Abstract:The clay minerals from the weathered crust rare earth ores of six areas in Jiangxi Province were studied for better understanding the effects of clay minerals on the rare earth fraction. The powder X-ray diffraction(XRD), infrared spectroscopy(IR) and scanning electron microscopy(SEM) results show that platy kaolinite and tubular 7Å halloysite are predominant constitutions in clays. Kaolinite and 7Å halloysite are dominant in ABT, CKW, SB, YC samples and ZD sample respectively, and both of them are abundant in SP sample. Inductively coupled plasma mass spectrometry(ICP-MS) analysis indicates that rare earth elements tend to be concentrated in clay minerals. The rare earth distribution patterns are influenced by both the original rock and the properties of clay minerals. A positive Ce-anomaly has been found in ZD and SP samples compared with a negative Ce-anomaly in other samples, which might be correlated to the well developed halloysite in these two samples. It is possible for Ce to be present as cerianite which is coating halloysite needles and/or be selectively absorbed by hallyosite which has higher specific surface area and cation exchange capacity than kaolinite.

Abstract:The alkali/surfactant/polymer(ASP) flooding technology can significantly enhance oil recovery. Nevertheless, the ASP injection fluid can easily react with reservoir minerals during the productive process which could do harm to reservoir strata and scale, resulting in plugging underground, reduction of the recovery rate and other technical problems. Therefore, the study of dissolution, transportation and plugging process and reaction mechanism of ASP in reservoir becomes a pressing matter of ASP flooding technology. The reaction process of ASP and reservoir minerals including potassium feldspar, quartz and kaolinite and minerals' changing characteristics in the Daqing oilfield were analyzed in detail through some testing means such as X-ray Diffraction(XRD), X-ray Photoelectron Spectroscopy(XPS), Field Emission Environmental Scanning Electron Microscope(ESEM) and Energy Dispersive Spectroscopy(EDS). The study of alkali dissolution reaction kinetics was conducted. And the Si and Al's dissolution kinetics equations of reservoir minerals indicating ions' dissolution and reprecipitation rules were calculated. Finally the reaction mechanism of ASP and reservoir minerals was analyzed. The results show that the dissolved amount of Si in potassium feldspar is three times that of Al after the interaction with ASP for 60 days. Gibbsite and some kinds of silicates are formed. The dissolved amount of Si in quartz increases linearly and exceeds 300×10^-6 after the interaction with pure alkali and ASP for 60 days. Carbonate particles are formed on quartz crystals' surfaces. The dissolved amount of Al in kaolinite is three times that of Si and the crystallinity of kaolinite decreases by 25.26% after the interaction with ASP for 60 days. Gismondine is formed. The corrosion and damage extent of reservoir minerals by alkali is positively correlated with alkali's concentration.

Abstract:The surface mechanism of arsenopyrite, which was treated in different spans of time(0.5h, 2h, 4h, 6 h and 8h) in an alkaline environment(initial pH=12.3), was investigated by SEM, XPS and frontier orbital theory calculation. The results showed that Fe atoms were most easily oxidized and shifted onto arsenopyrite surface due to its activity. The dissolution of As atoms almost synchronized with that of Fe atoms, but S atoms were hardly suitable for this phenomenon. The oxidation degree of arsenopyrite surface increased with the treatment time. It is inferred that the reaction mechanism was that Fe atom on the arsenopyrite surface was firstly oxidized to ferric ion in alkaline solution, then As and S atoms were respectively converted into As(Ⅲ) and sulfate under the presence of ferric ion and oxygen, and As(Ⅲ) was finally absorbed onto the ferric hydroxide with porous structure. Combined with calcium ion, sulfate completely entered gypsum. As a result, these sediments could adhere to arsenopyrite surface.

