ORCID Profile
0000-0002-9952-6584
Current Organisation
Australian National University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Geology | Igneous and Metamorphic Petrology | Inorganic Geochemistry | Ore Deposit Petrology | Mineralogy and Crystallography | Mineralogy And Crystallography | Igneous And Metamorphic Petrology | Seismology and Seismic Exploration | Structural Chemistry | Chemical Spectroscopy | Geochemistry | Transition Metal Chemistry | Physical Chemistry (Incl. Structural) | Structural Chemistry and Spectroscopy | Exploration Geochemistry | Exploration Geochemistry | Geology | Instruments And Techniques | Geochronology | Extraterrestrial Geology | Resource geoscience | Mineralogy and crystallography | Exploration geochemistry | Geochemistry not elsewhere classified |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Earth Sciences | Earth sciences | Chemical sciences | Copper Ore Exploration | Conserving Collections and Movable Cultural Heritage | First Stage Treatment of Ores and Minerals not elsewhere classified | Physical sciences | Production of Unrefined Precious Metal Ingots and Concentrates | Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Physical Sciences | Expanding Knowledge in Engineering | Precious (Noble) Metal Ore Exploration | Titanium Minerals, Zircon, and Rare Earth Metal Ore (e.g. Monazite) Exploration | Diamond Exploration
Related Links
Publications
A Picture of Disorder in Hydrous Wadsleyite—Under the Combined Microscope of Solid-State NMR Spectroscopy and Ab Initio Random Structure Searching
Publisher: American Chemical Society (ACS)
Date: 24-01-2019
DOI: 10.1021/JACS.8B11519
Oxidation state of iron in komatiitic melt inclusions indicates hot Archaean mantle
Publisher: Springer Science and Business Media LLC
Date: 10-2008
DOI: 10.1038/NATURE07377
Titanium-hydroxyl defect-controlled rheology of the Earth's upper mantle
Publisher: Elsevier BV
Date: 10-2016
Fractional crystallisation of eclogite during the birth of a Hawaiian Volcano
Publisher: Springer Science and Business Media LLC
Date: 26-05-2022
DOI: 10.1038/S41467-022-30108-X
Abstract: The initial melts erupted by a Hawaiian volcano have a range of alkalic compositions but are rarely observed as they are covered by enormous volumes of shield stage tholeiites. A remarkable record of the early evolution of Hawaiian volcanoes, however, is preserved by a volcanic sandstone dredged from the submarine flank of Kilauea, which contains a suite of petrogenetically related pre-shield basanite to nephelinite glasses. Here we show that the systematic variation in the rare earth element (REE) patterns of these s les requires the fractional crystallisation of garnet. A fractionating assemblage of Ca-rich garnet (32%), omphacitic clinopyroxene (63%), and minor phlogopite can explain the variation in the major and trace element contents of the suite. The results suggest fractional crystallisation of eclogite from a primitive Hawaiian melt near the base of the lithosphere ( km) and that a deep magma chamber is the first stage in the development of a Hawaiian volcano.
Redox-influenced seismic properties of upper-mantle olivine
Publisher: Springer Science and Business Media LLC
Date: 03-2018
DOI: 10.1038/NATURE25764
Abstract: Lateral variations of seismic wave speeds and attenuation (dissipation of strain energy) in the Earth's upper mantle have the potential to map key characteristics such as temperature, major-element composition, melt fraction and water content. The inversion of these data into meaningful representations of physical properties requires a robust understanding of the micromechanical processes that affect the propagation of seismic waves. Structurally bound water (hydroxyl) is believed to affect seismic properties but this has yet to be experimentally quantified. Here we present a comprehensive low-frequency forced-oscillation assessment of the seismic properties of olivine as a function of water content within the under-saturated regime that is relevant to the Earth's interior. Our results demonstrate that wave speeds and attenuation are in fact strikingly insensitive to water content. Rather, the redox conditions imposed by the choice of metal sleeving, and the associated defect chemistry, appear to have a substantial influence on the seismic properties. These findings suggest that elevated water contents are not responsible for low-velocity or high-attenuation structures in the upper mantle. Instead, the high attenuation observed in hydrous and oxidized regions of the upper mantle (such as above subduction zones) may reflect the prevailing oxygen fugacity. In addition, these data provide no support for the hypothesis whereby a sharp lithosphere-asthenosphere boundary is explained by enhanced grain boundary sliding in the presence of water.
