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Hainan Island is a key part of the eastern Tethyan region and contains detailed geological information that can enhance our understanding of the tectonic evolution of this region since the late Palaeozoic. In this paper, we report geochronological, geochemical, and Sr–Nd isotopic data for granitoids from Baomei and Chahe in the northern part of Hainan Island. Three new zircon U–Pb ages of 243.3 ± 1.7 Ma, 237.1 ± 5.1 Ma, and 257.0 ± 4.0 Ma were obtained for these granitoids. The late Permian Chahe granite (257 Ma) is weakly peraluminous to peraluminous, and has rare earth element patterns and Ga/Al and FeOT/MgO ratios typical of A‐type granites formed in an extensional tectonic setting. The Middle Triassic Baomei granitoids (243–237 Ma) are weakly peraluminous, and exhibit a negative correlation between P2O5 and SiO2, which is typical of I‐type granites. All the granitoids have EM II‐type‐enriched mantle Sr–Nd isotopic compositions, which indicate that they were derived from a mantle source that had experienced enrichment and metasomatism. Hainan Island was in an extensional tectonic setting from the late Permian to Middle Triassic when widespread A‐ and I‐type granites were generated. We speculate that Hainan Island was mainly affected by the Tethyan tectonic domain during the Permian–Triassic, which involved closure of the Palaeo‐Tethys Ocean, collision of the Indochina and South China blocks, and subsequent post‐collisional extension. [ABSTRACT FROM AUTHOR]

The Kelameili Ocean was one branch of the Palaeo‐Asian Ocean, the initiation and closure history of which remains elusive. Consequently, they hamper our understanding of the accretionary evolution of the southern Altaids. In this paper, we carried out field mapping and also geochronological and geochemical analyses on the Huangcaopo Group in the northern Harlik Mountains, NW China. Field investigation revealed that "block‐in‐matrix" structure develops with blocks of andesite, limestone, sandstone, and gabbro in matrices of turbidites. Combined with our recent work, our field investigation indicates that the Huangcaopo Group is the southern extension of the Kelameili accretionary complex. A gabbro block (19HAM057) was dated at 500 ± 4 Ma, its geochemical affinity was defined to be similar to arc magmatic rocks. Magmatisms represented by two gabbroic intrusions (19HAM057‐2 and 19HAM048) were dated at the latest Devonian (360 ± 5 Ma) and the latest Carboniferous (299 ± 4 Ma), respectively. Their geochemistry displays enrichments in light rare earth elements (LREE) and large ion lithophile elements (LILE), but depletions in high field strength elements (HFSE, especially Nb and Ta). And a younger gabbroic intrusion (19HAM052) yielded crystallization age of the latest Permian (254 ± 3 Ma), and its geochemistry also shows affinity to arc magmatism. The magmatism represented by the gabbro block (19HAM057) was coeval with the Zhaheba‐Aermantai ophiolite, indicating that it was the product of incipient arc magmatism following subduction initiation in the Kelameili branch of the Palaeo‐Asian Ocean. However, two episodes of gabbroic magmas (19HAM057‐2 and 19HAM048) that intruded the Kelameili accretionary complex from the latest Devonian to latest Carboniferous indicate southward rollback of the subducting Kelameili oceanic lithosphere and resulted in the development of a growing arc. Meanwhile, the youngest gabbroic intrusion (19HAM052) suggests that northward subduction of the Kelameili oceanic lithosphere may have at least lasted to the latest Permian, indicating that the closure of the Kelameili Ocean might have been later than the latest Permian, most likely in the early Triassic. Our new data provide further constraints on the initiation and closure history of the Kelameili Ocean, which shed light on the accretionary evolution of the Altaids. [ABSTRACT FROM AUTHOR]

The Devonian volcanic rocks are widely distributed in the East Junggar (Xinjiang, NW China), preserving important magmatic records for investigating Palaeozoic tectonic evolution. The Beitashan Formation is mainly composed of pyroclastic rocks and sedimentary rocks in the lower section and intermediate–basic volcanic lava and pyroclastic rocks in the upper section. In this paper, we present geochronological, geochemical, and in situ Lu–Hf isotopic data for Beitashan Formation volcanic rocks from the East Junggar. Zircon U–Pb analyses from a basalt sample by laser ablation inductively coupled plasma mass spectrometry yielded a weighted mean age of 387.8 ± 4.5 Ma, indicating that it was generated in the Middle Devonian. The basic–intermediate volcanic rocks are tholeiitic to calc‐alkalic and are characterized by MgO (2.29–5.91 wt.%), low TiO2 (0.75–1.36 wt.%), and relatively high Al2O3 (15.82–16.73 wt.%). Furthermore, they display enrichment in light rare‐earth elements and large‐ion lithophile elements (such as Ba and Sr) and depletion in Nb, Ta, and Ti, along with slightly positive Eu anomalies (δEu = 0.83–1.15) and Ce anomalies (δCe = 1.00–1.11). In addition, in situ zircon Hf isotopic analyses from basalt samples show εHf(t) values ranging from +4.33 to +15.2, indicating a depleted mantle source with minor crustal contamination. They also show relatively low Nb/Zr (0.04–0.06), Th/Yb (0.67–3.83), and Ba/La (6.79–67.53) and high Ce/Th (7.71–18.94), Ba/Rb (21.39–294.28), and Ba/Th (31.42–486.58). The geochemical data suggest these rocks were likely derived from 10% to 30% partial melting of a garnet‐rich with minor spinel‐bearing Iherzolite depleted mantle metasomatized by slab‐derived fluids, with crustal contamination. Combined with the geological setting and previous studies, we suggest that the northern East Junggar was in a northward‐subducted island‐arc setting in the Devonian. [ABSTRACT FROM AUTHOR]

