Speaker
Description
The European Project for Ice Coring in Antarctica (EPICA) Beyond EPICA – Oldest Ice aims at retrieving a continuous ice core record of climate feedback and forcing spanning about 1.5 Ma back in time. In that period the cyclicity of glacial/interglacial changes in continental ice sheet volume and temperature changed from 40 ka to the well-known 100 ka cycles encountered over the last 800 ka. After determining a suitable drill site Little Dome C (LDC), 35 km southwest of Concordia station, during an extensive pre-site survey, we penetrated to 2800 m depth during the third deep drilling season 2024/25, roughly spanning at least 1.2 Ma and a basal unit below 2584 m.
Here, we will focus on the implementation of the drilling operation: starting from an overview of the timeline of the project, the layout of the camp, upgrades to the drill system that enabled to drill 4.5 m long cores in a stable production mode, and ultimately drill in three seasons from the bottom of the pilot hole at 131.65 m below the surface to the bed at 2800 m depth. We will report on the drilling and core processing activities, that comprised Dielectric Profiling (DEP) and Laser Ringdown Spectrometry for water stable isotope determination already in the field, and provided a match of the record to existing ice core records like EPICA Dome C and marine records to estimate the climatic periods we recovered in the core.
References
Ahn, S. et al., A probabilistic Pliocene–Pleistocene stack of benthic δ18O using a profile hidden Markov model, Dynamics and Statistics of the Climate System, Volume 2, Issue 1, 2017, dzx002, https://doi.org/10.1093/climsys/dzx002
Bouchet, M. et al., The Antarctic Ice Core Chronology 2023 (AICC2023) chronological framework and associated timescale for the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core, Clim. Past, 19, 2257–2286, 2023. https://doi.org/10.5194/cp-19-2257-2023
Chung, A. et al., Stagnant ice and age modelling in the Dome C region, Antarctica, The Cryosphere, 17, 3461–3483, , 2023. https://doi.org/10.5194/tc-17-3461-2023
EPICA community members, Eight glacial cycles from an Antarctic ice core. Nature 429, 623–628, 2004. https://doi.org/10.1038/nature02599
Parrenin, F. et al., Volcanic synchronisation between the EPICA Dome C and Vostok ice cores (Antarctica) 0–145 kyr BP, Clim. Past, 8, 1031–1045, 2012. https://doi.org10.5194/cp-8-1031-2012
Wilhelms, F. et al., Precise dielectric profiling of ice cores: a new device with improved guarding and its theory. Journal of Glaciology. 1998;44(146):171-174. doi:10.3189/S002214300000246X
Wilhelms, F., Explaining the dielectric properties of firn as a density-and-conductivity mixed permittivity (DECOMP), Geophys. Res. Lett., 32, L16501, 2005. https://doi.org/10.1029/2005GL022808
