Magnetic properties of surface sediments in Schirmacher Oasis, East Antarctica: spatial distribution and controlling factors

Warrier, Anish Kumar and Sebastian, Joju George and Amrutha, K and Sali, Yamuna A S and Mahesh, B S and Mohan, Rahul (2021) Magnetic properties of surface sediments in Schirmacher Oasis, East Antarctica: spatial distribution and controlling factors. Journal of Soils and Sediments, 21 (2). pp. 1206-1221. ISSN 1439-0108

[img] PDF
11285.pdf - Published Version
Restricted to Registered users only

Download (2MB) | Request a copy

Abstract

Purpose We investigated the magnetic properties (abundance, grain size, and mineralogy) of iron oxides present in Lake L-55 sediments, Schirmacher Oasis, East Antarctica, with an aim to understand their spatial distribution and the underlying mecha�nisms that control their formation and distribution. Methods Twenty-five surficial sediments retrieved from different parts of Lake L-55 were subjected to the entire range of environmental magnetic (magnetic susceptibility, anhysteretic remanent magnetization (ARM), isothermal remanent magneti�zation (IRM)) measurements (at different field strengths). Inter-parametric ratios (χARM/SIRM, χARM/χlf, χARM/χfd, IRM20 mT/ SIRM, IRM20 mT/ARM, S-ratio, L-ratio) provided insights into the magnetic properties (abundance, grain size, and mineralogy of iron oxides). Scanning electron microscopic-energy dispersive X-ray spectroscopic (SEM-EDS) analysis was performed on magnetic extracts from a few sediments. Besides, organic matter (%) was also calculated for the sediment samples. Principal component analysis was performed to gain information on the presence of different components and their relative dominance. Results The iron oxides are strongly magnetic (high values of concentration-dependent parameters). The principal iron oxide is magnetite (S-ratio > 0.90) which is coarse-grained (multi-domain (MD) and stable single-domain (SSD) grains), and there is no influence of authigenic greigite, bacterial magnetite, and anthropogenic magnetite. The mineralogy is confirmed by SEM-EDS data. The iron oxides are of different grain sizes, and their contribution is in the order of MD > SSD > SP as shown by the principal component analysis. Pedogenic iron oxide minerals seem to be present in the samples whose formation is due to the oxidation of magnetite into hematite. However, they are of SSD size and not SP, suggesting that the intensity of pedogenesis is not sufficient to form SP grains. Conclusion The iron oxide minerals are mainly terrigenous, and the biogenic activity within the lake is not sufficient to modify the ferrimagnetic minerals. Spatial distribution patterns suggest the non-uniform distribution of magnetite/ titanomagnetite of varying sizes in the lake basin which is transported by both melt water streams and winds.

Item Type: Article
Uncontrolled Keywords: Iron oxides . Melt water . Sedimentary processes . Environmental magnetism . Aeolian . Weathering
Subjects: Engineering > MIT Manipal > Civil Engineering
Depositing User: MIT Library
Date Deposited: 23 Apr 2021 09:08
Last Modified: 23 Apr 2021 09:08
URI: http://eprints.manipal.edu/id/eprint/156659

Actions (login required)

View Item View Item