Low Zr Research Articles

Theoretical versus empirical secular change in zircon composition

We generate theoretical curves for zircon growth during cooling of tonalitic and A-type granitic magmas and compare these with empirical Ti-in-zircon populations from the Paleoarchean Pilbara Craton, Australia, Mesoarchean Akia Terrane, Greenland, and the Mesoproterozoic Musgrave Province, Australia. Our models predict variable zircon growth rates on magma cooling dependant on magma composition, crystallizing assemblage, and zircon growth process. In most modelled magma compositions, higher-temperature grains growing close to the zircon saturation temperature are more abundant, with yields decreasing continuously thereafter. However, there are important dissimilarities in the cumulative zircon growth curve for different magma compositions and whether zircon growth is by equilibrium or disequilibrium processes. For a given starting melt Zr concentration, A-type granite magmas grow zircon at higher temperatures than tonalitic magmas. This compositional distinction is most pronounced at lower starting melt Zr concentrations, and in low Zr tonalite the rate of zircon growth may even increase on cooling. The dependence of zircon growth on magma composition and crystallization process leads to predictive differences in cumulative Ti-in-zircon distributions. Greater disequilibrium growth yields more sigmoidal cumulative growth curves that are dissimilar to predictions from phase equilibrium models. When applied to Mesoarchean-aged zircon grains from the Akia Terrane, calculated Ti-in-zircon temperatures decrease over the 3100–2900 Ma interval. This magmatic episode also reveals a change in cumulative zircon growth curve topology from steeper to shallower, consistent with a reduction in the relative proportion of disequilibrium growth, greater crystal–liquid communication, and enhanced infracrustal reworking. The temporal variability in cumulative zircon growth and its implication for melt interconnectedness are powerful tools in understanding magmatic processes and indicate an important secular change point at c. 3.0 Ga in the Akia Terrane where zircon growth dynamics changed.

Achieving low-temperature Zr alloying for microstructural refinement of sand-cast Mg-Gd-Y alloy by employing zirconium tetrachloride

The large size and uneven distribution of Zr particles always lead to a high alloying temperature and low Zr yield when MgZr master alloy is used for grain refinement of sand-cast Mg-RE alloys. In this research, the feasibility of Zr alloying by applying ZrCl4 in sand-cast GW83 alloy at a low temperature (720 °C) was investigated. The interaction procedure between ZrCl4 and Mg melt, and corresponding grain refinement mechanisms were systematically studied by thermodynamic calculation, thermal analysis, and microstructure characterization. The results showed that the yield of Zr by applying ZrCl4 was higher than that of the MgZr master alloy. Zr can be generated via the in-suit reaction between ZrCl4 and Mg. Both the nucleation temperature and nucleation undercooling increased with the increasing addition of ZrCl4. The average grain size decreased from 832 μm to 229 μm with 2.606 wt% ZrCl4 addition due to the heterogeneous nuclei of Zr particles and the constitutional supercooling provided by solute Zr. A corresponding physical model depicting the solidification behavior and grain refinement mechanism was proposed. However, the ZrCl4 addition of 4.343 wt% led to a large amount of RECl3 inclusions generated during the Zr alloying process, deteriorating the mechanical properties of the alloy.

The effect of alloying elements on densification and mechanical behaviour of titanium based alloy

The allotropic behavior of titanium is affected by many factors such as processing temperature and alloying elements. Using processing method with parameters that enhaces properties of the resulting alloy is imperative. In this study, CP-Ti, binary systems Ti-1Nb, Ti-1Zr and ternary Ti-1Nb-1Zr, were produced using spark plasma sintering method at 1200˚C at the heating rate of 100˚C/min, a 10 min holding time and pressure of 50 MPa. The microstructures were analyzed by an optical microscope and scanning electron microscope and the XRD was used to examine phases formed. Furthermore, the microhardness and the compressive behavior of the materials were analyzed for mechanical properties. The microstructures obtained were of α phase for the CP Ti and Ti-1Nb binary alloy, and it was found to be α׳ for Ti-1Zr and Ti-1Nb-1Zr. The α׳ alloys had relatively the highest hardness at about 218HV and 225 HV for Ti-1Zr and Ti-1Nb-1Zr respectively. The developed alloys had densities above 99%. The results also showed that even at low additions, Zr and Nb improved the properties of CP-Ti, making them good contenders for biomedical implant applications.

