton to constrain the nature of recycled materials in the metasomatized subcontinental lithospheric mantle. Samples from the Hekanzi and Saima alkaline complexes display Tl isotope compositions (ε205Tl) identical to the present‐day upper mantle and continental crust, suggesting that neither the recycled low‐temperature altered oceanic crust nor the pelagic sediments were involved in their sources. The volcanic rocks from the Liaodong‐Jinan region, whose source was previously proposed to contain recycled low‐temperature altered oceanic crust, also display modern mantle‐like Tl isotope composition, suggesting a significant Tl‐loss in the recycled oceanic crust during the subduction due to the dehydration process. Our Tl isotope data provide complementary constraints to the Sr‐Nd‐Hf‐O isotopes on the nature of metasomatic agent in the subcontinental lithospheric mantle. Plain Language Summary: Recycling of crustal materials into Earth's mantle by subduction causes mantle heterogeneities. The sources of some alkaline rocks contain recycled crustal materials. Pelagic sediments, low‐temperature altered oceanic crust, and continental crust have sharp differences in thallium isotope compositions. Combined with Sr‐Nd‐Hf‐O isotopes, whole‐rock Tl isotopes place a better constraint on the metasomatic sources. Key Points: Thallium isotope compositions of the alkaline rocks were analyzed to track crustal recycling in the subcontinental lithospheric mantleThallium isotope suggested that low‐temperature altered oceanic crust and pelagic sediments were not involved in the investigated sourcesThe O‐Nd‐Hf‐Tl isotope data for the Liaodong‐Jinan volcanics reveal a significant Tl‐loss in the subducted slab during dehydration process [ABSTRACT FROM AUTHOR]

The genesis of Late Triassic granitoids in the central Qiangtang is significant for deducing the evolution of the Palaeo‐Tethys Ocean in Qiangtang Block. Herein, we present a comprehensive study of zircon U–Pb ages, whole‐rock geochemistry and zircon Lu–Hf isotopes for the mafic microgranular enclaves (MMEs) and host granodiorites from the Shuanghu area, in order to evaluate their petrogenesis and geodynamic implications. New zircon U–Pb dating show identical formation ages for host granodiorites (207.1 ± 2.2 Ma and 206.6 ± 3.8 Ma) and MMEs (205.4 ± 2.9 Ma and 209.2 ± 2.2 Ma). The Shuanghu granodiorites contain amphibole and biotite and are characterized by moderate SiO2 (64.74–66.40 wt%) and K2O contents (2.48–3.62 wt%) as well as low A/CNK (0.69–1.00), indicating I‐type granite affinity. Its enriched zircon Hf isotopes (εHf(t) = −12.04 to −5.09) indicate that they were derived from the ancient mafic lower crust. The MMEs have a similar mineral assemblage, emplacement ages, trace elemental and zircon Hf isotopic compositions with the host granodiorites, indicating the cognate origin. These MMEs represent autoliths captured by latter ascending host magmas in the middle‐upper magma chamber. The highly variable Mg# (37–53), Cr (16.9–190 ppm) and Ni (5.71–67.2 ppm) in the Shuanghu MMEs and host granodiorites indicate that the mantle‐derived magma provided not only the heat but also the mafic components. In combining with previous studies, we suggest that the Shuanghu granodiorites and MMEs were formed in the post‐collision stage, which were caused by the asthenosphere upwelling related to the slab breakoff. [ABSTRACT FROM AUTHOR]

The East Kunlun Orogenic Belt (E‐KOB) of the northern Tibetan Plateau is an accretionary orogenic belt, which has experienced complicated tectonic evolutionary processes of the Proto‐ to Palaeo‐Tethys Ocean. The Muztagh‐Buqingshan‐Anemaqen ophiolitic mélange zone (MBAM) is an accretionary complex related to the northward subduction of the Tethyan Ocean. Numerous intrusions outcropped in MBAM have witnessed the long‐term subduction‐accretionary process and thus site the key to comprehending the tectonic evolution of the E‐KOB, as well as the Tethyan Ocean. In this study, petrological, geochronological, and geochemical studies of the Marzheng diorites in the MBAM were carried out to explore the Early Palaeozoic tectonic evolution of the E‐KOB. Zircon U–Pb dating analysis suggests that the diorites were formed in the Early Ordovician at ca. 470 Ma. Furthermore, the εHf(t) values (5.3–14.1), Mg# values (39.7–51.2), and Nb/Ta (12.8–14.8), Zr/Hf (33.8–44.8), and Lu/Yb (0.15–0.16) ratios are generally close to those of depleted mantle‐derived rocks and the diorites were originated from a depleted asthenosphere mantle source. In addition, these diorites are characterized by enriched light rare earth elements (LREEs) (La and Nd) and depleted high‐field‐strength elements (HFSEs) (Nb, Ta, P, and Ti), similar to the fingerprints of arc‐related gabbroic‐dioritic rocks. This is also consistent with their high H2Omelt (6.0–8.3%) and oxygen fugacity (logfO2 = −14.3 to −13.5) features, indicating that they were formed in a subduction‐related setting. Our new investigations suggest that the Proto‐Tethys Ocean in the East Kunlun was still actively subducting northward during the Early Ordovician. [ABSTRACT FROM AUTHOR]