Detecting Micro‐ and Nanoscale Variations in Element Mobility in High‐Grade Metamorphic Rocks
Publisher: Wiley
Date: 12-2017
A new model for zircon saturation in silicate melts
Publisher: Springer Science and Business Media LLC
Date: 07-2022
DOI: 10.1007/S00410-022-01925-6
Abstract: A new model describing zircon saturation in silicate melts is presented that combines the results of 196 data from new experiments with data from previous experimental studies. In the new experiments, the concentration of Zr in melts coexisting with zircon was determined at temperatures between 800 and 1500 °C for 21 compositions (with alumina saturation index, ASI, from 0.20 to 1.15), containing ~ 1 to 16 wt % FeO T and, for a subset of these conditions, at variable pressure (0.0001 to 4.0 GPa) and water content (0 to 15 wt %). The collated dataset contains 626 data, with 430 from 26 literature studies, and covers conditions from 750 to 1620 °C, (including 45 new data and 106 literature data for temperatures 1000 °C), ASI 0.20 to 2.00, 0.0001 to 4.0 GPa and 0 to 17 wt % H 2 O. A limitation of previous models of zircon saturation is the choice of parameter used to describe the silicate melt, which may not be appropriate for all compositions and can result in differences in predicted temperatures of over 200 °C for granitic systems. Here we use optical basicity ( Λ ), which can be easily calculated from the major oxide components of a melt, to parameterise the composition. Using a non-linear least-squares multiple regression, the new zircon saturation model is: $$\\log{\\mathrm{Zr}} = 0.96(5) - 5790(95)/T - 1.28(8)P + 12.39(35){\\varLambda} + 0.83(9)x.\\text{H}{_2}\\text{O} + 2.06(16)P{\\varLambda} $$ log Zr = 0.96 ( 5 ) - 5790 ( 95 ) / T - 1.28 ( 8 ) P + 12.39 ( 35 ) Λ + 0.83 ( 9 ) x . H 2 O + 2.06 ( 16 ) P Λ where Zr is in ppm, T is temperature in K, P is pressure in GPa, Λ is the optical basicity of the melt, x .H 2 O is the mole fraction of water in the melt, and the errors are 1σ. This model confirms that temperature and melt composition are the dominant controls on zircon solubility. In addition, pressure and melt water content exert small but resolvable effects on the solubility and are included, for the first time, in a model. Using this new calibration, 92% of the predicted temperatures are within 10% of the experimental temperatures for the collated dataset (with an average temperature difference of 57 °C), while predicted temperatures for only 78 and 62% of the collated dataset are within 10% of the experimental temperature (with average temperature differences 80 °C) using the widely cited Watson and Harrison (Earth Planet Sci Lett 64:295–304, 1983) and Boehnke et al. (Chem Geol 351:324–334, 2013) models, respectively. This new model can be extrapolated to temperatures below those included in the calibration with greater accuracy and when applied to melt inclusions from the Bishop Tuff, gives temperatures that are in excellent agreement with independent estimates.
The oxidation state of sulfur in synthetic and natural glasses determined by X-ray absorption spectroscopy
Publisher: Elsevier BV
Date: 04-2009
A re-assessment of the oxidation state of iron in MORB glasses
Publisher: Elsevier BV
Date: 02-2018
The effects of temperature and pressure on the oxidation state of chromium in silicate melts
Publisher: Springer Science and Business Media LLC
Date: 29-04-2021
Substitution and diffusion of Cr2+ and Cr3+ in synthetic forsterite and natural olivine at 1200–1500 °C and 1 bar
Publisher: Elsevier BV
Date: 2018
The speciation of copper in natural fluid inclusions at temperatures up to 700 °C
Publisher: Elsevier BV
Date: 02-2009
Ti site occupancy in zircon
Publisher: Elsevier BV
Date: 02-2011
Relationships between oxygen fugacity and metasomatism in the Kaapvaal subcratonic mantle, represented by garnet peridotite xenoliths in the Wesselton kimberlite, South Africa
Publisher: Elsevier BV
Date: 2015
A combined Fourier transform infrared and Cr K-edge X-ray absorption near-edge structure spectroscopy study of the substitution and diffusion of H in Cr-doped forsterite
Publisher: Copernicus GmbH
Date: 09-02-2021
Abstract: Abstract. Single crystals of synthetic Cr-doped forsterite (Cr:Mg2SiO4) containing both Cr3+ and Cr4+ were partially hydroxylated in piston-cylinder apparatuses at 750–1300 ∘C and pressures from 0.5 to 2.5 GPa, with p(H2O) ≈Ptotal. The oxygen fugacity (fO2) was buffered by graphite-water, Ni–NiO, Re–ReO2, Fe2O3–Fe3O4 or Ag–Ag2O, and the silica activity (aSiO2) was buffered by powdered forsterite plus either enstatite (Mg2Si2O6), periclase (MgO) or zircon–baddeleyite (ZrSiO4–ZrO2). Profiles of OH content versus distance from the crystal edge were determined using Fourier transform infrared (FTIR) spectroscopy, and profiles of the oxidation state and coordination geometry of Cr were obtained, at the same positions, using K-edge X-ray absorption near-edge structure (XANES) spectroscopy. The techniques are complementary – FTIR spectroscopy images the concentration and nature of O–H bonds, where Cr K-edge XANES spectroscopy shows the effect of the added H on the speciation of Cr already present in the lattice. Profiles of defect-specific absorbance derived from FTIR spectra were fitted to solutions of Fick's second law to derive diffusion coefficients, which yield the Arrhenius relationship for H diffusion in forsterite: log10D̃[001]=-2.5±0.6+-(224±12+4.0±2.0P)2.303RT, where D̃ is the measured diffusion coefficient in m2 s−1, valid for diffusion parallel to [001] and calibrated between 1000 and 750 ∘C, P and T are in GPa and K, and R is 0.008314 kJK−1 mol−1. Diffusivity parallel to [100] is around 1 order of magnitude lower. This is consistent with previous determinations of H diffusion associated with M-site vacancies. The FTIR spectra represent a variety of Cr-bearing hydrous defects, along with defects associated with the pure Mg–Si–O–H system. It is proposed that all of the defects can form by interaction between the dry lattice, including Cr3+ and Cr4+, and fully hydroxylated M-site vacancies. The initial diffusive wave of hydroxylation is associated with neither reduction nor oxidation of Cr but with Cr4+ changing from tetrahedral to octahedral coordination. Superimposed on the H diffusion and concomitant change in Cr4+ site occupancy, but at a slower rate, producing shorter profiles, is reduction of Cr4+ to Cr3+ and potentially of Cr4+ and Cr3+ to Cr2+. In addition, by comparing FTIR data to trace element contents measured by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), constraints can be placed on absorption coefficients used for converting absorbance to H2O contents – our data support either wavenumber- or defect-dependent values of absorption coefficients. We estimate absorption coefficients of between 60 200 and 68 200 L mol−1 cm−1 for OH− associated with octahedral Cr3+ and an M-site vacancy and 18 700 to 24 900 L mol−1 cm−1 for two OH− associated with octahedrally coordinated Cr4+ and a Si vacancy (i.e. a “clinohumite-type” point defect).
