Xenon isotopes in the Fani Maoré lavas: Implications for upper mantle heterogeneity
Abstract
>Xenon isotopes provide unique constraints on mantle evolution but remain rarely investigated in oceanic intraplate lavas due to pervasive atmospheric contamination. The 2018-2021 Fani Maoré eruption (Mayotte) produced gas-rich lavas, allowing the first investigation of xenon in the Comoros. While helium, neon, and argon systematics are MORB-like, consistent with derivation from a depleted upper mantle, xenon displays a distinct behaviour: the Fani Maoré mantle 129 Xe/ 130 Xe is below 7.1, potentially consistent with a mantle plume contribution. Deconvolution of fissiogenic Xe isotopic signatures, however, reveals (1) substantial contribution from recycled air, and (2) nearly pure 238 U spontaneous fission pattern (Xe Pu /Xe U ∼ 0), arguing against derivation from a deep primordial plume reservoir. Instead, it supports a shallow origin, perhaps involving ancient, U-rich, strongly degassed recycled lithologies that have pervasively metasomatised the Comorian lithosphere. The low 129 Xe/ 130 Xe of the Comoros mantle may reflect a higher contribution of a recycled atmospheric component in the local mantle. Together, this points toward a shallow origin for the archipelago and shows that recycled volatiles in the upper mantle are spatially variable and not fully homogenised.
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BibTeX
@article{sauvalle2026xenon,
title = {{Xenon isotopes in the Fani Maoré lavas: Implications for upper mantle heterogeneity}},
author = {R. Sauvalle and M. Moreira and B. Scaillet},
journal = {Geochemical Perspectives Letters},
year = {2026},
month = oct,
doi = {10.7185/geochemlet.2639},
url = {https://hal.science/hal-05839406v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Xenon isotopes in the Fani Maoré lavas: Implications for upper mantle heterogeneity
AU - R. Sauvalle
AU - M. Moreira
AU - B. Scaillet
PY - 2026
DA - 2026/10/26
JO - Geochemical Perspectives Letters
DO - 10.7185/geochemlet.2639
UR - https://hal.science/hal-05839406v1
AB - >Xenon isotopes provide unique constraints on mantle evolution but remain rarely investigated in oceanic intraplate lavas due to pervasive atmospheric contamination. The 2018-2021 Fani Maoré eruption (Mayotte) produced gas-rich lavas, allowing the first investigation of xenon in the Comoros. While helium, neon, and argon systematics are MORB-like, consistent with derivation from a depleted upper mantle, xenon displays a distinct behaviour: the Fani Maoré mantle 129 Xe/ 130 Xe is below 7.1, potentially consistent with a mantle plume contribution. Deconvolution of fissiogenic Xe isotopic signatures, however, reveals (1) substantial contribution from recycled air, and (2) nearly pure 238 U spontaneous fission pattern (Xe Pu /Xe U ∼ 0), arguing against derivation from a deep primordial plume reservoir. Instead, it supports a shallow origin, perhaps involving ancient, U-rich, strongly degassed recycled lithologies that have pervasively metasomatised the Comorian lithosphere. The low 129 Xe/ 130 Xe of the Comoros mantle may reflect a higher contribution of a recycled atmospheric component in the local mantle. Together, this points toward a shallow origin for the archipelago and shows that recycled volatiles in the upper mantle are spatially variable and not fully homogenised.
SN - 2410-339X
SN - 2410-3403
ER -