MgO Ratios Research Articles

Post-collisional Ediacaran volcanism in oriental Ramada Plateau, southern Brazil

Ediacaran volcanic sequences in southernmost Brazil are related to intense post-collisional magmatism of the Brasiliano Orogeny. A portion of this volcanism occurs in the oriental Ramada Plateau located in the center part of the Rio Grande Sul State and is correlated with Hilário and Acampamento Velho formations. The first one is represented dominantly by lava flows and dikes of shoshonitic andesitic composition, besides of volcanogenic sedimentary deposits. The acid rocks of the Acampamento Velho Formation are expressive in the area, comprising high-silica ignimbrites, usually densely welded. Dikes and domes are common too and rhyolitic lava flows occur at the top and intercalated to ignimbrites in the middle of the sequence. The acid rock association has a sodic alkaline affinity. In this unit we mapped a subvolcanic sill of trachyte showing evidence for magma mixing with the rhyolitic magma. It has sodic alkaline affinity, and FeOt/FeO + MgO ratios and agpaitic index lower than those recorded in the rhyolites/ignimbrites. The Acampamento Velho Formation includes in this area, subordinately, basalts as àà flows and dikes intercalated with acid rocks. They have sodic alkaline nature and characteristics of intraplate basic rocks. New zircon U-Pb dating indicates crystallization age of 560 ± 2 Ma in a densely welded ignimbrite, 560 ± 14 Ma for a mafic trachyte and 562 ± 2 Ma for a subvolcanic rhyolite. The sodic alkaline rocks in this region evolved by fractional crystallization processes and magma mixing with major crustal contribution at approximately 560 Ma. The chemical characteristics are similar to those of A-type granites associated with Neoproterozoic post-collision magmatism in the Sul-rio-grandense Shield.

Solution combustion synthesis of porous Sn–C composite as anode material for lithium ion batteries

In this study, a Sn–C composite material as anode material for lithium ion batteries was fabricated via MgO template-assisted solution combustion synthesis, in which the starting material was a gel containing Sn(NO3)2, glycine (C2H5O2N) as the carbon source, and Mg(NO3)2·6H2O for the template. After the combustion reaction, the generated MgO was removed from the carbon, and the Sn nanoparticles were dispersed into a porous carbon structure during the carbon reduction of SnO2 under calcination in N2. The effects of ratios of glycine (n) and MgO (m) on the material phase, morphology, carbon content, and electrochemical properties were mainly investigated. At glycine (n) ratios of 2 and 3, the SnO2 phase was not fully reduced to Sn. With n>3, a composite material of metallic Sn nanoparticles and carbon was synthesized, in which the ratio of carbon increased with increasing n. With increasing m, the porosity of the particles increased, resulting in enhanced cyclic stability owing to the buffer space provided by the porous structure of carbon. The composite material obtained at n=4 and m=4 exhibited the highest reversible capacity of 588mAh/g after 100discharge/charge cycles at a current rate of 0.5A/g as compared to the 269mAh/g observed for n=4 and m=2.

A grit separation module for inorganic matter removal from activated sludge: investigation on characteristics of split sludge from the module

ABSTRACTA grit separation module was developed to prevent the accumulation of inorganic solids in activated sludge systems, and it achieved effective separation of organic matter and inorganic solids. To provide technical and theoretical support for further comprehensive utilization of split sludge (underflow and overflow sludge from the separation module), the characteristics of split sludge were investigated. The settling and dewatering properties of the underflow sludge were excellent, and it had high inorganic matter content, whereas the overflow sludge had higher organic matter content. The most abundant inorganic constituent was SiO2 (59.34%), and SiO2, Al2O3, and Fe2O3 together accounted for 79.53% of the inorganic matter in the underflow sludge. The mass ratio of Fe2O3, CaO, and MgO to SiO2 and Al2O3 was 0.245 in the inorganic component of the underflow sludge. The underflow sludge had the beneficial characteristics of simple treatment and disposal, and it was suitable for use as a base raw material for ceramsite production. The overflow sludge with higher organic matter content was constantly returned from the separation module to the wastewater treatment system, gradually improving the volatile suspended solid/total suspended solid ratio of the activated sludge in the wastewater treatment system.