Abstract:In this paper, chemical composition, mineral composition, thermal properties, microstructure and binding characteristics of hemi-hydrate phosphogypsum were studied. The results showed that the chemical composition of hemi-hydrate phosphogypsum mainly consists of CaO and SO₃(up to 70% by mass), with a small amount of crystal water and P₂O₅. The hemi-hydrate phosphogypsum has radioactive elements, which meet the requirement of GB/T6566-2010 Limit of radionuclides in building materials. Mineral composition of hemi-hydrate phosphogypsum is mainly bassanite, whose exothermic peak is weak. Hemi-hydrate phosphogypsum is almost in aggregation made of irregularly oriented calcium sulfate crystals, and its binding characteristics are poor, with dry strength being 0.38 MPa. There exists difference between hemi-hydrate phosphogypsum and bassanite prepared by gypsum as raw material, and hence the direct application of hemi-hydrate phosphogypsum to building materials needs further study.

Abstract:Calcium sulfate whisker(CSW) was prepared from phosphogypsum. Crystallization behavior of CSW was studied in four aspects of solid-liquid ratio, concentration of solvent, temperature and cooling rate. Phosphogypsum and CSW were tested, and the effects of experimental conditions on length, length-diameter ratio and morphology of CSW were determined by microscopic observation and image analysis. Crystallization behavior was analyzed based on crystallography. Some conclusions have been reached:With the increase of solid-liquid ratio, the length and length-diameter ratio decreased first and then increased; with the increase of the concentration of solvent, the length-diameter ratio increased; with the increase of temperature and cooling rate, the length-diameter decreased. The average length of whisker is between 200μm and 400μm, and the average length-diameter ratio is between 25 and 30. The change of length and length-diameter ratio can reflect the change of the morphology of the whiskers. Crystallization behavior of the whiskers is divided into two stages:the formation of crystal nucleus and the growth of the whisker. The experimental conditions affect the crystallization by influencing the nucleation rate, degree of supersaturation and the solution of phosphogypsum.

Abstract:Pollution index has limitations in assessing the pollution risk of heavy metals in the carbonate-type tailings(i.e., carbonate-rich sulfide tailings). In this paper, the authors probed into this problem by investigating the carbonate-type tailings in the Huangshaping Pb-Zn ore district. The study included the modes of occurrence of such elements as Zn, Cd, Pb, Cu and As, which included tailings profile structure, distribution of total values of elements and water soluble fraction, combination of secondary cement/lepidocrocite and elements, and mobility(water extraction percentage) and pollution index of elements in the tailings. On such a basis, the authors have reached the following conclusions:① A layered(banded) structure has developed in the tailings, which exhibits the order of strong cementation layer/hardpan(moderate brown, oxidized/acidified) → weak cementation layer(yellowish brown, sub-oxidation) → sand-like layer(olive gray-gray green, weak/non oxidation) from the surface to the deep part of the tailings; in addition, the elements are concentrated in the hardpan and weak cementation layer; ② The cement in the tailings consists mainly of lepidocrocite. The difference of binding force between lepidocrocite and elements may affect the stability/mobility of elements in the tailings; ③ Due to the high mobility and pollution index, zinc and cadmium are the major pollution factors; therefore, pollutions of Zn and Cd should be especially prevented and controlled in the mining site. Arsenic is regarded as a minor pollution factor, as it possesses lower mobility despite its high pollution index. Lead and copper have less impact on the environment, because their mobility and pollution indices are low. In conclusion, the combinational analysis of the pollution index and the modes of occurrence of elements can help avoid the limitations of the use of the pollution index in assessing the pollution risk of heavy metals in the carbonate rich sulfide tailings.

Abstract:Based on the fact that the compositions of chrysotile asbestos tailings are mainly SiO₂ and MgO, the authors efficiently extracted MgO from chrysotile asbestos tailings with ammonium bisulfate via mix-roasting, and investigated the interrelationships between MgO extracting rate, washing mix-roasting residue and phase so as to get the optimal mix-roasting parameters. According to the physical phase variation of the washing mix-roasting residues, the authors analyzed the change of minerals and products in the mix-roasting process. The result shows that the optimum conditions for the elimination of mental oxides in mix-roasting were 4 for NH₄HSO₄/MgO molar ratio, 500℃ for the roasting temperature, 2 h for the roasting time, and 120 mesh for the particle size. Brucite, calcite and kotschubeite were most reactive in the mix-roasting process, followed by serpentite and then by talc. The mental oxides in chrysotile asbestos tailings were changed into soluble sulfate after being reacted with ammonium bisulfate. Meanwhile, Si-O tetrahedral sheet was retained and modified, and finally active silica residue was preserved. The results obtained by the authors have an important significance for the efficient utilization of chrysotile asbestos tailings.