Calc‐alkaline granitoid intrusions with abundant mafic microgranular enclaves (MMEs) are widespread in the East Kunlun orogenic belt (EKOB). Here, we present petrological observations, zircon U–Pb ages, whole‐rock geochemical, and Sr–Nd–Hf isotopic data for quartz diorites and the MMEs in the Asiha gold ore deposit in the EKOB, to constrain their petrogenesis and tectonic setting. The laser ablation inductively coupled plasma mass spectrometer 206Pb–238U ages of zircons indicate that the host quartz diorites and their MMEs from the Asiha gold deposit crystallized at 228.4 ± 1.7 Ma and 229.0 ± 1.7 Ma, respectively, which is similar to the gold mineralization age. Whole‐rock geochemical data indicate that the quartz diorites are I‐type granites. The MMEs have εHf(t) values of −7.6 to −0.2, −2.1 on average, whereas those of the quartz diorites range from −3.2 to −0.8, with a mean value of −2.1, which is identical within analytical uncertainty. Moreover, the host quartz diorites and their MMEs have relatively homogeneous Sr–Nd isotopic compositions, with high initial 87Sr/86Sr ratios and low εNd(t) values ranging from 0.70914 to 0.70963 and from −5.9 to −5.5, respectively. In summary, the MMEs and host quartz diorites have similar geochemical characteristics, indistinguishable Sr–Nd–Hf isotopic composition, and almost simultaneous crystallization age. Geochemical evidence shows that they formed due to the mixing of crust‐ and mantle‐derived magmas. Combined with our new results and published geological, geochronological, and geochemical data, this paper proposes that the EKOB had evolved into a post‐collisional environment at about 230–228 Ma, and the host quartz diorites and their MMEs from the Asiha complex formed in the transitional stage from the syn‐collisional to the post‐collisional setting. [ABSTRACT FROM AUTHOR]

The Permian mafic dykes of Santanghu Basin offer an opportunity to study the nature of mantle source and tectonic setting of the basin, as well as to provide the theoretical basis for structural transformation of East Junggar region. In this study, zircon U–Pb geochronology, mineral composition analysis, whole‐rock elemental, and Sr‐Nd isotopic geochemistry were conducted to explore the origin and evolution of the primitive magma. LA‐ICPMS zircon U–Pb dating yields ages at 269 Ma. The elemental geochemistry results suggest enrichments in Ba, Pb, and Sr but depletions in Nb, Ta, Zr, and Hf, which indicate that the magma source was influenced by fluid metasomatism. All samples show moderate initial Sr‐Nd isotope results ((87Sr/86Sr)I = 0.704299 to 0.704490 and εNd(t) = +6.16 to +6.83) and have high Sm/Yb ratios, which suggest that the diabases were derived from partial melting of 5%–7% spinel‐garnet Iherzolite lithospheric mantle. Combined with petrological, geochronological data, and the regional tectonic background, it is interpreted that the diabases from Santanghu Basin originated from lithospheric mantle metasomatized by subduction fluids under the background of intracontinental extension. [ABSTRACT FROM AUTHOR]

Early Jurassic Kaoshan medium‐ and fine‐grained syenogranites emplaced along the Yitong–Shulan Fault Zone in the southern part the Zhangguangcai Range, central Jilin Province, intruded Middle Triassic granitoids and Carboniferous‐Devonian intrusive rocks. They have medium‐ and fine‐grained textures and contain K‐feldspar, quartz, plagioclase, and biotite. They are peraluminous (A/CNK = 1.13–1.20) and have high values of SiO2 (74.60–75.82 wt%), total alkalis (Na2O + K2O = 8.28–9.18 wt%), light rare earth elements (20.89–56.14 ppm), large‐ion lithophile elements, and FeO/MgO = 2.78–5.93. In contrast, they feature low values of CaO (0.40–0.49 wt%), TiO2 (0.05–0.14 wt%), P2O5 (0.02–0.04 wt%), Sr (24.20–62.59 ppm), heavy rare earth elements (5.14–11.80 ppm), high‐field‐strength elements, and δEu (0.41–0.76), and the calculated zircon saturation temperatures (Tzr) range from 804 to 870°C, all of which are similar to the geochemical signatures of anorogenic A1‐type granites. Zircon U–Pb geochronology analyses from the medium‐ and fine‐grained syenogranites yield concordia ages of 193.18 ± 0.95 Ma (MSWD = 6.7, n = 18) and 190.29 ± 0.92 Ma (MSWD = 8.7, n = 17), respectively, and belong to the Early Jurassic Sinemurian stage. In situ Hf isotope analyses of dated zircons yield εHf(t) values ranging from +17.0 to +9.7 and Hf model ages (TDMC) of 225–614 Ma. Their whole‐rock (87Sr/86Sr)i (0.704740–0.704133) and εNd(t) values (+2.8 to +0.2) are similar to those of many coeval A2‐type granites in this region, and they form an A‐type granite assemblage. Consequently, the Kaoshan medium‐ and fine‐grained syenogranites were probably derived from partial melting of juvenile lower crust and might be related to the subduction of the Palaeo‐Pacific Plate. [ABSTRACT FROM AUTHOR]