Diagenetic history and provenance of Devonian terrestrial sandstones at the margin of Gondwana: Padeha Formation, Eastern Alborz, Iran

• The northern margin of Gondwana in Iran rifted in the Devonian, forming a passive continental margin to the Paleotethys Ocean. • The Padeha sandstones were sourced by the late Neoproterozoic granitic gneisses of Iran. • Further mesodiagenesis was terminated by the Eocimmerian collision. The northern margin of Gondwana in Iran rifted in the Devonian, forming a passive continental margin to the Paleotethys Ocean, the details of which are obscured by later collision. A record of the early phase of opening of Paleotethys is preserved in the 600-m thick Padeha Formation, a Middle Devonian terrestrial rift basin succession. The sandstones are quartz arenite, sub-arkose and arkose and contain minimal detrital matrix (~1%). Bulk-rock geochemistry, according to major elements, suggests a source to the sandstones that was dominated by I-type granite, but also, based on trace elements, included small amounts of intermediate or mafic rocks. Low Zr and HREE contents suggest little or no sandstone in the source area and thus low abundance of fine-grained heavy minerals (<1%). The sandstones were sourced by the widespread granitic gneisses of central and northern Iran that formed at the northern margin of Gondwana in the late Neoproterozoic–Ediacarian. Diagenesis of the sandstones is dominated by compaction and fracturing of framework quartz without widespread stylolites in the sandstones, and cementation by silica, carbonates and Fe-oxides. Fractures within quartz grains are filled mostly by silica, but locally by carbonate and authigenic K-feldspar. Albitization of plagioclase, K-feldspar overgrowths and partial dissolution of detrital K-feldspar post-date silica cements and suggest temperatures between 70 and 120 °C. The particular diagenetic assemblage of altered K-feldspar and limited quartz stylolites was a consequence of a high geothermal gradient of ~70 °C/km at a burial depth of <1.5 km. Further mesodiagenesis was terminated by the Eocimmerian collision.

New light on plant ash glass found in Africa: Evidence for Indian Ocean Silk Road trade using major, minor, trace element and lead isotope analysis of glass from the 15th-16th century AD from Malindi and Mambrui, Kenya.

Seventeen glass vessels and twenty glass beads recovered from the excavations at the ancient city of Malindi and the archaeological site of Mambrui in Kenya, east Africa were analysed using electron probe microanalysis (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The results show that all of the glass samples are soda-lime-silica glass. They belong to the high alumina -plant ash glass type, characterised by high alumina and relatively low calcium contents, widely distributed in eastern (10th– 16th centuries AD) and southern Africa (13th - 15th centuries AD), Central Asia (9th– 14th centuries AD) and southeast Asia (12th– 13th centuries AD), made with plant ashes and sands. This is an understudied glass type for which previous research has indicated there were three types. When compared with published research on such glasses using Zr, Ti, Ba, Cr, La, Li, Cs, Na2O, MgO and CaO we have identified at least four different compositional groups of v-Na-Al glass: Types A, B, C and D. By comparing the results with contemporary v-Na-Al glass vessels and beads from Central Asia, Africa, and southeast Asia we show that most of the Malindi and Mambrui glass share similar characteristics to the compositions of Mapungubwe Oblate and some of the Madagascar glass beads from southern Africa. They belong to Type A v-Na-Al glass which is characterised by an elevated level of Ti and Ba and a relatively high ratios of Cr/La, relatively low Zr concentrations and low ratios of Zr/Ti. Differences in Zr, Li, MgO and Na2O concentrations in Type A glass indicates that there are subgroups which might derive from different glass workshop(s) specialising in Type A v-Na-Al glass production. Comparison with the chemical compositions of glass from Ghazni, Afghanistan and Termez, Uzbekistan, and by using lead isotope analysis, we suggest v-Na-Al glass was manufactured in Central Asia and possibly worked into vessels and beads there.

