Ferguson, Colin C., Al-Ameen, Sanaa I. (1985) Muscovite breakdown and corundum growth at anomalously low fH2o: a study of contact metamorphism and convective fluid movement around the Omey granite, Connemara, Ireland. Mineralogical Magazine, 49 (353) 505-514 doi:10.1180/minmag.1985.049.353.03
| Reference Type | Journal (article/letter/editorial) | ||
|---|---|---|---|
| Title | Muscovite breakdown and corundum growth at anomalously low fH2o: a study of contact metamorphism and convective fluid movement around the Omey granite, Connemara, Ireland | ||
| Journal | Mineralogical Magazine | ISSN | 0026-461X |
| Authors | Ferguson, Colin C. | Author | |
| Al-Ameen, Sanaa I. | Author | ||
| Year | 1985 (September) | Volume | 49 |
| Issue | 353 | ||
| Publisher | Mineralogical Society | ||
| Download URL | https://rruff.info/doclib/MinMag/Volume_49/49-353-505.pdf+ | ||
| DOI | doi:10.1180/minmag.1985.049.353.03Search in ResearchGate | ||
| Generate Citation Formats | |||
| Mindat Ref. ID | 3757 | Long-form Identifier | mindat:1:5:3757:4 |
| GUID | 0 | ||
| Full Reference | Ferguson, Colin C., Al-Ameen, Sanaa I. (1985) Muscovite breakdown and corundum growth at anomalously low fH2o: a study of contact metamorphism and convective fluid movement around the Omey granite, Connemara, Ireland. Mineralogical Magazine, 49 (353) 505-514 doi:10.1180/minmag.1985.049.353.03 | ||
| Plain Text | Ferguson, Colin C., Al-Ameen, Sanaa I. (1985) Muscovite breakdown and corundum growth at anomalously low fH2o: a study of contact metamorphism and convective fluid movement around the Omey granite, Connemara, Ireland. Mineralogical Magazine, 49 (353) 505-514 doi:10.1180/minmag.1985.049.353.03 | ||
| In | (1985, September) Mineralogical Magazine Vol. 49 (353). Mineralogical Society | ||
| Abstract/Notes | AbstractIn the aureole of the late Caledonian Omey granite corundum develops in the Dalradian country rocks in a zone up to 250 m from the granite contact. The distribution of andalusite and K-feldspar in pelites and calcite+wollastonite+grossularite in marbles is consistent with inner-aureole metamorphic conditions of 615±25°C at 2.5±0.25 kbar, and â 0.85. Corundum develops from the reaction muscovite â corundum + K-feldspar+H2O and first appears over 100 m further from the granite than the assemblage wollastonite + grossularite + anorthite. Experimentally determined equilibria can be satisfied only if for the corundum-producing reaction was less than 0.6 and perhaps as low as 0.4. Corundum always grows within large muscovite crystals;fH2O within the crystal lattice is unrelated to that in the grain-boundary fluid of the surrounding rock.Although whole-rock oxidation ratios are irregularly distributed within the aureole they are uniformly low in corundum-bearing rocks. Reducing conditions probably resulted from localized flow of H2O-rich fluid away from the granite in a diffuse channelway that contains most of the corundum localities and also a distinctive skarn. Although corundum growth within muscovite is sealed off from the external water vapour conditions, it is suggested that movement of H2O down a thermal gradient (and hence down an fH2O gradient at constant pressure) promotes the escape of (OH)â from the muscovite lattice and so allows the corundum reaction to proceed. | ||
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