Substitution of Ti3+ and Ti4+ in hibonite (CaAl12O19)
Publisher: Mineralogical Society of America
Date: 07-2014
DOI: 10.2138/AM.2014.4532
The oxidation state and coordination environment of antimony in silicate glasses
Publisher: Elsevier BV
Date: 10-2019
Refinement of hydrogen positions in natural chondrodite by powder neutron diffraction: implications for the stability of humite minerals
Publisher: Mineralogical Society
Date: 06-2002
Abstract: The structure of a natural s le of chondrodite (Mg 4.89 Fe 0.07 Si 2.04 O 8 F 1.54 (OH) 0.46 ) was refined using powder neutron diffraction data and the Rietveld technique ( P 2 1 / b Z = 2 a = 4.7204(1)Å b = 10.2360(3)Å c = 7.8252(2)Å α = 109.11(1)° V = 357.26(2)Å 3 ). Hydrogen was found to occupy the H1 site. The significance of hydrogen at this site is discussed in terms of hydrogen-bond stabilization of humite structures containing varying amounts of OH, F and Ti. Arguments are proposed as to why the F and Ti contents of natural humites usually result in only one H per formula unit when there is no crystal-chemical reason why fully hydrated s les should not be favoured.
The Ti-in-zircon thermometer revised: The effect of pressure on the Ti site in zircon
Publisher: Elsevier BV
Date: 11-2023
Electron exchange between V and Cr in silicate glasses
Publisher: Elsevier BV
Date: 08-2006
The infrared signature of water associated with trivalent cations in olivine
Publisher: Elsevier BV
Date: 09-2007
The effect of oxygen fugacity, melt composition, temperature and pressure on the oxidation state of cerium in silicate melts
Publisher: Elsevier BV
Date: 02-2014
Activity coefficients at low dilution of CrO, NiO and CoO in melts in the system CaO–MgO–Al2O3–SiO2 at 1400°C: Using the thermodynamic behaviour of transition metal oxides in silicate melts to probe t
Publisher: Elsevier BV
Date: 07-2006
Dynamics on the microsecond timescale in hydrous silicates studied by solid-state 2H NMR spectroscopy
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B924666E
Abstract: Solid-state (2)H NMR spectroscopy has been used to probe the dynamic disorder of hydroxyl deuterons in a synthetic s le of deuterated hydroxyl-clinohumite (4Mg(2)SiO(4).Mg(OD)(2)), a proposed model for the incorporation of water within the Earth's mantle. Both static and magic angle spinning (MAS) NMR methods were used. Static (2)H NMR appears to reveal little evidence of the dynamic process, yielding results similar to those obtained from deuterated brucite (Mg(OD)(2)), where no dynamics on the relevant timescale are expected to be present. However, in (2)H MAS NMR spectra, considerable line broadening is observed for hydroxyl-clinohumite and a (2)H double-quantum (DQ) MAS NMR spectrum confirms that this is due to motion on the microsecond timescale. Using a model for dynamic exchange of the hydroxyl deuterons between two sites identified in previous diffraction studies, first-principles density functional theory (DFT) calculations of (2)H (spin I = 1) quadrupolar NMR parameters, and a simple analytical model for dynamic line broadening in MAS NMR experiments, we were able to reproduce the observed motional line broadening and use this to estimate a rate constant for the dynamic process. From analysis of the observed (2)H linewidths in variable-temperature MAS experiments, an activation energy for the exchange process was also determined. A simulated static (2)H NMR lineshape based on our dynamic model is consistent with the observed experimental static NMR spectrum, confirming that the motion present in this system is not easily detectable using a static NMR approach. Finally, a (2)H DQMAS NMR spectrum of fluorine-substituted (2)H-enriched hydroxyl-clinohumite shows how the dynamic exchange process is inhibited by O-DF(-) hydrogen-bonding interactions.
