Three-Dimensional Multitrack Electrical Conductivity Method for Interpretation of Complex Ice Core Stratigraphy

Liam Reed Kirkpatrick, Austin Joseph Carter, Julia Marks Peterson, Sarah Shackleton, T.J. Fudge

Recent ice cores from the Allan Hills, a blue ice area in Antarctica, are nearly 3 million years old. These cores extend ice core chronologies, enabling new insight into key climate periods such as the Mid-Pleistocene Transition. The interpretation of these climate records is complex because of the disturbed stratigraphy in this ice. Here we present a new three- dimensional multitrack electrical conductivity measurement method (3D ECM) to resolve layer structure. We demonstrate this technique on a cumulative 60 m of two large-diameter (241 mm) ice cores, ALHIC2201 and ALHIC2302. We find well defined and dipping layering in both cores, averaging 28° and 68° from horizontal, respectively. Both cores show a statistically significant but gradual decrease in dip angle with depth. We discuss how this new method can be applied to enable accurate, high- resolution multi-proxy record development even in ice cores with steeply dipping layers. 3D ECM improves interpretation of blue ice area cores by providing accurate, non-destructive constraints on stratigraphy.