You are invited to join an upcoming Geoscience Seminar to be given by Professor Tais W. Dahl in the Geoscience Auditorium on September 30 at 15:00. The title and abstract can be found below. There will be coffee and cake.

The geological history of Earth’s O₂ - Tracking oceanic O₂ levels with hexavalent uranium isotopes in marine carbonates, d²³⁸U⁶⁺_carb

Abstract

Oxygen has profoundly shaped the evolution of Earth’s surface environment and life. In this presentation, I will discuss how geochemical records can be used to reconstruct changes in atmospheric and oceanic oxygen levels through deep time, with a particular focus on recent advances in uranium isotope geochemistry. New analytical approaches targeting hexavalent uranium preserved in marine carbonates provide a powerful window into the global extent of anoxic seafloor environments and oxygen-deficient water masses. These records allow us to quantify and time major transitions in marine oxygenation, from ancient oceanic anoxic events to long-term Earth system changes, offering new insights into the links between climate, biogeochemical cycles, and biological evolution.

Short bio

Tais W. Dahl is Professor of Geobiology at the Department of Geosciences and Natural Resource Management, University of Copenhagen. His research combines geochemistry, Earth system modelling, and stratigraphy to reconstruct Earth’s oxygenation history and environmental change. He develops novel geochemical proxies, including uranium isotope methods, to investigate ocean redox evolution and the co-evolution of life and Earth’s surface environment. Currently, he runs a research group with 6 members funded by the Danish Council for Independent Research and Novo Nordisk NERD programme.