Solid-State 17O NMR Spectroscopy of Hydrous Magnesium Silicates: Evidence for Proton Dynamics
Publisher: American Chemical Society (ACS)
Date: 05-12-2008
DOI: 10.1021/JP808651X
The oxidation state of iron in Mid-Ocean Ridge Basaltic (MORB) glasses: Implications for their petrogenesis and oxygen fugacities
Publisher: Elsevier BV
Date: 12-2018
Formation of Hadean granites by melting of igneous crust
Publisher: Springer Science and Business Media LLC
Date: 08-05-2017
DOI: 10.1038/NGEO2942
Titanium substitution mechanisms in forsterite
Publisher: Elsevier BV
Date: 07-2007
Three- and five-quantum17O MAS NMR of forsterite Mg2SiO4
Publisher: Mineralogical Society of America
Date: 08-1999
The oxidation state of chromium in basaltic silicate melts
Publisher: Elsevier BV
Date: 08-2021
A XANES study of Cu speciation in high-temperature brines using synthetic fluid inclusions
Publisher: Mineralogical Society of America
Date: 11-2006
DOI: 10.2138/AM.2006.1940
First-principles calculations of solid-state17O and29Si NMR spectra of Mg2SiO4polymorphs
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B618211A
Abstract: The nuclear magnetic resonance (NMR) shielding and electric field gradient (EFG) tensors of three polymorphs of Mg(2)SiO(4), forsterite (alpha-Mg(2)SiO(4)), wadsleyite (beta-Mg(2)SiO(4)) and ringwoodite (gamma-Mg(2)SiO(4)), have been calculated using a density functional theory (DFT) approach with a planewave basis set and pseudopotential approximation. These Mg(2)SiO(4) polymorphs are the principal components of the Earth down to depths of 660 km and have been proposed as the hosts of water in the Earth's upper mantle and transition zone. A comparison of our calculations with single-crystal spectroscopic data in the literature for the alpha-polymorph, forsterite, shows that both the magnitude and orientation of the shielding and EFG tensors for O and Si can be obtained with sufficient accuracy to distinguish subtle differences in atomic positions between published structures. We compare calculated (17)O MAS NMR quadrupolar powder lineshapes directly with experimental lineshapes and show that we are able to reproduce them within the precision with which the NMR parameters may be determined from multi-parameter fitting. The relatively small amounts of s le available for the beta- and gamma-polymorphs, arising from the high pressures required for synthesis, has hindered the extraction of NMR parameters in previous work. The application of DFT calculations to these high-pressure polymorphs confirms previous spectral assignments, and provides deeper insight into the empirical correlations and observations reported in the literature. These first-principles methods are highly promising for the determination of local bonding in more complex materials, such as the hydrated forms of Mg(2)SiO(4), by aiding analysis of their multinuclear NMR spectra.
The limitations of hibonite as a single-mineral oxybarometer for early solar system processes
Publisher: Elsevier BV
Date: 09-2017
Ligand dependence of the correlation crystal field
Publisher: American Physical Society (APS)
Date: 15-01-1998
Redox preconditioning deep cratonic lithosphere for kimberlite genesis - Evidence from the central Slave Craton
Publisher: Springer Science and Business Media LLC
Date: 14-02-2017
DOI: 10.1038/S41598-017-00049-3
Abstract: We present the first oxygen fugacity ( f O 2 ) profile through the cratonic lithospheric mantle under the Panda kimberlite (Ekati Diamond Mine) in the Lac de Gras kimberlite field, central Slave Craton, northern Canada. Combining this data with new and existing data from garnet peridotite xenoliths from an almost coeval kimberlite (A154-N) at the nearby Diavik Diamond Mine demonstrates that the oxygen fugacity of the Slave cratonic mantle varies by several orders of magnitude as a function of depth and over short lateral distances. The lower part of the diamond-bearing Slave lithosphere ( –130 km deep) has been oxidized by up to 4 log units in f O 2 , and this is clearly linked to metasomatic enrichment. Such coupled enrichment and oxidation was likely caused by infiltrating carbonate-bearing, hydrous, silicate melts in the presence of diamond, a process proposed to be critical for “pre-conditioning” deep lithospheric mantle and rendering it suitable for later generation of kimberlites and other SiO 2 -undersaturated magmas.
High-Resolution 17O NMR Spectroscopy of Wadsleyite (β-Mg2SiO4)
Publisher: American Chemical Society (ACS)
Date: 06-09-2003
DOI: 10.1021/JA036777K
Abstract: The sensitivity of high-resolution 17O (I = 5/2) NMR spectroscopy of solids has advanced significantly in recent years. Here, we show that excellent results are now obtainable from milligram quantities of 17O-enriched materials, thereby allowing the technique to be applied to silicate phases synthesized under very high pressures in a multiple-anvil apparatus. We report the first 17O NMR study of beta-Mg2SiO4 (9.6 mg of 35% 17O-enriched material, synthesized at p = 16 GPa and T = 1873 K), a dense phase believed to have a significant role in the Earth's mantle. Using STMAS at magnetic fields of B0 = 9.4 and 11.7 T and MQMAS at B0 = 18.8 T, we have resolved and assigned all four crystallographically distinct O sites and determined their chemical shift and quadrupolar parameters.
