Achim Herrmann (University of Arizona) and PhD student Stephen Romaniello are conducting field work at the Darby Island Research Station to test the application of uranium (U) isotopes preserved in carbonate sediments as a proxy for ancient redox conditions (i.e. oxidation state). The hypothesis is that U isotope composition of seawater is determined by the redox state of the global ocean. The field component of this research is investigating fractionation of U isotopes in natural carbonates, both biogenic and abiotic. This includes study of how low temperature alteration during deposition and burial might affect the preservation of the primary U isotope signal.
