Noble gases recycled into the mantle through cold subduction zones

Andrew J. Smye, Colin R.M. Jackson, Matthias Konrad-Schmolke, Marc A. Hesse, Steve W. Parman, David L. Shuster, Chris J. Ballentine

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Subduction of hydrous and carbonated oceanic lithosphere replenishes the mantle volatile inventory. Substantial uncertainties exist on the magnitudes of the recycled volatile fluxes and it is unclear whether Earth surface reservoirs are undergoing net-loss or net-gain of H2O and CO2. Here, we use noble gases as tracers for deep volatile cycling. Specifically, we construct and apply a kinetic model to estimate the effect of subduction zone metamorphism on the elemental composition of noble gases in amphibole – a common constituent of altered oceanic crust. We show that progressive dehydration of the slab leads to the extraction of noble gases, linking noble gas recycling to H2O. Noble gases are strongly fractionated within hot subduction zones, whereas minimal fractionation occurs along colder subduction geotherms. In the context of our modelling, this implies that the mantle heavy noble gas inventory is dominated by the injection of noble gases through cold subduction zones. For cold subduction zones, we estimate a present-day bulk recycling efficiency, past the depth of amphibole breakdown, of 5–35% and 60–80% for 36Ar and H2O bound within oceanic crust, respectively. Given that hotter subduction dominates over geologic history, this result highlights the importance of cooler subduction zones in regassing the mantle and in affecting the modern volatile budget of Earth's interior.

Original languageEnglish (US)
Pages (from-to)65-73
Number of pages9
JournalEarth and Planetary Science Letters
Volume471
DOIs
StatePublished - Aug 1 2017

Fingerprint

Noble Gases
noble gas
subduction zone
rare gases
Earth mantle
mantle
Amphibole Asbestos
subduction
amphiboles
amphibole
oceanic crust
recycling
Recycling
Earth (planet)
crusts
oceanic lithosphere
Fractionation
cold
Dehydration
dehydration

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Smye, A. J., Jackson, C. R. M., Konrad-Schmolke, M., Hesse, M. A., Parman, S. W., Shuster, D. L., & Ballentine, C. J. (2017). Noble gases recycled into the mantle through cold subduction zones. Earth and Planetary Science Letters, 471, 65-73. https://doi.org/10.1016/j.epsl.2017.04.046
Smye, Andrew J. ; Jackson, Colin R.M. ; Konrad-Schmolke, Matthias ; Hesse, Marc A. ; Parman, Steve W. ; Shuster, David L. ; Ballentine, Chris J. / Noble gases recycled into the mantle through cold subduction zones. In: Earth and Planetary Science Letters. 2017 ; Vol. 471. pp. 65-73.
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Smye, AJ, Jackson, CRM, Konrad-Schmolke, M, Hesse, MA, Parman, SW, Shuster, DL & Ballentine, CJ 2017, 'Noble gases recycled into the mantle through cold subduction zones', Earth and Planetary Science Letters, vol. 471, pp. 65-73. https://doi.org/10.1016/j.epsl.2017.04.046

Noble gases recycled into the mantle through cold subduction zones. / Smye, Andrew J.; Jackson, Colin R.M.; Konrad-Schmolke, Matthias; Hesse, Marc A.; Parman, Steve W.; Shuster, David L.; Ballentine, Chris J.

In: Earth and Planetary Science Letters, Vol. 471, 01.08.2017, p. 65-73.

Research output: Contribution to journalArticle

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AU - Smye, Andrew J.

AU - Jackson, Colin R.M.

AU - Konrad-Schmolke, Matthias

AU - Hesse, Marc A.

AU - Parman, Steve W.

AU - Shuster, David L.

AU - Ballentine, Chris J.

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AB - Subduction of hydrous and carbonated oceanic lithosphere replenishes the mantle volatile inventory. Substantial uncertainties exist on the magnitudes of the recycled volatile fluxes and it is unclear whether Earth surface reservoirs are undergoing net-loss or net-gain of H2O and CO2. Here, we use noble gases as tracers for deep volatile cycling. Specifically, we construct and apply a kinetic model to estimate the effect of subduction zone metamorphism on the elemental composition of noble gases in amphibole – a common constituent of altered oceanic crust. We show that progressive dehydration of the slab leads to the extraction of noble gases, linking noble gas recycling to H2O. Noble gases are strongly fractionated within hot subduction zones, whereas minimal fractionation occurs along colder subduction geotherms. In the context of our modelling, this implies that the mantle heavy noble gas inventory is dominated by the injection of noble gases through cold subduction zones. For cold subduction zones, we estimate a present-day bulk recycling efficiency, past the depth of amphibole breakdown, of 5–35% and 60–80% for 36Ar and H2O bound within oceanic crust, respectively. Given that hotter subduction dominates over geologic history, this result highlights the importance of cooler subduction zones in regassing the mantle and in affecting the modern volatile budget of Earth's interior.

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