Corrigendum to “The oxidation state of iron in Mid-Ocean Ridge Basaltic (MORB) glasses: Implications for their petrogenesis and oxygen fugacities” [Earth Planet. Sci. Lett. 504 (2018) 152–162]
Publisher: Elsevier BV
Date: 12-2019
Diffusion and partition coefficients of minor and trace elements in magnetite as a function of oxygen fugacity at 1150 ºC
Publisher: Springer Science and Business Media LLC
Date: 10-04-2020
DOI: 10.1007/S00410-020-01679-Z
Abstract: Lattice diffusion coefficients and partition coefficients have been determined for Li, Mg, Al, Sc, Ti, Cr, V, Mn, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, In, Lu, Hf, Ta and U in single crystals of natural magnetite as a function of oxygen fugacity ( f O 2 ) at 1150 °C and 1 bar by equilibration with a synthetic silicate melt reservoir. Most experiments were run for twelve hours, which was sufficient to generate diffusion profiles from 25 to 1000 µm in length. The results were checked at one condition with two additional experiments at 66.9 and 161 h. The profiles were analysed using scanning laser-ablation inductively-coupled-plasma mass-spectrometry. Diffusion coefficients ( D ) were calculated by fitting data from in idual element diffusion profiles to the conventional diffusion equation for one-dimensional diffusion into a semi−infinite slab with constant composition maintained in the melt at the interface. Equilibrium magnetite/melt partition coefficients are given by the ratio of the interface concentrations to those in the melt. Plots of log D as a function of log f O 2 produce V-shaped trends for all the investigated elements, representing two different mechanisms of diffusion that depend on ( f O 2 ) −2/3 and ( f O 2 ) 2/3 . Diffusion coefficients at a given f O 2 generally increase in the order: Cr Mo ≈ Ta V Ti Al Hf ≈ Nb Sc ≈ Zr ≈ Ga In Lu ≈ Y Ni U ≈ Zn Mn ≈ Mg Co Li Cu. Thus, Cu contents of magnetites are most susceptible to diffusive reequilibration, whereas the original content of Cr should be best preserved.
Observation of “hidden” magnesium: First-principles calculations and 25Mg solid-state NMR of enstatite
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.SSNMR.2011.08.004
Abstract: (25)Mg NMR parameters have been determined for two polymorphs of enstatite (MgSiO(3)), an important magnesium silicate phase present as a major component of the Earth's upper mantle. The crystal structures of both polymorphs contain two crystallographically distinct magnesium sites however, only a single resonance is observed in (25)Mg MAS NMR spectra recorded at 14.1 and 20.0 T. First-principles calculations performed on geometry-optimised crystal structures reveal that the quadrupolar interaction for the second site is expected to be very large, resulting in extensive broadening of the spectral resonance, explaining its apparent absence in the NMR spectrum. (25)Mg QCPMG NMR experiments employing variable offset cumulative spectroscopy (VOCS) are used to observe the broadened site and enable measurement of NMR parameters. The large difference in quadrupolar interaction between the two crystallographic magnesium sites is rationalised qualitatively in terms of the distortion of the local coordination environment as well as longer-range effects using a simple point charge model.
Hunting for hydrogen: random structure searching and prediction of NMR parameters of hydrous wadsleyite
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CP01529H
Abstract: Ab initio random structure searching is employed to generate candidate structures of hydrous wadsleyite, predicting NMR parameters for experimental comparison.
Iron oxidation state determination in garnets by EPMA and XANES
Publisher: Elsevier BV
Date: 08-2006
The Ti environment in natural hibonite: XANES spectroscopy and computer modelling
Publisher: IOP Publishing
Date: 05-2016
Fracture initiation in emulsion-polymerized poly(acrylonitrile-butadiene-styrene) (ABS)
Publisher: Springer Science and Business Media LLC
Date: 2001
An oxygen fugacity profile through the Siberian Craton — Fe K-edge XANES determinations of Fe3+/∑Fe in garnets in peridotite xenoliths from the Udachnaya East kimberlite
Publisher: Elsevier BV
Date: 05-2012
Motional broadening: an important distinction between multiple-quantum and satellite-transition MAS NMR of quadrupolar nuclei
Publisher: Elsevier BV
Date: 10-2002
Constraints on oxygen fugacity within metal capsules
Publisher: Springer Science and Business Media LLC
Date: 28-12-2017
17O and29Si NMR Parameters of MgSiO3Phases from High-Resolution Solid-State NMR Spectroscopy and First-Principles Calculations
Publisher: American Chemical Society (ACS)
Date: 10-2007
DOI: 10.1021/JA074428A
Abstract: The 29Si and 17O NMR parameters of six polymorphs of MgSiO3 were determined through a combination of high-resolution solid-state NMR and first-principles gauge including projector augmented wave (GIPAW) formalism calculations using periodic boundary conditions. MgSiO3 is an important component of the Earth's mantle that undergoes structural changes as a function of pressure and temperature. For the lower pressure polymorphs (ortho-, clino-, and protoenstatite), all oxygen species in the 17O high-resolution triple-quantum magic angle spinning (MAS) NMR spectra were resolved and assigned. These assignments differ from those tentatively suggested in previous work on the basis of empirical experimental correlations. The higher pressure polymorphs of MgSiO3 (majorite, akimotoite, and perovskite) are stabilized at pressures corresponding to the Earth's transition zone and lower mantle, with perovskite being the major constituent at depths >660 km. We present the first 17O NMR data for these materials and confirm previous 29Si work in the literature. The use of high-resolution multiple-quantum MAS (MQMAS) and satellite-transition MAS (STMAS) experiments allows us to resolve distinct oxygen species, and full assignments are suggested. The six polymorphs exhibit a wide variety of structure types, providing an ideal opportunity to consider the variation of NMR parameters (both shielding and quadrupolar) with local structure, including changes in coordination number, local geometry (bond distances and angles), and bonding. For ex le, we find that, although there is a general correlation of increasing 17O chemical shift with increasing Si-O bond length, the shift observed also depends upon the exact coordination environment.
