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dc.contributor.authorWhite, R.
dc.contributor.authorPowell, R.
dc.contributor.authorJohnson, Tim
dc.date.accessioned2017-01-30T15:34:52Z
dc.date.available2017-01-30T15:34:52Z
dc.date.created2015-02-02T20:00:44Z
dc.date.issued2014
dc.identifier.citationWhite, R. and Powell, R. and Johnson, T. 2014. The effect of Mn on mineral stability in metapelites revisited: new a–x relations for manganese-bearing minerals. Journal of Metamorphic Geology. 32 (8): pp. 809-828.
dc.identifier.urihttp://hdl.handle.net/20.500.11937/47661
dc.identifier.doi10.1111/jmg.12095
dc.description.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.

dc.publisherWiley - Blackwell
dc.subjectMn-end-members
dc.subjectTHERMOCALC
dc.subjectgarnet
dc.titleThe effect of Mn on mineral stability in metapelites revisited: new a–x relations for manganese-bearing minerals
dc.typeJournal Article
dcterms.source.volume32
dcterms.source.startPage809
dcterms.source.endPage828
dcterms.source.issn0263-4929
dcterms.source.titleJournal of Metamorphic Geology
curtin.note

This is the accepted version of the following article: White, R. and Powell, R. and Johnson, T. 2014. The effect of Mn on mineral stability in metapelites revisited: new a–x relations for manganese-bearing minerals. Journal of Metamorphic Geology. 32 (8): pp. 809-828, which has been published in final form at http://doi.org/10.1111/jmg.12095

curtin.departmentDepartment of Applied Geology
curtin.accessStatusOpen access


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