TY - JOUR
T1 - A 43-ka mineral magnetic record of environmental variations from lacustrine sediments of Schirmacher Oasis, East Antarctica
AU - Warrier, Anish Kumar
AU - Mahesh, Badanal Siddaiah
AU - Mohan, Rahul
AU - Shankar, Rajasekhariah
N1 - Funding Information:
We are grateful to the Secretary, MoES and the Director, NCPOR, Goa, for their valuable guidance, support and constant encouragement. The magnetic instruments used for this study were procured through a research project to RS (DOD Sanction no.: DOD/11-MRDF/1/48/P/94-ODII/12-10-96. We are thankful to the Antarctic Logistics Division, NCPOR and members of the 28 th Indian Scientific Expedition to Antarctica for their assistance during coring operations. AKW thanks and appreciates the help rendered by Sahina Gazi and Akshaya Teli, NCPOR, Goa, in generating the SEM-EDS data. AKW thanks Gokul Valsan for his help in preparing the schematic model. AKW acknowledges the financial support provided by the National Centre for Polar and Ocean Research, Ministry of Earth Sciences, in the form of a research project (Sanction: NCPOR/2019/PACER-POP/ES-02 dated 05/07/2019) under the PACER Outreach Programme (POP) initiative, to undertake this research. We thank the editor-in-chief and two anonymous reviewers for their valuable comments which improved the quality of the manuscript. This is NCPOR contribution no. J-126/2020-21.
Funding Information:
We are grateful to the Secretary, MoES and the Director, NCPOR, Goa, for their valuable guidance, support and constant encouragement. The magnetic instruments used for this study were procured through a research project to RS (DOD Sanction no.: DOD/11-MRDF/1/48/P/94-ODII/12-10-96. We are thankful to the Antarctic Logistics Division, NCPOR and members of the 28th Indian Scientific Expedition to Antarctica for their assistance during coring operations. AKW thanks and appreciates the help rendered by Sahina Gazi and Akshaya Teli, NCPOR, Goa, in generating the SEM-EDS data. AKW thanks Gokul Valsan for his help in preparing the schematic model. AKW acknowledges the financial support provided by the National Centre for Polar and Ocean Research, Ministry of Earth Sciences, in the form of a research project (Sanction: NCPOR/2019/PACER-POP/ES-02 dated 05/07/2019) under the PACER Outreach Programme (POP) initiative, to undertake this research. We thank the editor-in-chief and two anonymous reviewers for their valuable comments which improved the quality of the manuscript. This is NCPOR contribution no. J-126/2020-21.
Publisher Copyright:
© 2021 Elsevier B.V.
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/7
Y1 - 2021/7
N2 - Glacial-interglacial climatic and environmental variations recorded in lake-bed sediments of Schirmacher Oasis (SO), East Antarctica, are rare; limited data exist on the past behavior of the East Antarctic Ice Sheet (EAIS). In this work, we present the mineral magnetic properties of a radiocarbon-dated sediment core, spanning the past 43,000 years, from a land-locked lake L-49 in SO. We also performed Scanning Electron Microscopic-Energy Dispersive X-ray Spectroscopic (SEM-EDS) studies on magnetic extracts to confirm the magnetic mineralogy. The values of magnetic susceptibility (χlf) and saturation isothermal remanent magnetization (SIRM) are relatively low during the Holocene but high during the last glacial period. Sediments of the last glacial period are composed mainly of coarse-grained (multi-domain - MD) magnetite/titanomagnetite (high values of S20 – an MD proxy, low susceptibility of anhysteretic remanent magnetism (χARM)/SIRM ratio values and high S-ratio values) indicating a stronger intensity of physical weathering in the Lake L-49 catchment. The mineralogy is confirmed by SEM-EDS data for magnetic extracts. Principal Component Analysis (PCA) of the data suggests three processes affecting magnetic properties of the lake sediments, i.e., ferrimagnetic input, biogenic processes and aeolian input. During deglaciation, a shift in the magnetic properties is documented: a decrease in χlf values from 18.6 cal ka BP onwards suggests melting of the snow and ice in the catchment thus leading to a significant production of fine-grained iron oxide minerals. At ~12.77 cal ka BP, high values of χlf and S20 ratio indicates cooling which is related to the Antarctic Cold Reversal (ACR). The Early Holocene Climate Optimum is distinctly imprinted in our record as a sudden decrease in χlf values and an increase in magnetic grain size ratio values (indicating finer iron oxide grains), suggesting a rapid thawing of the ice-sheet in response to a warm climate. The Mid-Holocene Hypsithermal (from 5.8 to 3.5 cal ka BP) and Neoglaciation (3.6 cal ka BP onwards) that are evident in this study correspond with reconstructions from lake and marine sediment, and ice-core records from Antarctica.
AB - Glacial-interglacial climatic and environmental variations recorded in lake-bed sediments of Schirmacher Oasis (SO), East Antarctica, are rare; limited data exist on the past behavior of the East Antarctic Ice Sheet (EAIS). In this work, we present the mineral magnetic properties of a radiocarbon-dated sediment core, spanning the past 43,000 years, from a land-locked lake L-49 in SO. We also performed Scanning Electron Microscopic-Energy Dispersive X-ray Spectroscopic (SEM-EDS) studies on magnetic extracts to confirm the magnetic mineralogy. The values of magnetic susceptibility (χlf) and saturation isothermal remanent magnetization (SIRM) are relatively low during the Holocene but high during the last glacial period. Sediments of the last glacial period are composed mainly of coarse-grained (multi-domain - MD) magnetite/titanomagnetite (high values of S20 – an MD proxy, low susceptibility of anhysteretic remanent magnetism (χARM)/SIRM ratio values and high S-ratio values) indicating a stronger intensity of physical weathering in the Lake L-49 catchment. The mineralogy is confirmed by SEM-EDS data for magnetic extracts. Principal Component Analysis (PCA) of the data suggests three processes affecting magnetic properties of the lake sediments, i.e., ferrimagnetic input, biogenic processes and aeolian input. During deglaciation, a shift in the magnetic properties is documented: a decrease in χlf values from 18.6 cal ka BP onwards suggests melting of the snow and ice in the catchment thus leading to a significant production of fine-grained iron oxide minerals. At ~12.77 cal ka BP, high values of χlf and S20 ratio indicates cooling which is related to the Antarctic Cold Reversal (ACR). The Early Holocene Climate Optimum is distinctly imprinted in our record as a sudden decrease in χlf values and an increase in magnetic grain size ratio values (indicating finer iron oxide grains), suggesting a rapid thawing of the ice-sheet in response to a warm climate. The Mid-Holocene Hypsithermal (from 5.8 to 3.5 cal ka BP) and Neoglaciation (3.6 cal ka BP onwards) that are evident in this study correspond with reconstructions from lake and marine sediment, and ice-core records from Antarctica.
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U2 - 10.1016/j.catena.2021.105300
DO - 10.1016/j.catena.2021.105300
M3 - Article
AN - SCOPUS:85103015282
SN - 0341-8162
VL - 202
JO - Catena
JF - Catena
M1 - 105300
ER -
