Grain size distribution of pedogenic magnetic particles in Chinese loess/paleosols

Qingsong Liu, Michael J. Jackson, Yongjae Yu, Fahu Chen, Chenglong Deng, Rixiang Zhu

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55 Scopus citations

Abstract

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 (χfd%) and the decay-rate (DR) dependence of anhysteretic remanence magnetization (ARM) susceptibility (χARM,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 χARM,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.

Original languageEnglish (US)
Pages (from-to)1-4
Number of pages4
JournalGeophysical Research Letters
Volume31
Issue number22
DOIs
StatePublished - Nov 28 2004

Keywords

  • 1512 Geomagnetism and Paleomagnetism: Environmental magnetism
  • 1519 Geomagnetism and Paleomagnetism: Magnetic mineralogy and petrology
  • 540 Geomagnetism and Paleomagnetism: Rock and mineral magnetism

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