Search Results (105)

The most important bauxite deposits in Türkiye are located in the Seydişehir (Konya) and Akseki (Antalya) regions, situated along the western Taurus Mountain, with a total reserve of approximately 44 million tons. Some of the bauxite deposits have been exploited for alumina since the 1970s. In this study, bauxite samples, collected from six different deposits were examined to determine their mineralogical and chemical composition, as well as their REE content, with the aim of identifying which bauxite types are enriched in REEs and assessing their economic potential. The samples included massive, oolitic, and brecciated bauxite types, which were analyzed using optical microscopy, X-ray diffraction (XRD), X-ray fluorescence (XRF) and inductive coupled plasma-mass spectrometry (ICP-MS), field emission scanning electron microscopy (FESEM-EDX), and electron probe micro-analysis (EPMA). Massive bauxites were found to be more homogeneous in both mineralogical and chemical composition, predominantly composed of diaspore, boehmite, and rare gibbsite. Hematite is the most abundant iron oxide mineral in all bauxites, while goethite, rutile, and anatase occur in smaller quantities. Quartz, feldspar, kaolinite, dolomite, and pyrite were specifically determined in brecciated bauxites. Average oxide contents were determined as 52.94% Al₂O₃, 18.21% Fe₂O₃, 7.04% TiO₂, and 2.69% SiO₂. Na₂O, K₂O, and MgO values are typically below 0.5%, while CaO averages 3.54%. The total REE content of the bauxites ranged from 161 to 4072 ppm, with an average of 723 ppm. Oolitic-massive bauxites exhibit the highest REE enrichment. Cerium (Ce) was the most abundant REE, ranging from 87 to 453 ppm (avg. 218 ppm), followed by lanthanum (La), which reached up to 2561 ppm in some of the massive bauxite samples. LREEs such as La, Ce, Pr, and Nd were notably enriched compared to HREEs. The lack of a positive correlation between REEs and major element oxides, as well as with their occurrences in distinct association with Al- and Fe-oxides-hydroxides based on FESEM-EDS and EPMA analyses, suggests that the REEs are present as discrete mineral phases. Furthermore, these findings indicate that the REEs are not incorporated into the crystal structures of other minerals through isomorphic substitution or adsorption. Full article

Late Paleozoic to Early Mesozoic granitoids in the East Kunlun Orogenic Belt (EKOB) provide critical insights into the complex and debated relationship between Paleo–Tethyan magmatism and tectonics. This study presents integrated bulk-rock geochemical and zircon isotopic data for the Xingshugou monzogranite (MG) to address these controversies. LA-ICP-MS zircon U-Pb dating constrains the emplacement age of the MG to 247.1 ± 1.5 Ma. The MG exhibits a peraluminous and low Na₂O A₂-type granite affinity, characterized by high K₂O (4.69–6.80 wt.%) and Zr + Nb + Ce + Y (>350 ppm) concentrations, coupled with high Y/Nb (>1.2) and A/CNK ratios (1.54–2.46). It also displays low FeO^T, MnO, TiO₂, P₂O₅, and Mg^# values (26–49), alongside pronounced negative Eu anomalies (Eu/Eu* = 0.37–0.49) and moderately fractionated rare earth element (REE) patterns ((La/Yb)_N = 3.30–5.11). The MG exhibits enrichment in light rare earth elements (LREEs) and large ion lithophile elements (LILEs; such as Sr and Ba), and depletion in high field strength elements (HFSEs; such as Nb, Ta, and Ti), collectively indicating an arc magmatic affinity. Zircon saturation temperatures (T_Zr = 868–934 °C) and geochemical discriminators suggest that the MG was generated under high-temperature, low-pressure, relatively dry conditions. Combined with positive zircon ε_Hf(t) (1.8 to 4.7) values, it is suggested that the MG was derived from partial melting of juvenile crust. Synthesizing regional data, this study suggests that the Xingshugou MG was formed in an extensional tectonic setting triggered by slab rollback of the Paleo-Tethys Oceanic slab. Full article