Comparison of mathematical and artificial neural network models for inhibition of fuel oil ash under high temperature corrosion

This research reports the results of literature data of mass loss tests of high temperature corrosion inhibition of steel in different concentration ratios of MgO, Al2O3 and SiO2 to corrosive fuel ash of V2O5 in the temperature range of 550–590°C and time range of 8–100 h. Analysis focused on determining optimum mathematical equation and artificial neural network (ANN) architecture in order to gain good prediction properties. Three mathematical equations and five ANN architectures were suggested. A computer aided program was used for developing these models. Results show that polynomial mathematical equation and multilayer perceptron are able to accurately predict selected data with high correlation coefficients.

Stabilization and solidification of electric arc furnace dust originating from steel industry by using low grade MgO

Abstract In this study, solidification/stabilization (S/S) of electric arc furnace dust (EAFD) which is generated during the production of steel from scrap metals and classified as hazardous waste were investigated by using different ratios of cement and low grade MgO (LG MgO) as binding agents. Type I PC 42.5 R portland cement and LG MgO which contains 70–80% MgO were used. S/S blocks that contain different ratios of binding agents which have 1/0.5 – 1/1 – 1/2 – 1/3 – 1/4 – 1/5 cement/LG MgO ratio and S/S blocks which contain only cement and no LG MgO agents were prepared. These blocks, which contain 3 different waste ratios according to weight, 20%, 30% and 40% respectively, were produced and exposed to 28-day water purification. At the end of the purification process, S/S blocks were extracted using TCLP (Toxicity Characteristic Leaching Procedure) tests in order to determine the leaching behavior of Zn, Pb, and Cd in S/S blocks. By the end of this study, it was concluded that the recovery of EAFD is possible and applicable by immobilization. The findings of the study concluded that environmental performances or structural properties of blocks contain 30% waste by weight are suitable. This method is a proper one for recovering and treatment of EAFD with mixture of cement and LG MgO.

Composition-dependent reactive wetting of molten slag on coke substrates

The reactive wetting behavior of molten CaO–SiO2–Al2O3–MgO slag drops on a coke substrate was investigated using the sessile drop method at 1500 °C in flowing Ar. The wetting behavior of slags in blast furnaces is known to affect the energy efficiency of ironmaking, but has not yet been sufficiently characterized. In this study, the ratio of MgO to CaO was varied from 0.01 to 0.56, while the concentrations of SiO2 and Al2O3 were fixed at 34 and 17 wt%, respectively. The contact angle between slag and coke remained constant for a certain period of time, and then suddenly decreased remarkably. The time until this dramatic contact angle change increased with increasing the ratio of MgO to CaO. Chemical analysis revealed that the reduction of SiO2 in the slag improved the wettability by forming SiC on the coke substrate, while MgO in the slag was preferentially reduced and prevented the reduction of SiO2. Consequently, with increasing MgO content, the wettability of the molten slag on the coke substrate decreased.

Magnesium oxide suppression during nickel flotation

A South American nickel mine has been producing a nickel concentrate that also contains copper and iron (15 percent nickel, 5 percent copper, 28 percent iron) for the end use of stainless steel production. A critical specification for the quality of the steel is the iron to magnesium oxide ratio (Fe:MgO), with a ratio of below 3.5:1 having a substantial impact on the nickel value. This nickel concentrate producer historically mined the sulfur-rich mineral pyroxenite but had been forced to move to a magnesium oxide/silicate (MgO/SiO4)-rich mineral harzburgite, resulting in nickel recovery being reduced to around 50 percent to maintain the required Fe:MgO ratio. In this study, ore mineralogy, water chemistry and the chemistries associated with the flotation process were evaluated in an effort to increase nickel recovery while maintaining the Fe:MgO ratio according to specification. New chemistry was introduced with the specific goal of complexing with the MgO and retarding its interaction with the bubble flow in the flotation process.

Post-collisional subvolcanic rhyolites associated with the Neoproterozoic Pelotas Batholith, southern Brazil