Differentiating between Inherited and Autocrystic Zircon in Granitoids

AbstractInherited zircon, crystals that did not form in situ from their host magma but were incorporated from either the source region or assimilated from the wall-rock, is common but can be difficult to identify. Age, chemical and/or textural dissimilarity to the youngest zircon fraction are the primary mechanisms of distinguishing such grains. However, in Zr-undersaturated magmas, the entire zircon population may be inherited and, if not identifiable via textural constraints, can lead to erroneous interpretation of magmatic crystallization age and magma source. Here, we present detailed field mapping of cross-cutting relationships, whole-rock geochemistry and zircon textural, U–Pb and trace element data for trondhjemite, granodiorite and granite from two localities in a complex Archean gneiss terrane in SW Greenland, which reveal cryptic zircon inheritance. Zircon textural, U–Pb and trace element data demonstrate that, in both localities, trondhjemite is the oldest rock (3011 ± 5 Ma, 2σ), which is intruded by granodiorite (2978 ± 4 Ma, 2σ). However, granite intrusions, constrained by cross-cutting relationships as the youngest component, contain only inherited zircon derived from trondhjemite and granodiorite based on ages and trace element concentrations. Without age constraints on the older two lithologies, it would be tempting to consider the youngest zircon fraction as recording crystallization of the granite but this would be erroneous. Furthermore, whole-rock geochemistry indicates that the granite contains only 6 µg g–1 Zr, extremely low for a granitoid with ∼77 wt% SiO2. Such low Zr concentration explains the lack of autocrystic zircon in the granite. We expand on a differentiation tool that uses Th/U ratios in zircon versus that in the whole-rock to aid in the identification of inherited zircon. This work emphasizes the need for field observations, geochemistry, grain characterization, and precise geochronology to accurately determine igneous crystallization ages and differentiate between inherited and autocrystic zircon.

Assessment of magmatic fertility using pXRF on altered rocks from the Ordovician Macquarie Arc, New South Wales

This research presents a new method for assessing magmatic fertility using the portable X-ray fluorescence spectrometer (pXRF) in altered rocks from porphyry terranes. A study of Northparkes and global Cu--Au porphyries highlighted low Zr and Y trends associated with mineralising intrusions. Zircon saturation occurs at low Zr concentrations owing to low-temperature crystallisation depressed by high dissolved H2O in the melt. Yttrium depletion indicates hydrous magmatic conditions that cause hornblende to crystallise early. Previously geochemical differentiation of hydrous, potentially ore-forming (fertile) porphyries has relied on ratios of Sr/Y and Sr/MnO from geochemical and/or pXRF analysis of least altered rocks. Strontium is highly mobile and limits its use in altered terranes. Finding samples in porphyry terranes where Sr can be demonstrated to be retained is difficult given the ubiquity of alteration associated with porphyry emplacement. This precludes the widespread use of pXRF, as quantitative assessment of alteration is beyond the capabilities of pXRF technology. Using immobile elements overcomes issues with alteration and provides more reliable indicators of magmatic fertility. Using a systematic pXRF workflow, plots of Zr vs Y and Zr*Y vs Al2O3/TiO2 were successful in identifying 100% of the mineralising intrusions in the Northparkes intrusive complex and provide an indication of magmatic fertility and a proxy for melt hydration state. The ratios of Zr/Nb vs Y/Nb are insensitive to alteration including weathering and are indicative of evolution and dissolved H2O content of magmatic sources. Moving from bivariate plots to ratio plots shifts the data into a real-number space and provides a linear function to assess against magmatic fertility. Application of the fertility indicators to a regional dataset from New South Wales highlights areas of known porphyry mineralisation indicating that the method has the potential to be a useful indicator of fertility beyond the scope of the pilot study. KEY POINTS The fertility of porphyry intrusions is directly related to their dissolved H2O content and oxidation state. High dissolved H2O content in magmas causes early crystallisation of hornblende, and temperature depression. As a result Zr saturation occurs at low Zr concentrations that results in depletion of Y and the MREE in hydrous rocks compared with normal arc rocks. Magmatic fertility can be rapidly and cheaply assessed in the field using Zr and Y concentrations from pXRF analyses. The use of immobile elements facilitates magmatic fertility assessment in altered rock, which was previously impossible owing to the use of mobile elements Sr and MnO.

Geochemistry of two types of Palaeoproterozoic granites, and zircon U–Pb dating, and Lu–Hf isotopic characteristics in the Kuandian area within the Jiao‐Liao‐Ji Belt: Implications for regional tectonic setting

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

Geomorphic expressions of collisional tectonics in the Qilian Shan, north eastern Tibetan Plateau