The attributes of Late Paleozoic magmatic events are of paramount significance in elucidating the tectonic evolution of the Ulanhot region, which is located in the middle of the Hegenshan–Heihe tectonic belt (HHTB). This study undertook a comprehensive investigation of the petrography, LA–ICP–MS zircon U–Pb dating, whole rock geochemistry, and zircon Hf isotopes of the Early Carboniferous volcanic rocks. The volcanic rocks are predominantly composed of andesite, schist (which protolith is rhyolitic tuff), and rhyolitic tuff. The results of zircon U–Pb dating reveal that the formation ages of volcanic rocks are Early Carboniferous (343–347.4 Ma). Geochemical characteristics indicate that the andesites possess a comparatively elevated concentration of Al₂O₃, alongside diminished levels of MgO and TiO₂, belonging to the high-K calc-alkaline series. The zircon εHf(t) of the andesites range from −13 to 9.4, while the two-stage Hf model ages span from 697 to 1937 Ma. The felsic volcanic rocks have high contents of SiO₂ and Na₂O + K₂O, low contents of MgO and TiO₂, and belong to high-K to normal calc-alkaline series. The zircon εHf(t) values of the felsic volcanic rocks range from −12.8 to 10, while the two-stage Hf model ages span from 693 to 2158 Ma. The Early Carboniferous volcanic rocks exhibit a notable enrichment in large ion lithophile elements (LILEs, such as Rb, K, Ba) and light rare earth elements (LREEs), depletion in high-field-strength elements (HFSEs, including Nb, Ta, Ti, Hf), as well as heavy rare earth elements (HREEs). The distribution patterns of the rare earth elements (REEs) demonstrate a conspicuous right-leaning tendency, accompanied by weak negative Eu anomalies. These characteristics indicate that the andesites represent products of multistage mixing and interaction between crustal and mantle materials in a subduction zone setting. The felsic volcanic rocks originated from the partial melting of crustal materials. Early Carboniferous igneous rocks formed in a volcanic arc setting are characteristic of an active continental margin. The identification of Early Carboniferous arc volcanic rocks in the Central Great Xing’an Range suggests that this region was under the subduction background of the oceanic plate subduction before the collision and amalgamation of the Erguna–Xing’an Block and the Songnen Block in the Early Carboniferous. Full article

The Dehbid region, located in the southern part of the Sanandaj–Sirjan Zone (SSZ), is a significant iron oxide mining district with over 20 iron oxide deposits (IODs) and reserves of up to 50 million tons of iron oxide ores. The region features a NW–SE oriented ductile shear zone, parallel to the Zagros thrust zone, experienced significant deformation. Detailed structural studies indicate that the iron mineralization is primarily stratiform to stratabound and hosted in late Triassic to early Jurassic silicified dolomites and schists. These ore deposits consist of lenticular iron oxide orebodies and exhibit various structures and textures, including banded, laminated, folded, disseminated, and massive forms of magnetite and hematite. The Fe₂O₃ content in the mineralized layers varies from 30 to 91 wt%, whereas MnO has an average of 3.9 wt%. The trace elements are generally low, except for elevated concentrations of Cu (up to 4350 ppm) and Zn (up to 3270 ppm). Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) analysis of magnetite reveals high concentrations of Mg, Al, Si, Mn, Ti, Cu, and Zn, with significant depletion of elements such as Ga, Ge, As, and Nb. This study refutes the hypothesis of vein-like or hydrothermal genesis, providing evidence for a sedimentary origin based on the trace element geochemistry of magnetite and LA-ICP-MS geochemical data. The Dehbid banded iron ores (BIOs) are thought to have formed under geodynamic conditions similar to those of BIOs in back-arc tectonic settings. The combination of anoxic conditions, submarine hydrothermal iron fluxes, and redox fluctuations is essential for the formation of these deposits, suggesting that similar iron–manganese deposits can form during the Phanerozoic under specific geodynamic and oceanographic conditions, particularly in tectonically active back-arc environments. Full article