The oxidation states of niobium and tantalum in mantle melts
Publisher: Elsevier BV
Date: 11-2012
High-Resolution 19F MAS NMR Spectroscopy: Structural Disorder and Unusual J Couplings in a Fluorinated Hydroxy-Silicate
Publisher: American Chemical Society (ACS)
Date: 19-10-2010
DOI: 10.1021/JA105347Q
Abstract: High-resolution (19)F magic angle spinning (MAS) NMR spectroscopy is used to study disorder and bonding in a crystalline solid. (19)F MAS NMR reveals four distinct F sites in a 50% fluorine-substituted deuterated hydrous magnesium silicate (clinohumite, 4Mg(2)SiO(4)·Mg(OD(1-x)F(x))(2) with x = 0.5), indicating extensive structural disorder. The four (19)F peaks can be assigned using density functional theory (DFT) calculations of NMR parameters for a number of structural models with a range of possible local F environments generated by F(-)/OH(-) substitution. These assignments are supported by two-dimensional (19)F double-quantum MAS NMR experiments that correlate F sites based on either spatial proximity (via dipolar couplings) or through-bond connectivity (via scalar, or J, couplings). The observation of (19)F-(19)F J couplings is unexpected as the fluorines coordinate Mg atoms and the Mg-F interaction is normally considered to be ionic in character (i.e., there is no formal F-Mg-F covalent bonding arrangement). However, DFT calculations predict significant (19)F-(19)F J couplings, and these are in good agreement with the splittings observed in a (19)F J-resolved MAS NMR experiment. The existence of these J couplings is discussed in relation to both the nature of bonding in the solid state and the occurrence of so-called "through-space" (19)F-(19)F J couplings in solution. Finally, we note that we have found similar structural disorder and spin-spin interactions in both synthetic and naturally occurring clinohumite s les.
Quantitative mapping of the oxidative effects of mantle metasomatism
Publisher: Geological Society of America
Date: 06-2013
DOI: 10.1130/G34119.1
The effect of site geometry, Ti content and Ti oxidation state on the Ti K-edge XANES spectrum of synthetic hibonite
Publisher: Elsevier BV
Date: 08-2016
Back matter
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B715989G
A furnace design for XANES spectroscopy of silicate melts under controlled oxygen fugacities and temperatures to 1773 K
Publisher: International Union of Crystallography (IUCr)
Date: 24-06-2003
DOI: 10.1107/S0909049503007556
Abstract: A controlled-atmosphere furnace has been constructed for X-ray absorption spectroscopy experiments under imposed oxygen fugacities at temperatures up to 1773 K. The use of the furnace is demonstrated in a study of the oxidation state of Cr in a basaltic silicate melt (mid-ocean ridge basalt) by K-edge XANES spectroscopy. This is the first time the Cr(2+)/Cr(3+) ratio has been identified directly in an Fe-bearing melt. At typical terrestrial oxygen fugacities around half the Cr is present as Cr(2+), even though this oxidation state has never been identified in a terrestrial material and only Cr(3+) is observed after quenching to a glass. Cr(2+) oxidizes to Cr(3+) on cooling in the presence of Fe(3+) according to the electron exchange reaction Cr(2+) + Fe(3+) --> Cr(3+) + Fe(2+). This illustrates the importance of the in situ determination of metal oxidation states in melts.
Erratum to “An experimental study of trace element partitioning between zircon and melt as a function of oxygen fugacity” [Geochimica et Cosmochimica Acta (2012) 196–212]
Publisher: Elsevier BV
Date: 11-2013
Spectroscopic (XAS, FTIR) investigations into arsenic adsorption onto TiO2/Fe2O3 composites: Evaluation of the surface complexes, speciation and precipitation predicted by modelling
Publisher: Elsevier BV
Date: 11-2022
Thermodynamic controls on element partitioning between titanomagnetite and andesitic–dacitic silicate melts
Publisher: Springer Science and Business Media LLC
Date: 07-07-2017
The stability of divalent Ge in silicate melts and its geochemical properties
Publisher: Elsevier BV
Date: 2020
Fingerprinting the water site in mantle olivine
Publisher: Geological Society of America
Date: 2005
DOI: 10.1130/G21759.1
Water in the Earth's mantle: a solid-state NMR study of hydrous wadsleyite
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3SC21892A
An experimental determination of the effect of pressure on the Fe3+/ Fe ratio of an anhydrous silicate melt to 3.0 GPa
Publisher: Mineralogical Society of America
Date: 02-2006
DOI: 10.2138/AM.2005.1929
Two-photon (TP) spectroscopy of terbium(III) elpasolites
Publisher: Elsevier BV
Date: 12-1995
Three water sites in upper mantle olivine and the role of titanium in the water weakening mechanism
Publisher: American Geophysical Union (AGU)
Date: 05-2007
DOI: 10.1029/2006JB004620
17O Multiple-Quantum MAS NMR Study of Pyroxenes
Publisher: American Chemical Society (ACS)
Date: 2002
DOI: 10.1021/JP0130362
The Effects of Small Amounts of H2O, CO2 and Na2O on the Partial Melting of Spinel Lherzolite in the System CaO–MgO–Al2O3–SiO2 ± H2O ± CO2 ± Na2O at 1·1 GPa
