102 results found
Mare ER, O'Neill HSC, Berry AJ, et al., 2020, The stability of divalent Ge in silicate melts and its geochemical properties, CHEMICAL GEOLOGY, Vol: 532, ISSN: 0009-2541
O'Neill HSC, Berry AJ, Mallmann G, 2019, The oxidation state of iron in Mid-Ocean Ridge Basaltic (MORB) glasses: Implications for their petrogenesis and oxygen fugacities (vol 504, pg 152, 2018), EARTH AND PLANETARY SCIENCE LETTERS, Vol: 527, ISSN: 0012-821X
Miller LA, O'Neill HSC, Berry AJ, et al., 2019, The oxidation state and coordination environment of antimony in silicate glasses, CHEMICAL GEOLOGY, Vol: 524, Pages: 283-294, ISSN: 0009-2541
Le Losq C, Berry AJ, Kendrick MA, et al., 2019, Determination of the oxidation state of iron in Mid-Ocean Ridge basalt glasses by Raman spectroscopy, AMERICAN MINERALOGIST, Vol: 104, Pages: 1032-1042, ISSN: 0003-004X
McKay D, Moran RF, Dawson DM, et al., 2019, A Picture of Disorder in Hydrous Wadsleyite-Under the Combined Microscope of Solid-State NMR Spectroscopy and Ab Initio Random Structure Searching, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 141, Pages: 3024-3036, ISSN: 0002-7863
O'Neill HSC, Berry AJ, Mallmann G, 2018, The oxidation state of iron in Mid-Ocean Ridge Basaltic (MORB) glasses: Implications for their petrogenesis and oxygen fugacities, EARTH AND PLANETARY SCIENCE LETTERS, Vol: 504, Pages: 152-162, ISSN: 0012-821X
Faul UH, Cline CJ, Berry A, et al., 2018, Constraints on oxygen fugacity within metal capsules, PHYSICS AND CHEMISTRY OF MINERALS, Vol: 45, Pages: 497-509, ISSN: 0342-1791
Cline CJ, Faul UH, David EC, et al., 2018, Redox-influenced seismic properties of uppermantle olivine, NATURE, Vol: 555, Pages: 355-+, ISSN: 0028-0836
Berry AJ, Stewart GA, O'Neill HSC, et al., 2018, A re-assessment of the oxidation state of iron in MORB glasses, EARTH AND PLANETARY SCIENCE LETTERS, Vol: 483, Pages: 114-123, ISSN: 0012-821X
Jollands MC, O'Neill HSC, Van Orman J, et al., 2018, Substitution and diffusion of Cr2+ and Cr3+ in synthetic forsterite and natural olivine at 1200-1500 degrees C and 1 bar, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 220, Pages: 407-428, ISSN: 0016-7037
Kusiak MA, Wilde SA, Wirth R, et al., 2017, Detecting micro-and nanoscale variations in element mobility in high-grade metamorphic rocks: Implication for precise U-Pb dating of zircon, Microstructural Geochronology: Planetary Records Down to Atom Scale, Pages: 279-291, ISBN: 9781119227243
Reliable geochronology is fundamental to our understanding of planetary evolution and the geological events that have shaped the Earth. Zircon has a robust crystal structure and is a key mineral in geochronological studies because it incorporates small amounts of actinides during growth. Currently, the best physical evidence for the presence of differentiated crust in the first 500 million years of the Earth's history comes from intra-grain isotopic microanalysis of zircon crystals. However, it has been long recognized that isotope systematics in zircon can show great complexity, not only from the presence of multiple stages of growth in single grains, but also from disturbance of accumulated radiogenic Pb during subsequent geological events. Although geochronologists are aware of the problem of Pb mobilization during metamorphism, the nature of mobilization on a submicron scale is not entirely understood, especially where evidence has emerged of inhomogeneity and unsupported radiogenic Pb migration. The recent discovery of nanospheres of metallic radiogenic Pb in zircon from granulites explains, in part, instances of reversely discordant age measurements and irregular counts on Pb isotopes during analysis by secondary ion mass spectrometry (SIMS). Studies are continuing to reveal the nature of Pb nanospheres, so that possible mechanisms and conditions requisite for their formation can be proposed for testing by future investigations.
