Brady, A. E., Moore, K. R. (2012) A mantle-derived dolomite silicocarbonatite from the southwest coast of Ireland. Mineralogical Magazine, 76 (2) 357-376 doi:10.1180/minmag.2012.076.2.06
| Reference Type | Journal (article/letter/editorial) | ||
|---|---|---|---|
| Title | A mantle-derived dolomite silicocarbonatite from the southwest coast of Ireland | ||
| Journal | Mineralogical Magazine | ||
| Authors | Brady, A. E. | Author | |
| Moore, K. R. | Author | ||
| Year | 2012 (April) | Volume | 76 |
| Page(s) | 357-376 | Issue | 2 |
| Publisher | Mineralogical Society | ||
| DOI | doi:10.1180/minmag.2012.076.2.06Search in ResearchGate | ||
| Mindat Ref. ID | 244222 | Long-form Identifier | mindat:1:5:244222:2 |
| GUID | f5f45a9d-ef46-4eef-b838-4c218a4e4fa8 | ||
| Full Reference | Brady, A. E., Moore, K. R. (2012) A mantle-derived dolomite silicocarbonatite from the southwest coast of Ireland. Mineralogical Magazine, 76 (2) 357-376 doi:10.1180/minmag.2012.076.2.06 | ||
| Plain Text | Brady, A. E., Moore, K. R. (2012) A mantle-derived dolomite silicocarbonatite from the southwest coast of Ireland. Mineralogical Magazine, 76 (2) 357-376 doi:10.1180/minmag.2012.076.2.06 | ||
| Abstract/Notes | AbstractThe magma source and evolution of a zoned breccia pipe on the southern Beara Peninsula in southwest Ireland are investigated using the geochemistry of the host mineral assemblages. The clast-poor inner zone of the pipe has a magnesium-rich silicocarbonatite whole-rock composition (14.30 wt.% MgO; 31.80 wt.% SiO2). The silicocarbonatite has retained an ultimate mantle source 13C isotopic composition after metamorphism, consistent with the presence of mantle debris. The silicocarbonatite is Cr-, Ni- and Co-rich (847 ppm, 611 ppm and 60 ppm, respectively) but REE depleted compared with volcanic dolomite carbonatites worldwide. The mineral assemblage consists of Sr-rich (0.55 wt.% SrO) ferroan dolomite, magnesite and pseudomorphs of chlorite after phlogopite, consistent with derivation from a carbonated and hydrated mantle. However, chrome spinel crystals (≤4 40.14 wt.% Cr2O3) are compositionally indistinguishable from unmetasomatized spinel macrocrysts in kimberlites. The silicocarbonatite is inferred to represent a magma produced by partial melting of metasomatized mantle at physical conditions between those in which primary dolomite carbonatite and ultramafic magmas of high-pressure origin form. The primary silicocarbonatite magma ascended and sampled mantle material in a manner similar to kimberlite, and subsequently lost volatile components due to release of metasomatic fluids and later metamorphism. | ||
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