Abstract:With the increase of Ni demand and decrease of high-grade nickel sulfide resources, the utilization of nickeliferous laterite ores has aroused considerable attention among geologists. On the basis of the mineralogical study, the atmospheric sulfuric acid leaching of the serpentinic nickeliferous laterite ores was carried out, and the optimized conditions were gained, i.e., 1 mol/L of the sulfuric acid concentration, the ratio of liquid and solid of 10, not less than 70℃ of the reaction temperature, about 6 h reaction time and about 65%(-76μm) grinding fineness. The leaching ratios of Ni, Fe and Mg of the nickeliferous laterite ores are 94.4%, 72.1% and 88.64%, respectively. The results achieved by the authors provide the scientific support for the economical utilization of this type of nickeliferous laterite ores.

Abstract:In this paper, the Jinchuan copper-nickel sulfide flotation concentrates were studied to compare the Co, Ni and Cu extraction results of sulfuric acid leaching process and A.f. leaching process. Further enhancement of metals leaching rates was achieved by bio-chemical leaching and chemical-bioleaching. The results showed that the bio-chemical leaching rates of Co²⁺, Ni²⁺ and Cu²⁺ reached 85.05%,98.32% and 95.31%, respectively. The combination of first bioleaching process and the following chemical acid leaching process facilitated the dissolution of the sulfide and strengthened the leaching effects of Co²⁺, Ni²⁺ and Cu²⁺ from complex sulfide concentrate.

Abstract:Hydroxyl-iron polycations-intercalated montmorillonite(Fe-Mt) was successfully synthesized and characterized using the methods of XRD, FTIR, TEM, and N₂_adsorption/desorption analysis. The adsorption of the target contaminant tetracycline hydrochloride(TC) on Fe-Mt from aqueous solutions was examined in batch experiments. Effects of the pH values of solution and types and concentrations of anions were systematically investigated. The adsorption isotherms of Fe-Mt at pH=3.0 can be fitted well with both the Langmuir and Freundlich models, with the former(R²>0.98) better than the latter(R₂<0.98), which indicated that the monolayer adsorption was the dominant model for the TC adsorption. In contrast to the starting montmorillonite(Mt), the adsorption capacities of Fe-Mt were increased with the increasing concentration of anions under the acidic solution condition that was favorable for the TC adsorption. Under a certain optimum condition, the types of anions can dramatically influence the TC adsorption on Fe-Mt, and exert the effect on the adsorption capacity in order of SO₄^2->>NO₃^->Cl^-, corresponding to the theoretical maximums of 500.0, 339.0 and 316.5 mg/g, respectively. At the acidic pH, the TC adsorption on Fe-Mt displays the coexisting of multi-models and the surface complexation, with the anion electrostatic attraction being the dominant model.

Abstract:The aim of this study is to reveal the effects of the UO₂²⁺ complexes and P. Fluorescens on adsorption and reduction of uranium under the condition of different carbon and nitrogen sources of CZA(Czapek-Dox medium). On the basis of the formulation of CZA, sugar was replaced by glucose and sodium nitrate was replaced by ammonium chloride,and then the Visual MINTEQ was used to analyze the UO₂²⁺ complexes. The results show that different types of carbon and nitrogen sources have no effects on the growth of P. Fluorescens. There exist different types of complexes of UO₂²⁺ when uranium concentration is changed. UO₂²⁺ mainly occurs as UO₂PO₄^_ when uranium concentration is 10 mg/L, and as UO₂(SO₄)₂²⁺ when uranium concentration is 50 to 200 mg/L in CZA medium. UO₂²⁺ exists as UO₂HPO₄(aq) when dextrose serves as carbon source, and as UO₂Cl₂(aq) when ammonium chloride serves as nitrogen source. The tolerance concentration of uranium for fluorescent pseudomonas is higher than 100 mg/L in general, and loses its activity at 200 mg/L. Compared with live and inactivation of P. Fluorescens, carbon and nitrogen sources have little effects on the adsorption and reduction of uranium. The adsorptions range from 84.02% to 92.59% and 3.32% to 10.94%, and the reduction rates range from 3.32% to 10.94% for living P. Fluorescens. The adsorption rates are 24.33%~39.05% and the reduction rates are 37.50%~44.58% for inactivated P. Fluorescens. The reduction rate of uranium is 53.12% when glucose is used as carbon source. The results indicate that inactive bacteria and reductive glucose as carbon source synergistically reduce uranium. However, no obviously synergistically effects exist for P. Fluorescens under living conditions.