Publisher: Oxford University Press (OUP)
Date: 28-10-2005
The kinetics and mechanism of MgO dissolution
Publisher: Elsevier BV
Date: 12-1999
The effect of composition on Cr2+/Cr3+ in silicate melts
Publisher: Mineralogical Society of America
Date: 11-2006
DOI: 10.2138/AM.2006.2097
Electronic structure of ilmenite:X-ray absorption and DFT study
Publisher: IOP Publishing
Date: 11-2009
Study of local atomic and electronic structure of titanium-containing forsterite based on analysis of X-ray absorption spectra
Publisher: Pleiades Publishing Ltd
Date: 12-2011
Diffusion anisotropy of Ti in zircon and implications for Ti-in-zircon thermometry
Publisher: Elsevier BV
Date: 2022
Two-photon excitation spectroscopy of lanthanide elpasolites—implications for the correlation crystal field
Publisher: Elsevier BV
Date: 02-1997
An experimental study of trace element partitioning between zircon and melt as a function of oxygen fugacity
Publisher: Elsevier BV
Date: 10-2012
Experimental techniques for the study of hydrothermal fluids and silicate melts
Publisher: Elsevier BV
Date: 02-2009
The effect of composition, temperature and pressure on the oxidation state and coordination environment of copper in silicate melts
Publisher: Elsevier BV
Date: 08-2023
Chromium luminescence as a probe of site effects in the alum lattice
Publisher: Royal Society of Chemistry (RSC)
Date: 1997
DOI: 10.1039/A605705E
Two-photon Zeeman spectroscopy of terbium (III) elpasolites
Publisher: AIP Publishing
Date: 08-06-1997
DOI: 10.1063/1.474010
Abstract: Polarised two-photon excitation (TPE) spectroscopy is a powerful technique for probing the energy levels of f-block elements at high symmetry sites because most pure electronic transitions are allowed by the selection rules. TPE in a magnetic field provides additional information, through the resolution of Zeeman components, evaluation of g-values, and the appearance of intensity in forbidden transitions. Here we present the selection rules and polarisation dependence for two-photon absorption at cubic sites, in a magnetic field. Polarised TPE spectra for the elpasolites Cs2NaTbX6 (X=F, Cl) are in excellent agreement with theory. The sensitivity of the second order Zeeman effect to the orientation of a cubic crystal relative to the magnetic field is illustrated, together with successful modelling of the Zeeman interaction for a number of multiplets.
The controls of post-entrapment diffusion on the solubility of chalcopyrite daughter crystals in natural quartz-hosted fluid inclusions
Publisher: Elsevier BV
Date: 09-2015
Titanium solubility in olivine in the system TiO2–MgO–SiO2: no evidence for an ultra-deep origin of Ti-bearing olivine
Publisher: Springer Science and Business Media LLC
Date: 12-2004
A XANES calibration for determining the oxidation state of iron in mantle garnet
Publisher: Elsevier BV
Date: 11-2010
The oxidation state of europium in silicate melts as a function of oxygen fugacity, composition and temperature
Publisher: Elsevier BV
Date: 09-2015
The solubility and oxidation state of tungsten in silicate melts: Implications for the comparative chemistry of W and Mo in planetary differentiation processes
Publisher: Elsevier BV
Date: 10-2008
Determination of the oxidation state of iron in Mid-Ocean Ridge basalt glasses by Raman spectroscopy
Publisher: Mineralogical Society of America
Date: 07-2019
DOI: 10.2138/AM-2019-6887
Abstract: A series of synthetic Mid-Ocean Ridge Basalt (MORB) glasses with Fe3+/FeTOT from 0 to 1, determined previously by Mössbauer spectroscopy, were used to test methods for quantifying Fe3+/FeTOT by Raman spectroscopy. Six numerical data reduction methods were investigated, based on conventional approaches as well as supervised and unsupervised machine learning algorithms. For the set of MORB glass standards, with fixed composition, the precision of all methods was ≤±0.04 (1 St.dev.). However, Raman spectra recorded for 42 natural MORB glasses from a wide range of locations revealed a strong correlation between the spectra and composition, despite the latter varying only over a relatively limited range, such that the methods calibrated using the glass standards are not directly applicable to the natural s les. This compositional effect can be corrected by using a compositional term that links spectral variations to the Fe3+/FeTOT value of the glass. The resulting average Fe3+/FeTOT determined by Raman spectroscopy was 0.090 ± 0.067 (n = 42). This value agrees with the latest Fe K-edge XANES and wet-chemistry estimates of 0.10 ± 0.02. The larger uncertainty of the Raman determination reflects the sensitivity of Raman spectroscopy to small changes in the glass structure. While this sensitivity is detrimental for high precision Fe3+/FeTOT determinations, it allows the major element composition of natural MORB glasses to be determined within 1 mol% through the use of an artificial neural network. This suggests that Raman spectrometers may be used to determine the composition of s les in situ at difficult to access locations that are incompatible with X-ray spectrometry (e.g., mid-ocean ridges).