This paper reports on the petrography, geochemistry, and geochronology of late Mesozoic volcanic rocks in the Wenkutu area of the northern Great Xing'an Range, North‐east China, and discusses the formation age, petrogenesis, and tectonic environment of the Manketouebo, Manitu, Baiyingaolao, and Meiletu formations. Results of Zircon U–Pb dating show that the volcanic rocks in the Wenkutu area were formed during the Early Cretaceous (Manketouebo Formation at 145 ± 1 Ma, Manitu Formation at 141.3 ± 1.7 Ma, Baiyingaolao Formation at 128.7 ± 1.1 Ma, and Meiletu Formation at 129 ± 1 Ma). The Manketouebo, Manitu, and Baiyingaolao formations are dominated by intermediate to acid volcanic rocks that belong to the high‐K calc‐alkaline series, with Eu/Eu* values of 0.38–0.84.They are enriched in light rare earth elements (LREE) and depleted in heavy rare earth elements (HREE). The Meiletu Formation is dominated by intermediate to basic volcanic rocks, belongs to the high‐K calc‐alkaline series, has Eu/Eu* values of 0.89–0.97, and is enriched in Ba, K, Th, U, La, Ce, Sr, Nd, and Hf but relatively depleted in Nb, Ta, Zr, P, and Ti, with no obvious fractionation of LREE and HREE. Results indicate that the magma of the Manketouebo, Manitu, and Baiyingaolao formations had a crustal origin, whereas the Meiletu Formation was sourced from the mantle and subsequently contaminated by crustal materials. The late Mesozoic volcanic rocks in the study area were formed during an orogenic stage, and the compressional environment was caused by subduction of the paleo‐Pacific Plate below the Asian continental plate. [ABSTRACT FROM AUTHOR]

The Eastern Yanbian area, Northeast China is tectonically located in the easternmost margin of the Xing'an Mongolian Orogenic Belt, which is a key area for providing important evidence of mineral deposits to constrain the tectonic evolution of the Paleo‐Asian Ocean. Five quartz‐vein‐type scheelite deposits have been identified in the eastern Yanbian area. These deposits are hosted within the late Palaeozoic metamorphic and granitic rocks and form under the identical hydrothermal mineralization. Zircon U–Pb ages and whole‐rock geochemistry of the ore‐hosting biotite granite and Sm–Nd ages of scheelite crystals within quartz veins are presented in this paper. Zircon U–Pb dating of the biotite granite yields a weighted mean age of 251.9 ± 2.2 Ma (mean standard weighted deviation (MSWD) = 4), and Sm–Nd dating of scheelite samples yields an isochron age of 251.7 ± 2.9 Ma (MSWD = 0.87), which constrains the scheelite mineralization in Eastern Yanbian to the late Permian. Our results, integrated with published geochronological data, indicate three periods of Phanerozoic W mineralization in Northeast China, (a) Cambrian, (b) late Permian (this work), and (c) Jurassic. Geochemical data reveal that the biotite granite is a calc‐alkaline I‐type granite, and it exhibits enrichment in large‐ion lithophile and light rare earth elements and depletion in high‐field‐strength and heavy rare earth elements (especially in Nb and Ta), consistent with the characteristics of arc magma. The subduction‐related biotite granite intrusion and quartz‐vein‐type scheelite mineralization together indicate that the Paleo‐Asian Ocean had not closed before the late Permian in the Eastern Yanbian area, and its final closure occurred in the Early‐Middle Triassic. The late Permian subduction of the Paleo‐Asian Ocean induced the partial melting of the lower crust, thus forming the magmatic arc activity and related quartz‐vein‐type scheelite mineralization, which clearly justifies the proposed tectonic–metallogenic model. [ABSTRACT FROM AUTHOR]

The Kaiyuan tectonic mélange makes up the western part of the Kaiyuan–Yanji Accretionary Complex Belt, NE China, and there has been a long‐standing controversy about its age and tectonic setting. In this paper, we present new zircon U–Pb ages and geochemical data for the mafic rocks of the Lujiapuzi Formation in the Kaiyuan tectonic mélange, and these data provide insights into the tectonic setting during the late Paleozoic and the evolutionary history of the Paleo‐Asian Ocean in the eastern segment of the Central Asian Orogenic Belt (CAOB). SHRIMP U–Pb dating of zircons from samples of albite–actinolite schist and amphibolite yielded a crystallization age of 258 ± 5.5 Ma for the protoliths, suggesting that the protoliths formed during the late Permian. The albite–actinolite schists and amphibolites have similar geochemical characteristics, and they represent metamorphosed basaltic volcanic rocks. Major, rare earth and trace element data show that the mafic rocks have a close affinity with mid‐ocean ridge basalt. REE petrogenetic modelling indicates that the primary magma was generated through the partial melting of a mixed garnet‐ and spinel‐bearing mantle source, and assimilated crustal material and underwent crystal fractionation during ascent. The geochemical features and inherited/xenocrystic zircons in the mafic samples indicate that they formed in a tectonic setting similar to the back‐arc basin. These new findings, together with other previously published data, indicate that the Paleo‐Asian Ocean still existed in the eastern segment of the CAOB during the late Permian to Early Triassic. The Kaiyuan tectonic mélange formed during the Middle Triassic, and its formation may represent the timing of final closure of the Paleo‐Asian Ocean. [ABSTRACT FROM AUTHOR]

