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We present a new set of reference materials, the ND70‐series, for in situ measurement of volatile elements (H2O, CO2, S, Cl, F) in silicate glass of basaltic composition. The materials were synthesised in piston cylinders at pressures of 1 to 1.5 GPa under volatile‐undersaturated conditions. They span mass fractions from 0 to 6% m/m H2O, from 0 to 1.6% m/m CO2 and from 0 to 1% m/m S, Cl and F. The materials were characterised by elastic recoil detection analysis for H2O, by nuclear reaction analysis for CO2, by elemental analyser for CO2, by Fourier transform infrared spectroscopy for H2O and CO2, by secondary ion mass spectrometry for H2O, CO2, S, Cl and F, and by electron probe microanalysis for CO2, S, Cl and major elements. Comparison between expected and measured volatile amounts across techniques and institutions is excellent. It was found however that SIMS measurements of CO2 mass fractions using either Cs+ or O− primary beams are strongly affected by the glass H2O content. Reference materials have been made available to users at ion probe facilities in the US, Europe and Japan. Remaining reference materials are preserved at the Smithsonian National Museum of Natural History where they are freely available on loan to any researcher. [ABSTRACT FROM AUTHOR]

This study presents a new experimental approach for determining H.sub.2O solubility in basaltic melt at upper mantle conditions. Traditional solubility experiments are limited to pressures of ~600 MPa or less because it is difficult to reliably quench silicate melts containing greater than ~10 wt% dissolved H.sub.2O. To overcome this limitation, our approach relies on the use of secondary ion mass spectrometry to measure the concentration of H dissolved in olivine and on using the measured H in olivine as a proxy for the concentration of H.sub.2O in the co-existing basaltic melt. The solubility of H.sub.2O in the melt is determined by performing a series of experiments at a single pressure and temperature with increasing amounts of liquid H.sub.2O added to each charge. The point at which the concentration of H in the olivine first becomes independent of the amount of initial H.sub.2O content of the charge (added + adsorbed H.sub.2O) indicates its solubility in the melt. Experiments were conducted by packing basalt powder into a capsule fabricated from San Carlos olivine, which was then pressure-sealed inside a Ni outer capsule. Our experimental results indicate that at 1000 MPa and 1200 °C, the solubility of H.sub.2O in basaltic melt is 20.6 ± 0.9 wt% (2 x standard deviation). This concentration is considerably higher than predicted by most solubility models but defines a linear relationship between H.sub.2O fugacity and the square of molar H.sub.2O solubility when combined with solubility data from lower pressure experiments. Further, our solubility determination agrees with melting point depression determined experimentally by Grove et al. (2006 (See CR30)) for the H.sub.2O-saturated peridotite solidus at 1000 MPa. Melting point depression calculations were used to estimate H.sub.2O solubility in basalt along the experimentally determined H.sub.2O-saturated peridotite solidus. The results suggest that a linear relationship between H.sub.2O fugacity and the square of molar solubility exists up to ~1300 MPa, where there is an inflection point and solubility begins to increase less strongly with increasing H.sub.2O fugacity., Author(s): Alexandra L. Mitchell [sup.1] [sup.2] , Glenn A. Gaetani [sup.3] , Julie A. O'Leary [sup.3] [sup.4] , Erik H. Hauri [sup.5] Author Affiliations: (1) Department of Earth, Atmospheric and [...]

This experimental study examines the mineral/ melt partitioning of incompatible trace elements among high-Ca clinopyroxene, garnet, and hydrous silicate melt at upper mantle pressure and temperature conditions. Experiments were performed at pressures of 1.2 and 1.6 GPa and temperatures of 1,185 to 1,370[degrees]C. Experimentally produced silicate melts contain up to 6.3 wt% dissolved [H.sub.2]O, and are saturated with an upper mantle peridotite mineral assemblage of olivine + orthopyroxene + clinopyroxene+spinel or garnet. Clinopyroxene/ melt and garnet/melt partition coefficients were measured for Li, B, K, Sr, Y, Zr, Nb, and select rare earth elements by secondary ion mass spectrometry. A comparison of our experimental results for trivalent cations (REEs and Y) with the results from calculations carried out using the Wood-Blundy partitioning model indicates that [H.sub.2]O dissolved in the silicate melt has a discernible effect on trace element partitioning. Experiments carried out at 1.2 GPa, 1,315[degrees]C and 1.6 GPa, 1,370[degrees]C produced clinopyroxene containing 15.0 and 13.9 wt% CaO, respectively, coexisting with silicate melts containing ~1-2 wt% [H.sub.2]O. Partition coefficients measured in these experiments are consistent with the Wood-Blundy model. However, partition coefficients determined in an experiment carried out at 1.2 GPa and 1,185 [degrees]C, which produced clinopyroxene containing 19.3 wt% CaO coexisting with a high-[H.sub.2]O (6.26 [+ or -] 0.10 wt%) silicate melt, are significantly smaller than predicted by the Wood-Blundy model. Accounting for the depolymerized structure of the [H.sub.2]O-rich melt eliminates the mismatch between experimental result and model prediction. Therefore, the increased [Ca.sup.2+] content of clinopyroxene at low-temperature, hydrous conditions does not enhance compatibility to the extent indicated by results from anhydrous experiments, and models used to predict mineral/melt partition coefficients during hydrous peridotite partial melting in the sub-arc mantle must take into account the effects of [H.sub.2]O on the structure of silicate melts.