The southern Jiangxi Province is an important part of the fluorite mineralization belt in South China. Fluorite ore bodies are primarily in the contact zone between the Devonian Huitong granitic complex and the Late Cretaceous Ganzhou Formation, controlled by the NE‐trending faults. Zircon U–Pb dating of the Huitong granitic complex yields emplacement ages of 410.7 ± 1.4 Ma and 400.7 ± 4.6 Ma, while the Sm–Nd dating of the fluorite yields an isochron age of 94 ± 2 Ma, suggesting that the Huitong granitic complex is the host rock. Fluid inclusions in the fluorite show low homogenization temperatures (136–207°C), salinities (1.23–3.87 wt% NaCl), and densities (0.87–0.95 g/cm3), suggesting that the ore‐forming fluid is an NaCl‐H2O system of low temperature, salinity, and density. Raman spectroscopy showed that the fluid phase is dominated by water. The δDVSMOW values of the fluid inclusions in the Tongda fluorite ranged between −59.5 and −55.2‰, while the δ18OVSMOW values of the fluorite ranged from −7.2 to −5.6‰. Collectively, the ore‐forming fluid is dominated by meteoric water, possibly with a minor contribution of hydrothermal fluid. Both the interaction with host rocks and the cooling of hydrothermal fluids are the likely mechanisms of underlaying fluorite precipitation at low temperatures. The mineralization occurred in extensional faults during the Late Cretaceous related to the subduction of the Palaeo‐Pacific Oceanic Plate. [ABSTRACT FROM AUTHOR]

Late Mesozoic extensional mechanisms in the Great Xing'an Range (GXR) and relevant crust–mantle interactions are complicated, which result in widespread magmatisms with diverse parental origins and petrogenesises. In this paper, we present the lithology, whole‐rock geochemistry, and zircon U–Pb–Lu–Hf isotopes for granodiorite‐monzogranite rocks (GM) and their enclaves of quartz monzodiorites in the Zhalantun area, east of central GXR. Zircon U–Pb dating results reveal that both GM rocks and their enclaves of quartz monzodiorites yield a nearly identical crystallization age of ~125 Ma. The GM rocks exhibit weak peraluminous and high‐K calc‐alkaline compositions with high SiO2, Na2O + K2O, and Al2O3 contents, and low MgO, Mg#, Fe2O3T, and TiO2 contents, which are characterized by fractionated REE patterns, relatively strong negative Eu anomalies, enrichments of LILEs (e.g., Rb, Ba, and K), and depletions of Nb, Ta, P, and Ti. The parental origins for GM samples were juvenile crustal materials, with positive zircon εHf(t) values of +2.5 to +12.9. The whole‐rock and zircon geochemical simulations limit slightly lower GM magma crystallization temperatures (TTi‐Zrn) of 683–824°C and relatively more oxidizing conditions (log(fO2) = FMQ+7.6–FMQ‐6.8), and further confine that they were probably formed by ~10–35% degrees of fluid‐present partial melting of lower to middle crustal materials, with fractional crystallization and/or residual mineral phases of plagioclase, amphibole, clinopyroxene, and garnet. By contrast, the enclaves of quartz monzodiorites possess lower SiO2 and Na2O + K2O compositions, but higher MgO, Mg#, Fe2O3T, and TiO2 values, which are consistent with metaluminous–weak peraluminous and high‐K calc‐alkaline series. All quartz monzodiorites exhibit sub‐parallel right‐declined REE patterns, negligible to none Eu anomalies, enrichments of LILEs, and depletions of Nb, Ta, and Ti. Combined with mineral morphology and disequilibrium structures, the whole‐rock geochemical and Hf isotopic simulations imply that parental magmas for quartz monzodiorites were hybrid mixtures between ~50% host GM acid magmas and ~50% ancient crust compositions, with a wide range of zircon εHf(t) of +14.0 to −7.7, slightly higher TTi‐Zrn of 710–835°C, and lower log(fO2) of FMQ+8.2–FMQ‐10.5. Taken together, felsic plutons in the Zhalantun area correspond to an episode of extensional mechanism‐related crust–mantle interactions, which might be induced by either the Mongol‐Okhotsk domain or Palaeo‐Pacific tectonic domain, or both of them. [ABSTRACT FROM AUTHOR]