The Early Precambrian magmatism in the Archean–Palaeoproterozoic basement Yudongzi Complex is critical for understanding the early crustal formation and evolutionary history of the Yangtze Block in the South China Craton. In this paper, combined zircon UPb geochronological, zircon Hf isotopic, and whole‐rock geochemical studies are carried out on the granitoid gneisses from the Yudongzi Complex, north‐western Yangtze Block. The magmatic zircons from the granitoid gneiss yield a UPb upper intercept age of 2,477±18 Ma, interpreted as the crystallization age of the granitoid gneiss. The granitoid gneiss samples are characterized by high Al2O3 contents, moderate to high Sr/Y, (La/Yb)N and Na2O/K2O ratios, no obvious Eu and Sr anomalies, and depleted Nb, Ta, and Ti values that are similar to those of Archean trondhjemite–tonalite–granodiorite (TTG) suites, indicating that the investigated rocks belonging to TTG‐series rocks. They display pronounced enriched‐LREE patterns with high La/Yb values and relatively high Zr/Sm and Eu/Eu* but low Nb/Ta and Dy/Yb ratios, implying that these rocks were formed by partial melting within amphibolite‐facies conditions with mainly residual amphibole, garnet, and accessory rutile in the magma source. These rocks also display apparently low MgO, Mg#, Ni, and Cr contents, suggesting derivation from partial melting of thickened ancient lower crust. Zircon εHf(t) values from the granitoid gneiss sample vary from −10.1 to −6.9 with TDM2 of ca. 3.59–3.40 Ga, what demonstrates their crustal source nature as well. Thus, taking all these factors together, we propose that the ca. 2.48 Ga granitoid gneisses in the Yudongzi Complex might have been produced by partial melting of ancient crust material under amphibolite‐facies conditions, with primarily residual assemblages of amphibole, garnet, and attached rutile. Taking together our new data and such from previous studies, the Yangtze Block has been probably involved into a significant reworking of ancient crust event during the Early Palaeoproterozoic time. [ABSTRACT FROM AUTHOR]

The Banjing tungsten deposit, which has been discovered recently, is located in the northernmost part of the Dabu pluton, southern Jiangxi Province, China. In this study, zircon LA‐ICP‐MS U–Pb dating of the fine‐grained porphyritic biotite granite indicate that it was formed in the early Yanshanian (159.4 ± 2.5 Ma–161.6 ± 0.8 Ma). Whole‐rock geochemical studies have shown the fine‐grained porphyritic biotite granite has SiO2 of 75.82%–76.84%, Al2O3 12.50%–12.87%, MgO 0.07%–0.20%, and CaO 0.64%–1.09%, with A/CNK of 1.017–1.038. It has a total rare earth elements content of 93.9–118.9 ppm with strong negative Eu anomalies (δEu = 0.021–0.081). The biotite granite is enriched in Rb, Th, U, Nd and depleted in Ba, Sr, Nb, Ti. These data suggest the Dabu pluton belongs to S‐type granite. This pluton has ISr of 0.71212–0.72929 and εNd(t) from −9.60 to −10.62 with Nd model ages concentrated in 1732–1838 Ma. These isotopic data in combination with zircon Hf isotopes suggest the biotite granite originated from partial melting of the Middle Proterozoic metamorphic supracrustal rocks in South China, with a minor contribution from juvenile crust. Meanwhile, this study has obtained Re–Os isochron ages of the intrusion‐related and quartz vein‐type molybdenum mineralization are 156.3 ± 2.7 Ma and 157.0 ± 1.1 Ma in the Banjing tungsten deposit, respectively. Sericite from the greisen‐type tungsten‐molybdenum ore has an 40Ar–39Ar plateau age of 156.4 ± 1.0 Ma, interpreted as the formation age of this deposit. Collectively, the Banjing tungsten deposit is considered as a product of the early Yanshanian large‐scale peak mineralization in South China, which was formed in an extensional intracontinental environment caused by the subduction of the Palaeo‐Pacific Plate. [ABSTRACT FROM AUTHOR]

The Bayan Obo–Duolun–Chifeng–Kaiyuan (BDCK) Fault is considered the boundary between the North China Craton (NCC) and Central Asian Orogenic Belt (CAOB). However, the site of this boundary from Duolun to Chifeng and Kaiyuan remains highly controversial. Here, we present an integrated study of petrology, whole‐rock geochemistry, and zircon U–Pb and Sr–Nd–Hf isotope compositions for tonalites and amphibolites in the Bainaimiao arc belt (BAB) to better constrain the northern NCC margin. The tonalites are similar to NCC tonalite–trondhjemite–granodiorites (TTGs), characterized by relatively high Na2O/K2O and Sr/Y ratios and fractionated rare earth element (REE) patterns, with high light REE (LREE) but low heavy REE (HREE) concentrations. Laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) zircon U–Pb dating yields formation ages of 2599–2674 Ma, with a weighted average of 2649.6 ± 3.7 Ma. The εHf(t) values (3.5–7.5), two‐stage model ages (2673–2793 Ma), whole‐rock positive εNd(t) values (1.3–1.9), and two‐stage model ages (2841–2880 Ma) suggest that the Neoarchean tonalites likely originated from remelting of thickened Meso‐Neoarchean mafic crust. LA–ICP–MS U–Pb isotope data reveal that the amphibolites formed at ~2610 Ma. They have high‐Fe tholeiitic compositions and are close to normal mid‐ocean ridge basalt (N‐MORB)‐like rocks, indicating that they were generated from partial melting of the depleted mantle. The existence of Neoarchean basement rocks, combined with seismic and isotope data, suggests that the Jiefangyingzi area is part of the Trans‐North China Orogen (TNCO) in the NCC rather than part of the CAOB and that the northern boundary of the NCC in Chifeng is located north to the Jiefangyingzi area. [ABSTRACT FROM AUTHOR]

