A critical challenge in our understanding of Earth surface evolution is to discern which signals preserved in the sedimentary record result from global processes, such as changes in the sources and sinks of marine sulfate, and which signals are local, reflecting the ambient depositional environment and the burial and exhumation history of the sediments

Using modern low-sulfate environments, we can observe the control of sulfate levels on (i) the microbial fractionation and (ii) on the extent and rates of early diagenetic processes in controlling the preserved isotopic composition of pyrite.  

In the first study, I'll use natural environments and microscale δ34S, to investigate the effect of sulfate limitation. A first, and necessary step before attempting to extract robust information from early Earth's archives? 

Pyrite preserved in stromatolites provides a unique opportunity to identify and quantify biological sulfur metabolism on Earth. With Alice Bosco-Santo, we use stromatolite cultivation and (in)organic isotope geochemistry to study how the local sea-water redox state constrains the microbial physiology and subsequently pyrite precipitation rate and isotopic composition.

To tease apart the complexity of Precambrian bulk S-isotopes measurements, I use microscale (in-situ) secondary ion mass spectrometry to decipher the ‘true’ geo-bio-signals from late diagenetic overprints resulting from the long history of those rocks.