An occurrence of grandidierite, kornerupine, and tourmaline in southeastern Ontario, Canada

Lonker, Steven W.

doi:10.1007/bf00372367

Cited by 34 publications

(12 citation statements)

References 34 publications

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“…Lonker (1988;personal communication with D. London, 1987) reported that tourmaline disappears completely near the second sillimanite isograd in south-central New England, USA, and that leucosomes of probable anatectic origin are tourmaline-free. Additionally, similar kinds of limited distributions of tourmaline are also de®ned in the Yanai area of the Ryoke belt (T. Kawakami, unpublished data).…”

Section: General Importance Of the Tourmaline-out Isogradmentioning

confidence: 99%

Tourmaline breakdown in the migmatite zone of the Ryoke metamorphic belt, SW Japan

Kawakami

2001

Journal Metamorphic Geology

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A sharp line delimitating the distribution of tourmaline (termed as a`tourmaline-out isograd') is de®ned in the migmatite zone of the Ryoke metamorphic belt, Japan. The trend of the tourmaline-out isograd closely matches that of the isograds formed through the regional metamorphism, suggesting that it represents the breakdown front of tourmaline during regional metamorphism. This is con®rmed by the presence of the reaction textures of tourmaline to sillimanite and cordierite near the tourmaline-out isograd. The breakdown of tourmaline would release boron into associated melts or¯uids and be an important factor in controlling the behaviour of boron in tourmaline-bearing high-temperature metamorphic rocks. Near the tourmaline-out isograd, large tourmaline crystals occur in the centre of interboudin partitions containing leucosome. In the melanosome of the intervening matrix, reaction textures involving tourmaline are locally observed. These observations imply that tourmaline breakdown is related to a melting reaction and that the boron in the leucosome is derived from the breakdown of tourmaline in the melanosome during prograde metamorphism. Boron released by tourmaline breakdown lowers both the solidus temperature of the rock and the viscosity of any associated melt. Considering that the tourmaline-out isograd lies close to the schist±migmatite boundary, these effects might have enhanced melt generation and segregation in the migmatite zone of the Ryoke belt.The evidence for the breakdown of tourmaline and the almost complete absence of any borosilicates throughout the migmatite zone suggest that boron was effectively removed from this region by the movement of melt and/or¯uid. This implies that the tourmaline-out isograd can re¯ect a signi®cant amount of mass transfer in the anatectic zones.

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Section: General Importance Of the Tourmaline-out Isogradmentioning

confidence: 99%

Tourmaline breakdown in the migmatite zone of the Ryoke metamorphic belt, SW Japan

Kawakami

2001

Journal Metamorphic Geology

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“…Grew et al, 1991a;Grew, 1982;Lonker, 1988;Ackermand et al, 1991;Waters and Moore, 1985). It is often found in paragneiss sequences in association with Mg-aluminous associations such as sillimanite, sapphirine (but not sapphirine + quartz), orthopyroxene, cordierite and spinel and rarely with quartz and plagioclase.…”

Section: Introductionmentioning

confidence: 99%

“…Kornempine-grandidierite __+ tourmaline assemblages have rarely been described (Lonker, 1988), with occurrences of other combinations of borosilicates similarly infrequent (e.g. Vr~ina, 1979).…”

Section: Introductionmentioning

confidence: 99%

“…GRANDIDIERITE is a Fe-Mg aluminous borosilicate [(Mg,Fe)A13BSiO9], and has been reported from around 20 localities world-wide (Lonker, 1988). Most reported occurrences are from low-pressure, high-temperature environments such as contact aureoles (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Grew et al (1989Grew et al ( , 1991 describe kornerupine-bearing slyudites from the Aldan Shield in which both grandidierite and tourmaline are considered to be post-peak mineral phases, associated with partial melting (Grew et al, 1989). Similarly, Lonker (1988) describes kornerupine-grandidierite-tourmaline assemblages in migmatitic pelitic granulites from Ontario, Canada, with grandidierite formation occurring during decompressional heating and postdating komerupine growth. However, in this case, no textural relationships between the borosilicates were observed.…”

Section: Introductionmentioning

confidence: 99%

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

1995

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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)A13BSiO9. 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 komerupine and grandidierite.The grandidierite-and kornerupine-bearing segregations from Seal Cove largely postdate structures developed during a crustal thickening event (Da) which was coeval with peak metamorphism. At McCarthy Point, grandidierite, kornerupine and late-tourmaline growth predates, or is synchronous, with F3 fold structures developed during a extensive granulite grade, normal shearing event (D3) 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~ for formation of the grandidierite-kornerupine assemblage.

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Experimental reactions of amphibolite with boron-bearing aqueous fluids at 200 MPa: implications for tourmaline stability and partial melting in mafic rocks

Morgan

London

1989

Contrib Mineral Petrol

125

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An occurrence of grandidierite, kornerupine, and tourmaline in southeastern Ontario, Canada

Cited by 34 publications

References 34 publications

Tourmaline breakdown in the migmatite zone of the Ryoke metamorphic belt, SW Japan

Tourmaline breakdown in the migmatite zone of the Ryoke metamorphic belt, SW Japan

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

Experimental reactions of amphibolite with boron-bearing aqueous fluids at 200 MPa: implications for tourmaline stability and partial melting in mafic rocks

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