The Pushi area of South‐west China features a large area of purple soil that formed by the weathering of Cretaceous terrigenous clastic rocks. In this study, four vertical profiles of the purple soil (P1, P2, P3, and P4) derived from different pedogenic parent rocks were investigated. Specifically, the chemical weathering intensity and element migration, enrichment, and differentiation characteristics were analysed and the influencing factors of chemical weathering were explored. According to the discrimination map of major and trace elements and content characteristics of rare earth elements, the soil profiles are controlled by complex chemical weathering processes. Various geochemical parameters and indicators exhibited good correlation, and the chemical weathering intensity of the profiles followed the order P1 (mudstone) > P3 (silty mudstone) > P4 (argillaceous siltstone) > P2 (sandstone). The overall chemical weathering intensity of argillaceous rocks was slightly higher than that of sandstone, and the four profiles generally reflected medium to strong chemical weathering. The migration, enrichment, and differentiation characteristics of geochemical elements were found to be mainly affected by different chemical weathering intensities and stages, followed by leaching deposition. The chemical weathering characteristics varied for the four profiles with different pedogenic parent rocks, which could be mainly attributed to internal factors such as the lithology of the pedogenic parent rock and external topographic factors such as altitude. [ABSTRACT FROM AUTHOR]

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

Ophiolite provides key information on subduction–accretion processes along convergent plate margins. The Wunuer ophiolite in the Great Xing'an Range of NE China was considered to be an accreted fragment of the Palaeo‐Oceanic Plate. Based on field investigation, we evaluate the petrotectonic assemblages, geochemical features, and formation age of the ophiolite, which comprises gabbro, diabase, metabasalt, and radiolarian bedded chert with serpentinized amphibole‐pyroxene peridotites. Zircon U–Pb dating shows ages of 346 ± 6 Ma and 341 ± 6 Ma suggesting the timing of formation of the ophiolite as Early Carboniferous. The ophiolitic mafic rocks in Wunuer can be divided into two types based on their geochemical features. Type I is characterized by high Ti and low Al, with weakly negative Nb‐Ta and positive Pb anomalies and low light rare earth elements (LREE). These rocks display MORB‐like features, and correspond to partial melting product of depleted mantle. Type II has low Ti, high Al, notably negative Nb‐Ta and positive Pb anomalies, and is obviously enriched in LREE, large‐ion lithophile elements (LILE), and depleted in high‐field‐strength elements (HFSE), characterized by IAB‐like features, and may be formed by partial melting of more depleted mantle, which was strongly metasomatized by subduction fluids, resulted in high LILE/HFSE. The two types of ophiolites belong to SSZ type, obviously influenced by subduction, and their tectonic setting is inferred to be within a spreading ridge in a back‐arc basin. Combined with regional geological background, the Wunuer ophiolite probably represents a shrinking ocean basin and may be the late product of the long‐term and mature back‐arc basin, related to the terminal stage of ridge spreading within the back‐arc basin. [ABSTRACT FROM AUTHOR]

