The School of Geography, Earth and Environmental Sciences organises a regular series of research seminars throughout the academic year to which everyone is welcome to attend. Speakers - both external and internal to the University - will talk on topics related to all aspects of Earth Sciences.
Today's speaker is Dr Alex Dickson from Royal Holloway.
Redox changes, typically observed as intensifying and expanding oxygen minimum zones, have the potential to substantially modify the composition and biological functioning of organisms that live in the oceans. Redox changes can also significantly alter the biogeochemical cycles that help to modulate Earth’s environmental systems through time. Changes in the concentration of oxygen in the oceans have been inferred to take place throughout Earth’s geological past, but quantifying the rate and magnitude of such changes has proved to be immensely challenging.
In this presentation, Alex will show how ‘non-traditional’ stable isotopes, particularly those of the elements molybdenum, uranium, zinc and cadmium, offer a potential route towards addressing these questions. Alex will show case studies where these isotope systems have been applied to reconstruct changes in ocean redox during the mid-Cretaceous and the Early Cenozoic. The talk will highlight the major advances these new proxy approaches have made for reconstructing the chemical history of Earth’s oceans and will stress that many challenges remain. These challenges include: (i) The difficulty of reconstructing rates of redox change over ‘abrupt’ climatic events; (ii) An incomplete understanding of the factors controlling the cycling of these elements in the natural environment.