The stability of hydrous phases beyond antigorite breakdown for a magnetite-bearing natural serpentinite between 6.5 and 11 GPa

  • J. MauriceEmail author
  • N. Bolfan-Casanova
  • J. A. Padrón-Navarta
  • G. Manthilake
  • T. Hammouda
  • J. M. Hénot
  • D. Andrault
Original Paper


Phase relations for a natural serpentinite containing 5 wt% of magnetite have been investigated using a multi-anvil apparatus between 6.5 and 11 GPa and 400–850 °C. Post-antigorite hydrous phase assemblages comprise the dense hydrous magnesium silicates (DHMSs) phase A (11.3 wt% H2O) and the aluminous phase E (Al-PhE, 11.9 wt% H2O). In addition, a ferromagnesian hydrous silicate (11.1 wt% H2O) identified as balangeroite (Mg,Fe)42Si16O54(OH)40, typically described in low pressure natural serpentinite, was found coexisting with Al-PhE between 650 and 700 °C at 8 GPa. In the natural antigorite system, phase E stability is extended to lower pressures (8 GPa) than previously reported in simple chemical systems. The reaction Al-phase E = garnet + olivine + H2O is constrained between 750 and 800 °C between 8 and 11 GPa as the terminal boundary between hydrous mineral assemblages and nominally anhydrous assemblages, hence restricting water transfer into the deep mantle to the coldest slabs. The water storage capacity of the assemblage Al-PhE + enstatite (high-clinoenstatite) + olivine, relevant for realistic hydrated slab composition along a relatively cold temperature path is estimated to be ca. 2 wt% H2O. Attempts to mass balance run products emphasizes the role of magnetite in phase equilibria, and suggests the importance of ferric iron in the stabilization of hydrous phases such as balangeroite and aluminous phase E.


Hydrous phases stability Natural serpentinite Water transfer Subduction 



We gratefully acknowledge constructive reviews by R. Stalder, P. Fumagalli and K. Iacovino and the editorial handling. We thank D. Mainprice for providing us with the natural sample of serpentinite that was used for our experiments. This study is part of J. Maurice PhD financed by the ANR HYDEEP “Hydrogen in the Deep Earth” project to N. Bolfan-Casanova and the ANR OxyDeep project to Denis Andrault. We also thank J.-L. Devidal (Laboratoire Magmas et Volcans, Clermont-Ferrand) for his assistance during microprobe analysis, F. Schiavi (LMV, Clermont-Ferrand) for Raman analyses support, P. Bouilhol (CRPG, Nancy) for instructive discussions and assistance during garnets Fe3+ measurements using the flank method. We thank L. Jouffret (Institut de Chimie, Clermont-Ferrand) for providing balangeroite X-Ray single crystal structure refinement. This is Laboratory of Excellence Clervolc contribution number 314.

Supplementary material

410_2018_1507_MOESM1_ESM.bmp (508 kb)
Supplementary material 1 (BMP 507 KB)


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© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • J. Maurice
    • 1
    Email author
  • N. Bolfan-Casanova
    • 1
  • J. A. Padrón-Navarta
    • 2
  • G. Manthilake
    • 1
  • T. Hammouda
    • 1
  • J. M. Hénot
    • 1
  • D. Andrault
    • 1
  1. 1.Laboratoire Magmas et VolcansAubiere CedexFrance
  2. 2.Géosciences Montpellier, Université de Montpellier 2 & CNRSMontpellier Cedex 05France

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