Impurity geochemistry at blue ice areas

The oldest ice preserved in Antarctica offers an unprecedented window into Earth's past, but it has also spent millions of years flowing through the ice sheet before reaching the surface. During that journey, interactions with the glacier bed can introduce minerals, dust, and dissolved chemical species that complicate the interpretation of climate records. At the same time, deformation within the ice sheet can alter the relative proportions of glacial and interglacial ice preserved within an individual sample. Understanding these processes is essential for determining how faithfully Earth's oldest ice records past climate.

In this project, I use trace elements, major ions, particle size distributions, and scanning electron microscopy to characterize the impurities preserved in the Allan Hills ice cores. These measurements reveal that many impurity-rich layers contain material incorporated from the glacier bed rather than atmospheric deposition alone, providing new insight into how basal processes modify ancient ice. By combining these observations with climate proxies, we can distinguish between signals caused by basal alteration and those that reflect changes in atmospheric composition or climate, while also investigating how different glacial and interglacial weightings may be preserved within neighboring packets of ancient ice.