A major glacial-interglacial change in aeolian dust composition inferred from Rare Earth Elements in Antarctic ice

Abstract

a b s t r a c tWe present the first Rare Earth Elements (REE) concentration record determined in 294 sections of an Antarctic ice core (EPICA Dome C), covering a period from 2.9 to 33.7 kyr BP. REE allow a detailed quantitative evaluation of aeolian dust composition because of the large number of variables (i.e. 14 elements). REE concentrations match the particulate dust concentration profile over this period and show a homogeneous crustal-like composition during the last glacial stage (LGS), with only a slight enrichment in medium REE. This signature is consistent with the persistent fallout of a mixture of dust from heterogeneous sources located in different areas or within the same region (e.g. South America). Starting at w15 kyr BP, there was a major change in dust composition, the variable character of which persisted throughout the Holocene. This varying signature may highlight the alternation of single dust contributions from different sources during the Holocene. We observe that the frequent changes in REE composition at the onset of the Holocene (10-13.5 kyr BP) are linked to dust size and in turn to wind strength and/or the path of the atmospheric trajectory. This may indicate that atmospheric circulation dictated the composition of the dust fallout to East Antarctica at that time. Although the dust concentrations remained fairly low, a notable return towards more glacial dust characteristics is recorded between 7.5 and 8.3 kyr BP. This happened concomitantly with a widespread cold event around 8 kyr BP that was 400-600 years long and suggests a moderate reactivation of the dust emission from the same potential source areas of the LGS.Published by Elsevier Ltd.

Lead isotopic compositions in the EPICA Dome C ice core and Southern Hemisphere Potential Source Areas

“…1a,b) follow well-defined glacialinterglacial variations, with the lowest concentrations during the Holocene MIS 1 (14 samples, average 0.36 pg Pb/g, 10.2 pg Ba/g) and Eemian MIS 5.5 (4 samples, average 0.41 pg Pb/g, 11.2 pg Ba/g) and the highest concentrations during the Last Glacial Maximum (LGM) MIS 2 (10 samples, average 13.4 pg Pb/g, 278 pg Ba/g). The data are in good agreement with LGM/Holocene REE concentrations ratios found in the EDC ice core (Gabrielli et al, 2010). A comparison of Pb and Ba concentrations to dD demonstrates the well-reported nonlinear sensitivity of dust fallout to climate , in which low Pb and Ba concentrations are observed at warmer temperatures (dD > À435&) while Pb and Ba concentrations increase steeply at colder temperatures (dD < À435&).…”

The significant inputs of trace elements and rare earth elements from melting glaciers in Antarctic coastal waters

“…5). All our ice floats and snow exhibited MREE enrichment, which could be from Patagonian origin because this pattern resembles those from volcanic rocks sampled in that region (Gaiero et al 2004) and/or those shown by South American dust (Gabrielli et al 2010).…”

Comparing modeled and observed changes in mineral dust transport and deposition to Antarctica between the Last Glacial Maximum and current climates

“…Grousset and Biscaye 2005). More recently, new isotopic and elemental composition systems (e.g., Pb, Li, He isotopes) have been utilized to fingerprint geochemically the dust (Vallelonga et al 2010;Gabrielli et al 2010;Marino et al 2008;Winckler and Fischer 2006;Siggaard-Andersen et al 2007); yet, geochemical data There is increasing consensus that dust deposited in Antarctica during interglacial time periods is derived from a mixture of dust sources rather than a single source. Potential sources include different regions within southern South America and other sources like AUS (Revel-Rolland et al 2006;Delmonte et al 2007) or possibly the PunaAltiplano area (Delmonte et al 2008a;Gaiero 2008), and match the limited data on the isotopic signature of interglacial dust from the studied ice cores.…”