Sulfur stories, from the sea to the sediments

Séminaire de Guillaume Paris (CRPG)

Abstract

The sulfur cycle is one of the main contributors to the control of O₂ and CO₂ atmospheric levels during Earth’s history. It interacts with both the carbon and oxygen cycles during weathering on land and diagenesis in the ocean. It is thus paramount to better constrain those connections and to reconstruct accurately the variations of the sulfur cycle in the past. To do so, sulfur isotope ratios in carbonates are an increasingly used archive, though major questions remains about (1) how sulfur isotope ratios are recorded in carbonate, (2) how well they are preserved and (3) what they mean. Reliably reconstructing past sulfur isotope ratios of seawater from carbonates will help to unpack various steps of diagenetic alteration and thus collect key information about the activity of microorganisms in deep ocean sediments. 

I will present recent progress about how sulfate is incorporated in biocarbonates, its role in biomineralization, and how carbonates help us better understand paleoenvironmental changes.