The Qilian Shan, north eastern Tibetan Plateau, is an area of active deformation caused by convergence in the India-Eurasia collision zone. Geomorphic indices capture the landscape response to competition between tectonics and climate, reflecting the spatial distribution of erosion. We use geomorphic indices (hypsometric integral (HI), normalised channel steepness (ksn), elevation-relief ratio (ZR) and surface roughness (SR)) to identify areas of active deformation and erosion, highlight landscape variations and we interpret the results for potential tectonic and climatic drivers. High HI (> 0.15), ksn (> 100) and low ZR (< 2) occur in the hanging wall of thrust faults, consistent with active uplift of these structures. Relatively high HI (> 0.15) and ksn (> 100) values in the eastern region are attributed to thrust parallel rivers in this region excavating wide valleys between the faults. The east-west precipitation variation across the Qilian Shan (>500 mm/yr to <100 mm/yr) is not a first order control on the regional landscape. There is an abrupt northwards transition from low to high HI, ksn and SR and high to low ZR partially coincident with the left-lateral Haiyuan Fault. We suggest that this transition is due to a difference in deep structure. A south-to-north transition from creeping to locked behaviour on an underlying detachment thrust has previously been suggested to occur along the intersection of this thrust detachment with the overlying Haiyuan Fault, providing a potential explanation for the location of the geomorphic change. Our results show these geomorphic indices to be sensitive to the underlying tectonic structure of the area. These methods could be applied to other fold-and-thrust belts and tectonic settings, to help understand the underlying structure, and the processes responsible for deformation.

Structure, Acidity, and Redox Aspects of VOx/ZrO2/SiO2 Catalysts for the n-Butane Oxidative Dehydrogenation

ZrOx/SiO2 and VOx/ZrOx/SiO2 catalysts (5 wt %–25 wt % Zr, 4 wt % V) were prepared by grafting zirconium and vanadium alkoxides on Aerosil 380. All samples were characterized by temperature programmed reduction, N2 physisorption, X-ray diffraction, Raman spectroscopy, and ammonia adsorption microcalorimetry. Tetragonal ZrO2 and zircon (ZrSiO4) were present at 25 wt % Zr, but only amorphous zirconia overlayer existed for lower loadings. At lower Zr loadings (5 wt %–10 wt % Zr), exposed silica surface leads to V2O5 crystallites and isolated VO4 species, although V reducibility behavior changes, from being similar to VOx/SiO2 (5 wt % Zr) to showing VOx/ZrO2 behavior at 10 wt % Zr, and a diminished total amount of reducible V. Highly acidic ZrO2 sites are covered by the vanadium grafting, forming weaker sites (60–100 kJ/mol NH3 adsorption strength). Catalytic conversion and selectivity for the oxidative dehydrogenation of n-butane (673 K, n-C4/O2 = 2.2) over VOx/ZrOx/SiO2 show that 1,3-butadiene is favored over cis-2-butene and trans-2-butene, although there is some selectivity to the 2-butenes when VOx/ZrO2 behavior is evident. At low Zr loadings, butadiene formed during reaction acts as the diene species in a Diels–Alder reaction and gives rise to a cyclic compound that undergoes further dehydrogenation to produce benzaldehyde.

Preparation and Characterization of Metal Oxide Sensors and Their Application for the Detection of Organophosphate Insecticides

