Experimental melting of phlogopite-peridotite in the garnet stability field

Abstract : Melting experiments have been performed at 3 GPa, between 1150 and 1450 °C, on a phlogopite-peridotite source in the garnet stability field. We succeeded to extract and determine the melt compositions of both phlogopite-bearing lherzolite and harzburgite from low to high degrees of melting (ϕ = 0.008–0.256). Accounting for the presence of small amounts of F in the mantle, we determined that phlogopite coexists with melt >150 °C above the solidus position (1150–1200 °C). Fluorine content of phlogopite continuously increases during partial melting from 0.2 to 0.9 wt% between 1000 and 1150 °C and 0.5 to 0.6 wt% between 1150 and 1300 °C at 1 and 3 GPa, respectively. The phlogopite continuous breakdown in the lherzolite follows the reaction: 0.59 phlogopite + 0.52 clinopyroxene + 0.18 garnet = 0.06 olivine + 0.23 orthopyroxene + 1.00 melt. In the phlogopite-harzburgite, the reaction is: 0.93 phlogopite + 0.46 garnet = 0.25 olivine + 0.14 orthopyroxene + 1.00 melt. Melts from phlogopite-peridotite sources at 3 GPa are silica-undersaturated and are foiditic to trachybasaltic in composition from very low (0.8 wt%) to high (25.6 wt%) degrees of melting. As observed at 1 GPa, the potassium content of primary mantle melts is buffered by the presence of phlogopite, but the buffering values are higher, from 6.0 to 8.0 wt% depending on the source fertility. We finally show that phlogopite garnet-peridotite melts are very close to the composition of the most primitive post-collisional lavas described worldwide.
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Article dans une revue
Contributions to Mineralogy and Petrology, Springer Verlag, 2016, 171 (11), 〈10.1007/s00410-016-1306-0〉
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https://hal-clermont-univ.archives-ouvertes.fr/hal-01637103
Contributeur : Sylvaine Jouhannel <>
Soumis le : vendredi 17 novembre 2017 - 12:44:33
Dernière modification le : mercredi 30 mai 2018 - 01:18:01

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Pierre Condamine, Etienne Médard, Jean-Luc Devidal. Experimental melting of phlogopite-peridotite in the garnet stability field. Contributions to Mineralogy and Petrology, Springer Verlag, 2016, 171 (11), 〈10.1007/s00410-016-1306-0〉. 〈hal-01637103〉

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