scholarly journals Oxygen fugacity and melt composition controls on nitrogen solubility in silicate melts

2020 ◽  
Vol 284 ◽  
pp. 120-133 ◽  
Author(s):  
Julien Boulliung ◽  
Evelyn Füri ◽  
Célia Dalou ◽  
Laurent Tissandier ◽  
Laurent Zimmermann ◽  
...  
Keyword(s):  
Oxygen Fugacity ◽  
Nitrogen Solubility ◽  
Silicate Melts ◽  
Melt Composition

scholarly journals The quintet completed: The partitioning of sulfur between nominally volatile-free minerals and silicate melts

2020 ◽  
Vol 105 (5) ◽  
pp. 697-707
Author(s):  
Sara Callegaro ◽  
Kalotina Geraki ◽  
Andrea Marzoli ◽  
Angelo De Min ◽  
Victoria Maneta ◽  
...  
Keyword(s):  
Partition Coefficient ◽  
Oxygen Fugacity ◽  
Partition Coefficients ◽  
Iron Concentration ◽  
Mean Value ◽  
High Oxygen ◽  
Silicate Melts ◽  
Total Sulfur ◽  
Low Oxygen ◽  
Melt Composition

Abstract Magmatic systems are dominated by five volatiles, namely H2O, CO2, F, Cl, and S (the igneous quintet). Multiple studies have measured partitioning of four out of these five volatiles (H2O, CO2, F, and Cl) between nominally volatile-free minerals and melts, whereas the partitioning of sulfur is poorly known. To better constrain the behavior of sulfur in igneous systems we measured the partitioning of sulfur between clinopyroxene and silicate melts over a range of pressure, temperature, and melt composition from 0.8 to 1.2 GPa, 1000 to 1240 °C, and 49 to 66 wt% SiO2 (13 measurements). Additionally, we determined the crystal-melt partitioning of sulfur for plagioclase (6 measurements), orthopyroxene (2 measurements), amphibole (2 measurements), and olivine (1 measurement) in some of these same run products. Experiments were performed at high and low oxygen fugacities, where sulfur in the melt is expected to be dominantly present as an S6+ or an S2– species, respectively. When the partition coefficient is calculated as the total sulfur in the crystal divided by the total sulfur in the melt, the partition coefficient varies from 0.017 to 0.075 for clinopyroxene, from 0.036 to 0.229 for plagioclase, and is a maximum of 0.001 for olivine and of 0.003 for orthopyroxene. The variation in the total sulfur partition coefficient positively correlates with cation-oxygen bond lengths in the crystals; the measured partition coefficients increase in the order: olivine < orthopyroxene < clinopyroxene ≤ amphibole and plagioclase. At high oxygen fugacities in hydrous experiments, the clinopyroxene/melt partition coefficients for total sulfur are only approximately one-third of those measured in low oxygen fugacity, anhydrous experiments. However when the partition coefficient is calculated as total sulfur in the crystal divided by S2– in the melt, the clinopyroxene/melt partition coefficients for experiments with melts between ~51 and 66 wt% SiO2 can be described by a single mean value of 0.063 ± 0.010 (1σ standard deviation about the mean). These two observations support the hypothesis that sulfur, as S2–, replaces oxygen in the crystal structure. The results of hydrous experiments at low oxygen fugacity and anhydrous experiments at high oxygen fugacity suggest that oxygen fugacity has a greater effect on sulfur partitioning than water. Although the total sulfur clinopyroxene-melt partition coefficients are affected by the Mg/(Mg+Fe) ratio of the crystal, partition coefficients calculated using S2– in the melt display no clear dependence upon the Mg# of the clinopyroxene. Both the bulk and the S 2– partition coefficients appear unaffected by IVAl in the clinopyroxene structure. No effect of anorthite content nor of iron concentration in the crystal was seen in the data for plagioclase-melt partitioning. The data obtained for orthopyroxene and olivine were too few to establish any trends. The partition coefficients of total sulfur and S 2– between the crystals studied and silicate melts are typically lower than those of fluorine, higher than those of carbon, and similar to those of chlorine and hydrogen. These sulfur partition coefficients can be combined with analyses of volatiles in nominally volatile-free minerals and previously published partition coefficients of H2O, C, F, and Cl to constrain the concentration of the igneous quintet, the five major volatiles in magmatic systems.

scholarly journals The effect of melt composition and oxygen fugacity on manganese partitioning between apatite and silicate melt

2019 ◽  
Vol 506 ◽  
pp. 162-174 ◽  
Author(s):  
T.N. Stokes ◽  
G.D. Bromiley ◽  
N.J. Potts ◽  
K.E. Saunders ◽  
A.J. Miles
Keyword(s):  
Oxygen Fugacity ◽  
Silicate Melt ◽  
Melt Composition

scholarly journals An experimental study of the partitioning of trace elements between rutile and silicate melt as a function of oxygen fugacity

2014 ◽  
Vol 86 (4) ◽  
pp. 1609-1629 ◽  
Author(s):  
GUILHERME MALLMANN ◽  
RAÚL O.C. FONSECA ◽  
ADOLFO B. SILVA
Keyword(s):  
Oxygen Fugacity ◽  
Silicate Melt ◽  
Accessory Mineral ◽  
High Field Strength ◽  
Arc Magmas ◽  
Melt Polymerization ◽  
Incompatible Elements ◽  
Order Of Magnitude ◽  
Melt Composition ◽  
Partitioning Behavior

Subduction zone or arc magmas are known to display a characteristic depletion of High Field Strength Elements (HFSE) relative to other similarly incompatible elements, which can be attributed to the presence of the accessory mineral rutile (TiO2) in the residual slab. Here we show that the partitioning behavior of vanadium between rutile and silicate melt varies from incompatible (∼0.1) to compatible (∼18) as a function of oxygen fugacity. We also confirm that the HFSE are compatible in rutile, with D(Ta)> D(Nb)>> (D(Hf)>/∼ D(Zr), but that the level of compatibility is strongly dependent on melt composition, with partition coefficients increasing about one order of magnitude with increasing melt polymerization (or decreasing basicity). Our partitioning results also indicate that residual rutile may fractionate U from Th due to the contrasting (over 2 orders of magnitude) partitioning between these two elements. We confirm that, in addition to the HFSE, Cr, Cu, Zn and W are compatible in rutile at all oxygen fugacity conditions.

The oxidation state of europium in silicate melts as a function of oxygen fugacity, composition and temperature

2015 ◽  
Vol 411 ◽  
pp. 248-259 ◽  
Author(s):  
A.D. Burnham ◽  
A.J. Berry ◽  
H.R. Halse ◽  
P.F. Schofield ◽  
G. Cibin ◽  
...  
Keyword(s):  
Oxygen Fugacity ◽  
Oxidation State ◽  
Silicate Melts
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