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Grain size distribution of pedogenic magnetic particles in Chinese loess/paleosols
Author(s) -
Liu Qingsong,
Jackson Michael J.,
Yu Yongjae,
Chen Fahu,
Deng Chenglong,
Zhu Rixiang
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl021090
Subject(s) - pedogenesis , loess , paleosol , geology , aeolian processes , superparamagnetism , remanence , magnetic susceptibility , grain size , particle size distribution , environmental magnetism , mineralogy , soil water , magnetite , magnetization , soil science , magnetic field , geomorphology , condensed matter physics , particle size , paleontology , physics , quantum mechanics
Variations in magnetic parameters of the long Chinese loess/paleosol sequences reflect paleoclimatic fluctuations. However, there remain ambiguities whether the magnetic proxies are controlled by the concentration or by the distribution of magnetic grain sizes. We systematically investigated the frequency‐dependence of low‐field magnetic susceptibility (χ fd %) and the decay‐rate (DR) dependence of anhysteretic remanence magnetization (ARM) susceptibility (χ ARM,DR %) for a set of representative loess/paleosol samples from the Yuanbao section, western Chinese loess plateau. After removing the effect of aeolian coarse‐grained magnetites, both χ fd % and χ ARM,DR % are nearly independent of the degree of pedogenesis, indicating a presence of fine‐grained magnetic particles ranging from superparamagnetic to single domain with an almost constant grain size distribution. Therefore, the magnetic enhancement of magnetic susceptibility or ARM is caused dominantly by changes in the concentration of these fine‐grained pedogenic grains.