Glacial-interglacial climatic variations at the Schirmacher Oasis, East Antarctica: The first report from environmental magnetism

We discuss in this paper the first detailed environmental magnetic record of glacial-interglacial climatic variations in the Schirmacher Oasis, East Antarctica. We determined environmental magnetic properties and interparametric ratios (chi(If), chi fd%, chi(ARM), SIRM, chi(ARM)/SIRM, chi(ARM)/chi(If), chi(ARM)/chi(fd), SIRM/chi(If,) S-ratio and HIRM) for sediment samples of a core from the Sandy Lake. Accelerator mass spectrometer (AMS) C-14 dates were obtained on the organic matter from bulk sediment samples. The sediment core spans the past similar to 42.5 cal. ka B.P. The magnetic minerals are mainly detrital and catchment-derived, as there is no evidence for the presence of authigenic greigite, bacterial magnetite or diagenetic dissolution. The last glacial period is characterized by a high concentration of ferrimagnetic minerals such as titanomagnetite (high values of chi(If), SIRM etc.) and coarse magnetic grain size (low chi(ARM)/SIRM and chi(ARM)/chi(If) values and high S-ratio values). Deglaciation in the Schirmacher Oasis began around 21 cal. ka B.P. as suggested by the low magnetic mineral concentration. The Holocene period is characterized by relatively warm climatic events as seen in the low values of magnetic susceptibility which is primarily contributed by fine-grained titanomagnetite resulting from pedogenesis (high chi(fd) % values). Several of the relatively warm and cold events that we deciphered from the environmental magnetic data are correlatable with lake sediments from the Schirmacher Oasis and other ice-free areas in East Antarctica and from ice-core records on the Antarctic Plateau. (c) 2014 Elsevier B.V. All rights reserved.