Tracking Anoxia in Ancient Oceans: Insights from uranium isotopes

Presenter

Dr. Kimberly Lau
Assistant Professor
Department of Geosciences
Penn State University

Abstract

The redox state of the oceans strongly influences organic carbon burial, habitability for marine biota, and biogeochemical cycling of nutrients and critical redox-sensitive elements. There are various methods for reconstructing oxygenation and deoxygenation through Earth history: Of these, inorganic geochemical proxies offer the potential to track redox conditions across a range of temporal and spatial scales. In particular, uranium isotopes (238U/235U) have emerged as a useful tool for reconstructing the redox conditions of the Earth’s oceans. Variations in 238U/235U, particularly when recorded in carbonate sediments, can track global trends in marine oxygenation and de-oxygenation. Rapid development continues to refine the accuracy of interpretations of 238U/235U records. In this talk, I will discuss two case studies: one of how U isotopes can help eluciate the end-Permian mass extinction and another of how diagenetic modeling can help advance interpretations of these records.