The Youjiang Basin is situated at the junction between the Tethyan and Pacific tectonic domains, and its Permian–Triassic volcanic rocks provide important geological archives recording the tectonic evolution and collisional interactions between the South China and Indochina blocks. This study employed LA-ICP-MS zircon U-Pb geochronology and whole-rock geochemistry to investigate interbedded Triassic felsic volcanics. Felsic volcanic rocks in Youjiang Basin were erupted during the Early–Middle Triassic period (ca. 241~251 Ma) and are situated within the strata of the Beisi, Baifeng, and Banba Formations. These rocks in the Daqingshan area are rich in SiO₂ (66.8~72.7 wt%), K₂O (1.4~5.1 wt%), U (5.2~6.7 ppm), and Th (26~32.1 ppm). Conversely, they are depleted in MgO (0.6~1.4 wt%), TiO₂ (0.5~0.9 wt%), Cr (13.1~19.7 ppm), Ni (7.3~10.1 ppm), and negative Eu anomalies (Eu/Eu* = 0.41~0.52), and they also exhibit negative zircon ε_Hf(t) values. It is inferred that these Triassic felsic volcanics originated from the partial melting of crustal rocks in high-pressure environments such as the garnet stability zone within the deep mantle. These felsic volcanic rocks were likely generated during the transitional stage from island arc subduction to syn-collisional settings. Notably, the syn-collisional interaction between South China and Indochina blocks exerted significantly greater tectonic control on the Youjiang Basin than oceanic subduction. Full article

The water contents and geochemical evidence of nominally anhydrous minerals in peridotite xenoliths provide critical insights into lithospheric mantle features, offering a deep understanding of cratonic destruction and mantle evolution processes. Damaping, located in the central part of the intra-North China Craton, hosts abundant mantle peridotite xenoliths’ samples, providing new constraints on lithospheric mantle evolution. In this study, spinel lherzolite samples from Damaping Cenozoic basalts were analyzed for major and trace elements, water content, and oxygen isotope to investigate the factors controlling mantle water distribution and lithospheric mantle modification. The olivines of Damaping spinel lherzolite have a range of Mg# values from 89.73 to 91.01, indicating moderately refractory mantle characteristics. Clinopyroxenes display an LREE-depleted pattern, suggesting a consistency with 1–6% of batch partial melting and 1–5% fractional partial melting. The high (La/Yb)_N (0.20–0.73) and low Ti/Eu (3546.98–5919.48) ratios of Damaping clinopyroxenes reveal that the lithosphere mantle beneath the Damaping has undergone silicate metasomatism. The water contents of Damaping clinopyroxenes and orthopyroxenes range from 13.39 to 19.46 ppm and 4.60 to 7.82 ppm, respectively. The water contents of the olivines are below the detection limit (<2 ppm). The whole-rock water contents can be estimated based on the mineral modes and partition coefficients, with values ranging from 3.21 to 5.44 ppm. Partial melting indicators (Mg# in Ol and Yb_n in Cpx) correlate with the water content in clinopyroxenes and orthopyroxenes but show no correlation with the redox state (Fe³⁺/∑Fe ratios in spinel) or metasomatism ((La/Yb)_N in clinopyroxene). These results suggest that the degree of partial melting primarily controls the heterogeneous water distribution in Damaping spinel lherzolite, rather than the redox state or metasomatism. The δ¹⁸O values of clinopyroxenes from Damaping spinel lherzolites (5.27–5.59‰) fall within the range of mid-ocean ridge basalts (MORB), indicating a mantle source characterized by MORB-like isotopic signatures. The low whole-rock water contents are attributed to lithospheric reheating resulting from asthenospheric upwelling during the Late Mesozoic–Early Cenozoic. Therefore, the lithosphere is predominantly composed of ancient Proterozoic residues, with localized contributions of younger asthenospheric material near deep faults. Full article