Neoproterozoic volcanic and subvolcanic rhyolitic systems in southernmost Brazil are correlated with acid magmatism linked to different petrotectonic associations of the Sul-Rio-Grandense Shield. A portion of this volcanism in the Dom Feliciano Belt is associated with the Pelotas Batholith, which resulted from magmatic episodes associated with the Ediacaran post-collisional evolution of southern Brazil. Ana Dias Rhyolite is the main subvolcanic occurrence of this volcanism that took place in the Quitéria region, in the central part of Rio Grande do Sul State. The acid magmatism has been commonly associated with the most differentiated granite suite phases during the final stages of emplacement of the Pelotas Batholith. The Ana Dias Rhyolite is characterized as an intrusive body with rocks that present a porphyritic to seriated texture and a gradational variation to fine-grained equigranular rocks. New zircon U–Pb dating indicates crystallization age of 581.9 ± 1.9 Ma for the Ana Dias Rhyolite. Geochemistry data characterize the rhyolites as belonging to the alkaline series; they present a metaluminous to peraluminous character; elevated SiO2 and alkali concentrations, high FeOt/FeOt + MgO ratios and agpaitic index; and low Al2O3, CaO, and MgO contents. The Zr, Rb, Y, Nb, and Ga concentrations are moderate when compared with the relatively low Ba and Sr contents. These geochemistry characteristics are common in acid magmas with alkaline affinity. The behavior of certain trace elements and REE demonstrate enrichment in more incompatible elements, in addition to the negative anomaly of Ba, the slight enrichment in Ce relative to adjacent elements, as well as the enrichment in K2O and Rb relative to Nb, suggesting magmas derived from mantle sources enriched in incompatible elements with some crustal contamination. The chemical characteristics are similar to those of A-type granites associated with Neoproterozoic post-collision magmatism in the Sul-Rio-Grandense Shield.

Thermal Stability Enhancement of Magnetic Perpendicular-Magnetic Tunnel Junctions Using Double MgO Interface Structure

Perpendicular spin-transfer-torque magnetic-random-access-memory (p-STT MRAM) has been investigated widely as a next generation memory, due to their capability of non-volatility, low power consumption, write endurance and high speed operation. Many efforts have been done to develop of p-STT MRAM, especially CoFeB/MgO-based perpendicular magnetic tunnel junction (p-MTJ) have widely studied because it shows high tunneling magnetoresistance (TMR) ratio caused by Δ1coherent tunneling effect and relatively low current density required than that of in-plane easy axis MTJ. To accommodate the p-MTJ to p-STT MRAM, p-MTJ should be increased the thermal stability (Δ=KuV/kBT where Ku is the anisotropy energy density, V is the volume of recording layer, kB is Boltzmann constant and T is absolute temperature respectively) of 74 to assure the data retention for 10 years. Thus, in this work, we investigated the effect of double MgO interface CoFeB-MgO based p-MTJ on the thermal stability. In CoFeB-MgO based p-MTJs, thermal stability is improve with increasing the thickness of CoFeB free (recording) layer [1]. However, magnetic anisotropy become in plane when CoFeB thickness over 1.3 nm [2]. With double MgO interface, CoFeB free layer maintain perpendicular magnetic anisotropy even the thickness is over 1.3 nm and lead to higher thermal stability. We prepared CoFeB-MgO based p-MTJs utilizing magnetron sputtering on TiN electrode constructed 12-inch Si wafers. Afterword p-MTJs were annealed at several ex-situ annealing temperatures (Tex ) for 1 hour under perpendicular magnetic field of 3T. And we analyzed p-MTJ magnetic properties by using Vibrating-Sample-Magnetometer (VSM), crystallinity by observing high resolution cross-sectional TEM (x-TEM) images and TMR ratio by using a current-in-plane tunnelling (CIPT) technique. Fig. 1 shows the anisotropy energy density (Kut) of p-MTJs as a function of CoFeB thickness and spacer thickness. Single MgO interface p-MTJ with Ta seed layer exhibited Δ=21 at Tex =275°C as shown in Fig. 1 (A). On the other hand, single MgO interface p-MTJ with bcc seed layer showed Δ=26 even after it was annealed at 400°C, as shown in Fig. 1 (B). We could improve D and annealing temperature at onetime using bcc seed layer, actually improving of annealing temperature is also required to accommodate p-STT-MRAM. Kut of Double MgO interface p-MTJ with bcc seed layer are shown in Fig. 1 (C). It showed almost two times higher Δ (61) than that of single MgO interface at Tex=400°C, and almost independent of spacer thickness. Fig. 2 shows the x-TEM images of single and double MgO interface p-MTJ spin-valves. We could obtain well crystallinity MgO barrier layer at both of single and double MgO interface p-MTJs, and those TMR ratio were 163 and 141% respectively. TMR ratio of double interface p-MTJ was decreased because of increasing of resistance area product (RA), which caused by bottom MgO layer. In the conference, we will present how thermal stability of p-MTJ using MgO double interface structures was improved and review those mechanisms by analyzing magnetic property, crystallinity of MgO and TMR ratio using VSM, x-TEM and CIPT respectively. * This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) grant funded by the Korea government (No. 2014R1A2A1A01006474 & No. 1004608) and Brain Korea 21 PLUS Program in 2014.

