EGU2020-4179
https://doi.org/10.5194/egusphere-egu2020-4179
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

New δ18Oatm, δ18Oice and δDice profiles from deep ice of the TALDICE core

Ilaria Crotti1,5, Carlo Barbante1,2, Massimo Frezzotti3, Wei Jiang4, Amaelle Landais5, Zheng-Tian Lu4, Florian Ritterbusch4, Barbara Stenni1,2, and Guo-Min Yang4
Ilaria Crotti et al.
  • 1Department of Environmental Sciences, Informatics and Statistics, Ca’ Foscari University of Venice, Venice, Italy
  • 2Institute for Polar Sciences (ISP), CNR, Venice, Italy
  • 3Department of Science, Roma Tre University, Rome, Italy
  • 4Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, China
  • 5Laboratoire des Sciences du Climat et de l’Environnement IPSL/CEA-CNRS-UVSQ UMR, Gif-sur-Yvette, France

The study of the deep portions of ice cores still represents a poorly explored field due to the presence of processes acting in the lowermost layers and possibly affecting the preservation of the original climatic signal. 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 ~1450 m (150 kyr BP) (Stenni et al., 2011, Bazin et al., 2013). Our aim is to investigate the portion below 1460 m depth to the bottom of the core, where radargrams show the presence of an unconformity in the ice sheet, to define a preliminary chronology and identify a discernible climatic signal.

Here we present the new TALDICE δ18Oatm record in the air bubbles, in association with the new high-resolution δ18Oice and δDice profiles and an 81Kr radiometric date. New 46 measurements of δ18Oatm  allowed to increase the resolution of the available profile from 1357 to 1553.95 m depth and to extend the record till the bottom of the core at 1617 m depth. The comparison between the δ18Oatm profile of TALDICE and the one of EPICA Dome C (EDC) ice core (Extier et al., 2018) allows to solidly define a preliminary age-depth relationship for the TALDICE core until 1500 m depth, where the gas age is estimated to be ~200 kyr BP. Below 1500 m, supplementary δ18Oatm measurements will be needed to identify older precession cycles and to extend the age-depth relationship further back in time. On the other hand, the high-resolution isotopic profiles in the ice (18O/16O and D/H ratios) obtained below the depth of 1528 m and compared with the EDC ones suggest that the climatic signal in the ice is preserved until to the lower level of 1547.8 m, which is dated back to 343 kyr BP. However, the lack of similarities with the EDC water isotopes record below this depth, in spite of the 81 Kr radiometric age 459 ± 50 kyr BP at the depth of 1574-1578 m, indicates the missing of the MIS 11 in the isotopic profiles. Moreover, the increase of high-frequency variability in the δ18Oice and δDice below 1547.8 m depth implies that this part of the core lays in an area of the ice sheet characterized by different properties in comparison to the ice above.

Additional δ18Oatm, 40Ar, δ18Oice, and δDice measurements will be performed in the lowermost portion of the core and the results will be compared with the new 81Kr radiometric dating at the depth of 1560-1564 m and 1614-1619 m to better constrain the chronology and to investigate the ice properties in the deeper portion of the core.

How to cite: Crotti, I., Barbante, C., Frezzotti, M., Jiang, W., Landais, A., Lu, Z.-T., Ritterbusch, F., Stenni, B., and Yang, G.-M.: New δ18Oatm, δ18Oice and δDice profiles from deep ice of the TALDICE core, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4179, https://doi.org/10.5194/egusphere-egu2020-4179, 2020

Comments on the presentation

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Presentation version 4 – uploaded on 04 May 2020
This revised version includes the latest data of Kr radio dating
  • CC1: Comment on EGU2020-4179, Giuliano Dreossi, 05 May 2020

    You wrote "Below 1548 m the climatic record seems not to be entirely preserved due to lack of stratigraphic order"

    The 470 Ka 81Kr point, taking into consideration the large uncertainty of the measure, might still fit between the other two, more precise, 81Kr-dated points, thus not entirely ruling out a progressive chronology even in the deepest part.

Presentation version 3 – uploaded on 04 May 2020 , no comments
Typo correction
Presentation version 2 – uploaded on 01 May 2020
This revised version includes the latest data of Kr radio dating
  • CC1: Comment on EGU2020-4179, Eric Wolff, 04 May 2020

    Really nice work and exciting to see Talos so old. On your last slide you wrote 0.14 ka/m, did you mean that? To me it seems less well-resolved since you have about a complete climate cycle in 20 metres.

  • AC1: Comment on EGU2020-4179, Ilaria Crotti, 04 May 2020

    Thank you for your comment and for spotting this typing this mistake that I didn't see before! The estimated resolution for MIS 9.3 is 0.16 ky / 5cm ( 3.2 ky/m). I'm going to upload the correct version. 

Presentation version 1 – uploaded on 26 Apr 2020 , no comments