Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/117604
Citations
Scopus Web of Science® Altmetric
?
?
Type: Journal article
Title: The effect of Mn on mineral stability in metapelites revisited: new a-x relations for manganese-bearing minerals
Author: White, R.
Powell, R.
Johnson, T.
Citation: Journal of Metamorphic Geology, 2014; 32(8):809-828
Publisher: Wiley-Blackwell
Issue Date: 2014
ISSN: 0263-4929
1525-1314
Statement of
Responsibility: 
R. W. White, R. Powell, T. E. Johnson
Abstract: The a–x relations recently presented in White et al. (2014, Journal of Metamorphic Geology, 32, 261–286) are extended to include MnO. This provides a set of internally consistent a–x relations for metapelitic rocks in the MnO–Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O2 (MnNCKFMASHTO) system. The mixing parameters for the Mn‐bearing minerals were estimated using the micro‐ϕ approach of Powell et al. (2014, Journal of Metamorphic Geology, 32, 245–260). Then the Mn‐end‐member thermodynamic properties were calibrated using a database of co‐existing minerals involving literature data from rocks and from experiments on natural materials. Mn‐end‐members were calibrated for orthopyroxene, cordierite, staurolite, chloritoid, chlorite, biotite, ilmenite and hematite, assuming known properties for the garnet end‐member spessartine. The addition of MnO to phase diagram calculations results in a marked expansion of the stability of garnet‐bearing assemblages. At greenschist facies conditions garnet stability is extended down temperature. At amphibolite facies conditions, the garnet‐in boundary shifts to lower pressure. While the addition of MnO greatly influences the stability of garnet, it has relatively little effect on the stability of other common metapelitic minerals, with the resultant diagrams being topologically very similar to those calculated without MnO. Furthermore, the addition of MnO in the amounts measured in most metapelites has only a small effect on the mode of garnet, with calculated garnet modes remaining smaller than 1% in the P–T range outside its predicted Mn‐free P–T range.
Keywords: Garnet; Mn‐end‐members; thermocalc
Rights: © 2014 John Wiley & Sons Ltd.
RMID: 0030105716
DOI: 10.1111/jmg.12095
Grant ID: http://purl.org/au-research/grants/arc/DP0451770
http://purl.org/au-research/grants/arc/DP0987731
Appears in Collections:Geology & Geophysics publications

Files in This Item:
There are no files associated with this item.


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.