Baddeleyite (ZrO2) is a common late‐stage accessory mineral in basaltic shergottites and is a robust geochronometer for obtaining igneous crystallization ages via high‐precision in situ SIMS U‐Pb analysis. Amenability to SIMS U‐Pb dating depends in large part on the size and abundance of baddeleyite grains, which are generally surveyed using microbeam methods. We examine the petrography, mineralogy, geochemistry, and baddeleyite distribution in eight basaltic shergottites to identify factors that may be used to predict baddeleyite distribution in unknown samples of Mars. Results suggest that fractional crystallization controls baddeleyite occurrence in shergottites to the first order; samples with pyroxene major element compositions extending beyond the 1‐bar stability boundary generally have higher baddeleyite abundance compared with samples with pyroxene compositions terminating at or before the stability boundary. In samples which display two pyroxene composition trends (high‐Ca and low‐Ca), the largest baddeleyite grains tend to be associated with Fe‐Ti oxides; in samples where pyroxene composition forms a continuous trend extending beyond the 1‐bar stability boundary, the largest baddeleyite grains are typically associated with polymineralic late‐stage pockets. Bulk HFSE content and fO2 do not appear to directly influence baddeleyite distribution. Based on our findings, we propose that pyroxene composition is a useful proxy for assessing baddeleyite abundance and distribution in shergottites and may aid in determining a sample's feasibility for U‐Pb geochronology prior to conducting detailed surveys for baddeleyite characterization. [ABSTRACT FROM AUTHOR]

The Elashan magmatic belt is located at the eastern margin of the East Kunlun orogenic belt (E‐KOB) in northwestern China, where voluminous magmatism occurred during the Late Permian to Late Triassic. Mid‐Triassic volcanism produced the Xilikete Formation, which shows a geochemistry similar to that of highly fractionated I‐type (HFI) volcanic rocks. These rocks are characterized by high SiO2 (73.82–74.97 wt%), differentiation index (DI; 91.01–94.69), and alkalis (e.g., high K2O + Na2O, with K2O/Na2O ratios greater than 1.0) and by enrichment in some large‐ ion lithophile elements (LILEs; e.g., Rb, K, and Pb) and depletion in other LILEs (e.g., Ba and Sr) as well as some high‐field‐strength elements (HFSEs; e.g., Nb, Ta, and Ti); these features confirm that they are HFI volcanic rocks. Zircon U–Pb ages indicate that the volcanic rocks were emplaced at ~239 Ma. These zircons have εHf(t) values ranging from −2.26 to +0.36, with two‐stage model ages (TDM2) of 1,441–1,221 Ma, indicating a magma source that involved partial melting of Mesoproterozoic lower crust accompanied by a minor juvenile mantle component. The ~240 Ma magmatism in the E‐KOB was probably developed in response to subduction of the Palaeo‐Tethys oceanic plate. Previous studies indicate that a tectonic transformation from subduction to continental collision occurred at ~240 Ma. Combining these data with regional geological observations, we conclude that the Daheba volcanic rocks formed in an active continental margin setting related to the subduction of the Palaeo‐Tethys oceanic plate beneath the E‐KOB. [ABSTRACT FROM AUTHOR]

The Guang‐Tou‐Shan (GTS) granites, located in the Xing'an Block (XB), record Late Palaeozoic magmatism during the stage of convergence between micro‐blocks in the eastern Central Asian Orogenic Belt (CAOB). We performed a detailed geochronological and geochemical study of GTS granites intending to obtain better constraints on the subduction processes of the Palaeo‐Asian Ocean (PAO) in eastern CAOB. LA–ICP–MS U–Pb dating of zircons from GTS granitic rocks in western XB yielded emplacement ages of 332 ± 2 Ma and 301 ± 2 Ma, respectively, indicating a two‐stage emplacement process. Geochemical analyses show that the Early Carboniferous monzogranite (332 ± 2 Ma) have low values of the A/CNK and A/NK, are enriched in LILE (Rb, Sr, Ba) and LREE (LREE/HREE = 5.6–10.8), and depleted in HFSE (Nd, Ta, Zr, Hf) and P, Ti, which belong to I‐type granites. The Late Carboniferous granodiorite (301 ± 2 Ma) also displays LILE, LREE enrichment, and HFSE depletion with negative Nb–Ta anomalies, and contains relatively high Zr + Nb + Ce + Y contents (495–524 ppm) and high zircon crystallization temperature, indicating the Late Carboniferous granodiorite shows geochemical characteristics similar to those of typical A‐type granites. The two‐stage granitic rocks have εHf(t) values of +7.7 to +11.6 and yield a two‐stage depleted mantle Hf model age of 0.66–0.88 Ga, suggesting that the GTS granitic rocks were derived from partial melting of juvenile arc‐related mafic to intermediate rocks. The results, combined with regional magmatic information, indicate that the eastern CAOB experienced a subduction setting in the Early Carboniferous and extension setting in the Late Carboniferous. This change was most likely caused by the subduction slab break‐off of PAO from the Late Carboniferous. [ABSTRACT FROM AUTHOR]