The Kamust sandstone‐hosted uranium deposit was recently discovered within the Middle Jurassic Toutunhe Formation of the eastern Junggar Basin. In this study, polarizing microscope and scanning electron microscope observation, electron microprobe analysis, and laser ablation inductively coupled plasma mass spectrometry measurement were carried out to define the petrology, mineralogy, and geochemistry of these sandstone‐hosted uranium ores. In addition, sulphur isotope signatures for the associated ore‐stage pyrites and the ore‐forming age were determined. The results show that the mineralized sandstones, which exhibit excellent reducibility with abundant organic matter and pyrites, are characterized by the secondary accumulation of uranium and are slightly enriched in rare earth elements (REE) and light REE (LREE). The uranium deposits are mainly composed of a large amount of uraninite, followed by some coffinites and uranium‐bearing titanium minerals and very few sorptive uranium‐bearing materials. Uranium minerals primarily exist within the interior and edge of clastic particles in colloidal, dispersed, and vein form, and some are closely interweaved with the colloidal and framboidal pyrites and carbonaceous detritus. Both uraninite and coffinite are strongly enriched in REE and LREE, as determined by in situ trace element measurements. Moreover, the δ34S values of the associated ore‐stage pyrites mostly range from −41.66 to −19.33‰, indicating biological origin, and light 32S demonstrates the relatively low‐temperature and open‐system mineralization processes related to the microbial anaerobic action on the organic matter. One of the δ34S values (6.88‰) is possibly caused by Rayleigh isotope fractionation due to the utilization of residual heavy 34S in the relatively later closed‐like mineralization system. The ore‐reforming ages of 27 ± 3.2 Ma, 22.4 ± 3.9 Ma, and 21.3 ± 2.3 Ma were obtained by U–Pb isotopic dating combined with U–Ra balance correction, corresponding to the rapid uplift event caused by the remote effect of the collision between the Indian and Eurasian plates at the end of the Palaeogene. In conjunction with the tectonic–sedimentary evolution of the study region, a four‐stage ore‐forming model for the Middle Jurassic Toutunhe Formation is preliminarily constructed: ① Development of ore‐bearing strata, ② initiation of the mineralization stage from the Late Jurassic to the Early Cretaceous, ③ deep burial by lacustrine and flood mudstone from the Cretaceous to the Palaeogene, and ④ the superimposed ore‐forming stage during the Neogene. These research results provide significant benefits for further uranium prospecting and in situ leach process mining in this basin. [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 depositional environment and sediment provenance of the third member of Palaeogene Shahejie Formation (Es3) in the Nanpu Sag of the Bohai Bay Basin, eastern China, are reconstructed by analysing trace element and rare earth element (REE), and the formation mechanism of organic‐matter‐rich shales of the same member is also evaluated. These results show that the terrigenous detrital supply in the Nanpu Sag was relatively sufficient during the Es3 interval, and the total REE contents range from 148.23 to 319.28 ppm, close to or higher than that of the upper crust. The Sr concentrations are 214.22–525.54 ppm and the Sr/Ba ratios are 0.31–0.74, which represent the coexistence of fresh, brackish, and saline waters during the Es3 interval. The V/(V + Ni) ratios of 0.71–0.82, Th/U ratios of 0.82–4.05, and positive δCe anomaly confirm that the water column was suboxic condition, with moderate stratification during the Es3 interval. Comparison of REE behaviours suggests that the Es3 sediments were primarily derived from Yanshanian granites at the Yanshanian fold belt at the active continental margin. The development of organic‐matter‐rich shales in the Es3 member in the Nanpu Sag was closely related to major palaeoenvironmental and palaeogeographical variations in that time, which can be summarized: (a) suitable palaeosalinity as well as sufficient nutrients in water column contributed to the boom of various planktonic algae, improving the production efficiency of aquatic organic matter; (b) suboxic water column slowed down the degradation of oxygen‐sensitive materials during the burial process, enhancing the preservation efficiency of aquatic organic matter. [ABSTRACT FROM AUTHOR]

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

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

The Ayishan Group in the Lajishan area is sandwiched between the South Qilian Belt and the Qilian Block, which is transitionally interpreted to represent the products of the post‐collision setting or the continental marginal arc during the Early Ordovician or Silurian and is associated with the evolution of the Proto‐Tethyan Ocean. While the detailed information about the age, geochemistry, and tectonic setting of the Ayishan Group is lacking, our geological mapping and analyses demonstrates that the Ayishan Group consists of andesites, rhyolites, ignimbrites, sandstones, and conglomerates, which unconformably overlies the Cambrian–Ordovician arc‐ophiolite complex. Zircon U–Pb dating of the rhyolites demonstrated that the Ayishan Group formed between 447 and 442 Ma and is Late Ordovician. Geochemical analyses demonstrated that rhyolites have high and variable SiO2 contents of 69.6–76.5 wt% and an aluminium saturation index (A/CNK) of 0.85–1.45, belonging to calc‐alkaline to high K calc‐alkaline series. They are subdivided into two subtypes of high‐Sr/Y rhyolites (HSRs) and normal rhyolites (NRs) based on the geochemical characteristics. The HSRs show lower total rare earth elements (34.77–62.78 ppm), lower Yb (0.19–0.21 ppm) and Y (1.77–1.99 ppm) contents, and relatively higher Sr contents (159–193 ppm), compared with NRs, and with positive Eu anomalies. Both subtypes exhibit extremely high whole‐rock δ18O values of 12.63–13.21‰, but various initial 87Sr/86Sr ratios and εNd(t) values, indicating a dominant origin of terrigenous sediments and the HSRs exhibit a more terrestrial composition than the NRs. Various magma sources further caused the assorted residual phase leading to the different geochemistry between the HSRs and the NRs. Combined with the previous data, these results imply that the rhyolites of the Ayishan Group were produced in the process of the amalgamation of the Qilian Block with the Qaidam Block during the Late Ordovician, which further indicated that the Proto‐Tethyan Ocean closed 450 Ma ago. [ABSTRACT FROM AUTHOR]

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

New LA–ICP–MS zircon U–Pb geochronology, whole‐rock major and trace element geochemistry data, and petrographic observations are presented for three granitic dykes in the Changlingzi area of NE China. These data provide precise age and petrogenesis information with respect to the late Palaeozoic–Mesozoic intrusions in the area, which further constrain the geodynamic evolution of the southern Great Xing'an Range. Our zircon U–Pb data denote that the felsic dykes were emplaced during the Late Permian (~254 Ma) and Late Jurassic (143–142 Ma). Geochemically, the Late Permian monzonite porphyries are characterized by high Al2O3 (16.52–16.92 wt%) and Sr (490–579 ppm) contents and low Yb (0.52–0.57 ppm), Y (5.7–6.3 ppm), and heavy rare earth element (HREE) contents, which indicate an adakitic affinity. The Late Jurassic felsic dykes are characterized by high FeOt/MgO (8.2–11.9) and Ga/Al (3.3–3.8) ratios, high zircon saturation temperatures (888–929°C), and remarkable negative Eu (Eu/Eu* = 0.25–0.42) anomalies, indicating they are akin to A‐type granites. The Late Permian adakitic magma resulted from the partial melting of thickened lower crust, and was formed during collisional orogenesis related to subduction of Palaeo‐Asian Ocean crust. The Late Jurassic A‐type magmas were probably generated by the partial melting of amphibolite‐facies lower crustal materials. The melting occurred in response to the upwelling of asthenospheric material caused by collapse of thickened crust, due to gravitational instability during closure of the Mongol–Okhotsk Ocean. Subsequently, the latest stage of magmatic activity in this area and elsewhere in NE China was controlled mainly by subduction of Palaeo‐Pacific Ocean crust. [ABSTRACT FROM AUTHOR]