This study investigates the mineral chemistry and iron isotope composition of the Pertek Fe-skarn deposit in the Eastern Taurides, Turkey, to elucidate skarn formation and ore genesis through chemical and isotopic parameters. The deposit consists of substantial and dispersed magnetite ores formed by the intrusion of a dioritic suite into marbles. Mineral assemblages, including hematite, goethite, andradite garnet, hedenbergite pyroxene, calcite, and quartz, exhibit compositional variations at different depths within the ore body. Magnetite is commonly associated with hematite, goethite, garnet, pyroxene, calcite, and quartz. Extensive LA–ICP–MS analysis of magnetite chemistry reveals elevated trace element concentrations of titanium (Ti), aluminum (Al), vanadium (V), and magnesium (Mg), distinguishing Pertek magnetite from low-temperature hydrothermal deposits. The enrichment of Ti (>300 ppm) and V (>200 ppm), along with the presence of Al and Mg, suggests formation from high-temperature hydrothermal fluids exceeding 300 °C. Discriminant diagrams, such as Al+Mn versus Ti+V, classify Pertek magnetite within the skarn deposit domain, affirming its medium- to high-temperature hydrothermal origin (200–500 °C), characteristic of skarn-type deposits. Magnetite thermometry calculations yield an average formation temperature of 414.53 °C. Geochemical classification diagrams, including Ni/(Cr+Mn) versus Ti+V and TiO₂-Al₂O₃-MgO+MnO, further support the skarn-type genesis of the deposit, distinguishing Pertek magnetite from other iron oxide deposits. The Fe-skarn ore samples display low total REE concentrations, variable Eu anomalies, enrichment in LREEs, and depletion in HREEs, consistent with fluid–rock interactions in a magmatic–hydrothermal system. The δ⁵⁶Fe values of magnetite range from 0.272‰ to 0.361‰, while the calculated δ⁵⁶Fe_aq values (0.479‰ to 0.568‰) suggest a magmatic–hydrothermal origin. The δ⁵⁷Fe values (0.419‰ to 0.530‰) and the calculated 10³lnβ value of 0.006397 indicate re-equilibration of the magmatic–hydrothermal fluid during ore formation. Full article

LaFeO₃/TiO₂ composites were prepared in the range 0–12.2 wt% of LaFeO₃, characterized, and tested for both benzoic acid (BA) and 4-methoxycinnamic acid (MCA) degradation in aqueous solution, and hydrogen evolution. The preparation method was via ball-milling without thermal treatment. The composite materials presented agglomerates of LaFeO₃ with an average size from 1 to 5 μm, and the TiO₂ powder was well dispersed onto the surface of each sample. They showed varying activities for BA degradation depending on composition and light wavelength. The 6.2 wt% and 12.2 wt%-LaFeO₃/TiO₂ composites exhibited the highest activity under 380–800 nm light and could degrade BA in 300 min at BA concentration 13.4 mg L⁻¹ and catalyst 0.12 g L⁻¹. Using a 450 nm LED light source, all composites degraded less than 10% of BA, but in the presence of H₂O₂ (1 mM) the photocatalytic activity was as high as 96% in <120 min, 6.2 wt%-LaFeO₃/TiO₂ composite being the most efficient sample. It was found that in the presence of H₂O₂, BA degradation followed first order kinetic with a reaction rate constant of 4.8 × 10⁻⁴ s⁻¹. The hydrogen production rate followed a classical volcano-like behavior, with the highest reactivity (1600 μmol h⁻¹g⁻¹ at 60 °C) in the presence of 3.86%wt- LaFeO₃/TiO₂. It was also found that LaFeO₃/TiO₂ exhibited high stability in four recycled tests without losing activity for hydrogen production. Furthermore, a discussion on photogenerated charge-carrier transfer mechanism is briefly provided, focusing on lacking significant photocatalytic activity under 450 nm light, so p-n heterojunction formation is unlikely. Full article