This study focuses on the synthesis and characterization of metal oxides doped with transition metals with the purpose of enhancing their sensitivity to detect organophosphate insecticides, Chlorpyrifos and Malathion, on air. The moderate toxicity of these organophosphorus pesticides and their extensive use in small-scale agriculture reveals the urgency of continuous air quality monitoring in the work environments of communities with restricted access to sophisticated techniques for detecting these contaminants, such as high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS).The selected metal oxides are Zr doped zinc oxide (ZnO) and tin oxide (SnO2) doped with both Pt and Zr. These semiconductors (ZnO and SnO2) have the advantage of showing a sensing response at low working temperatures, in the range of 200°C and 250°C. Additionally, both have great thermal and chemical stability. The synthesis of ZnO is performed through the application of a hydrothermal synthesis methodology in an autoclave; while ZnO doping is conducted by adding the dopant precursor (ZrOCl2) to the reaction mixture. In the case of SnO2, commercial tin oxide is used for doping with Zr and Pt. The doping process was carried out in two separate processes: 1) mechanical mixing and sintering of ZrO2 and SnO2, and 2) chemical reduction of H2Cl6Pt with SnSO4 on the surface of SnO2. The characterization of these materials is carried out by employing X-ray diffraction (DRX), Fourier-transformed infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), scanning electron microscopy / energy dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM) and sorption of N2 analysis. In addition, the quantification of pesticide concentration in commercial samples, that are used in the sensing essays, is performed with HPLC.The Pt doped SnO2 is prepared with a content of Pt between 0.05 and 0.2 wt. %, while the concentration of Zr is in the range of 0.3 and 0.7 wt. %. In the case of ZnO, the concentration of Zr is between 0.9 and 2.0 wt. %. The characterization by DRX reveals a substitutional doping for both materials. Additionally, the dopants produce an increase of the lattice strain and a small contraction of the unit cell in both metal oxides. The SEM analysis of Zr doped ZnO allows to identify changes in their morphology, which confirms an increase in particle size at Zr concentration of 2.0 wt. % in comparison to 1.2 wt. %.The sensing tests of the doped metal oxides are evaluated in an electronic nose. This equipment allows to test four sensors each time and the vapors of the pesticides are produced through a bubbling process of a liquid suspension of one organophosphate insecticide in water. The prepared doped oxides present an enhanced sensibility for the detection of organophosphates on air. Response signals are obtained with greater stability for long sensing times with zinc oxide sensors doped with Zr at 2.0 wt. % in comparison to sensors of Zr doped ZnO with lower Zr content.A study of the optimum temperature conditions (between 210°C and 220°C) and concentration of the dopant in zinc oxide and tin oxide is carried out. The temperature has a positive effect on the sensitivity of all the sensors tested. At the test temperature of 220°C, the sensitivity of the best sensors (AT-Zr-2.0-ZnO and Pt-0.13-ZrO2-0.15-SnO2) for Malathion can be maximized. In the case of Chlorpyrifos, better results are obtained for the Pt-0.13-ZrO2-0.15-SnO2 sensor, whose signal is favored at 210°C. In addition, the sensitivity of Pt-0.13-ZrO2-0.15-SnO2 with respect to AT-Zr-2.0-ZnO at 220°C is higher for Chlorpyrifos, but lower for Malathion.The statistical treatment method of principal component analysis (PCA) allows the evaluation of the signals of samples with different concentrations of pesticides. The best PCA, obtained with the data of the measurements using the most sensitive sensors, show a total explained variance greater than 90% and a better differentiation between air samples contaminated with pesticides and air samples without contamination. Figure 1

Dependence of macromagnetic properties on the microstructure in high-performance Sm2Co17-type permanent magnets

Microstructure characteristics are important for the high-performance Sm2Co17-type permanent magnets to achieve high intrinsic coercivity (Hcj) and large magnetic field at the knee-point (Hknee). In this work, the correlation between microstructures and magnetic properties has been systematically studied. The different microstructures were obtained by two procedures: by adjusting the aging temperature and optimizing the Zr content. On one hand, with increase of aging temperature from 1063 K to 1103 K, the cell size and the lamellar phase density increase from 75.1 nm and 0.014 1/nm to 101.5 nm and 0.043 1/nm, respectively, and the average peak Cu concentration at the cell boundaries reaches 21.9 at% which is helpful for obtaining relatively high Hcj and Hknee. As the aging temperature increases further to 1143 K, a much larger cell size and with incomplete cell boundaries results in an irregular distribution of Cu concentration at the cell boundaries. In this case, the Hknee is low even though the magnet shows a high Hcj. On the other hand, the increase of Zr content also promotes an increase in both the lamellar phase density and the average peak Cu concentration at the cell boundaries, giving rise to high Hcj and Hknee. Taking into consideration the aging temperature and Zr content, one can conclude that a lower aging temperature and lower Zr content produce a lower lamellar phase density and average Cu concentration at the cell boundaries and this leads to a lower Hcj and Hknee of the magnets. To further confirm this correlation between the microstructures and magnetic properties, a magnet of Sm(CobalCu0.062Fe0.285Zr0.016)7.6 was aged at a higher temperature of 1143 K to increase the lamellar phase density. As expected, the lamellar phase density increases from 0.008 to 0.013 1/nm; however, the cell size increases simultaneously from 142.5 to 247 nm. The magnet exhibits a much higher but uneven Cu concentration at the cell boundaries. As a result, the Hcj increases from 1.64 to 10.18 kOe, while Hknee just increases from 1.09 to 3.91 kOe.

Tantalum and zirconium induced structural transitions at complex [111] tilt grain boundaries in copper

Alloying nanocrystalline copper (Cu) with immiscible elements, such as tantalum (Ta) and zirconium (Zr), is a promising technique to manipulate grain boundary properties and by this suppress grain growth at elevated temperatures. However, insights on the atomistic origins on the influence of impurity elements on grain boundaries are lacking. In this study, the atomistic effects of Ta and Zr on [111] tilt grain boundaries in Cu are investigated by high resolution scanning transmission electron microscopy techniques. In case of Ta, the formation of spherical, nano-scale precipitates in close vicinity to the grain boundaries is observed, but no sign of segregation. The particles induce a repelling force to migrating boundaries and act as local pinning points. The segregation of Zr is observed to occur either at confined grain boundary steps or homogeneously along the boundaries without steps. In both cases a strong disordering of the defect or grain boundary structure is revealed. Furthermore, at low Zr concentrations it induces structural grain boundary transitions and partial atomic reordering of the grain boundary structural units.