Potassic magmatic rocks provide significant insights in understanding of mantle composition, evolution, and interaction with crust. Potassic magmatism along the Jinshajiang–Ailaoshan Paleo‐Tethyan suture has drawn much attention. Whereas igneous intrusion in the Simao terrane, west to Jinshajiang–Ailaoshan potassic magmatic belt has rarely been investigated. Hence, we present zircon U–Pb ages and Lu–Hf isotope and whole‐rock geochemistry for the Lianhuashan pluton. Zircon U–Pb dating from monzonite and quartz monzonite porphyry yield ages of 33.6 ± 0.2 and 33.5 ± 0.3 Ma, respectively. Monzonites are characterized by high K2O (4.93–5.16%) and K2O/Na2O (1.46–1.71), high Y (22.90–23.80 ppm), and Yb (1.87–2.21 ppm), relatively enrichment of light rare earth element (LREE). Zircons from monzonites show εHf(t) values ranging from −1.1 to +0.6 and crustal model ages (TDMC) between 1.04 and 1.15 Ga. These geochemical features suggest that parent magmas of the rocks originated from a metasomatized lithospheric mantle. Quartz monzonite porphyries are characterized by high Sr (836.00–1,529.00 ppm), Sr/Y (70.85–99.93) and La/Yb (32.31–49.83), low Y (11.80–15.60 ppm), and Yb (0.95–1.30 ppm), enrichment in LREE and depletion in heavy rare earth elements (HREE). Quartz monzonite porphyries have higher Mg#, MgO, Ni, and Cr contents than the lower crust‐derived adakite‐like rocks. It is suggested that they were derived by variable degree of mixing between lower‐crustal melts and mafic magmas. Based on petrology and geochemistry features, the following evolution process are concluded. During the Neoproterozoic, metasomatic‐enriched mantle magma resulted from the bisubduction of oceanic plate; meanwhile, the crust thickened, and juvenile lower crust formed. During late Eocene, hot asthenosphere upwelled and K‐rich mafic magmas resulted from the decompression of delamination, followed by magmatism emplacing, crystallizing, and the forming of the Lianhuashan pluton. [ABSTRACT FROM AUTHOR]

There are widely developed carbonate formations in the lower Palaeozoic, Ordos Basin, China. However, previous studies have paid more attention to the Ordovician formations and largely ignored the Cambrian formations, which also have a larger sediment thickness. Recently, with the continuous discovery of dolomite gas fields in the Ordovician Majiagou formation, more investigations have begun to focus on the deeper dolomite in the Cambrian Sanshanzi Formation (Є3s). This study looks into the origin of the dolomite through a combination of petrology, major–trace elements, and stable isotope and rare earth element (REE) analysis of samples from five outcrops. The results show that the main dolomite types in the study area are dolarenite (Type 1), micrite‐fine crystalline dolomite (Type 2), and medium crystalline dolomite (Type 3). The δ13C values and δ18O values of each dolomite formation are close to those of seawater‐derived dolomite and have slightly higher Na2+ concentrations, suggesting that dolomite formation is closely related to the denser seawater. The REE compositions are characterized by enrichment for light REEs and depletion for heavy REEs, exhibiting an apparent negative Eu anomaly and a slight negative Ce anomaly, indicating that the dolomites of the Є3s may form in a weak‐reduction to the weak‐oxidation environment. The total REE (ΣREE) concentrations of Type 3 dolomites are lower than other types, suggesting that those dolomites may mean that the REEs are lost during the diagenesis. Type 1 dolomite has lower MgO and CaO values and a higher Mn2+ concentration than the other two types of dolomites, indicating that Type 1 dolomite suffered the action of atmospheric fresh water. Type 2 dolomite has lower Mg and Ca values than Type 3 dolomite, suggesting that Type 3 dolomite has a higher dolomitization degree. Further study into the combined palaeogeographical background confirms the dolomitization model of the study area: Type 1 and Type 2 dolomites may have been formed by penecontemporaneous or seepage–reflux dolomitization during early‐stage diagenesis. Subsequently, stratigraphic uplift lead to the Type 1 dolomite suffering the action of atmospheric fresh water, but there was no dorag dolomitization. Type 2 dolomite became the main dolomite type by seepage–reflux dolomitization in this period. Later, Type 2 dolomite was converted into Type 3 dolomite during progressive burial. [ABSTRACT FROM AUTHOR]

