Deconvolving sources and sinks of carbon and sulfur in magmas to reconstruct DEGASsing from Large Igneous Provinces

The magnitude and consequences of future climate change depend on how Earth’s climate will respond to atmospheric chemistry alterations – vastly related to human activities. However, the complexity of the climate system makes future scenarios hard to predict. The geological record is our best source of information to constrain these scenarios by studying periods of Earth’s history during which volcanic degassing from outstanding magmatic episodes (Large Igneous Provinces, LIPs) acted as major forcing agents of climate and environmental change. Earth-system models that aim to reconstruct the global consequences of LIPs degassing proliferated in recent years, but they urgently need ground-truth gas emission data. The goal of DEGAS is to offer a new framework for obtaining these data by deconvolving sources and sinks of LIP magmatic volatiles, from the mantle source, across the crustal filter. DEGAS aims to: 1) quantify sulfur and carbon concentrations in LIPs parental magmas, hinging on the S-in-clinopyroxene method, pioneered by the PI; 2) investigate emblematic natural examples of magma-host rock interaction in volcanic basins from a within-sill perspective and with special focus on sulfur; 3) evaluate the role of the “crustal filter” as carbon and sulfur sink, with an unprecedented basin-scale approach. DEGAS investigates carbon and sulfur in LIPs magmas through multiple lenses, from the mineral to the basin-scale, in two natural laboratories, the Skagerrak-centered LIP (Oslo Rift), and the Karoo LIP. Knowing the initial volatile load and the modalities of magma-host-rock interaction is fundamental if we want to gauge the effect of the crustal filter and reconstruct source-sensitive parameters of degassing, such as isotopic signatures. DEGAS will constrain the magmatic side of the intricate volatile exchange between LIP magmas and crust, marking a fundamental step forward towards a full portrait of LIPs degassing, the only past analogue to anthropogenic emissions.