The intermediate step in fractionation trends of mildly alkaline volcanic suites: An experimental insight from the Pavin trachyandesite (Massif Central, France) - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Comptes Rendus Géoscience Year : 2019

The intermediate step in fractionation trends of mildly alkaline volcanic suites: An experimental insight from the Pavin trachyandesite (Massif Central, France)

Abstract

We examined magma storage conditions and eruptive dynamics for the trachyandesite (~58 wt% SiO2, 9–10 wt% alkalis) of the Pavin monogenetic volcano, a maar-like explosive crater belonging to a small group of youngest volcanoes in the Massif Central. By confronting the natural samples to experimental products, we constrained pre-eruptive conditions around 950–975 °C, 150–200 MPa (~5.5–7.0 km in depth), NNO+1.5, and 4.5–5.5 wt% melt H2O. There is petrological evidence of magma crystallization in the conduit up to shallow levels (~50 MPa; 2 km in depth) before fragmentation into pumice clasts in the last kilometre of ascent. The experiments highlight the role of biotite and of crystallization pressure in defining separate compositional trends of residual liquids, i.e. alkaline (trachytes) versus sub-alkaline (dacite-rhyolite).
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insu-02310393 , version 1 (14-10-2019)

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Morgane Rondet, Caroline Martel, Jean-Louis Bourdier. The intermediate step in fractionation trends of mildly alkaline volcanic suites: An experimental insight from the Pavin trachyandesite (Massif Central, France). Comptes Rendus Géoscience, 2019, 351, pp.525-539. ⟨10.1016/j.crte.2019.07.003⟩. ⟨insu-02310393⟩
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