Stable coexistence of grandiderite and kornerupine during medium pressure granulite facies metamorphism

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dc.contributor.authorCarson, C.
dc.contributor.authorHand, M.
dc.contributor.authorDirks, P.
dc.date.issued1995
dc.description.abstract<jats:title>Abstract</jats:title><jats:p>Petrological and mineral chemical data are presented for two new occurrences of co-existing borosilicate minerals in the Larsemann Hills, East Antarctica. The assemblages contain kornerupine and the rare borosilicate, grandidierite (Mg,Fe)A1<jats:sub>3</jats:sub>BSiO<jats:sub>9</jats:sub>. Two distinct associations occur: (1) At McCarthy Point, 1–10 mm thick tourmaline-kornerupine-grandidierite layers are hosted within quartzofeldspathic gneiss; and (2) Seal Cove, where coexisting kornerupine and grandidierite occur within coarse-grained, metamorphic segregations with Mg-rich cores of cordierite-garnet-spinel-biotite-ilmenite and variably developed plagioclase halos. The segregations are hosted within biotite-bearing, plagio-feldspathic gneiss. Textural relationships from these localities indicate the stability of co-existing kornerupine and grandidierite.</jats:p><jats:p>The grandidierite- and kornerupine-bearing segregations from Seal Cove largely postdate structures developed during a crustal thickening event (D<jats:sub>2</jats:sub>) which was coeval with peak metamorphism. At McCarthy Point, grandidierite, kornerupine and late-tourmaline growth predates, or is synchronous, with F<jats:sub>3</jats:sub> fold structures developed during a extensive granulite grade, normal shearing event (D<jats:sub>3</jats:sub>) which occurred prior to, and synchronous with, near-isothermal decompression. Average pressure calculations on assemblages that coexist with the borosilicates at Seal Cove, indicate the prevailing conditions were 5.2–5.5 kbar at ∼ 750°C for formation of the grandidierite-kornerupine assemblage.</jats:p>
dc.identifier.citationMineralogical Magazine, 1995; 59(395):327-339
dc.identifier.doi10.1180/minmag.1995.059.395.16
dc.identifier.issn0026-461X
dc.identifier.issn1471-8022
dc.identifier.orcidHand, M. [0000-0003-3743-9706]
dc.identifier.urihttp://hdl.handle.net/2440/13819
dc.language.isoen
dc.publisherMineralogical Society
dc.source.urihttps://doi.org/10.1180/minmag.1995.059.395.16
dc.titleStable coexistence of grandiderite and kornerupine during medium pressure granulite facies metamorphism
dc.typeJournal article
pubs.publication-statusPublished

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