Magnetic properties of aerosol dust in peripheral and inner Antarctic ice cores as a proxy for dust provenance

摘要

We use laboratory-induced remanent magnetization of polar ice to measure the rock-magnetic properties of the aerosol dust directly in ice samples. Former studies on Vostok and EPICA-Dome C ice core, recovered on the inner East Antarctic ice sheet, revealed that glacial and interglacial periods of the latter are characterized by distinct magnetic mineralogies at Dome C, which might reflect different dust source areas. In this work we present the first results on glacial and Holocene samples from the TALDICE ice core, collected at the peripheral site of Talos Dome located at high-elevation on the ice sheet close to some ice-free areas of the Transantarctic mountains. Magnetic properties of interglacial samples from both Dome-C and Talos Dome ice cores turned out to have peculiar characteristics that suggest an enhanced concentration of Fe-rich minerals in the aerosol dust compared to Vostok. The most likely explanation for the extremely high dust magnetization measured in interglacial samples is the presence of volcanic material, although occasional occurrence of meteoritic material (micrometeorites) cannot be ruled out. The volcanic nature of the Holocene aerosol dust and its variability between sites provides further constrains on dust geographic provenance that are complementary to geochemical and physical evidences. Moreover, the calculations of the flux of the highly magnetic dust provide information on wind transport toward the continent interior during the Holocene.