Not just carbon: Quantifying the role of intraplate lithospheric mantle in global volatile element cycles

• Applicant: Dr. Sonja Aulbach
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 566692259

Deep Earth volatile element cycles and their intersection with surficial reservoirs through time constitute fundamental aspects of planetary evolution, with profound effects on habitability and resources. The lithospheric mantle (LM) is increasingly recognised as a significant volatile element reservoir, but with large uncertainties on abundances and fluxes, and only a faint understanding of the conditions and processes that allow volatile elements to be retained or mobilised and ultimately released to the surface. Volatile-rich melts, typical of intraplate settings, are powerful agents of mantle modification (metasomatism), and often carry fragments of wehrlite, a prominent lithology that can form via interaction of mantle rocks with such melts. Much has been learned about the various metasomatic agents involved in wehrlite formation and about the consequent release of mantle-CO2 to the atmosphere, manifested as passive surficial gas emissions. In contrast, ubiquitous volatile-bearing minerals (e.g. sulphide and hydrous minerals) and volatile trace constituents (e.g. H in nominally anhydrous minerals; F and Cl in amphibole and phlogopite) in wehrlites have received surprisingly scant attention. We propose to comprehensively study representative refractory to strongly wehrlitised mantle xenoliths from continental on-craton, off-craton, and oceanic intraplate localities, combining state-of-the-art microbeam and high-resolution spectroscopic techniques with the latest oxy-thermobarometers. Combining petrographic, geochemical and multi-isotopic constraints with diffusion and phase equilibria modelling, we will constrain the abundance and origin of volatile elements, as well as the timescales, physicochemical conditions (P-T-ƒO2) and pathways involved in their sequestration vs. release in LM across tectonic settings. This will provide a step-change towards accurately estimating the budget and residence time of volatile elements in LM that are needed in global reservoirs-and-fluxes models.

• DFG Programme: Research Grants
• International Connection: Austria
• Partner Organisation: Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
• Cooperation Partner: Dr. Federico Casetta