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 reconstruct accurately its variations 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.

I will present recent progress about how sulfate is incorporated in carbonates and a few examples of paleoenvironmental investigations, both on land and in the ocean. In continental environments, carbonates help retrace the origin of sulfur and understand the role of sulfuric acid in diagenetical processes. In oceanic sediments, 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.