Coordination change of Ge4+ and Ga3+ in silicate melt with pressure
Publisher: Elsevier BV
Date: 06-2021
γ-MgH2 induced by high pressure for low temperature dehydrogenation
Publisher: Elsevier BV
Date: 2021
Pseudomonas aeruginosa modulates neutrophil granule exocytosis in an in vitro model of airway infection
Publisher: Wiley
Date: 11-04-2022
DOI: 10.1111/IMCB.12547
Abstract: A population of neutrophils recruited into cystic fibrosis (CF) airways is associated with proteolytic lung damage, exhibiting high expression of primary granule exocytosis marker CD63 and reduced phagocytic receptor CD16. Causative factors for this population are unknown, limiting intervention. Here we present a laboratory model to characterize responses of differentiated airway epithelium and neutrophils following respiratory infection. Pediatric primary airway epithelial cells were cultured at the air–liquid interface, challenged in idually or in combination with rhinovirus (RV) and Pseudomonas aeruginosa , then apically washed with medical saline to s le epithelial infection milieus. Cytokine multiplex analysis revealed epithelial antiviral signals, including IP‐10 and RANTES, increased with exclusive RV infection but were diminished if P. aeruginosa was also present. Proinflammatory signals interleukin‐1α and β were dominant in P. aeruginosa infection milieus. Infection washes were also applied to a published model of neutrophil transmigration into the airways. Neutrophils migrating into bacterial and viral–bacterial co‐infection milieus exhibited the in vivo CF phenotype of increased CD63 expression and reduced CD16 expression, while neutrophils migrating into milieus of RV‐infected or uninfected cultures did not. In idually, bacterial products lipopolysaccharide and N ‐formylmethionyl‐leucyl‐phenylalanine and isolated cytokine signals only partially activated this phenotype, suggesting that additional soluble factors in the infection microenvironment trigger primary granule release. Findings identify P. aeruginosa as a trigger of acute airway inflammation and neutrophil primary granule exocytosis, underscoring potential roles of airway microbes in prompting this neutrophil subset. Further studies are required to characterize microbes implicated in primary granule release, and identify potential therapeutic targets.
Energy levels of terbium(III) in the elpasolite Cs2NaTbF6
Publisher: Informa UK Limited
Date: 1998
17O Multiple-Quantum MAS NMR Study of High-Pressure Hydrous Magnesium Silicates
Publisher: American Chemical Society (ACS)
Date: 07-06-2001
DOI: 10.1021/JA004290V
Abstract: Two (17)O-enriched hydrous magnesium silicates, the minerals hydroxyl-chondrodite (2Mg(2)SiO(4).Mg(OH)(2)) and hydroxyl-clinohumite (4Mg(2)SiO(4).Mg(OH)(2)), were synthesized. High-resolution "isotropic" (17)O (I = (5)/(2)) NMR spectra of the powdered solids were obtained using three- and five-quantum MAS NMR at magnetic field strengths of 9.4 and 16.4 T. These multiple-quantum (MQ) MAS spectra were analyzed to yield the (17)O isotropic chemical shifts (delta(CS)) and quadrupolar parameters (C(Q), eta and their "product" P(Q)) of the distinct oxygen sites resolved in each s le. The values obtained were compared with those found previously for forsterite (Mg(2)SiO(4)). The (17)O resonances of the protonated (hydroxyl) sites were recorded and assigned with the aid of (17)O [(1)H] cross-polarization and comparison with the spectrum of (17)O-enriched brucite (Mg(OH)(2)). Using all of these data, complete assignments of the five crystallographically inequivalent oxygen sites in hydroxyl-chondrodite and of the nine such sites in hydroxyl-clinohumite are suggested. The validity of these assignments are supported by the observation of a correlation between (17)O isotropic chemical shift and Si-O bond length. The (29)Si MAS NMR spectra of the two minerals were also obtained.
Oxygen Content, Oxygen Fugacity, the Oxidation State of Iron, and Mid‐Ocean Ridge Basalts
Publisher: Wiley
Date: 17-09-2021
Havre 2012 pink pumice is evidence of a short-lived, deep-sea, magnetite nanolite-driven explosive eruption
Publisher: Springer Science and Business Media LLC
Date: 03-02-2022
DOI: 10.1038/S43247-022-00355-3
Abstract: The Havre 2012 deep-sea rhyolite eruption went unobserved and was initially recognised from a massive pumice raft at the sea surface. Havre pumices are predominantly white or grey, however pink pumice is common in the raft. In subaerial explosive eruptions, pink pumice is understood to result from high-temperature atmospheric iron-oxidation. The presence of pink pumice questions the effusive eruption model for the Havre raft. Here we report results from X-ray Absorption Near Edge Structure spectroscopy, magnetic measurements, TEM imaging and glass chemistry that collectively show the colour results from increasing amounts of magnetite nanolites in the raft pumice glass oxidizing to hematite. This suggests a short-lived but powerful explosive eruption phase penetrated the water column allowing hot pyroclasts to oxidise in air. Our results therefore challenge the known depth limits for explosive eruptions in the marine realm and suggest pink pumice can be an indicator of magnetite nanolite-driven explosive eruptions.
OH-bearing planar defects in olivine produced by the breakdown of Ti-rich humite minerals from Dabie Shan (China)
Publisher: Springer Science and Business Media LLC
Date: 21-11-2006
X-RAY ABSORPTION NEAR-EDGE SPECTROSCOPY FOR DIAGNOSTICS OF 3D LOCAL ATOMIC STRUCTURE OF GEOLOGICAL MATERIALS
Publisher: Stef92 Technology
Date: 20-06-2017
High-resolution 17O MAS NMR spectroscopy of forsterite ( -Mg2SiO4), wadsleyite ( -Mg2SiO4), and ringwoodite ( -Mg2SiO4)
Publisher: Mineralogical Society of America
Date: 11-2005
DOI: 10.2138/AM.2005.1915
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