Third party funded individual grant
Acronym: TraceS
Start date : 01.01.2025
End date : 31.12.2027
Despite the large impact of human activity on the global S cycle, the natural S fluxes from oceans and lithosphere to atmosphere may be still poorly constrained. Especially in mid-ocean ridges (MORs), estimating the mantle-derived S flux to the surface remains a challenge due to (1) a lack of data on S concentrations in basaltic glasses, (2) variable S sources obscuring a possible mantle origin and (3) unknown amounts of S sequestrated in the oceanic crust upon fluid-rock interaction. This project aims to determine the sources and fluxes of S within a MORs using the Icelandic crust as an analogue. In conjunction with geochemical isotope modelling and state-of-the-art mass spectrometric techniques, S concentrations, along with isotope compositions (S, Fe, O) in thermal fluids, bulk rock, pyrite and anhydrite will be used to constrain the fluxes from different sources (e.g. seawater, rock leaching) of S at MORs. Furthermore, the potential of fluid-rock interaction in hydrothermal systems along MORs of permanently fixing S by mineral formation upon fluid-rock interaction will be investigated. Remelting of such modified oceanic crust within subduction zones might greatly affect the S isotopic values of melts, volcanic gasses and geothermal fluids in volcanic arcs. Findings of this study will also have an impact on ongoing research on sequestration of anthropogenic S within the Earth’s crust.