The Kongco area of Nima in the northern part of the Lhasa terrane has a suite of alkaline granitic porphyry dykes associated with Early Cretaceous granites and accompanied by Cu/Mo mineralization. LA-ICP-MS ²⁰⁶Pb/²³⁸U zircon geochronology performed on the dykes produced an age of 104.15 ± 0.94 Ma (MSWD = 0.98), indicating the Early Cretaceous emplacement of the dykes. The dykes exhibit high silica (SiO₂ = 76.22~77.90 wt.%), high potassium (K₂O = 4.97~6.21 wt.%), high alkalinity (K₂O + Na₂O = 8.07~8.98 wt.%), low calcium (CaO = 0.24~0.83 wt.%), low magnesium (MgO = 0.06~0.20 wt.%), and moderate aluminum content (Al₂O₃ = 11.93~12.45 wt.%). The Rieterman index (σ) ranges from 1.93 to 2.34. A/NK (molar ratio Al₂O₃/(Na₂O + K₂O)) and A/CNK (molar ratio Al₂O₃/(CaO + Na₂O + K₂O)) values of the dykes range from 1.06 to 1.18 and 0.98 to 1.09, respectively. The dykes are relatively enriched in Rb, Th, U, K, Ta, Ce, Nd, Zr, Hf, Sm, Y, Yb, and Lu, and they show a noticeable relative depletion in Ba, Nb, Sr, P, Eu, and Ti, as well as an average differentiation index (DI) of 96.42. The dykes also exhibit high FeO_T/MgO ratios (3.60~10.41), Ga/Al ratios (2.22 × 10⁻⁴~3.01 × 10⁻⁴), Y/Nb ratios (1.75~2.40), and Rb/Nb ratios (8.36~20.76). Additionally, they have high whole-rock Zr saturation temperatures (884~914 °C), a pronounced Eu negative anomaly (δEu = 0.04~0.23), and a rightward-sloping “V-shaped” rare earth element pattern. These characteristics suggest that the granitic porphyry dykes can be classified as A2-type granites formed in a post-collisional tectonic environment and that they are weakly peraluminous, high-potassium, and Calc-alkaline basaltic rocks. Positive ε_Hf(t) values = 0.43~3.63 and a relatively young Hf crustal model age (T_DM2 = 826~1005 Ma, ⁸⁷Sr/⁸⁶Sr ratios = 0.7043~0.7064, and ε_Nd(t) = −8.60~−2.95 all indicate lower crust and mantle mixing. The lower crust and mantle mixing model is also supported by (²⁰⁶Pb/²⁰⁴Pb)t = 18.627~18.788, (²⁰⁷Pb/²⁰⁴Pb)t = 15.707~15.719, (²⁰⁸Pb/²⁰⁴Pb)t = 39.038~39.110). Together, the Hf, Sr and Pb isotopic ratios indicate that the Kongco granitic porphyry dykes where derived from juvenile crust formed by the addition of mantle material to the lower crust. From this, we infer that the Kongco granitic porphyry dykes are related to a partial melting of the lower crust induced by subduction slab break-off and asthenospheric upwelling during the collision between the Qiangtang and Lhasa terranes and that they experienced significant fractional crystallization dominated by potassium feldspar and amphibole. These dykes are also accompanied by significant copper mineralization (five samples, copper content 0.2%), suggesting a close relationship between the magmatism associated with these dykes and regional metallogenesis, indicating a high potential for mineral exploration. Full article

Late Permian–Early Triassic basic rocks, which are widespread in the western margin of the Yangtze block (SW China), provide critical information for regional tectonic evolution. The Qiaoqi intrusion, distributed in the western margin of the Yangtze block, is selected as a representative for discussion in this paper. LA-ICP-MS zircon U-Pb dating results show that the Qiaoqi intrusion was formed at 245 ± 1 Ma. It belongs to the medium-K calc-alkaline and tholeiitic basalt series. It is characterized by high concentrations of Fe₂O₃^T (11.53 wt. % to 15.50 wt. %), TiO₂ (1.81 wt. % to 3.20 wt. %), Al₂O₃ (11.80 wt. % to 15.60 wt. %), and low concentrations of MgO (4.51 wt. % to 8.93 wt. %). The LREE and LILE (such as Cs, Rb, Ba and Th) are enriched, with insignificant Eu anomalies (Eu/Eu* = 0.92 to 1.13). The chondrite-normalized REE distribution diagram shows a right-leaning pattern, similar to ocean island basalts (OIB), displaying the geochemical characteristics of enriched mantle sources. The zircon εHf(t) values are relatively high (+12.7 to +15.5) and the single-stage Hf model ages are relatively young (t_DM = 272 to 386 Ma). Modeling further reveals that the parent magma was derived from 13% to 19% partial melting of garnet peridotite. Comprehensive analysis shows that the geochemical characteristics of the Qiaoqi intrusion bear resemblance to those of the Emeishan basalts, which are attributed to volumetrically minor melting of the fossil Emeishan plume head beneath the Yangtze crust following the eruption of the Emeishan Large Igneous Province (ELIP). This understanding further constrains the duration of the Emeishan Large Igneous Province and provides new support for understanding the formation, evolution and distribution of the Emeishan Large Igneous Province. Full article

