Insight into Provenance and Variability of Atmospheric Dust in Antarctic Ice Cores During the Late Pleistocene from Ice Magnetization
Abstract
We measured saturation isothermal remanent magnetization (SIRM), coercivity of remanence (H cr ) and insoluble dust concentration of 52 ice samples from Vostok and EPICA Dome-C ice cores (Antarctica) as a measure of magnetic properties of the aerosol dust entrapped in the ice. Samples range in age from marine isotopic (MIS) stage 7 to 19 in EPICA Dome-C ice core and from MIS 1 to 11 in Vostok ice core. Data from ice samples were integrated with 86 samples from possible source areas (PSA) from East Antarctica corroborating available samples from South America and New Zealand. Previous results from MIS 1 to MIS 6 found that magnetic properties of aerosol dust could be divided in two distinct groups characterised by high-H cr and low-SIRM dust for glacial samples, and low-H cr and high-SIRM dust , for interglacial samples. The new data from older ice samples highlighted several discrepancies from these expectations with significant differences between Vostok and Dome-C sites. Magnetic properties of antarctic PSA sample show a large variability, but samples from "MESA range" e "Intermediate Hill" have magnetic properties compatible with that of the glacial dust, or more precisely with samples characterised by high dust flux. We did not found any PSA sample with magnetic properties compatible with highly magnetic samples mostly occurring in low dust flux stages, and, given the very unusual magnetic properties of these samples, this was not unexpected. While the provenance of this highly magnetic aerosol dust remains unknown, we consider very unlikely that it represent a reliable proxy of atmospheric dust. The new data from Pleistocene ice and from PSA samples on one hand confirm the South American provenance with antarctic contribution of the largest atmospheric dust load typical of glacial stages. On the other hand suggest a more complex picture then that resulting from the analysis of MIS 1-6, when dust magnetic properties are investigated during periods with low dust flux. Interestingly the the samples from Vostok ice core were found to be more coherent with the above model and more predictable, hence, we suggest that they represent a less-biased record of atmospheric dust.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGP31B0717L
- Keywords:
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- 0419 Biomineralization;
- BIOGEOSCIENCES;
- 1512 Environmental magnetism;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1522 Paleomagnetic secular variation;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1540 Rock and mineral magnetism;
- GEOMAGNETISM AND PALEOMAGNETISM