Abstract:In order to improve the comprehensive utilization of iron sulfide minerals in the abandoned mine in Inner Mongolia, this study focused on making full use of the effective components of pyrite and pyrrhotite to treat Cr-containing wastewater. The optimal experimental conditions were found. Compared with the previous studies, the grain size of samples used in this study was lowered to 80~100 mesh, the dosage was decreased by 70%, and the concentration of chromium-containing wastewater treatment was increased to 50 mg/mL. It is worth mentioning that most of the Cr(Ⅲ) appeared in Cr₂S₃ phases by XPS scanning analysis after the treatment of Cr(Ⅵ)_containing wastewater by natural pyrite and pyrrhotite. The content of Cr₂S₃ accounted for 77.99%, 86.53 and 100% of total chromium phase respectively when natural pyrite was use to deal with Cr(Ⅵ) under the reaction system whose pH values were 1.84 and 4.15 and 10.87. There also appeared a considerable amount of trivalent chromium in Cr₂S₃ phase after using pyrrhotite in the pH of 6.5 and using modification pyrite heated under the condition of 500℃ and pH 4.15. The removal rate for processing directly the tannery of actual wastewater containing Cr(Ⅲ) was up to 73% when the optimum conditions obtained in this study for the treatment of Cr(Ⅵ) were directly used. This research provides a means for the comprehensive treatment of Cr(Ⅵ) and Cr(Ⅲ), and it has become one of the ways of producing useful resources in the course of mining.

Abstract:In this study, the preparation of Al-pillared montmorillonite(Al-Mt) was conducted using aluminum salt reacting with montmorillonite(Na-Mt). Meanwhile, the thermally treated Al-pillared montmorillonite samples(Al-Mt-X) at different temperatures(200~600℃) were characterized using X-ray diffraction(XRD) and infrared spectra(FTIR) methods. The reductive transformation of 2-nitrophenol(2-NP) by Fe(Ⅱ)/the thermally treated Al-pillared montmorillonite complex system was investigated, with a consideration of the effects of calcination temperature, surface acid sites and solution pH on the transformation efficiency of 2-NP. The results showed that, with increasing calcinations temperature, the surface acid sites of Al-Mt-X were gradually reduced, and thus the reduction transformation efficiency of 2-NP was enhanced. As the calcination temperature was higher than 500℃, Fe(Ⅱ) and the thermally treated Al-pillared montmorillonite(Al-Mt-X) formed an Fe(Ⅱ)/Al-Mt-X complex system that could effectively improve the reaction capability of Fe(Ⅱ) species for 2-NP reductive transformation. In addition, the reduction transformation of 2-NP by the Al-Mt-X complex system could be described well by the pseudo first-order kinetic equation. The reaction apparent constant(k) of 2-NP reduction was increased with the increasing calcination temperature and solution pH. Therefore, the thermally treated Al-pillared montmorillonite as functional materials can effectively improve the reductive capability of the adsorbed species of Fe(Ⅱ) to degrade pollutants in an anaerobic environment. It should be indicated that the calcination temperatures and solution pH were two important impact factors.

Abstract:The comprehensive utilization of the coal-derived mineral resources is faced with technical difficulties. In the present work, the associated diatomite with high organic matter and high iron content in Xianfeng lignite was utilized for removal of TNT in Fenton system. The diatomite after purification was subjected to calcination at high temperature for the formation of ternary composite materials of diatomite-amorphous carbon-iron with N₂ as protective atmosphere. The influence factors such as processing conditions of diatomite, reaction time, H₂O₂ concentration, amount of diatomite and pH values for removal efficiency of TNT were investigated. The optimized technological conditions for adsorption and degradation of 50 mg/L with removal rate of 98% are 2 g/L ternary composite diatomite, 4 mL/L(30%) H₂O₂, 1 pH and 2.5 h of reaction time.

