Insight Into Provenance and Variability of Atmospheric Dust in Antarctic Ice Cores During the Late Pleistocene From Magnetic Measurements

Luca Lanci,Barbara Delmonte,Maria Cristina Salvatore,Carlo Baroni

doi:10.3389/feart.2020.00258

Abstract

We measured saturation isothermal remanent magnetization (SIRM), coercivity of remanence (Hcr) and insoluble dust concentration (IDC) 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 stage (MIS) 7 to 19 in EPICA Dome-C ice core and from MIS 1 to 11 in Vostok ice core. Data from ice samples were compared with 86 samples from possible source areas (PSA) from East Antarctica, and 10 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 characterized by high-Hcr and low-SIRMdust for glacial samples, and low-Hcr and high-SIRMdust, for interglacial samples. The new data from older ice samples highlighted several discrepancies from this expectation with significant differences between Vostok and Dome-C sites. Magnetic properties of Antarctic PSA sample show a large variability, however PSA samples from Victoria Land and few other, have magnetic properties compatible with that of the glacial dust, or more precisely with samples characterized by high dust flux. The new data from Pleistocene ice and from PSA samples confirm the South American and Antarctic provenance of the largest atmospheric dust load typical of glacial stages. On the other hand, we did not found any PSA sample with properties compatible with the highly magnetic samples (mostly from interglacial stages), which are characterized by low IDC. These samples from the oldest and deepest part of the cores revealed a more complex picture than previously outlined from the analysis of MIS 1–6, and show unusual magnetic properties which can be tentatively attributed to chemical.

Highlights

The provenance of wind-blown dust and its characteristics are key issues to understand climate, atmospheric and environmental changes
Samples from VK (Figure 4A) suggest a main linear trend indicating a proportionality between insoluble dust mass concentration (IDC) and SIRMice
According to a widely accepted interpretation of the Antarctic dust record based on the study of the lasted climatic stages, during glacial conditions dust deposition is dominated by a large load of long-distance transported dust, while during interglacial conditions other, unknown, contributions became significantly large compared to the much smaller atmospheric dust load

Summary

Introduction

The provenance of wind-blown dust and its characteristics are key issues to understand climate, atmospheric and environmental changes. Vostok (VK) and EPICA Dome-C (EDC) ice cores, drilled in the interior of the Antarctic ice sheet (Figure 1), provide the best known and longest dust records from Antarctica. VK gave the first dust record of the last 420,000 years (Petit et al, 1999) and revealed that the dust input to Antarctica was highest during glacial periods, lower during stadial and interstadial stages, and lowest in interglacial stages. The EDC ice core confirmed earlier findings from Vostok and, extended the dust record into the last ca. 800,000 years (Community Members EPICA, 2004; Jouzel et al, 2007), the longest polar ice core record. The identification of dust provenance and its characteristics are important for understanding climate, atmospheric and environmental changes, and potentially provides key constraints to dust transport processes

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Conclusion