Biological activities, including cell viability, oxidative stress, genotoxicity/antigenotoxicity, and antimicrobial activity, were evaluated for a visible-light-responsive TiO₂-based ICT complex with dihydroquercetin (DHQ) and compared with pristine TiO₂, its inorganic component. Pristine TiO₂ did not induce cytotoxicity in MRC-5 or HeLa cells within the tested concentration range (1–20 mg/mL), while TiO₂/DHQ displayed a significant reduction in cell viability in both cell lines at higher concentrations (≥10 mg/mL). The analysis of reactive oxygen species (ROS) production revealed that TiO₂/DHQ significantly reduced ROS levels in both cell types (MRC-5 and HeLa), with HeLa cells showing a more substantial reduction at lower concentrations. Genotoxicity assessment using the comet assay demonstrated that TiO₂ induced DNA damage in MRC-5 cells, while TiO₂/DHQ did not, indicating that DHQ mitigates the genotoxic potential of TiO₂. Furthermore, TiO₂/DHQ exhibited antigenotoxic effects by reducing H₂O₂-induced DNA damage in MRC-5 cells, supporting its protective role against oxidative stress. Preliminary antimicrobial tests revealed that TiO₂/DHQ exhibits antimicrobial activity against E. coli under visible-light excitation, while TiO₂ does not. These findings suggest that the TiO₂-based ICT complex with DHQ with enhanced antioxidant properties can potentially serve as a safe, non-toxic biocide agent. Full article

The microwave dielectric properties of (1−x)Ca_0.6(La_0.9Y_0.1)_0.2667TiO₃-x(Nd_1/2La_1/2)(Mg_(1+δ)1/2Ti_1/2)O₃ ((1−x)CYTO-xNLMTO) ceramics were investigated in this study. It was discovered that the addition of 1 wt% CuB₂O₄ effectively enhanced the densification and improved the microwave dielectric properties of (1−x)CYTO-xNLMTO, where δ = 0.02. The new ceramic systems of (1−x)CYTO-xNLMTO could achieve ultra-low loss and a high dielectric constant. The novel ceramic systems comprising (1−x)CYTO-xNLMTO exhibited remarkably low loss and a significantly high dielectric constant. Full article

For the first time, inductively coupled plasma mass spectrometry (ICP-MS) was developed for determining the target elemental composition of gadolinium–aluminum garnets with the varying composition Gd_3–xCe_xSc_yAl_5–yO₁₂, where x = 0.01–0.16 and y = 0.25–1.75. This fact has a fundamental importance for obtaining optical ceramics with predictable properties. Using the proposed acid mixture and temperature-time program, microwave digestion of these materials and complete transfer of the sample’s components into solution were possible. Moreover, we estimated the influence of the matrix composition, sample introduction system and collision cell on the limits of determination (LOD) of impurity elements by ICP-MS (Mg, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, La, Pr, Nd, Sm, Eu, Tb, Er, Ho, Tm, Yb, and Lu). It has been shown that the conditions of mass spectral analysis proposed in this work provide LOD of target analytes in the range of 1∙10⁻⁶–4.15∙10⁻³ wt.%. The accuracy of the obtained results has been confirmed by the added-found method and by analyzing samples with known chemical composition. The standard deviation of repeatability (S_r) of the developed technique lies in the range from 1 to 6%. The developed analysis method is characterized by sensitivity, robustness and multi-elementality. It has application potential for other optical and ceramic materials of similar composition. Full article