The geodynamic mechanism of the Early Cretaceous magmatic rocks in the southern Lhasa Terrane remains controversial. To constrain the Early Cretaceous petrogenesis and tectonic evolution of the Neo‐Tethyan oceanic slab, we have undertaken zircon U–Pb dating, whole‐rock major and trace element analyses, and Sr–Nd–Pb–Hf isotopic studies of the Cuocun gabbro from the southern Lhasa Terrane. The zircon U–Pb dating yielded an Early Cretaceous crystallization age of 146.9 ± 0.6 Ma (MSWD = 0.77, 2σ). The Cuocun gabbro is enriched in large‐ion lithophile elements (e.g., Rb, Sr, and Ba) and depleted in high‐field‐strength elements (e.g., Nb, Ta, and Ti). The initial 87Sr/86Sr value are low (0.70361–0.70460), εNd(t) and εHf(t) values are high and positive (from +5.1 to +6.6 and from +11.0 to 17.0, respectively), and Pb isotope specific value are homogeneous (initial 206Pb/204Pb = 18.163–18.457, 207Pb/204Pb = 15.541–15.632, and 208Pb/204Pb = 38.262–38.673). The gabbro originated from the partial melting of a depleted mantle wedge that had reacted with slab‐derived fluids, and the ascending magmas underwent fractional crystallization without significant crustal contamination. Combining our data with those from previous studies of Early Cretaceous magmatism in the southern Lhasa Terrane, we suggest that the Early Cretaceous magmatic rocks (147–130 Ma) in the southern Lhasa Terrane were generated within a continental marginal arc setting related to the rollback of the northwards subducting Neo‐Tethyan oceanic slab. [ABSTRACT FROM AUTHOR]

Pusangguo is a high‐grade skarn‐type Cu‐dominated polymetallic deposit and the only large‐sized Cu‐Pb‐Zn‐(Co‐Ni) deposit in the Gangdese metallogenic belt (GMB); the magmatic rocks associated with this deposit are poorly documented, and their petrogenesis and geodynamic setting are unclear. To explore these issues, we present zircon U–Pb ages along with Hf isotopic, whole‐rock geochemical, and Sr–Nd–Pb isotopic data for Pusangguo biotite granodiorite (PBG) and Pusangguo diorite porphyrite (PDP) in this deposit. Zircon U–Pb dating for these rocks indicates that they were emplaced during the Miocene (13.6–14.6 Ma). Geochemically, both PBG and PDP show characteristics of adakites, with intermediate SiO2 (65.55–67.30 wt% and 60.56–58.27 wt%, respectively), relatively high Al2O3 (15.28–15.85 wt% and 17.71–16.71 wt%, respectively) and Sr (599–723 ppm and 687–1,616 ppm, respectively) and low Y and Yb. In addition, they show relatively low ratios of (87Sr/86Sr)i and (206Pb/204Pb)i, (207Pb/204Pb)i and (208Pb/204Pb)i and relatively low values of εNd(t) and εHf(t). The Sr‐Nd‐Pb‐Hf isotopes of PBG and PDP are similar to those of the Miocene adakitic rocks associated with the porphyry–skarn deposits in the GMB, indicating that they were predominantly generated by partial melting of the thickened juvenile Lhasa Terrane lower crust and the PDP were likely to be generated through mixing between the magma parental to the PBG and a mafic end‐member. By combining our results with the previously reported results, we suggest that the model of delamination of the overthickened mantle lithosphere of Lhasa Terrane and convective upwelling of mantle asthenosphere which may involve Indian continental lithosphere. [ABSTRACT FROM AUTHOR]

Palaeoproterozoic granites accompanied with granulite‐facies gneisses can be recognized in the Kuandian area, northern Jiao‐Liao‐Ji Belt (JLJB). This study highlights two episodes of Palaeoproterozoic magmatism, identified by granites and biotite monzogranitic gneisses herein. Zircon grains from biotite monzogranitic gneiss with homogeneous oscillatory zoning yielded a U–Pb age of 2,153 ± 16 Ma, in accordance with the age of zircon cores from the monzogranitic gneiss. Zircon grains from the two granites yielded upper intercept ages of 1,892 ± 38 Ma and 1,859 ± 36 Ma respectively. Monzogranitic gneiss samples are enriched in Th, Rb, Pb, U, and REE, but depleted in Sr and P. They have high 1,000 × Ga/Al ratios versus Zr, Ce, Nb, Y contents, which are usually interpreted as the features of classical A‐type granite that originated in a lithospheric extension setting. The ~1.89–1.86 Ga granite samples have relatively high Al, Rb, Th, U and low Sr, Zr, and Hf contents. These features, combined with the observation of minor apatite grains under the microscope are similar with the I‐type granites. In situ zircon Lu–Hf isotopic analyses revealed that ~1.89–1.86 Ga granite had a similar range and TDM2 ages with the monzogranitic gneiss, but with much lower εHf(t) values. The monzogranitic gneiss may have originated from an Archean crust, while the later granite may be derived from melting of the partial melting of the monzogranitic gneiss or the Archean crust that generated the monzogranitic gneiss. The ~1.89–1.86 Ga granites, together with the coeval S‐type granites in the JLJB, represent an orogeny process that may involve a Palaeoproterozoic subduction. [ABSTRACT FROM AUTHOR]

