Evidence of sub-arc mantle oxidation by sulphur and carbon

A. Rielli; A. G. Tomkins; O. Nebel; J. Brugger; B. Etschmann; R. Zhong; G. M. Yaxley; D. Paterson

doi:10.7185/geochemlet.1713

Evidence of sub-arc mantle oxidation by sulphur and carbon

A. Rielli^*, A. G. Tomkins, O. Nebel, J. Brugger, B. Etschmann, R. Zhong, G. M. Yaxley, D. Paterson

^*Corresponding author for this work

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

53 Citations (Scopus)

Abstract

The oxygen fugacity (fO₂) of the Earth's mantle at subduction zones exerts a primary control on the genesis of mineral deposits in the overlying magmatic arcs and on speciation of volcanic gases emitted into the atmosphere. However, the processes governing mantle fO₂ such as the introduction of oxidised material by subduction are still unresolved. Here, we present evidence for the reduction of oxidised fluid-borne sulphur and carbon during alteration of depleted mantle by slab fluids at ultra-high pressure in the Bardane peridotite (Western Gneiss Region, Norway). Elevated ferric iron in metasomatic garnet, determined using synchrotron X-ray absorption near edge structure (XANES) spectroscopy, indicates that this process drove oxidation of the silicate assemblage. Our finding indicates that subduction oxidises the Earth's mantle by cycling of sulphur and carbon.

Original language	English
Pages (from-to)	124-132
Number of pages	9
Journal	Geochemical Perspectives Letters
Volume	3
Issue number	2
DOIs	https://doi.org/10.7185/geochemlet.1713
Publication status	Published - 2017

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title = "Evidence of sub-arc mantle oxidation by sulphur and carbon",

abstract = "The oxygen fugacity (fO2) of the Earth's mantle at subduction zones exerts a primary control on the genesis of mineral deposits in the overlying magmatic arcs and on speciation of volcanic gases emitted into the atmosphere. However, the processes governing mantle fO2 such as the introduction of oxidised material by subduction are still unresolved. Here, we present evidence for the reduction of oxidised fluid-borne sulphur and carbon during alteration of depleted mantle by slab fluids at ultra-high pressure in the Bardane peridotite (Western Gneiss Region, Norway). Elevated ferric iron in metasomatic garnet, determined using synchrotron X-ray absorption near edge structure (XANES) spectroscopy, indicates that this process drove oxidation of the silicate assemblage. Our finding indicates that subduction oxidises the Earth's mantle by cycling of sulphur and carbon.",

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AU - Rielli, A.

AU - Tomkins, A. G.

AU - Nebel, O.

AU - Brugger, J.

AU - Etschmann, B.

AU - Zhong, R.

AU - Yaxley, G. M.

AU - Paterson, D.

PY - 2017

Y1 - 2017

N2 - The oxygen fugacity (fO2) of the Earth's mantle at subduction zones exerts a primary control on the genesis of mineral deposits in the overlying magmatic arcs and on speciation of volcanic gases emitted into the atmosphere. However, the processes governing mantle fO2 such as the introduction of oxidised material by subduction are still unresolved. Here, we present evidence for the reduction of oxidised fluid-borne sulphur and carbon during alteration of depleted mantle by slab fluids at ultra-high pressure in the Bardane peridotite (Western Gneiss Region, Norway). Elevated ferric iron in metasomatic garnet, determined using synchrotron X-ray absorption near edge structure (XANES) spectroscopy, indicates that this process drove oxidation of the silicate assemblage. Our finding indicates that subduction oxidises the Earth's mantle by cycling of sulphur and carbon.

AB - The oxygen fugacity (fO2) of the Earth's mantle at subduction zones exerts a primary control on the genesis of mineral deposits in the overlying magmatic arcs and on speciation of volcanic gases emitted into the atmosphere. However, the processes governing mantle fO2 such as the introduction of oxidised material by subduction are still unresolved. Here, we present evidence for the reduction of oxidised fluid-borne sulphur and carbon during alteration of depleted mantle by slab fluids at ultra-high pressure in the Bardane peridotite (Western Gneiss Region, Norway). Elevated ferric iron in metasomatic garnet, determined using synchrotron X-ray absorption near edge structure (XANES) spectroscopy, indicates that this process drove oxidation of the silicate assemblage. Our finding indicates that subduction oxidises the Earth's mantle by cycling of sulphur and carbon.

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DO - 10.7185/geochemlet.1713

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JO - Geochemical Perspectives Letters

JF - Geochemical Perspectives Letters

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Evidence of sub-arc mantle oxidation by sulphur and carbon

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