An environmental magnetism approach for soils and sediments of Schirmacher Oasis, East Antarctica

ADYASHA RATH; WARRIER, ANISH KUMAR; JOJU, G.S.; FIROZ BADESAB; CHAPARRO, MARCOS A.E.; B.S. MAHESH; MOHAN, RAHUL

Kochi

Conferencia; 2nd International Conference on Frontiers in Marine Sciences; 2024

School of Marine Sciences CUSAT-NCPOR Centre for Polar Sciences Cochin University of Science and Technology (CUSAT) & National Centre for Polar and Ocean Research (NCPOR) INSA-Scientific Committee on Antarctic Research (INSA-SCAR)

Environmental magnetism helps in understanding the properties of iron-bearing minerals present in soils and sediments, which provides information on the environmental processes, governing their transportation, deposition, and alteration. The present study provides insights into the mineral magnetic properties and their relationship to weathering processes occurring under the extreme conditions of Schirmacher Oasis, East Antarctica. Environmental magnetic analysis was carried out for the surface sediments (n = 50) and soil samples (n = 78) collected from Schirmacher Oasis to identify the mechanisms that control the formation and distribution of the iron oxide minerals. Low-field magnetic susceptibility (χlf), indicative of the concentration of magnetic minerals, shows a mean value of 109.5 x 10-8 m3kg-1 for the soil samples and 126.376 x 10-8 m3kg-1 for the sediment samples, suggesting the presence of magnetically strong minerals. The frequency-dependent susceptibility (χfd) and the percentage frequency-dependent susceptibility (χfd%) are indicative of the presence of superparamagnetic (SP) grains, hence they are indicative of the degree of pedogenesis. χfd% remains < 2 % for most of the samples, indicating the absence of SP grains. The parameter χARM/SIRM, reflective of the magnetic granulometry show mean values of 53.1 x 10−5 mA−1 for soil and 49.66 x 10−5 mA−1 for sediment samples indicating the predominance of coarse-grained magnetic minerals.Statistically significant correlation between χlf and SIRM for the soil (r=0.786, p<0.05, n=78) and sediment samples (r=0.679, p<0.05, n=50) reflects the dominance of ferrimagnetic grains in the samples. The parameter S-ratio represents the proportions of minerals with low and high coercivity. Most samples show S-ratio ranging from 0.97 to 0.99, demonstrating that low-coercivity magnetic minerals regulate the magnetic signal. The various interparametric ratios revealed the absence of bacterial magnetite, anthropogenic magnetite, and authigenic greigite, suggesting that the magnetic minerals are formed due to weathering processes in the region.