Molecular Geochemistry of Paleo-Redox Proxies in Black Shales (Prof. Anthony Chappaz)

Title: Molecular Geochemistry of Paleo-Redox Proxies and Critical Elements in Black Shales
Speaker: Prof. Anthony Chappaz (Central Michigan University)

“Where do we come from?” and “Where are we going?”. These two fundamental questions about the origin and future of humanity are associated with a famous painting made by French artist Paul Gauguin at the end of the 19th century. Studying the molecular geochemistry of trace elements in sedimentary rocks like black shales can contribute to answer these questions.
The origin of life is tied to the raise of oxygen concentration on Earth. Trace elements like molybdenum or rhenium have been used to reconstruct paleo redox conditions. Demand for critical elements (e.g., vanadium) to support the green energy transition is soaring. Therefore, exploring alternative resources like black shale is absolutely needed to meet the global demand. However, when studying trace element geochemistry, scientists keep relying mainly on bulk elemental concentration and often neglect three other aspects: isotopic signature, speciation and spatial heterogeneity.
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 and critical elements bring new insights that strongly enhance our understanding of the processes governing their reactivity.