EES Guest Speaker - Dr. Anthony Chappaz

Do not neglect the heterogeneity of paleo-redox proxies in black shales

Anthony Chappaz

Professor of Molecular Geochemistry & Director of the STARLAB

Central Michigan University

The origin of life is tied to the raise of oxygen concentration on Earth. Examining trace elements (e.g., molybdenum, vanadium or rhenium) geochemistry in sedimentary systems like black shales have been used to reconstruct paleo redox conditions. However, when studying trace element signals in environmental archives, most of the geoscientists keep relying mainly on bulk elemental concentration and sometimes isotope ratios but often neglect two other aspects: speciation and spatial distribution.

Unfortunately, these omissions can lead to major misunderstanding of the geochemical processes at play. Using synchrotron-based techniques to characterize the molecular geochemistry of paleo-redox proxies bring new insights that strongly enhance our understanding of the processes governing their reactivity.