An Ultra-High Resolution Investigation of 1 Ma Old Ice from Allan Hills Blue Ice Area, Antarctica

Here we present continuous sampling data from the oldest known ice recovered from a 125.64 -126.31 m depth interval at the Allan Hills Blue Ice area in Antarctica during 2010-2011 field season. The ca. 1-Ma old ice is investigated with our unique sampling technique, laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS) and complimented by traditional glaciochemical measurements. The LA-ICP-MS achieves a realistic measure of variability of select chemical species from an ultra-high resolution (as low as 121 mm), non-destructive sampling method. Elements are measured using single-element or multi-element line scans, producing a continuous LA profile along the length of the ice sample. Multiple single-element passes for Ca, Na and Fe along with a multi-element pass for Na, Al and Mg were ablated and analyzed along parallel tracks down the ice core. Additionally, we further examine the 1-Ma old ice using novel very-high resolution (3 mm) stable water ∂18O and ∂D sampling system Our results show evidence of environmental signals preserved within the 1-Ma old ice. The signals from the stable water isotope measurements and ablated chemical elements, previously established as a proxy for marine and continental (dust) air-mass sources, show fluctuations and variability that are consistent with existing ice core based paleoclimate records. The extensive data collected by the combination of these techniques may enable us to provide a snapshot of climate that operated before transition from 40ka to 100ka world. Research was funded by Division of Polar Programs NSF