Studies on copra oil self-cured ester as a sustainable material for surface coatings

In this paper, synthesis, characterization, and optimization of a copra oil self-cured ester have been studied. The oil was first analyzed to examine the physico-chemical properties (iodine value, viscosity, refractive index, acid value, and specific gravity) and subsequently neutralized and dehydrated. The synthesis of self-cured ester was accomplished by reduction of the triglycerides in the oil by alcoholysis and functional group modification with phthalic anhydride and styrene via free radical co-polymerization reaction. Structural elucidation of the resin was enhanced by the Fourier transform infrared (FT-IR) spectroscopic technique. The response surface methodology (RSM) based on a central composite rotatable design (CCRD) involving 30 experiments of four process variables at five levels was employed for the optimization study as an economical way of obtaining an optimal response with fewest number of experiments. The studied process parameters were reaction temperature, reaction time, catalyst concentration, and phthalic anhydride-to-monoglyceride oil (PA:MGO) ratio. A predictive model describing the fractional conversion in terms of process variables was derived from multiple regression analysis. An optimum fractional conversion of 96.55% was predicted at a reaction temperature of 241.94 °C, reaction time of 124.2 min, catalyst concentration of 0.1% and PA:MGO ratio of 0.38:1, for the process. The extent of reaction at 135 min of polycondensation of the monomers was more than 85%. A model validation experiment shows a good agreement between the actual (97.19%) and predicted (96.55%) values. Physico-chemical properties and performance characteristics of the ester indicate its suitability in surface coating applications.

Isotopic geochemistry, zircon U–Pb ages and Hf isotopes of A-type granites from the Xitian W–Sn deposit, SE China: Constraints on petrogenesis and tectonic significance

Zircon U–Pb geochronological, geochemical and petrological analyses have been carried out on the Xitian granite emplaced in the middle part of Shi-Hang zone, which is closely related to the economically important Xitian tungsten–tin deposit in Hunan Province, Southeast China. LA-ICP-MS zircon U–Pb dating of two representative samples yielded weighted means 206Pb/238U age of 151.7±1.2Ma and 151.8±1.4Ma. These granites are comprised mainly of K-feldspar, quartz, plagioclase, Fe-rich biotite and minor fluorite, and are characterized by enrichments in Rb, Th, REEs (total REE=159–351ppm), and HFSEs (e.g., Zr and Y) but depletions in Ba, Sr, P, Eu and Ti. They are metaluminous to weakly peraluminous and show a clear A-type granite geochemical signature with high SiO2 (73.44–78.45wt.%), total alkalis (Na2O+K2O=2.89–8.98wt.%), Fe2O3∗/MgO ratios and low P2O5, CaO, MgO and TiO2 contents. In-situ zircon Hf isotope analysis suggests their εHf(t) values ranging from –7.43 to –14.69. Sr–Nd isotope data show their εNd(t) values in the range of –9.2 to –7.3, with corresponding TDM2 ages of 1.72–1.56Ga. These characteristics indicate that the Xitian granite originated from partial melting of metamorphic basement rocks with a certain amount of mantle-derived materials. Combined with previous geochemical and isotopic data, it is derived that mantle–crust interaction was gradually enhanced from the early to late stages of magmatism. The ore-forming materials and fluids of the Xitian W–Sn deposit are mainly produced by the Early Yanshanian granitic magmatism, which is also responsible for the Late Jurassic (ca. 152Ma) A-type granitic rocks that host the W–Sn polymetallic deposits distributed along the Shi-Hang zone, implying a significant Mesozoic extensional event in Southeast China likely caused by the subduction of the Paleo-Pacific plate.

Ethanol Conversion to 1,3-Butadiene on ZnO/MgO–SiO2 Catalysts: Effect of ZnO Content and MgO:SiO2 Ratio

Effect of ZnO on ethanol conversion to 1,3-butadiene (BD) on ZnO/MgO–SiO2 catalysts consists in the enhancement of selectivity and yield of BD due to higher rate of ethanol dehydrogenation to acetaldehyde. It has been shown that two types of Lewis acid sites formed in the contact zones of MgO–SiO2 and ZnO–SiO2 in the catalysts play an important role in BD synthesis from ethanol. The highest BD yield is achieved at ratio of MgO:SiO2 = 1:1.