Study of non-centrosymmetric to centrosymmetric structural transformation in Zr-doped Barium Titanate

ABSTRACTNon-centrosymmetric to centrosymmetric structural transformation of BaZrxTi1−xO3 (x = 0, 0.05, 0.1, 0.3) as prepared by soilid state reaction was investigated from X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), pair distribution function (PDF) and Raman spectra. Tetragonal BaTiO3 transformed to orthorhombic phase for lower Zr concentration (x = 0.05) and changed to tetragonal to cubic with increasing Zr concentration at room temperature. Dielectric constant changed with the addition of Zr due to the change in local atomic arrangement and achieved highest value 1444 for mole fraction x = 0.1. Change occurred in the intensity for the first Ti–O pair in the PDF pattern due to the incorporation Zr in barium titanate lattice. An extra shoulder due to addition of Zr for the cubic phase of BZT has appeared at 5.64 Å in the PDF pattern. Structural and electrical properties of BZT were influenced by additions of Zr due to the change in local atomic arrangement.

Geochemistry and geochronology of Carboniferous magmatic rocks in the Sawur Mountains, northern West Junggar, NW China: implications for accretionary orogeny

The accretionary orogeny of the Central Asian Orogenic Belt (CAOB) has been a popular topic over the past decades due to its complex tectonic process. The Carboniferous magmatism in the Sawur Mountains of the northern West Junggar plays an important role in understanding the accretionary process of West Junggar. Detailed geological mapping has revealed that the Carboniferous Heishantou Formation in the Sawur Mountains consists mainly of pillow lavas, basaltic andesites, dacites, tuffs and sedimentary rocks, which were intruded by the Lasite intrusion. The pillow lavas display low SiO2 and TiO2 as well as high MgO and FeOt contents and enrichment in light rare earth elements (LREEs) and Nb–Ta, suggesting derivation from an enriched lithospheric mantle in an oceanic island setting. With the oceanic crust subduction, they were scraped off and accreted in a fore-arc setting. Basaltic andesites exhibit high SiO2 and Al2O3 contents, low Mg#, Zr, and Nb contents as well as Nb/La ratios, and a clear depletion of Nb–Ta, indicating derivation from a mantle wedge affected by the inputs of slab-derived fluids in an island arc setting. Dacites possess calc-alkaline and adakitic geochemical features with high Sr and Ba contents, high Th/Yb ratios, enrichment in LREEs, low Nb/La ratios, a depletion of Nb–Ta and positive eHf(t) values (10.3–15.0). Accordingly, they are interpreted as being derived from the melting of subducted oceanic crust mixed with minor sediments in an island arc setting. Magmatic zircons from dacite yield a weighted 206Pb/238U mean age of 326.8 ± 1.6 Ma, constraining the crystallization age of the dacite as well as the timing of the oceanic crust subduction. The Lasite intrusion that intruded the Heishantou Formation is K-feldspar granite, exhibiting pronounced I-type affinity and a high potassic calc-alkaline series. This granite shows low Na2O and Mg# (36.9–40.3) values; low Zr and Y contents as well as 10,000 × Ga/Al ratios; high LREE, K and Pb contents; and a depletion of Nb and Ta. Altogether, the low (87Sr/86Sr)i (0.7037–0.7043) and positive eNd(t) (6.22–6.36) and eHf(t) (10.1–15.5) values suggest that the granites were derived from the partial melting of a juvenile lower crust affected by mantle materials in a subduction setting. The zircon weighted 206Pb/238U mean age of 316.6 ± 2.8 Ma represents the intrusive age of the granite and related subduction during the late Carboniferous. All of the above geochemistry and geochronology of the magmatic rocks constrain the subduction–accretion tectonics in the Sawur Mountains of the northern West Junggar during ~ 327–317 Ma and confirm the subduction of the Paleo-Asian Ocean (PAO) lasted until the late Carboniferous in this region.

