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Preservation of the water concentration of mantle xenoliths in the Ray Pic volcano (FMC)

Résumé

The ability of xenoliths to preserve water lithospheric signatures remains an unsolvedquestion for many years. We report water content in olivine and pyroxenes of peridotitexenoliths from Ray Pic volcano (Massif central, France). Xenoliths were sampled fromproducts of an explosive eruption (pyroclastic deposit) and an effusive eruption at five differentlocations along the 10 km lava flow.Water content in xenoliths from the lava flow is independent of its location in the lava:ol < 1, opx 190-270 and cpx 430-640 wt. ppm H2O. Results suggest that the cooling andsolidification of the lava had no impact on water content.The xenoliths from the explosive event have systematically more water: ol 3-12, opx330-460 and cpx 810-890 wt. ppm H2O. These values are either comparable with or lower thanthe values reported previously from the same locality (1). It shows that xenoliths recoveredfrom explosive eruptions have higher water content than the ones from effusive eruptions, butalso that water content can be different from one explosive event to another Conclusion is thatwater content can rapidly be reset during magma degassing prior to eruption. Degassingcontrols water content of xenoliths.Among the xenoliths studied, two have spectral signatures different from others. Thisdifferent spectral signature has also been reported from other volcanoes (2, 3). The coexistingof different spectral signatures, which have not been erased during degassing, are probably theonly OH signatures fully preserved from depth.1 Azevedo-Vannson S.,et al. Chemical Geology 575 120257 (2021)2 Denis C.M.M. et al. Lithos 226 256-274 (2015)3 Patkó L. et al. Chemical Geology 507 23-41 (2019)
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Dates et versions

hal-03759592 , version 1 (24-08-2022)

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  • HAL Id : hal-03759592 , version 1

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Konstantinos Thomaidis, Jannick Ingrin. Preservation of the water concentration of mantle xenoliths in the Ray Pic volcano (FMC). IMA 2022, Jul 2022, Lyon, France. ⟨hal-03759592⟩
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