The ages and source of Late Cretaceous mafic dolerite dykes of the Songliao Basin were determined using geochronological, geochemical, zircon Hf, whole‐rock Sr–Nd isotopic, and zircon fission tract. The results show that (a) petrographic data reveal doleritic, poikiloblastic textures, and amygdale structures of the dolerite dykes. (b) LA‐MC‐ICP‐MS U–Pb analysis of zircons yielded an age of 70.0 ± 3.0 Ma of one of these mafic dykes in agreement with the zircon fission track age (69–68 Ma) of host rocks within uncertainty, placing them within the Late Cretaceous. (c) Geochemical researches indicate that the dykes are classified as the alkaline and tholeiitic series according to their major elements and characterized by high Na2O (2.79–4.89 wt.%), TiO2 (1.63–2.71 wt.%), and low K2O (0.46–2.45 wt.%). And they have enrichment of incompatible elements (e.g., K, Ti, Rb, Ba, Th, U, Nb, Ta, and REEs), high Rb/Sr (0.026–0.066), LaN/YbN (3.83–15.93), near‐chondritic HREEs ([Gd/Yb]N = 1.78–3.37), low Sm/Nd (0.202–0.282) ratios, and with negligible Eu anomalies (Eu/Eu* = 0.98–1.06). The dykes contain relatively low amounts of radiogenic Sr, as shown by (87Sr/86Sr)i values (0.7037–0.7045), and have positive values of εNd(t) (3.66–5.40) and εHf (t) (2.66–7.45), suggesting that the mafic dykes have been derived from partial melting of the depleted lithospheric mantle and contaminated by crust in the source region and formed in back‐arc rift settings caused by the subduction of the Pacific Oceanic Plate. All the above indicate large‐scale extensional event in Songliao Basin NE China at about 70 Ma. [ABSTRACT FROM AUTHOR]

The Yinshan Block constitutes the northwestern segment of the North China Craton. We characterized the geochemistry, zircon U–Pb geochronology, and Hf isotopic composition of a diorite pluton in the Yinshan Block. The zircon U–Pb data yield a protolith formation age of 2535 ± 8 Ma (MSWD = 0.46), followed by recrystallization at 2465 ± 14 Ma or 2431 ± 30 Ma; the granite vein which intruded into the diorite pluton gives a formation age of 2453 ± 5 Ma (MSWD = 1.6), according with the recrystallization age of the diorite. These diorites are characterized by moderate Mg# value and MgO, Cr, and Ni content and have relatively low Sr/Y and (La/Yb)N ratios and slightly Eu anomalies and are enriched in LILEs and depletion in high field strength elements. High‐Sr + Ba granites with low K2O/Na2O characteristics are also shown by these diorites, and the εHf(t) of zircons lie between +1.3 and −7.2, imply these diorites are most likely derived from partial melting of a thickened lower crust with minor involvement of enriched mantle. These geochemical and isotopic characteristics suggest the diorite magmas derived from an accreted arc‐related rocks remelting in a low‐pressure environment along the continent margin. Hereby, we propose a supplement to the model of crustal growth and evolution in the Yinshan Block, involving subduction and collision in the Neoarchean. [ABSTRACT FROM AUTHOR]

This study presents zircon U–Pb ages and geochemical and Sr–Nd isotopic data for acid granites from the Uliastai continental margin, which is located in the Ulaan Tolgoi area of the south‐eastern Central Asian Orogenic Belt (CAOB). Although most samples have similar calc‐alkaline (K2O/Na2O = 0.55–1.70, average of 1.35) and peraluminous (A/CNK = 1.02–1.20 and A/NK = 1.09–1.87) characteristics, the granodiorites, monzogranites, and alkali feldspar granites exhibit distinct light rare earth element (LREE)/heavy REE (HREE) anomalies, including negative Nb, P, Ti, Sr, and Ba anomalies and negative εNd(t) values. These characteristics indicate that this complex massif comprises lower Early Carboniferous subduction‐related calc‐alkaline granodiorites (348 ± 1 Ma); an upper Early Carboniferous syn‐collisional segment characterized by S‐type, high‐K, calc‐alkaline, and peraluminous monzonitic granites (334 ± 1 Ma); and Late Carboniferous post‐orogenic extensional A2‐type peraluminous alkali feldspar granites (317 ± 1 Ma). Previous studies performed on coeval volcanic rocks and Early Palaeozoic granites in the same area have demonstrated that the Early Carboniferous granodiorites have the same geochemical characteristics as volcanic arc granites (VAGs), thus indicating that the northward subduction of the Hegenshan Ocean may have continued through the Early Carboniferous. The monzogranite and alkali feldspar granites, in conjunction with the Late Carboniferous lagged arc volcanic rocks observed in this area, suggest a syn‐collisional to post‐collisional setting. The new data presented in this study provide constraints on the timing of the transition from island‐arc magmatism to post‐collisional extension‐related magmatism in this region during the later stage of the Early Carboniferous. [ABSTRACT FROM AUTHOR]

