High-Resolution Chemical Imaging and Dating of Oldest Ice Using LA-ICP-MS
For my NSF Office of Polar Programs Postdoctoral Fellowship at Princeton, I am developing a
cryo-cell LA-ICP-MS method to produce two-dimensional impurity maps for layer
identification at micrometer resolution, and to measure ⁸⁷Sr/⁸⁶Sr as an independent
chronometer in marine salts trapped within the folded and stratigraphically disturbed ice of Antarctic
blue-ice areas (1–6 Ma). This complements the NSF Center for Oldest Ice Exploration (COLDEX) goal of
recovering a direct atmospheric sample from the mid-Pliocene, the most recent time atmospheric CO₂ was
near today's levels.
Top left: sample location (Allan Hills, Antarctica) and the complex blue-ice stratigraphy there, disrupted by both folding and layer thinning. Top right: sample-preparation and cryo-cell LA-ICP-MS workflow for 2D impurity mapping of ice cores. Bottom left: cryo-cell loaded with a section of Allan Hills ice core and calibration standards, including NIST glass and frozen HPS-68A and NIST SRM 1643f solutions. Bottom right: preliminary low-resolution 2D elemental maps (Na, Mg, Al, Ca, Sr) reconstructed from raw ablation data using the recorded raster-scan geometry (50 to 60 µm/s scan velocity, 50 µm line spacing, ~20 to 25 µm along-track sampling).