The Heyu fluorite ore district is newly discovered in the East Qinling metallogenic belt (EQMB), central China. In this district, the large Madiu fluorite deposit contains five Mesozoic granite‐hosted orebodies. The deposit may have formed at shallow depth and occurred as continuous veins controlled by a series of N‐S‐ or NE‐trending, steeply dipping faults. The fluorite mineralization can be divided into two stages (I and II). Fluid inclusions in stage I fluorite homogenized at 132.2°C to 342.5°C (peak at 170°C–210°C) with salinities of 0.18 to 4.43 wt% NaCl equiv, whilst those in stage II fluorite homogenized at 122.2°C to 305.7°C (peak at 130°C–170°C) and salinities of 0.18 to 3.71 wt% NaCl equiv. Raman spectroscopic analysis of the fluid inclusions reveals that they comprise predominantly H2O. The rare earth element (REE) characteristics indicate that the deposit is of hydrothermal origin. The δ18OH2O (−8.8‰ to −0.5‰) and δDH2O (−69.0‰ to −61.9‰) values show a subhorizontal trend, suggesting that the oxygen isotopic compositions were modified by fluid–rock interactions. Fluid inclusion and stable isotopic data suggest that the ore‐forming fluids belong to a meteoric water‐sourced, medium–low temperature, and low salinity NaCl–H2O system. Initial fluorite 87Sr/86Sr ratios (0.708879–0.709682) resemble those of the Heyu batholith. The water–rock reaction, which leached Ca from the host rock and increased the fluid pH, was likely causative to the ore precipitation. Geochemical and mineralization features suggest that the Madiu fluorite deposit is best classified as a fault‐controlled hydrothermal vein‐type fluorite deposit. The Sm–Nd isochron age of 118.9 ± 7.8 Ma and its regional age correlation suggest that the fluorite mineralization occurred under regional extension or lithospheric thinning setting and that the fluorite mineralization was an important component of the Early Cretaceous mineralization event in the EQMB. [ABSTRACT FROM AUTHOR]

Xierqu is a skarn Fe–Cu deposit associated with porphyritic diorite, in the Kalatag district of eastern Tianshan, China. The diorite yields a sensitive high‐resolution ion microprobe U–Pb zircon date of 391 ± 3 Ma interpreted as its age of emplacement. Major element geochemistry shows that the diorite is a calc‐alkaline assaying 16.7–19 wt.% of Al2O3, with Mg# values of 56.8–67.1, and Al2O3/(CaO + Na2O + K2O) (A/CNK) values of 0.55–0.94. Trace element characteristics of the diorite show that it is enriched in Ba, K, and Sr and depleted in Nb, Ta, and Ti, with a positive Eu (1.18–1.44) anomaly and high Sr/Y and La/Yb ratios. Sr–Nd isotopic analyses yielded positive εNd(t) values ranging from 7.1 to 9.8 with low initial 87Sr/86Sr ratios of 0.703806 to 0.703856. These geochemical and isotopic characteristics indicate that the diorite is adakite‐like emplaced in an island‐arc setting and resulted from partial melting of subducted oceanic crust in a mantle wedge during the Devonian. [ABSTRACT FROM AUTHOR]

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

The recently discovered Bulage Pb–Zn deposit is located in the central part of the Erlianhot–Dongwuqi Metallogenic Belt (eastern Central Asian Orogenic Belt) in Inner Mongolia, China. The ore bodies of the deposit are hosted in alkali feldspar granite and in dacitic crystal tuff within Unit 2 of the Carboniferous Baoligaomiao Formation. The Bulage deposit is a low to moderate temperature hydrothermal vein‐type deposit and is controlled by fractures. The hydrothermal mineralization can be divided into three stages: early (quartz + specularite ± magnetite), middle (quartz + sphalerite + galena ± chalcopyrite ± pyrite), and late (calcite ± quartz + sphalerite + galena). The deposit contains liquid‐rich two‐phase (VL‐type) and pure‐liquid (L‐type) fluid inclusions. The initial ore‐forming fluids are attributed to the low to moderate temperature and low salinity of a NaCl–H2O system. Hydrogen and oxygen isotopic compositions of quartz and calcite indicate that the ore‐forming fluids were dominated by meteoric water with minor contributions of magmatic water. The quartz diorite, monzonite porphyry, and alkali feldspar granite in the deposit yield LA–ICP–MS zircon U–Pb ages of 305–300 Ma. These high‐K calc‐alkaline I‐type granitoids are enriched in large‐ion lithophile elements (LILEs; e.g., Rb, Cs, and K) and light rare earth elements (LREEs) and are depleted in high‐field‐strength elements (HFSEs; e.g., Nb, Ta, and Ti) and heavy rare earth elements (HREEs). The primary magma of these granitoids was derived from the partial melting of lower crust. The parental magma of the quartz diorite may have provided part of the ore‐forming material and acted as a heat source for mineralization. Therefore, we infer that the Bulage Pb–Zn deposit was formed as a result of the southward subduction of the Paleo–Asian Ocean beneath the North China Craton during the Late Carboniferous. [ABSTRACT FROM AUTHOR]

