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Inter-profile correlation of the Chinese loess/paleosol sequences during Marine Oxygen Isotope Stage 5 and indications of pedogenesis

Inter-profile correlation of the Chinese loess/paleosol sequences during Marine Oxygen Isotope Stage 5 and indications of pedogenesis
Inter-profile correlation of the Chinese loess/paleosol sequences during Marine Oxygen Isotope Stage 5 and indications of pedogenesis
Low-field magnetic susceptibility has been widely used to determine the pedostratigraphy of the Chinese loess/paleosol sequences. However, uncertainties remain in correlating between the loess magnetic susceptibility and the marine oxygen isotope records because susceptibility variations are affected by both global and local paleoclimatic changes. To provide a more sound paleoclimatic interpretation of magnetic susceptibility variations, age models across Marine Oxygen Isotope Stage (MIS) 5 for the Jiuzhoutai (JZT) and Yuanbao (YB) sections, western Chinese Loess Plateau, were constructed through an integrated approach by linking the major pedostratigraphic boundaries of the loess profiles to the SPECMAP oxygen isotope curve, and by correlating relative magnetic paleointensity records with both the SINT800 global paleointensity stack from marine sediments and 36Cl records from the GRIP ice core. Results indicate good correlation of SIRM60 mT (a residual remanence of saturation isothermal remanent magnetization after a 60 mT alternating field demagnetization) variations between these two sites, which agree well with fluctuations in subtropical Atlantic sea surface temperatures. All cooling events recorded by ice-core and Atlantic marine sediments within MIS5 have counterparts in SIRM60 mT. SIRM60 mT is partially controlled by the degree of low-temperature oxidation, which is strongly temperature dependent. However, strong pedogenesis can decrease SIRM60 mT due to further oxidation of partially oxidized magnetites above some critical points. Therefore, we propose that SIRM60 mT is best suited to record paleotemperature changes in loess profiles from the western Chinese Loess Plateau, where pedogenesis is the weakest. Furthermore, by inter-profile correlation between the YB and JZT sections, we note that the seemingly uniform sub-paleosol unit with a broad susceptibility peak (previously assigned to MIS5c) between 34.4 and 37.4 m in the YB profile actually consists of two independent units (lower part of S1L1/MIS5b and S1S2/MIS5c). This indicates that susceptibility values can be strongly affected by local factors (e.g., mainly precipitation). Therefore, beside the simplistic traditional paleoclimatic interpretation of variations in loess susceptibility involving only cold/dry and warm/humid scenarios, cold/humid and warm/dry scenarios should also be considered.
0277-3791
195-210
Liu, Qingsong
fbaf8851-e943-4ece-91f5-c5f30306dff1
Banerjee, Subir K.
f6d95b5e-8c50-47e2-8e6c-f87fc368bd69
Jackson, Michael J.
e0200cfd-dc38-4060-b116-ee1d2d31fb8e
Deng, Chenglong
2f7f344c-97bb-445e-bb69-440aeb555861
Pan, Yongxin
70611af6-4fde-454e-9764-9e6ef696e92f
Zhu, Rixiang
9118dd03-a226-4eba-8891-7c892c17bb37
Liu, Qingsong
fbaf8851-e943-4ece-91f5-c5f30306dff1
Banerjee, Subir K.
f6d95b5e-8c50-47e2-8e6c-f87fc368bd69
Jackson, Michael J.
e0200cfd-dc38-4060-b116-ee1d2d31fb8e
Deng, Chenglong
2f7f344c-97bb-445e-bb69-440aeb555861
Pan, Yongxin
70611af6-4fde-454e-9764-9e6ef696e92f
Zhu, Rixiang
9118dd03-a226-4eba-8891-7c892c17bb37

Liu, Qingsong, Banerjee, Subir K., Jackson, Michael J., Deng, Chenglong, Pan, Yongxin and Zhu, Rixiang (2005) Inter-profile correlation of the Chinese loess/paleosol sequences during Marine Oxygen Isotope Stage 5 and indications of pedogenesis. Quaternary Science Reviews, 24 (1-2), 195-210. (doi:10.1016/j.quascirev.2004.07.021).

Record type: Article

Abstract

Low-field magnetic susceptibility has been widely used to determine the pedostratigraphy of the Chinese loess/paleosol sequences. However, uncertainties remain in correlating between the loess magnetic susceptibility and the marine oxygen isotope records because susceptibility variations are affected by both global and local paleoclimatic changes. To provide a more sound paleoclimatic interpretation of magnetic susceptibility variations, age models across Marine Oxygen Isotope Stage (MIS) 5 for the Jiuzhoutai (JZT) and Yuanbao (YB) sections, western Chinese Loess Plateau, were constructed through an integrated approach by linking the major pedostratigraphic boundaries of the loess profiles to the SPECMAP oxygen isotope curve, and by correlating relative magnetic paleointensity records with both the SINT800 global paleointensity stack from marine sediments and 36Cl records from the GRIP ice core. Results indicate good correlation of SIRM60 mT (a residual remanence of saturation isothermal remanent magnetization after a 60 mT alternating field demagnetization) variations between these two sites, which agree well with fluctuations in subtropical Atlantic sea surface temperatures. All cooling events recorded by ice-core and Atlantic marine sediments within MIS5 have counterparts in SIRM60 mT. SIRM60 mT is partially controlled by the degree of low-temperature oxidation, which is strongly temperature dependent. However, strong pedogenesis can decrease SIRM60 mT due to further oxidation of partially oxidized magnetites above some critical points. Therefore, we propose that SIRM60 mT is best suited to record paleotemperature changes in loess profiles from the western Chinese Loess Plateau, where pedogenesis is the weakest. Furthermore, by inter-profile correlation between the YB and JZT sections, we note that the seemingly uniform sub-paleosol unit with a broad susceptibility peak (previously assigned to MIS5c) between 34.4 and 37.4 m in the YB profile actually consists of two independent units (lower part of S1L1/MIS5b and S1S2/MIS5c). This indicates that susceptibility values can be strongly affected by local factors (e.g., mainly precipitation). Therefore, beside the simplistic traditional paleoclimatic interpretation of variations in loess susceptibility involving only cold/dry and warm/humid scenarios, cold/humid and warm/dry scenarios should also be considered.

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Published date: January 2005

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Local EPrints ID: 41267
URI: http://eprints.soton.ac.uk/id/eprint/41267
ISSN: 0277-3791
PURE UUID: 9e117a7a-f32b-44b1-a0d4-e5bb9c189ccc

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Date deposited: 11 Aug 2006
Last modified: 15 Mar 2024 08:26

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Contributors

Author: Qingsong Liu
Author: Subir K. Banerjee
Author: Michael J. Jackson
Author: Chenglong Deng
Author: Yongxin Pan
Author: Rixiang Zhu

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