Direct reduction of magnesium oxide to magnesium using thermal plasma technology

A direct route for the reduction of magnesium oxide to magnesium using thermal plasma processing, with methane as the reducing gas, has been systematically evaluated. A feasibility study of the reduction reaction has been performed on the MgO-CH4 system at different methane concentrations and temperatures. The effects of changes in the key process parameters, such as the oxide-to-methane ratio and plasma power, on the yield of magnesium have been systematically evaluated. A maximum yield of about 61 mol% Mg was obtained using power of 20.0 kW and a molar ratio of MgO:CH4=1:1. Phase, morphological, elemental and binding energy analyses were performed on the product powders to understand the reduction reaction. Surface oxidation was observed in smaller magnesium particles in all the experiments, while the in-situ sintering of magnesium rods was observed at a molar ratio of MgO:CH4=1:1.5. Magnesium carbide (Mg2C3) was observed in the product, and its mechanism of formation is proposed using phase equilibrium data and a predominance diagram.

Synthesis and characterization of CNTs using polypropylene waste as precursor

We study the synthesis of MWCNTs using polypropylene waste as a precursor and Ni/Mo/MgO as a catalyst by the combustion technique. Molar ratios of Ni, Mo and MgO in the Ni/Mo/MgO catalyst were optimized using response surface methodology (RSM) to obtain the maximum yield of CNTs. The mole ratio 4/0.2/1 was found to yield more carbon product. Further, process parameters such as combustion temperature, combustion time, polymer and catalyst weight were optimized by RSM using Box–Behnken three-level and four-factorial design. The best possible combination of process parameters (combustion time of 10 min, combustion temperature of 800 °C, polymer weight of 5 g and catalyst weight of 150 mg) for maximum yield of CNTs was obtained. HRTEM indicates that the diameter of CNTs depends on the catalyst composition used for the synthesis of CNTs. The results of the study indicate a facile method for producing CNTs from polypropylene waste.

Study on the Effects of Molar Ratio of MgO and MgCl<sub>2</sub> on the Properties of Magnesium Cement Straw Board Based on Experiment

Magnesium cement-based straw board is made of chloride-oxy-magnesium concrete as gel phase, a new building material with straw as reinforcing phase. The effects of molar ratio of MgO and MgCl2on the static bending strength, softening coefficient and start time back to halogen moisture absorption of magnesium cement-based straw board are analyzed in detail. The result showed that,when n(MgO)/n(MgCl2)=7(molar ratio),the mechanical properties and water resistance are the best, hydration products at this time is dominated by 518 phase.

宮城県北部，石越安山岩の地質・岩石学的特徴とマグマプロセス

Ishikoshi Andesite is the Middle Miocene, amphibole-bearing, two pyroxene andesite lava flow located in the forearc area of the Northeast Japan arc, which covers the area of 8 km EW and 7 km NS and has the thickness of >180 m. In this study it is divided into peripheral lava (PL) and central lava (CL), which are distributed in the peripheral and central parts of the volcanic edifice, respectively. PL bears groundmass pigeonite or shows higher FeO*/MgO trend with fractionation and CL does not bear pigeonite and lower FeO*/MgO trend, therefore PL is tholeiitic and CL is calc-alkaline. PL shows petrological features that are compatible with crystallization differentiation. CL has several features that suggest magma mixing such as non-equilibrium plagioclase phenocrysts, but evidences for magma mixing are not robust. In comparison to similar lava flows, PL and CL seem to form a composite lava flow because clear geological boundary between PL and CL cannot be observed and FeO*/MgO ratio of CL tend to be higher in the marginal portion. We also find that two-pyroxene equilibrium temperature of CL (760-850 ℃)is lower than that of PL (970-990 ℃). CL should have been too viscous at this temperature (>1010 Pa·s in anhydrous state) to form a dike, thus it should have effused through the vent which PL formed to be composite lava flow with PL. Ishikoshi Andesite has columnar joints rather than platy joints. In comparison to other lava flows which have platy joints in Japan, it is possible that less anisotropic crystals, low eruption temperature (high viscosity) and/or large phenocryst size have prevented Ishikoshi Andesite from formation of foliation along which platy joints develop in the lava.