Jinchanshan is a medium-sized, granitoid-hosted gold deposit located in the Kalaqin area of Inner Mongolia. Mineralization predominantly occurs in the contact zone between biotite granites and quartz porphyry rocks, associated with the Jinchanshan minor intrusion, suggesting a genetic link to the granitoid-hosted gold deposit. In this study, the petrography, geochemistry, and LA-ICP-MS zircon U–Pb chronology of these two granitoid samples were studied. The results indicate that the zircon U–Pb age of the biotite granites is 127.9 ± 3.0 Ma, while that of the quartz porphyry is 121.4 ± 1.5 Ma, both dating back to the Early Cretaceous. The average SiO₂ content of the granites is 66.64%, and the rocks have high total alkali (K₂O + Na₂O) content, averaging 9.13%. The average K₂O content is 4.39%, with a K₂O/Na₂O ratio of 0.93. The quartz porphyry rocks are enriched in SiO₂ (74.41%–76.85%) and have high Na₂O + K₂O content (8.67%–9.59%), but are low in MgO (0.03%–0.09%), CaO (0.44%–1.02 %), and TiO₂ (0.08%–0.12%). Most samples of the biotite granite and the quartz porphyry rocks exhibit high-K peraluminous and medium-K calc-alkaline characteristics, respectively. Both rock types are enriched in Rb, Th, U, K, Zr, Hf, and Gd and relatively depleted in Ba, Sr, P, Ti, Nb, Ta, and Eu, with a pronounced negative Eu anomaly. The biotite granites show high ∑LREE/∑HREE ratios (6.1–6.9), while the quartz porphyry rocks exhibit lower ratios (2.0–4.2). Both granitoid types have elevated FeO^T content and FeO^T/(FeO^T + MgO) ratios, indicating that the Jinchanshan granitoids are A-type granites. The zircon U–Pb ages, combined with the regional tectonic settings, suggest that these granitoids formed during large-scale metallogenic events in the Early Cretaceous, within the Yanshanian post-orogenic extensional tectonic regime. This is consistent with the lithospheric thinning and extensional processes in Eastern China during this period. Full article

The late Permian Emeishan large igneous province (ELIP) in SW China is a melting product of the Emeishan mantle plume. Recently, it has been debated whether peridotite or pyroxenite is the dominant lithology of the mantle source in the ELIP. To address this, systematic analyses of bulk-rock and coexisting spinel and olivine compositions were conducted on picrites from Lijiang–Yongsheng, Dali–Binchuan, Yumen, Muli, and Ertan. The ELIP picrites exhibit positive TiO₂–CaO and negative MgO–CaO correlations, as well as low FC3MS values (−0.24–0.1), supporting a peridotite-dominated mantle source. This lithology of the mantle source is also supported by the high 100 × Mn–Fe (1.43–1.73) and Mn–Zn (13.6–18.4) values but low 10,000 × Zn–Fe (8.0–12.7) ratios of the olivine phenocrysts. The estimated mantle potential temperature for Lijiang, Yongsheng, Yumen–Ertan, Muli, and Dali–Binchuan picrites decreased away from Lijiang and Yongsheng, suggesting that the Lijiang and Yongsheng areas were the center of the ELIP. The Lijiang–Yongsheng primary magma shows similar SiO₂ content but lower Al₂O₃ contents (average of 8.24 wt.%) and higher MgO contents (average of 21.42 wt.%) than those of Dali–Binchuan primary magma (Al₂O₃: 9.86 wt.%; MgO: 19.02 wt.%). Also considering the high Gd–Yb (average of 3.05) and La–Yb (average of 14.61) ratios and mantle potential temperature (average of 1599 °C), we proposed that Lijiang–Yongsheng lavas are produced via the melting of a garnet–peridotitic mantle. In contrast, the Dali–Binchuan lavas with low Gd–Yb (average of 1.91) and La–Yb (average of 5.88) ratios can be explained by their formation in the garnet–spinel transition zone of a peridotitic mantle. The Yumen–Ertan primary magma displays similar mantle potential temperature (average of 1600 °C), Al₂O₃ and FeO content, and Gd–Yb ratios to those of Lijiang–Yongsheng lavas, indicating that YumenvErtan primary magma may be attributed to the partial melting of garnet with minor peridotite. Therefore, heterogeneous plume-head mantle sources lead to the evaluation of melting conditions of the late Permian ELIP picrites. Full article