The Solonker zone is widely accepted as the suture between the North China Craton and the Siberia–Mongolia continental plate. The Baolige granite complex is located to the north side of the Solonker Suture and is mainly composed of monzogranite and granite. Zircon U–Pb ages, geochemistry, and Sr‐Nd‐Hf isotopic data of the Baolige granites were presented to constrain their petrogenesis and tectonic settings. Two monzogranite samples from Baolige yielded weighted mean zircon 206Pb/238U ages of 310.7 ± 2.1 Ma (mean square of weighted deviates (MSWD) = 1.3) and 307.4 ± 1.6 Ma (MSWD = 0.77), whereas the granite intruded into the monzogranite yielded an age of 296.2 ± 2.0 Ma (MSWD = 1.2). Both the Baolige monzogranite and granite contain high contents of SiO2, K2O, and Al2O3, low contents of TiO2, MgO, and CaO, and are peraluminous high‐K calc‐alkaline. These rocks are characterized by enrichments of K, Rb, U, Pb, Th, and light rare earth elements and depletions of Nb, Ta, Ti, and heavy rare earth elements and contain slightly negative or no Eu anomalies, similar to typical arc‐related granitoids. The Ti‐in‐zircon thermometry yielded 650–759 °C for the monzogranite and 645–796 °C for the granite. The monzogranite shows positive zircon εHf(t) values (4.7–13.2) and whole‐rock εNd(t) values (3.6–5.2), with TDM2(Hf) ages of 1,324–557 Ma and TDM2(Nd) ages of 1,015–821 Ma, and ISr of 0.70363–0.70386. The granite shows εHf(t) values of 15.6–20.9 and εNd(t) values of 4.0–5.1, with TDM2(Nd) ages of 957–832 Ma, and ISr of 0.70364–0.70406. Geochemical evidence indicates that the Baolige granite complex is highly fractionated I‐type and was likely formed by partial melting of the Neoproterozoic juvenile crust in a continental arc setting. We concluded that the Paleo‐Asian Ocean may have undergone north‐dipping subduction beneath the Siberia–Mongolia continental plate during the Late Carboniferous, and the subduction may have continued to the Early Permian (ca. 296 Ma). [ABSTRACT FROM AUTHOR]

New data from mineralogy, geochemistry, zircon U–Pb dating, and Hf isotopes have revealed Late Cretaceous to Eocene magmatic intrusions in the Tengchong terrane and constrained the origin, tectonic setting, and characteristics of tin‐bearing and barren granitoids. We divide the studied granitoids into two groups: (a) the Late Cretaceous Zhinaxiang (70 Ma) and Early Paleocene Dazhupeng (65 Ma) S‐type barren granites and (b) the Eocene Lailishan A2‐type tin‐bearing granite (50 Ma). All these granitoids display Si‐ and K‐rich and calc‐alkaline characteristics and have similar chondrite‐normalized rare earth element patterns. However, geochemical differences do exist between the two groups of granites. The Zhinaxiang and Dazhupeng S‐type granites are slightly peraluminous, enriched in large‐ion lithophile elements (e.g., Rb and K), and depleted in high‐field‐strength elements (e.g., Nb, Ta, Zr, and Hf), whereas the Lailishan A2‐type granite has higher TFe2O3, high‐field‐strength element content, and Ga/Al ratios. The geochemical and Hf isotopic data indicate that the granites in this study were generated by partial melting of Paleoproterozoic metasedimentary rocks. Due to the subduction of the Neo‐Tethyan Ocean beneath the Eurasian plate, the Zhinaxiang and Dazhupeng S‐type granites were formed in a thickened‐crustal environment, whereas the Lailishan A2‐type granite was emplaced in a post‐collisional extensional setting attributed to slab break‐off. By comparison between tin‐bearing and barren granites, we propose that the Sn mineralization could be related to relatively high‐temperature and low‐pressure crystallization conditions. [ABSTRACT FROM AUTHOR]