Abstract:A novel photocatalyst, namely BiOBr/Fe-Mt, was synthesized successfully via the combination of Fe-modified montmorillonite with BiOBr at low temperature. The as-prepared BiOBr/Fe-Mt composites were characterized by the techniques of X-ray diffraction(XRD), transmission electron microscopy(TEM), Fourier transform infrared spectroscopy(FTIR) and UV-Vis diffuse reflectance spectroscopy(UV-Vis DRS). The batch experiments of Rhodamine B(RhB) degradation in solution under visible light(λ>400 nm) by the catalysts were carried out to evaluate the photocatalytic activities. Under the condition with the same supporter mass amount of 2.5 g, BiOBr/Fe-Mt catalyst showed a higher photocatalystic capacity as compared with BiOBr/Na-Mt. The significantly enhanced photocatalysis may be ascribed to the following two main reasons:① the decrease of band gap(Eg) of Fe-Mt/BiOBr to 2.46 eV, and/or the possible formation of BiOBr/iron oxide heterojunction structure; and ② just less residue of cetyltrimethylammonium bromide that can provide the source of bromide ion in BiOBr/Fe-Mt composite. These structural factors would effectively promote the photocatalystic degradation of RhB over BiOBr/Fe-Mt catalyst.

Abstract:A series of hazes occurred over the North China plain in January 2013. In this paper, the authors analyzed the morphologies, elemental compositions and sulfation characteristics of the individual aerosol particles collected in Beijing, Tianjin and Tangshan cities in January 2013 by Transmission Electron Microscopy(TEM) coupled with Energy Dispersed X-ray Spectrometry(EDX). The results showed that the individual aerosol particles could be subdivided into mineral particles, sulfate particles, metal oxide particles, soot aggregates, organic particles, and fly ash. A small amount of sea salt particles was found only in the Tianjin samples. According to element compositions, the individual particles were dominated by Si(31.0%), Ca(18.3%), Fe(14.1%) and Cl(12.2%) in the sunny days, and by S(47.4%), Si(21.1%) and Fe(13.4%) in the haze days. The high-S particles were commonly associated with higher values of Ca and K, indicating that alkaline minerals could be buffered against the acid mist. An analysis of sulfation characteristics showed that the S-bearing particles were more common in haze days, and that the S/Ca ratio was higher(>0.8) in the hazy days, indicating that the haze day is favorable for secondary reactions and formation of the S-rich particles.

Abstract:In this study, aerosol samples were collected in different cities, and morphologies and elemental compositions of individual particles were determined by Field Emission Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectrometer(FESEM-EDX). Size distribution of individual particles in FESEM images were further analyzed by an image analysis system. The result shows that mineral, soot, and spherical particles(fly ash and secondary particles) were dominant particles. The quantity proportionof mineral particles of Beijing aerosol was the highest, the amount of fly ash and soot of Zhengzhou aerosol was the highest, and the quantity proportionof regular mineral particles of Shenzhen aerosol was the highest in three cities. Number-size distribution of individual aerosol particles was unimodal in three cities. Particle size of Shenzhen aerosol was relatively small, followed by Zhengzhou, Beijing. Sources of individual aerosol particles of three cities were partly influenced by traffic pollution source, but the effect of coal burning on Beijing and Zhengzhou could not be ignored.

Abstract:In this paper, the effects of contacted sulfate-reducing bacteria(SRB) and metabolites(with molecular weight in the scales of 0~200, 200~2000, 2000~10000, respectively) on the reductive decomposition of gypsum were investigated, and the results showed that:① in bacterial experiments, SRB produced more alkalinity, which led to the increase of pH values; ② the decomposition of gypsum became stronger with the strengthening of the contact; ③ SRB and metabolites induced the formation of carbonates, including well crystallized calcite and amorphous carbonates; under suitable conditions, metabolites could also constrain the decomposition of gypsum. It is inferred that the adhesion of SRB and metabolites on gypsum has a significant effect on mineral decomposition. Two mechanisms can be used to explain such process:complexation between organic groups and Ca²⁺ in gypsum, and construction of microenvironment by contacted SRB with high pH and HCO₃^-.