The Derbur lead–zinc deposit is located in the Derbugan metallogenic belt in the north‐western portion of the Mesozoic Hailaer‐Genhe volcanic basin in the northern Great Xing'an Range. This deposit occurs in the Middle Jurassic intermediate–mafic volcanic rocks of the Tamulangou Formation and is spatially and temporally associated with acidic pyroclastic rocks. The host rocks are bedded trachyandesite and rhyolitic lithic‐crystal tuffs, and basaltic‐andesitic aplite veins are associated with the ore body. Because the deposit is a hypabyssal low‐temperature hydrothermal Pb–Zn deposit associated with volcanism, to determine the precise petrogenesis of the volcanic rocks, this study analysed the zircon U–Pb ages of the trachyandesite and rhyolitic lithic‐crystal tuffs, the Sr–Nd–Pb isotopic geochemistry of the trachyandesite and basaltic‐andesitic aplite, and the whole‐rock geochemistry of all three rock types. The results showed that the trachyandesite and basaltic‐andesitic aplite belong to the shoshonitic series and have similar whole‐rock and isotopic geochemical characteristics, including enrichments in large‐ion lithophile elements and light rare earth elements and depletions in high‐field‐strength elements. They also have low initial 87Sr/86Sr values of 0.705007–0.705240 and εNd(t) values of +0.6 to +1.7, with model ages (TDM) of 699–883 Ma. The ratios of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb vary from 18.438 to 18.476, 15.570 to 15.577, and 38.254 to 38.320, respectively, with μ values of 9.40–9.41. In contrast, the rhyolitic lithic‐crystal tuffs are characterized by high SiO2 contents (73.44–79.48 wt.%); low Al2O3 (11.36–12.53 wt.%), TiO2 (0.14–0.18 wt.%), and K2O + Na2O (3.48–3.89 wt.%, Na2O ≤ K2O) contents; and low Mg# values (0.17–0.41), indicating that they belong to the calc–alkaline series. Additionally, they have relatively low REE contents and strong Sr depletions. LA‐ICP‐MS zircon U–Pb dating of the trachyandesite and rhyolitic lithic‐crystal tuffs indicates that their ages are 167.0 ± 2.0 Ma and 164.8 ± 1.6 Ma, respectively. We conclude that the trachyandesite and the basaltic‐andesitic aplite were derived from the partial melting of lower crustal material assimilated by a depleted lithospheric mantle that was subsequently metasomatized by subducted slab‐derived fluids. The rhyolitic lithic‐crystal tuffs likely originated from the partial melting of accreted lower crust. In summary, because the acidic volcanism was accompanied by increasingly felsic volcanism, bimodal volcanic rocks were produced. Among volcanogenic deposits, bimodal volcanic rocks are the most favourable ore‐hosting rocks, and ore‐forming materials were contributed by the magmatic system. These processes created conditions conducive to the formation of large‐scale Ag, Pb, and Zn mineralization in this area. [ABSTRACT FROM AUTHOR]

Detailed petrological, whole‐rock geochemical, and zircon Hf isotopic researches were conducted on the Late Carboniferous–Triassic sedimentary rocks in the Bogda region to evaluate the effects of weathering, sorting, and alteration, as well as to understand their provenance and tectonic setting. These rocks show variable major element compositions, but most are generally similar to post‐Archean Australian shales. The relatively narrow range of TiO2–Zr variation and good correlation between Th/Sc and Zr/Sc signify no obvious sorting and recycling of the sedimentary rocks. The relatively high index of compositional variability (0.8–3.1) and low chemical index of alteration values (44.4–76.4) of the sedimentary rocks indicate that they are immature and probably undergo weak to moderate chemical weathering. In the chondrite‐normalized diagrams, almost all the samples are distinguished by moderately enriched light rare earth element and flat heavy rare earth element patterns with negative Eu anomalies (Eu/Eu* = 0.5–0.8). In conjunction with their Th/Sc, Zr/Sc, La/Th, Zr/Al2O3, TiO2/Zr, Co/Th, and La/Sc ratios, we infer that the major sources of these sedimentary rocks were the intermediate–acidic igneous rocks from the North Tianshan and Yili–Central Tianshan. Combining the orientation of the Bogda region in the Palaeozoic that was roughly perpendicular to the Tianshan and/or East Junggar orogens with the sedimentologic, petrologic, and tectonic researches, we suggest that the Bogda region was a rift basin that occurs at high angles to the orogenic belt. On the other hand, the zircons from these sediments have minor Precambrian grains (<0.2%), positive εHf(t) values (mostly +7.1–+15.0) and young 2‐stage Hf model ages (major peak <1,000 Ma), suggesting that a juvenile continental crust exists as the basement of the Junggar Basin. The geochemical data reveal weakly to moderately weathering of the source, compositionally immature and poorly sorted.The rift model appears as the most likely geodynamic interpretation of the Bogda region.The juvenile continental crust exists as the basement of the Junggar Basin. [ABSTRACT FROM AUTHOR]

In order to evaluate rare earth elements (REEs) as a potential proxy for solid bitumen classification, we employed traditional correlation approaches, such as carbon isotopes and V/(V + Ni) ratios, to infer the source rocks of Sinian-Cambrian reservoir solid bitumens in the Sichuan Basin and analyse solid bitumens for their REE compositions by inductively coupled plasma-mass spectrometry. Our data suggested that Sinian-Cambrian reservoir solid bitumens were primarily sourced from the lower Cambrian shales deposited under anoxic-euxinic conditions. REE and their associated parameters seemed to be more sensitive to classify solid bitumens than traditional correlation approaches. REE concentrations played a dominant role and fractionation degree between light and heavy REE and played a secondary role in solid bitumen classification. REE concentration and pattern in solid bitumens might be controlled by two processes, including inheritance from source rocks and water-rock interaction. The major factor controlling REE concentrations in solid bitumens was the type of organic matter of source rocks. Authigenic minerals in solid bitumens formed by water-rock interaction appeared to have little influence on REE compositions of solid bitumens because of their trace contents. Overall, REE could be used as a novel complementary approach to solid bitumen classification in complicated petroleum systems. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]