Porphyry fertility in the Northparkes district: indicators from whole-rock geochemistry

Four economic porphyry Cu–Au deposits and several prospects have been investigated in the Northparkes district, part of the Ordovician to early Silurian Junee–Narromine Belt of the Macquarie Arc, New whole-rock geochemical data from the Northparkes porphyry Cu–Au district, NSW, indicate that the mineralising intrusive complexes exhibit distinct arc signatures that are transitional from high-K calc-alkaline to silica-saturated alkalic. Based on ratios of Sr/Y vs Y (e.g. Sr/Y > ∼20 and Y < ∼17 ppm) the mineralising intrusions are interpreted to have crystallised from fractionated hydrous melts indicating the suppression of plagioclase crystallisation in favour of hydrous mineral phases. This interpretation is supported by listric-shaped rare earth element curves and the presence of primary hornblende phenocrysts indicating elevated magmatic water contents. There is an association of mineralising intrusions with a low Zr trend both in the mineralised Northparkes district intrusive rocks and in mineralised porphyry-related intrusive rocks globally. A newly developed fertility indicator ratio Zr/Y ∼10% is more accurate at identifying the mineralised rocks at Northparkes than the conventional Sr/Y vs Y fertility indicator diagram, successfully identifying 92% of the mineralising intrusions, mainly owing to the fact that it is less affected by hydrothermal alteration. The insensitivity of Zr–Y to alteration makes this indicator a useful new tool that may lead to enhanced probabilities for future discoveries in the Northparkes district, broader Macquarie Arc and altered rocks globally.KEY POINTSMineralising intrusions in the Northparkes district have distinct Zr vs Y concentrations.The Zr vs Y indicator of magmatic fertility is less sensitive to alteration than Sr-based indicators.The Zr vs Y magmatic fertility indicator identified at Northparkes is not unique and identifies mineralising intrusions in other porphyry fields.

Geochemistry, zircon geochronology, and isotopic systematics of the Zhanbuzhale granites in the East Kunlun, Qinghai Province, northwestern China: implications for the tectonic setting

The Zhanbuzhale region, in the Eastern Kunlun Orogen of northwestern China, is characterized by large volumes of Phanerozoic granitoid rocks and is an ideal region for investigating the tectonic evolution of the Paleo-Tethys system. However, the exact timing of the final closure of the Paleo-Tethys Ocean and initial continental collision remains controversial because of a lack of precise geochronological and detailed geochemical data. In this paper, we report new zircon U–Pb ages and mineralogical, petrographic, and geochemical data for samples of Middle Triassic granodiorite and alkali feldspar granite from the Zhanbuzhale region. The zircon U–Pb ages indicate that the granodiorite and alkali feldspar granite formed at 239 and 236 Ma, respectively. The granodiorites are high-K calc-alkaline, metaluminous, high Sr content, high Sr/Y ratios, low Y content, and show adakite-like affinities. The alkali feldspar granites display high SiO2, extremely low MgO, and low Zr+Nb+Ce+Y contents as well as low Fe2O3t/MgO ratios, showing metaluminous to peraluminous and high-K calc-alkaline features. Geochemical and petrological characteristics of the alkali feldspar granites suggest that they are highly fractionated I-type granites. The granodiorites and alkali feldspar granites have zircon εHf(t) values ranging from –2.26 to –0.18, and from –2.17 to +2.18, respectively. Together with regional geological data, we propose that the Triassic (approximately 239–236 Ma) granitoids were generated during the later stages of northward subduction of the Paleo-Tethys oceanic plate, and that the initial stage of collision between the East Kunlun and the Bayan Har–Songpan Ganzi terrane occurred at approximately 236–227 Ma.

The Permian Sn metallogenic event and its geodynamic setting in East Kunlun, NW China: Evidence from zircon and cassiterite geochronology, geochemistry, and Sr–Nd–Hf isotopes of the Xiaowolong skarn Sn deposit

