Development of a Continuous Flow Analysis system for studying Allan Hills, Antarctica ice cores

Extending ice core records beyond 800 thousand years (kyr) is a pivotal goal in paleoclimate research. Allan Hills, East Antarctica, provides a unique opportunity to evaluate old ice and reconstruct climate well beyond 800 kyr with preliminary research uncovering ice ages up to 4.5 million years. Although old ice has been found and proven to be valuable, the ice in this area demonstrates several peculiarities—such as strong layer thinning, folding, and non-atmospheric CO2 – that warrant an in-depth investigation of the ice at this site and the climate record it holds. To address these challenges, we aim to initially conduct a high-resolution continuous flow analysis (CFA) of dust, water stable isotopes, water chemistry, and methane on the upper 70m of an ice core drilled in the 2022-2023 field season at the Allan Hills. A new CFA system has been developed at Oregon State University to analyze old ice, consisting of separate laser spectrometers for water stable isotopes and methane, an Abakus particle sensor for dust, and a fraction collector for sample analysis of melt-water chemistry. Here, we aim to present preliminary data on dust and methane and demonstrate the newly developed CFA system. Preliminary analyses on this ice have revealed the surface ice to be ~400 kyr old, with the majority of the upper 70m likely in stratigraphic order. This enables meaningful comparisons to other Antarctic ice cores and strengthens our comprehension of the climate-recording behavior of the ice. A high-resolution investigation of this ice is a critical step in understanding the discrete records from the Allan Hills that extend beyond the Mid-Pleistocene Transition and into the Pliocene, pushing our ice core records into unique and enigmatic parts of Earth’s climate history.