Deep ice as a geochemical reactor: Insights from iron speciation and mineralogy of dust in the Talos Dome ice core (East Antarctica)

• Published in: The Cryosphere
• Main Authors: Baccolo, Giovanni, Delmonte, Barbara, Di Stefano, Elena, Cibin, Giannantonio, Crotti, Ilaria, Frezzotti, Massimo, Hampai, Dariush, Iizuka, Yoshinori, Marcelli, Augusto, Maggi, Valter
• Other Authors: Department of Earth and Environmental Sciences Milano, Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), DIAMOND Light source, Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Earth Sciences Roma, Università degli Studi di Roma "La Sapienza" = Sapienza University Rome (UNIROMA), Laboratori Nazionali di Frascati = National Laboratory of Frascati (LNF), Istituto Nazionale di Fisica Nucleare (INFN), Institute of Low Temperature Science Sapporo, Hokkaido University Sapporo, Japan, RICMASS Rome Int Ctr Mat Sci Superstripes, I-00185 Rome, Italy, This research has been supported by the Ministero dell'Istruzione, dell'Università e della Ricerca (grant no. PNRA18-00098); Horizon 2020 (grant no. Beyond EPICA (815384)); and Diamond Light Source (grant nos. sp7314, sp8372 and sp9050)., Primary logistical support was provided by PNRA at Talos Dome. This is TALDICE publication no. 62. This publication was generated in the frame of Beyond EPICA. The project has received funding from the European Union’s Horizon 2020 Research And Innovation Programme under grant agreement no. 815384 (Oldest Ice Core). It is supported by national partners and funding agencies in Belgium, Denmark, France, Germany, Italy, Norway, Sweden, Switzerland, the Netherlands and the United Kingdom. Logistic support is mainly provided by PNRA and IPEV through the Concordia Station system. The opinions expressed and arguments employed herein do not necessarily reflect the official views of the European Union funding agency or other national funding bodies. This is Beyond EPICA publication number 22. We thank Paolo Gentile for providing mineral standards and also Paul Niles and Tanya Peretyazhko for the fruitful discussions., European Project: 331615,EC:FP7:PEOPLE,FP7-PEOPLE-2012-IIF,TALDICE HOLOCENE(2013), European Project: 815384,Beyond EPICA
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: [SDU]Sciences of the Universe [physics]; East Antarctica; Ross Sea; Talos Dome; Antarc*; Antarctica; ice core; The Cryosphere
• Online Access: https://hal.science/hal-03434954; https://hal.science/hal-03434954/document; https://hal.science/hal-03434954/file/bacc1.pdf; https://doi.org/10.5194/tc-15-4807-2021

International audience Thanks to its insolubility, mineral dust is considered a stable proxy in polar ice cores. With this study we show that the Talos Dome ice core (TALDICE, Ross Sea sector of East Antarctica) displays evident and progressive signs of post-depositional processes affecting the mineral dust record below 1000g m deep. We apply a suite of established and cutting-edge techniques to investigate the properties of dust in TALDICE, ranging from concentration and grain size to elemental composition and Fe mineralogy. Results show that through acidic/oxidative weathering, the conditions of deep ice at Talos Dome promote the dissolution of specific minerals and the englacial formation of others, affecting primitive dust features. The expulsion of acidic atmospheric species from ice grains and their concentration in localized environments is likely the main process responsible for englacial reactions. Deep ice can be seen as a "geochemical reactor"capable of fostering complex reactions which involve both soluble and insoluble impurities. Fe-bearing minerals can efficiently help in exploring such transformations.