Abstract:This paper aims to investigate the phenomena and the mechanism of the interaction between Bacillus pumilus and Ca-montmorillonite. SEM results showed that a large number of Bacillus pumilus attached to and wrapped up the surface of Ca-montmorillonite. The content of organic acids of the Bacillus pumilus-Ca-montmorillonite system decreased obviously after joining the Ca-montmorillonite. XRD results showed that the interlayer spacing of Ca-montmorillonite increased, and diffraction peak of 001 exhibited passivation after interacting with Bacillus pumilus. FTIR results showed that peaks assigned to soil bacteria appeared, and peaks of the structural groups of Ca-montmorillonite exhibited blue-shift or red-shift as well. Verification by second derivative FTIR spectroscopy analysis is that Ca-montmorillonite really shows the vibration of other group assigned to soil bacteria. It is thus inferred that there is a preliminary possibility that the metabolic products of soil bacteria enter the interlayer space of Ca-montmorillonite. The result obtained by the authors will provide a new basis for the mechanism of the interaction between mineral and microorganism.

Abstract:In this study, the methyl thiazolyl tetrazolium(MTT) colorimetric assay, micronucleus test and single cell gel electrophoresis(SCGE) were used to detect the per-millage of micronucleus, the survival rate and the degree of DNA damage of three kinds of silicate mineral dusts to V79 and A549 cells which included sericite, quartz and albite. The results show that the three kinds of silicate mineral dusts have different degrees of inhibition of cell proliferation, cell chromosome and DNA damage, with the effect from high to low being sericite >quartz >albite, and the cell proliferation inhibition rate and damage rate of DNA on V79 cells is significantly stronger than those of A549 cells. It is thus inferred that a certain concentration of silicate mineral dusts may affect the stability of the genetic material of cells and the genetic toxicity of the human body.

Abstract:Calcium phosphates were synthesized in simulated body fluid(SBF) which had the same calcium phosphate ratio with the human blood at 37℃ with different values of pH. The mineral phase and micromorphology of the products were studied by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), scanning electron microscope(SEM) and transmission electron microscope(TEM). The results indicate that mixture of crystalline dicalcium phosphate dihydrate(DCPD), octacalcium phosphate(OCP), and hydroxylapatite(HA) can be formed when the value of pH is 5.9. The DCPD are lamellar crystals with length of 10μm and width of 3μm. The OCP are also lamellar with their length being about 200 nm and the width between 50 nm and 100 nm. The rod-like HA are between 40 nm and 50 nm in length and 20 nm in width. When the value of pH is between 5.9 and 6.4, the length of crystals increases with the increase of pH and the crystals grow along axis c. When the value of pH exceeds 6.4, the product is HA and its length decreases with the increase of pH. When the value of pH ranges from 5.9 to 8.9, the crystallinity of HA decreases with the increase of pH. In the experiment, CO₂ in the air can dissolve in the mineral solution and develop into CO₃^2-, and CO₃^2- can enter the lattices of HA, which makes the composition of the synthesized HA in accordance with the biogenic carbonated hydroxyapatite.

Abstract:Synchrontron radiation performs much better than conventional light source in that it is capable of examining the mineral phase, crystal structure, morphology and chemical composition of biomineralizaiton samples in a tiny amount. Based on synchrontron radiation, the authors employed several test methods to study human breast cancer calcification, including X-ray diffraction, Fourier transform infrared spectroscopy, X-ray fluorescence and three-dimensional imaging. According to the results, breast cancer calcification is mainly composed of(carbonated) hydroxylapatite, with trace elements like Sr and Zn. The psammoma body holds special layered structure. These results provide mineralogical information for the pathological study and diagnosis of breast cancer.

