This award supports a project to develop and refine analytical techniques to characterize and date volcanic ash, or tephra, that is often found in ice cores from large ice sheets. Tephras layers in ice sheets are particularly valuable because, if they are from large eruptions, they form unique time-stratigraphic markers. The chemistry of the tephra can be used to determine the provenance, or origin, of the material and 40Ar/39Ar dating has potential to provide an absolute age of the layer. However, because the amount of material in tephra layers is very small, both in total mass and in terms of particle size, it is important to develop appropriate analytical techniques that can successfully characterize and date small samples. Refinement of the laser fusion technique for argon extraction prior to isotopic analysis of is a significant challenge. However, if successful, this work would be a substantial benefit to studies of ice cores as an independent dating tool. Furthermore, characterization and dating of tephra from ice cores will provide important information to climate models.