Transition of interface oxide layer from porous Mg(OH)2 to dense MgO induced by polyaniline and corrosion resistance of Mg alloy therefrom

The feasibility of polyaniline emeraldine base (EB) for enhancing long-term corrosion resistance of magnesium alloy (AZ91D Mg alloy) was confirmed, since the complex impedance of Mg alloy protected by EB/epoxy resin (ER) composite coating with 10wt% EB loading maintained around 2GΩcm2 even after 80 day exposure in 0.5M NaCl solution, while that of pure ER coated analogue decreased to 0.17MΩcm2 only after 31 days. The improvement in corrosion resistance was attributed to the transition of interface layer from porous Mg(OH)2 dominated one underneath pure ER coating to dense MgO dominated one underneath EB/ER coating, induced by the redox interaction of EB with Mg alloy. When the EB loading in EB/ER coating increased from 0 to 10wt%, the relative XPS peak area ratio of MgO to Mg(OH)2 increased from 0.78 to 1.18, indicating that EB behaved as effective corrosion inhibitor causing the transformation of oxide layer from porous Mg(OH)2 to dense MgO.

Hydrogen adsorption of carbon nanotubes grown on different catalysts

Single wall carbon nanotubes (SWCNTs) were synthesized by catalytic chemical vapor deposition of C2H2 at 800 °C for 60 min. Catalysts were prepared by impregnation of transition metals (Fe, Co, Ni, V and bimetallic mixture of Fe–Co) on MgO powder substrate with a metal to MgO ratio of 5:100. After the synthesis, the samples were purified by liquid phase oxidation method with 1.5 M HNO3 for 30 min at 210 °C. The samples were characterized by thermal gravimetric analysis, scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The hydrogen storage capacities of purified SWCNTs were investigated by volumetric method. It was found that the hydrogen uptake was in the range of 2.76–5.25 wt% at cryogenic temperature and 100 bar pressure. The maximum capacity was obtained with purified SWCNTs produced on Fe catalyst whereas purified SWCNTs grown on Fe–Co catalyst had the minimum hydrogen uptake.

Compositional tuning of atomic layer deposited MgZnO for thin film transistors

Thin film transistors (TFTs) have been fabricated using magnesium zinc oxide (MgZnO) layers deposited by atomic layer deposition at 200 °C. The composition of the MgZnO is systematically modified by varying the ratio of MgO and ZnO deposition cycles. A blue-shift of the near band-edge photoluminescence after post-deposition annealing at 300 °C indicates significant activation of the Mg dopant. A 7:1 ratio of ZnO:MgO deposition cycles was used to fabricate a device with a TFT channel width of 2000 μm and a channel length of 60 μm. This transistor yielded an effective saturation mobility of 4 cm2/V s and a threshold voltage of 7.1 V, respectively. The on/off ratio was 1.6×106 and the maximum interface state density at the ZnO/SiO2 interface is ∼6.5×1012 cm−2.

Petrogenesis of Late Cretaceous I-type granites in the southern Yidun Terrane: New constraints on the Late Mesozoic tectonic evolution of the eastern Tibetan Plateau

Abstract The collision between the Lhasa and Qiangtang terranes, prior to the Indo–Asian collision, is a critical aspect in terms of development of the Tibetan Plateau. It has been demonstrated that the occurrence of the Late Cretaceous granites (110–80 Ma) in the Yidun Terrane, eastern Tibetan Plateau (ETP) associates with the Lhasa–Qiangtang collision. The Xiuwacu Late Cretaceous pluton in the southern Yidun Terrane, consists three phases including biotite granitic porphyry (phase 1), monzogranite (phase 2), and alkali–feldspar leucogranite (phase 3), which have zircon U–Pb ages ranging from 85.5 Ma to 84.4 Ma. All these three phases are metaluminous or slightly peraluminous granites (A/CNK = 0.96–1.07), with high SiO2 (70.0–76.0 wt.%), K2O + Na2O (7.5–10.7 wt.%), and Ga/Al (2.5–4.7), and relatively low CaO (0.39–1.67 wt.%), MgO (0.01–0.57 wt.%), and P2O5 (0.01–0.17 wt.%). The granites are enriched in light rare earth elements (LREEs), Rb, Th, U and Ta, but depleted in heavy REEs (HREEs), Ba, Sr, P, and Ti, with significantly negative Eu anomalies (Eu/Eu* = 0.24–0.59). Comparing to classic A-type granites, these samples present higher Sr (10.1–256 ppm, mostly > 100 ppm) and lower FeO*/MgO ratios (1.2–9.9) and Zr + Nb + Ce + Y (248–483 ppm, mostly