The depth of the spinel to garnet transition at the peridotite solidus

J. Andrew C Robinson; Bernard J. Wood

doi:10.1016/S0012-821X(98)00213-1

The depth of the spinel to garnet transition at the peridotite solidus

J. Andrew C Robinson, Bernard J. Wood^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

431 Citations (Scopus)

Abstract

We have determined the pressure and temperature of the spinel-garnet transition close to the solidus of fertile and depleted peridotite from a combination of synthesis, sandwich and garnet-seeded experiments. Garnet is unstable in MORB-Pyrolite below 2.8 GPa (depths <85 km) at a solidus temperature of 1470°C. In Tinaquillo Lherzolite, which is related to MORB-Pyrolite by about 7% fractional melting, the transformation occurs at 3.1 GPa at a solidus temperature of 1520°C. In both cases the transformation interval is narrow, approximately 0.1-0.2 GPa. Because the solidus temperature increases by 7°C and the spinel-garnet transformation pressure by 0.05 GPa for every 1% melt extracted, extremely high potential temperatures (T(p) > 1450°C) are required to generate the 3-5% melting in the garnet field implied by recent trace element and isotope studies. It appears likely, therefore, that the 'garnet signature' arises from some mechanism other than anhydrous melting of garnet peridotite.

Original language	English
Pages (from-to)	277-284
Number of pages	8
Journal	Earth and Planetary Science Letters
Volume	164
Issue number	1-2
DOIs	https://doi.org/10.1016/S0012-821X(98)00213-1
Publication status	Published - 15 Dec 1998

Keywords

Garnet group
Lherzolite
Peridotites
Pyrolite
Spinel

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10.1016/S0012-821X(98)00213-1

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title = "The depth of the spinel to garnet transition at the peridotite solidus",

abstract = "We have determined the pressure and temperature of the spinel-garnet transition close to the solidus of fertile and depleted peridotite from a combination of synthesis, sandwich and garnet-seeded experiments. Garnet is unstable in MORB-Pyrolite below 2.8 GPa (depths <85 km) at a solidus temperature of 1470°C. In Tinaquillo Lherzolite, which is related to MORB-Pyrolite by about 7% fractional melting, the transformation occurs at 3.1 GPa at a solidus temperature of 1520°C. In both cases the transformation interval is narrow, approximately 0.1-0.2 GPa. Because the solidus temperature increases by 7°C and the spinel-garnet transformation pressure by 0.05 GPa for every 1% melt extracted, extremely high potential temperatures (T(p) > 1450°C) are required to generate the 3-5% melting in the garnet field implied by recent trace element and isotope studies. It appears likely, therefore, that the 'garnet signature' arises from some mechanism other than anhydrous melting of garnet peridotite.",

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author = "Robinson, {J. Andrew C} and Wood, {Bernard J.}",

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doi = "10.1016/S0012-821X(98)00213-1",

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T1 - The depth of the spinel to garnet transition at the peridotite solidus

AU - Robinson, J. Andrew C

AU - Wood, Bernard J.

PY - 1998/12/15

Y1 - 1998/12/15

N2 - We have determined the pressure and temperature of the spinel-garnet transition close to the solidus of fertile and depleted peridotite from a combination of synthesis, sandwich and garnet-seeded experiments. Garnet is unstable in MORB-Pyrolite below 2.8 GPa (depths <85 km) at a solidus temperature of 1470°C. In Tinaquillo Lherzolite, which is related to MORB-Pyrolite by about 7% fractional melting, the transformation occurs at 3.1 GPa at a solidus temperature of 1520°C. In both cases the transformation interval is narrow, approximately 0.1-0.2 GPa. Because the solidus temperature increases by 7°C and the spinel-garnet transformation pressure by 0.05 GPa for every 1% melt extracted, extremely high potential temperatures (T(p) > 1450°C) are required to generate the 3-5% melting in the garnet field implied by recent trace element and isotope studies. It appears likely, therefore, that the 'garnet signature' arises from some mechanism other than anhydrous melting of garnet peridotite.

AB - We have determined the pressure and temperature of the spinel-garnet transition close to the solidus of fertile and depleted peridotite from a combination of synthesis, sandwich and garnet-seeded experiments. Garnet is unstable in MORB-Pyrolite below 2.8 GPa (depths <85 km) at a solidus temperature of 1470°C. In Tinaquillo Lherzolite, which is related to MORB-Pyrolite by about 7% fractional melting, the transformation occurs at 3.1 GPa at a solidus temperature of 1520°C. In both cases the transformation interval is narrow, approximately 0.1-0.2 GPa. Because the solidus temperature increases by 7°C and the spinel-garnet transformation pressure by 0.05 GPa for every 1% melt extracted, extremely high potential temperatures (T(p) > 1450°C) are required to generate the 3-5% melting in the garnet field implied by recent trace element and isotope studies. It appears likely, therefore, that the 'garnet signature' arises from some mechanism other than anhydrous melting of garnet peridotite.

KW - Garnet group

KW - Lherzolite

KW - Peridotites

KW - Pyrolite

KW - Spinel

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U2 - 10.1016/S0012-821X(98)00213-1

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SN - 0012-821X

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JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

IS - 1-2

ER -

The depth of the spinel to garnet transition at the peridotite solidus

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Keywords

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