We undertook zircon U-Pb dating and geochemical analyses of the Weitingchagan (WT) pluton in the Dong Ujimqi area, Northeast China, with an aim of determining their ages, petrogenesis and sources, which are important for understanding the Late Palaeozoic tectonic evolution of the Xing-Meng Orogenic Belt. The WT pluton consists of coarse- to medium-grained porphyritic granites in the core and medium- to fine-grained monzogranites in the rim, contains abundant microgranular enclaves and is intruded by small amounts of muscovite monzogranites. The results of LA-ICP-MS zircon U-Pb dating indicate that the WT composite pluton formed during the Late Carboniferous-Early Permian with the ages ranging from 289 Ma to 312 Ma. Petrological and geochemical characteristics of the WT pluton were derived from the partial melting of crustal materials, and the AFC process played an important role in the magmatic evolution. The porphyritic granites are I-type granite, and the monzogranites and muscovite monzogranites are highly fractionated I-type granite. Combined with previous studies on the contemporaneous magma-tectonic activities in the Uliastai Continental Margin, the study suggests that the WT pluton formed in an extensional environment, which may relate to the closure of the Palaeo-Asian Ocean. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Miaoya syenite and carbonatite complex is located in the southern margin of the South Qinling belt, central China. LA-ICP-MS zircon U-Pb dating reveals that the syenite and carbonatite have crystallization ages of 445.2 ± 2.6 Ma (MSWD = 0.66) and 434.3 ± 3.2 Ma (MSWD = 1.08), respectively. Both syenite and carbonatite display low ISr values (0.7004 to 0.7053) and depleted εNd(t) values of +1.1 to +5.5, with one-stage Nd model ages of 0.65 to 0.94 Ga. Their zircon εHf(t) values are also similarly positive (+3.1 to +8.9), and one-stage Hf model ages range from 0.71 to 0.92 Ga. Whole-rock geochemistry suggests that the syenite belongs to the shoshonitic series and both syenite and carbonatite show identical REE and trace element patterns. The coeval intrusive ages, similar geochemical and Sr-Nd-Hf isotopic compositions suggest that the Miaoya carbonatite and associated syenite are genetically related to each other. We consider that the carbonatite could be a final product by protracted fractionation of a CO2-rich alkaline melt. The depleted εNd(t) and zircon εHf(t) isotopes also indicate that the associated syenite and carbonatite could be originated from a mantle-derived magma. The sources are likely composed of dominated HIMU mantle and minor EMI mantle. We propose that the Silurian Miaoya Complex was formed in the extensional rifting setting, associated with the mantle upwelling. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Taolaituo porphyry-type molybdenum deposit is located in the eastern Inner Mongolia Autonomous Region in China. The mineralization occurs mainly as veins, lenses and layers within the host porphyry. To better understand the link between the mineralization and the host igneous rocks, we studied samples from the underground workings and report new SHRIMP II zircon U-Pb and Re-Os molybdenite ages, and geochemical data from both the molybdenites and the porphyry granites. Five molybdenite samples yield a Re-Os isochron weighted mean age of 133.0 ± 0.82 Ma, whereas the porphyry granitoids samples yield crystallization ages of 133 ± 1 Ma and 130.4 ± 1.3 Ma. The U-Pb and Re-Os ages are similar, suggesting that the mineralization is genetically related to the Early Cretaceous porphyry emplacement. Re contents of the molybdenites range from 21.74 to 42.45 ppm, with an average of 32.69 ppm, whereas δ34S values vary between 3.7‰ and 4.2‰, which is typical of mantle sulphur. The 206Pb/204Pb, 207Pb/ 204Pb and 208Pb/204Pb vary in the ranges of 18.276-18.385, 15.566-15.580 and 38.321-38.382, respectively. The Taolaituo Early Cretaceous granitoids are A-type granites. These observations indicate that the molybdenites and the porphyry granites were derived from a mixed source involving young accretionary materials and enriched subcontinental lithospheric mantle. A synthesis of geochronological and geological data reveals that porphyry emplacement and Mo mineralization in the Taolaituo deposit occurred contemporaneously with the Early Cretaceous tectonothermal events associated with lithospheric thinning, which was caused by delamination and subsequent upwelling of the asthenosphere associated with intra-continental extension in northeast China. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Yingchengzi gold deposit, located 10 km west of Shalan at the eastern margin of the Zhangguangcai Range, is the only high commercially valuable gold deposit in southern Heilongjiang Province, NE China. This study investigates the chronology and geodynamic mechanisms of igneous activity and metallogenesis within the Yingchengzi gold deposit. New zircon U-Pb data, fluid inclusion 40Ar/39Ar dating, whole-rock geochemistry and Sr-Nd isotopic analysis is presented for the Yingchengzi deposit to constrain its petrogenesis and mineralization. Zircon U-Pb dating of the granite and diabase-porphyrite rocks of the igneous complex yields mean ages of 471.7 ± 5.5 and 434 ± 15 Ma respectively. All samples are high-K calc-alkaline or shoshonite rocks, are enriched in light rare earth elements and large ion lithophile elements, and are depleted in high field strength elements, consistent with the geochemical characteristics of arc-type magmas. The Sr-Nd isotope characteristics indicate that the granite formed by partial melting of the lower crust, including interaction with slab-derived fluids from an underplated basaltic magma. The primary magma of the diabase-porphyrite was likely derived from the metasomatized mantle wedge by subducted slab-derived fluids. Both types of intrusive rocks were closely related to subduction of the ocean plate located between the Songnen-Zhangguangcai Range and Jiamusi massifs. However, fluid inclusion 40Ar/39Ar dating indicates that the Yingchengzi gold deposit formed at ~249 Ma, implying that the mineralization is unrelated to both the granite (~472 Ma) and diabase-porphyrite (~434 Ma) intrusions. Considering the tectonic evolution of the study area and adjacent regions, we propose that the Yingchengzi gold deposit was formed in a late Palaeozoic-Early Triassic continental collision regime following the closure of the Paleo-Asian Ocean. In addition, the Yingchengzi deposit could be classified as a typical orogenic-type gold deposit occuring in convergent plate margins in collisional orogens, and unlikely an intrusion-related gold deposit as reported by previous studies. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]