Berry AJ, Schofield PF, Kravtsova AN, et al., 2017, The limitations of hibonite as a single-mineral oxybarometer for early solar system processes, CHEMICAL GEOLOGY, Vol: 466, Pages: 32-40, ISSN: 0009-2541
Sievwright RH, Wilkinson JJ, O'Neill HSC, et al., 2017, Thermodynamic controls on element partitioning between titanomagnetite and andesitic–dacitic silicate melts, Contributions To Mineralogy and Petrology, Vol: 172, ISSN: 1432-0967
Titanomagnetite–melt partitioning of Mg, Mn, Al, Ti, Sc, V, Co, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Hf and Ta was investigated experimentally as a function of oxygen fugacity (fO2) and temperature (T) in an andesitic–dacitic bulk-chemical compositional range. In these bulk systems, at constant T, there are strong increases in the titanomagnetite–melt partitioning of the divalent cations (Mg2+, Mn2+, Co2+, Ni2+, Zn2+) and Cu2+/Cu+ with increasing fO2 between 0.2 and 3.7 log units above the fayalite–magnetite–quartz buffer. This is attributed to a coupling between magnetite crystallisation and melt composition. Although melt structure has been invoked to explain the patterns of mineral–melt partitioning of divalent cations, a more rigorous justification of magnetite–melt partitioning can be derived from thermodynamic principles, which accounts for much of the supposed influence ascribed to melt structure. The presence of magnetite-rich spinel in equilibrium with melt over a range of fO2 implies a reciprocal relationship between a(Fe2+O) and a(Fe3+O1.5) in the melt. We show that this relationship accounts for the observed dependence of titanomagnetite–melt partitioning of divalent cations with fO2 in magnetite-rich spinel. As a result of this, titanomagnetite–melt partitioning of divalent cations is indirectly sensitive to changes in fO2 in silicic, but less so in mafic bulk systems.
Burnham AD, Berry AJ, 2017, Formation of Hadean granites by melting of igneous crust, NATURE GEOSCIENCE, Vol: 10, Pages: 457-+, ISSN: 1752-0894
Yaxley GM, Berry AJ, Rosenthal A, et al., 2017, Redox preconditioning deep cratonic lithosphere for kimberlite genesis - evidence from the central Slave Craton, SCIENTIFIC REPORTS, Vol: 7, ISSN: 2045-2322
Kravtsova AN, Soldatov AV, Berry A, 2017, X-ray absorption near-edge spectroscopy for diagnostics of 3D local atomic structure of geological materials, Pages: 711-718, ISSN: 1314-2704
X-ray absorption near-edge (XANES) spectroscopy is an effective modern tool that can provide unique information on local atomic structure (bond lengths and bond angles) of geological materials. To extract such information with high precision from experimental XANES spectra, advanced theoretical analysis based on supercomputer modeling is needed. XANES spectroscopy and computer modeling have been applied to investigate local atomic structure of some terrestrial and extraterrestrials geological materials. XANES identification of garnet from Taman peninsula has been done on the basis of “fingerprint” method. Local atomic structure of Ti-bearing forsterite and hibonite has been analyzed. Comparison of the experimental Ti K-XANES spectra with theoretical those calculated for different structural models obtained on the basis of density functional theory allowed to determine the local structure around titanium impurities in the minerals under study.
Faul UH, Cline CJ, David EC, et al., 2016, Titanium-hydroxyl defect-controlled rheology of the Earth's upper mantle, EARTH AND PLANETARY SCIENCE LETTERS, Vol: 452, Pages: 227-237, ISSN: 0012-821X
Doyle PM, Berry AJ, Schofield PF, et al., 2016, The effect of site geometry, Ti content and Ti oxidation state on the Ti K-edge XANES spectrum of synthetic hibonite, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 187, Pages: 294-310, ISSN: 0016-7037
Moran RF, McKay D, Pickard CJ, et al., 2016, Hunting for hydrogen: random structure searching and prediction of NMR parameters of hydrous wadsleyite, Physical Chemistry Chemical Physics, Vol: 18, Pages: 10173-10181, ISSN: 1463-9076
The structural chemistry of materials containing low levels of nonstoichiometric hydrogen is difficult to determine, and producing structural models is challenging where hydrogen has no fixed crystallographic site. Here we demonstrate a computational approach employing ab initio random structure searching (AIRSS) to generate a series of candidate structures for hydrous wadsleyite (β-Mg2SiO4 with 1.6 wt% H2O), a high-pressure mineral proposed as a repository for water in the Earth's transition zone. Aligning with previous experimental work, we solely consider models with Mg3 (over Mg1, Mg2 or Si) vacancies. We adapt the AIRSS method by starting with anhydrous wadsleyite, removing a single Mg2+ and randomly placing two H+ in a unit cell model, generating 819 candidate structures. 103 geometries were then subjected to more accurate optimisation under periodic DFT. Using this approach, we find the most favourable hydration mechanism involves protonation of two O1 sites around the Mg3 vacancy. The formation of silanol groups on O3 or O4 sites (with loss of stable O1–H hydroxyls) coincides with an increase in total enthalpy. Importantly, the approach we employ allows observables such as NMR parameters to be computed for each structure. We consider hydrous wadsleyite (∼1.6 wt%) to be dominated by protonated O1 sites, with O3/O4–H silanol groups present as defects, a model that maps well onto experimental studies at higher levels of hydration (J. M. Griffin et al., Chem. Sci., 2013, 4, 1523). The AIRSS approach adopted herein provides the crucial link between atomic-scale structure and experimental studies.
