C046-0005
Towards a New Dating of the Deep Portion of TALDICE Ice Core

Monday, 14 December 2020
Poster
Ilaria Crotti1,2, Barbara Stenni1, Amaelle Landais2, Carlo Barbante3, Massimo Frezzotti4, Florian Ritterbusch5, Zheng-Tian Lu6, Anais J Orsi2, Guo-Min Yang5, Wei Jiang6 and Lucie Bazin2, (1)University of Venice, Venice, Italy, (2)LSCE Laboratoire des Sciences du Climat et de l'Environnement, Gif-Sur-Yvette Cedex, France, (3)Ca' Foscari University, Department of Environmental Sciences, Informatics and Statistics, Venice, Italy, (4)University of Roma 3, Rome, Italy, (5)University of Science and Technology of China (USTC), Hefei, China, (6)University of Science and Technology of China, Hefei, China
Abstract:
Improving dating techniques for the deeper portions of ice cores as well as extending climate records further back in time is still a poorly explored field, but it represents one of the main challenges in the near future. For the 1620 m TALDICE ice core, drilled at Talos Dome (East Antarctica), the high-resolution climate reconstruction and chronology definition are available only until the depth of 1438 m (~ 154 kyr BP) (Stenni et al., 2011, Bazin et al., 2013). Our aim is to investigate the portion below 1438 m depth, in order to define a preliminary chronology and identify a discernible climatic signal.

Here we present 46 new measurements of δ18Oatm in the air bubbles, in association with three 81Kr radiometric dates for the TALDICE core. New δ18Oatm data allowed to extend the record till the bottom of the core at 1617 m depth and to define orbital tie points until ~1548 m depth, where the gas age is estimated to be ~ 340 kyr BP, through the comparison with EPICA Dome C (EDC) ice core δ18Oatm profile (Extier et al., 2018). In addition, three samples were devoted to 81Kr radiometric dating performed on the air trapped in the ice bubbles. The obtained radiometric ages are: 397±20 ky BP at 1560-1564 m depth, 470±50 ky BP at 1574-1578 m depth and 404±20 ky BP at 1615-1617 m depth. Such results suggest that the stratigraphic integrity of the core is probably preserved until 1578 m, while the very bottom of the core (1615-1617 m) might be affected by mixing/folding phenomena. To better constrain the chronology in the deep part, where the core is influenced by extreme thinning conditions, 37 additional δ18Oatm measurements are planned to be performed between 1500 and 1570 m depth.

The chronology below 1438 m depth is built integrating new orbital tie points and absolute age data in the probabilistic model PaleoChrono, an implementation of IceChrono1 (Parrenin et al.,2015), to define a solid chronology for the deep part of the TALDICE ice core and to allow past climate reconstruction in this unexplored portion.

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