TY - JOUR
T1 - The effect of melt composition on mineral-melt partition coefficients
T2 - The case of beryllium
AU - Burnham, A. D.
AU - O'Neill, H. St C.
N1 - Funding Information:
We are grateful to Jung-Woo Park, Mike Jollands and Pete Tollan for assistance with the LA-ICP-MS analyses, and to Bob Rapp for assistance with the electron probe. Brian Harrold and Sarah Miller are thanked for assistance with implementing the thermodynamic model of Berman (1983) . We thank Sascha Borisov, David London and Andreas Pack for their reviews and suggestions, and Don Dingwell for his editorial handling. This work was supported by Australian Research Council Laureate Fellowship FL130100066 to HO'N.
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/11/28
Y1 - 2016/11/28
N2 - The divalent cation Be2 + is considerably smaller than other divalent cations (Mg2 +, Fe2 +, Ca2 +, et cetera), leading to a strong preference for tetrahedral coordination in minerals. Its thermodynamic properties in silicate melts may accordingly differ from these other divalent cations, potentially distinguishing its mineral/melt partition coefficients. In order to investigate this possibility, the partitioning of Be between silicate melt and forsterite was examined for 16 melt compositions in the systems CaO–MgO–Al2O3–SiO2 at 1400 °C with additional experiments to investigate the effect of added Na2O and TiO2, and temperature at 1300 °C. The relative activity coefficient of BeO in the melts decreases with increasing CaO and NaO1.5. The results are compared to Mg and Ca partitioning in the same experiments, and to the partitioning of other divalent cations (Ni, Co, Mn) from the literature. While the partition coefficient of the latter correlate positively with the Mg partition coefficient, Be shows only a weak negative correlation. Compared to Ca, Be partitions less strongly into forsterite when the melt has high Na and/or Ca. Partition coefficients for Na, Al and Ti are also reported.
AB - The divalent cation Be2 + is considerably smaller than other divalent cations (Mg2 +, Fe2 +, Ca2 +, et cetera), leading to a strong preference for tetrahedral coordination in minerals. Its thermodynamic properties in silicate melts may accordingly differ from these other divalent cations, potentially distinguishing its mineral/melt partition coefficients. In order to investigate this possibility, the partitioning of Be between silicate melt and forsterite was examined for 16 melt compositions in the systems CaO–MgO–Al2O3–SiO2 at 1400 °C with additional experiments to investigate the effect of added Na2O and TiO2, and temperature at 1300 °C. The relative activity coefficient of BeO in the melts decreases with increasing CaO and NaO1.5. The results are compared to Mg and Ca partitioning in the same experiments, and to the partitioning of other divalent cations (Ni, Co, Mn) from the literature. While the partition coefficient of the latter correlate positively with the Mg partition coefficient, Be shows only a weak negative correlation. Compared to Ca, Be partitions less strongly into forsterite when the melt has high Na and/or Ca. Partition coefficients for Na, Al and Ti are also reported.
KW - Beryllium
KW - Melt structure
KW - Olivine
KW - Partitioning
KW - Trace elements
UR - http://www.scopus.com/inward/record.url?scp=84987974253&partnerID=8YFLogxK
U2 - 10.1016/j.chemgeo.2016.09.012
DO - 10.1016/j.chemgeo.2016.09.012
M3 - Article
AN - SCOPUS:84987974253
VL - 442
SP - 139
EP - 147
JO - Chemical Geology
JF - Chemical Geology
SN - 0009-2541
ER -