Abundant granitoids are exposed along the East Kunlun orogenic belt (EKOB), and many skarn deposits occur at the contacts between intrusions and strata. One such is the Xiaowolong deposit, a skarn-type tin polymetallic deposit that is temporally and spatially associated with porphyry monzogranite. Tin mineralization is mainly hosted by the skarn. In this study, we reported zircon and cassiterite U–Pb ages, whole-rock geochemistry, and Sr–Nd–Hf isotopic data, and used these to constrain the timing of intrusion and mineralization in the Xiaowolong deposit and identify the origin of the ore-related granites and the link between Sn mineralization and granitic magmatism. Age determinations by LA-ICP-MS U–Pb zircon dating indicated that the porphyry monzogranite formed at 260.0 ± 0.7 Ma. Cassiterite from the ore-bearing skarn yielded a Tera-Wasserburg U–Pb lower intercept age of 258.0 ± 3.7 Ma. These ages suggested that both granitic intrusion and related Sn mineralization in the Xiaowolong deposit were initiated during the Permian (ca. 260 Ma). The porphyry monzogranites had high SiO2 (71.26–73.13 wt%) and Al2O3 (13.84–14.46 wt%) contents, were alkali-enriched (K2O + Na2O = 7.08–7.69 wt%), had A/CNK values that ranged from 1.01 to 1.05, were enriched in light REEs and large ion lithophile elements such as Rb, Th, U and K, were depleted in high field strength elements, and had relatively low Zr, Nb, Y and Ce contents. They thus exhibited the geochemical characteristics of I-type granite. The porphyry monzogranite had consistent negative whole rock ɛNd(t) (−6.8 to −7.1) and magmatic zircon ɛHf(t) values ranging from −7.4 to −1.6, and two-stage Hf model ages ranging from 1393 Ma to 1758 Ma. Detailed elemental and isotopic data demonstrated that the porphyry monzogranite were derived from partial melting of ancient crustal source, and emplacement in a subduction tectonic setting. The Xiaowolong tin mineralization event indicated that the EKOB has great potential for exploration focusing on Permian-Triassic Sn skarn deposits.

Effects of process parameters on the mechanical properties of additively manufactured Zr–1Mo alloy builds

In order to solve the artifact problem in magnetic resonance images, a low magnetic Zr–1Mo(wt%) alloy with high mechanical performance was successfully fabricated by laser powder bed fusion (L-PBF) using gas-atomized Zr–1Mo alloy powder. The as-built Zr–1Mo alloy showed superior strength and elongation compared to the as-cast Zr–1Mo alloy due to grain refinement and the inexistence of large casting defects. The microstructure of L-PBF-processed Zr–1Mo alloy builds was not sensitive to process parameters. On the other hand, morphology and distribution of defects, interstitials concentration, and crystallographic orientation comprehensively influenced the mechanical properties of the builds. Increasing interstitials concentration caused by increasing energy density render to increasing strength. Large pores caused by balling effect lead to a severe decrease of both strength and ductility of builds using high energy density (over 70.3 J·mm−3) and high scanning speed (1050/1200 mm·s−1). On the contrary, spherical pores possessing several microns in size has much less effect on mechanical properties than the large-size pores. There are two kinds of texture({1 1 0}α texture and {1 1 0}α+{1 0 2}α bi-texture) were confirmed in this study. {1 1 0}α texture contributed to the slight increase of elongation with increasing energy density in low scanning speed case (600/750 mm·s−1) and the superior elongation of low scanning speed specimens compare to that of high scanning speed specimens in medium energy density range (about 48 J·mm−3). From the viewpoints of the ultimate tensile strength(UTS) and elongation, it was found that an energy density of 84.4 mm·s−1 with a scanning speed of 600 mm·s−1 is preferable for the L-PBF-processed Zr–1Mo alloy in this study. These experimental results may provide direct guidelines regarding the applicability of Zr–1Mo alloy fabricated by L-PBF for biomedical applications.

Analysis of prehistoric glass from Slovenia

A series of prehistoric glass beads and other glass items (bracelets, brooches with glass overlays, spindles, amphoriskos) from Slovenia was analyzed by a combined PIXE-PIGE method. The items were selected from seven late prehistoric horizons spanning uniformly from the 11th c. BCE to 2nd and 1st c. BCE. Totally 74 measurements on 60 objects were made on bulk material and on some ornamental bands. The beads of the Late Bronze Age (LBA) were made of mixed alkalis that we estimate to be plant ash origin (precipitated potash and non-precipitated ash of halophytic plants). According to the type of pigmentation (Co or Cu) there are hints, either direct or indirect, to connect particular beads with Egyptian workshops. Egyptian influence continues well into the Early Iron Age (EIA), until the 5th c. BCE when the low Zr values signalize glass of Levantine origin. Sorting the measured glass by discriminant analysis considering the elements Al, Ti, Mn and Fe we observe grouping of the beads according to historic horizons. This indicates particular beads were made in specific workshops and spread over a large area by exchange and commerce. Local production for traded or recycled glass may be presumed in LBA, as well as in later phases of the EIA, around 5th–4th c., when the beads show a variety of forms.