Kravtsova AN, Soldatov AV, Walker AM, et al., 2016, The Ti environment in natural hibonite: XANES spectroscopy and computer modelling, 16th International Conference on X-ray Absorption Fine Structure (XAFS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Burnham AD, Berry AJ, Halse HR, et al., 2015, The oxidation state of europium in silicate melts as a function of oxygen fugacity, composition and temperature, CHEMICAL GEOLOGY, Vol: 411, Pages: 248-259, ISSN: 0009-2541
Spencer ET, Wilkinson JJ, Nolan J, et al., 2015, The controls of post-entrapment diffusion on the solubility of chalcopyrite daughter crystals in natural quartz-hosted fluid inclusions, Chemical Geology, Vol: 412, Pages: 15-25, ISSN: 1872-6836
The presence of chalcopyrite daughter crystals in natural quartz-hosted fluid inclusions that do not dissolve when heated to trapping conditions suggests that inclusions are subject to post-entrapment modifications that affect chalcopyrite solubility. Previous double capsule experiments conducted by Mavrogenes and Bodnar (1994) concluded that the post-entrapment outward diffusion of H2 is responsible for the presence of non-dissolvable chalcopyrite crystals in natural, quartz-hosted brine inclusions. However, recent studies have shown that quartz-hosted inclusions can also be modified by diffusional H+ loss and Cu+ gain. This means that multiple factors may influence chalcopyrite solubility in different fluid inclusion types. In this study, the experimental procedure of Mavrogenes and Bodnar (1994) was recreated in order to rehydrogenate quartz-hosted, chalcopyrite-bearing fluid inclusions from the El Teniente Cu–Mo porphyry deposit, Chile. These inclusions had a range of salinities and densities. Results show that the experimental technique is successful for fluid inclusions that contain relatively small chalcopyrite daughter crystals and have moderate salinities (> 5 wt.% NaCleq). In contrast, chalcopyrite crystals do not dissolve in low density vapor inclusions even after rehydrogenation. The failure of chalcopyrite crystals to dissolve in these inclusions is attributed to their lower initial pH and higher sulfide concentrations, which led to greater post-entrapment H+ loss and Cu+ gain. This considered, Cu concentrations in moderate to high salinity inclusions are likely to reflect those present at trapping, suggesting that H2 loss is the primary control on the failed dissolution of chalcopyrite. By contrast, Cu concentrations in S-rich vapor inclusions can increase considerably via inward Cu+ diffusion in the presence of an external Cu-bearing fluid and a pH gradient between the inclusion and this fluid (Lerchbaumer and Audétat, 2012; Seo and He
Hanger BJ, Yaxley GM, Berry AJ, et al., 2015, Relationships between oxygen fugacity and metasomatism in the Kaapvaal subcratonic mantle, represented by garnet peridotite xenoliths in the Wesselton kimberlite, South Africa, LITHOS, Vol: 212, Pages: 443-452, ISSN: 0024-4937
Stephen NR, Schofield PF, Berry AJ, 2014, MID-IR MAPPING OF MARTIAN METEORITES WITH 8 MICRON SPATIAL RESOLUTION, 77th Annual Meeting of the Meteoritical-Society, Publisher: WILEY, Pages: A381-A381, ISSN: 1086-9379
Doyle PM, Schofield PF, Berry AJ, et al., 2014, Substitution of Ti3+ and Ti4+ in hibonite (CaAl12O19), AMERICAN MINERALOGIST, Vol: 99, Pages: 1369-1382, ISSN: 0003-004X
Burnham AD, Berry AJ, 2014, The effect of oxygen fugacity, melt composition, temperature and pressure on the oxidation state of cerium in silicate melts, CHEMICAL GEOLOGY, Vol: 366, Pages: 52-60, ISSN: 0009-2541
Burnham AD, Berry AJ, 2013, An experimental study of trace element partitioning between zircon and melt as a function of oxygen fugacity (pg 196, 2012), GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 120, Pages: 561-561, ISSN: 0016-7037
Berry AJ, Yaxley GM, Hanger BJ, et al., 2013, Quantitative mapping of the oxidative effects of mantle metasomatism., Geology
Brownscombe W, Herrington RJ, Wilkinson JJ, et al., 2013, Geochemistry of the Sakatti magmatic Cu-Ni-PGE deposit, northern Finland, 12th Biennial SGA Meeting on Mineral Deposit Research for a High-Tech World, Publisher: SGU-SVERIGES GEOLOGISKA UNDERSOKNING-GEOLOGY SURVEY SWEDEN, Pages: 956-+
Griffin JM, Berry AJ, Frost DJ, et al., 2013, Water in the Earth's mantle: a solid-state NMR study of hydrous wadsleyite, CHEMICAL SCIENCE, Vol: 4, Pages: 1523-1538, ISSN: 2041-6520
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