Abstract:Cerebral artery calcification is closely associated with cerebrovascular diseases. In this study, mineralogical analytic techniques were applied to cerebral artery samples with atherosclerotic calcification, including scanning electron microscope(SEM), transmission electron microscope(TEM), micro-Fourier transform infrared spectroscopy(micro-FTIR), micro-area synchrotron radiation X-ray powder diffraction(μ_SRXRD) and micro-area synchrotron radiation X-ray fluorescence(μ_SRXRF). The results show that calcification mainly exists in two aggregated forms, i.e., spherical and massive. Spherical calcification has concentric layers or radiated-concentric structure, with a diameter of 0.3~5μm. Spherical calcification could be observed in the massive calcification, which is surrounded by randomly arranged prismatic crystals. The mineral phase of calcification is type-B carbonate hydroxyapatite(B-CHA), which contains Na, Mg, Zn, Fe and Sr. The mineral phase in calcification is similar to that of the minerals in cardiovascular artery calcification. Spherical calcification appears at the initial stage of calcification, which is eventually filled with CHA nanocrystals and developed into massive ca_lcification.

Abstract:The Baleigong granitic pluton, located in the western part of South Ti anshan Accretionary Orogenic Belt, Xinjiang, is composed mainly of biotite monzogranite. LA-ICP-MS zircon U-Pb analysis of two samples yielded crystallization ages of 291±3 Ma and 283±3 Ma. The pluton possesses high SiO₂(65.88%~72.99%), K₂O(4.23%~6.86%) and total alkali(K₂O+Na₂O=7.45%~9.96%) values. With respect to trace(including REE) elements, the samples are characterized by strong troughs in Ba, Nb-Ta, Sr, P and Ti, slight to moderate enrichment of LREEs and negative Eu anomalies(δEu=0.27~0.60). These features suggest that the Baleigong pluton is of A-type in genesis. Zircons from the pluton show εHf(t) values from-4.3 to +1.7 and corresponding two-stage Hf model ages from 1.20 Ga to 1.58 Ga. Zircon Hf isotope and whole-rock geochemistry implies that the parental magma was derived from the partial melting of Mesoproterozoic amphibolite-facies mafic lower crust rocks at high temperature and low pressure. The country rocks of the pluton belong to parts of ophiolitic mélange that represent the remnant of Paleo-South Tianshan Ocean. The Baleigong pluton, which was undeformed and intruded into the unit of ophiolite mélange, can be regarded as a "stitching pluton". Therefore, the final closure of the oceanic basin and the collision of continental blocks is expected to have occurred before the emplacement of the pluton(before Early Permian). On a regional scale, zircons from Early Permian granitoids and acid volcanic lavas predominately show Late Paleoproterozoic to Late Mesoproterozoic two-stage Hf model ages, implying that sources for those felsic magmas were dominantly composed of ancient crustal rocks with negligible juvenile materials.

Abstract:Exposed in the middle segment of the Palaeoproterozoic Trans-North China Orogen, the Yixingzhai pluton on the southern slope of the Hengshan Mountain and the Chechang-Beitai pluton on the northern slope of the Wutai Mountain experienced amphibolite facies metamorphism and were cut by metamorphosed diabase dykes. The Yixingzhai pluton consists of transitional granodioritic gneiss, quartz dioritic gneiss and dioritic gneiss. Its metamorphic peak p-T conditions are estimated to be of 710~760℃/0.65~0.75 GPa and the retrograde metamorphism occurred at 560~690℃/~0.46 GPa. The metamorphic peak is ascribed to typical middle p-T facies series. K-Ar dating of metamorphic hornblende suggests that the metamorphic peak occurred at about 1.84~1.82 Ga. The Chechang-Beitai pluton consists of biotite-muscovite granitic gneiss and the metamorphic peak p-T conditions are estimated to be of 550~690℃/0.92~1.14 GPa, belonging to the top middle p/T facies seies. K-Ar dating of metamorphic biotite implies that the metamorphic peak occurred at about 1.80 Ga. Geochronologic research indicates that these two plutons were involved in the late Palaeoproterozoic orogenic event of Trans-North China Orogen deciphered at about 1.96~1.80 Ga.