Testing assumptions on last interglacial seawater δ²³⁴U composition

Alexandra Villa

Abstract: The use of U-series dating of fossil corals has proved to be a crucial tool in creating Last Interglacial (LIG) chronologies of sea level change. These archives preserve the primary chemistry used to calculate a radiometric age, and track the position in sea level using their assumed paleodepth habitat. Using the U-series dating, we can achieve extremely accurate and precise measurements of age and elevation, under the assumption of presumed LIG δ²³⁴U value of seawater. This has been assumed to reflect modern day values of about 145‰, given the fact that U in the ocean is relatively constant. However, recent studies have suggested a 5-10 per mil δ²³⁴U change during the LGM, which challenges the assumption that LIG fossil corals reflect modern day values. This study seeks to determine possible values and changes in LIG δ²³⁴U values through a series of leaching experiments.

Advisor: Andrea Dutton

Email: avilla2@wisc.edu

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