Abstract
Abstract. 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 1000 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.
Highlights
Antarctic ice cores are a valuable archive which allows the reconstruction of the climatic history of the Earth during the last 800 000 years (Wolff et al, 2010)
During the Holocene, fine particle percentage (FPP) has a mean value of 50 %, while during Marine Isotope Stage (MIS) 2 it increases to 63 %, revealing that under glacial conditions dust particles deposited at Talos Dome are smaller than in interglacial periods
This study provides a first description of dust chemical weathering in deep polar ice
Summary
Antarctic ice cores are a valuable archive which allows the reconstruction of the climatic history of the Earth during the last 800 000 years (Wolff et al, 2010). Studying the properties of dust trapped in ice cores, it is possible to obtain information on how the climate influences the dust cycle (Delmonte et al, 2004) and about the effects of dust under different climatic regimes (Mahowald et al, 1999; Wolff et al, 2006; Potenza et al, 2016). It is known that the physical and compositional properties of dust trapped in ice cores are influenced by climatic, environmental and atmospheric processes (Sugden et al, 2009; Delmonte et al, 2017; Markle et al, 2018). The dust concentration in ice is strictly controlled by climate (Delmonte et al, 2002); dust grain size is related to its atmospheric transport (Delmonte et al, 2017; Albani et al, 2012a) and geochemistry to dust sources (Delmonte et al, 2004)
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