Year: 2026
Type: article
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 129Xe/130Xe 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 238U spontaneous fission pattern (XePu/XeU ∼ 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 129Xe/130Xe 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.
Source: Geochemical Perspectives Letters
Authors: R. Sauvalle, M. Moreira, B. Scaillet
Language: English
Subfield: Geochemistry and Petrology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7223329249