Thermodynamic controls on element partitioning between titanomagnetite and andesitic–dacitic silicate melts
Name:
Sievwright_et_al_2017.pdf
Size:
2.016Mb
Format:
PDF
Description:
Published/publisher's PDF version
Average rating
Cast your vote
You can rate an item by clicking the amount of stars they wish to award to
this item.
When enough users have cast their vote on this item, the average rating will also be shown.
Star rating
Your vote was cast
Thank you for your feedback
Thank you for your feedback
Issue date
07/07/2017Submitted date
2017-07-10Subject Terms
MagnetiteTrace-element partitioning
Andesite
Dacite
Oxygen fugacity
Petrogenetic indicator
Metadata
Show full item recordAbstract
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.Citation
Sievwright, R.H., Wilkinson, J.J., O’Neill, H.S.C. et al. Thermodynamic controls on element partitioning between titanomagnetite and andesitic–dacitic silicate melts. Contrib Mineral Petrol 172, 62 (2017). https://doi.org/10.1007/s00410-017-1385-6Publisher
SpringerLinkType
Journal ArticleItem Description
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The attached file is the published pdf.NHM Repository
ISSN
0010-7999EISSN
1432-0967ae974a485f413a2113503eed53cd6c53
10.1007/s00410-017-1385-6
Scopus Count
Collections