Archean subduction-derived noble gases in the lithospheric mantle beneath the São Francisco Craton

While mid-ocean ridge basalts (MORB) and ocean island basalts (OIB) are well characterized in terms of helium, neon, argon, and xenon isotopes, the continental lithosphere, especially cratonic domains and subduction settings, remain poorly constrained. Here, we report noble gas (He, Ne, Ar, Kr, and Xe) isotope ratios in peridotite, pyroxenite, and eclogite xenoliths from the SW margin of the São Francisco Craton, Brazil. Helium isotopes reveal a strong radiogenic component, while neon shows MORB-like and nucleogenic signatures. This divergence indicates the recycling of subduction-derived materials within the stratified cratonic mantle (2.0–5.5 GPa). Xenon reveals a cratonic lithosphere where air and fissiogenic (crustal) components variably mix with a MORB source. The recycling of ancient hydrated oceanic crust and overlying sediments, characterized by high (U+Th)/(3He, 22Ne, 132Xe) ratios, is associated with a complex and long-lived subduction system established along the SW margin of the São Francisco Craton since the Archean. This study reveals that noble gas isotopes in mantle rocks beneath the São Francisco Craton, Brazil, record the recycling of volatiles from Archean subduction into the continental mantle.