Enhancement mechanisms of magnetic susceptibility in the Chinese red‐clay sequence
Enhancement mechanisms of magnetic susceptibility in the Chinese red‐clay sequence
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DOI：
10.1029/2007gl031430
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发表时间：
2007-10
影响因子：
5.2
通讯作者：
J. Nie;J. King;X. Fang
中科院分区：
文献类型：
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作者：
J. Nie;J. King;X. Fang
相对于上覆黄土-古土壤序列，黄土高原红粘土序列磁化率（χ）增强的机制还知之甚少。在这里，我们提出了一个岩石磁性研究的红粘土沉积物从中央CLP。我们的研究结果表明，频率依赖性的χ（χfd = χlf − χhf，其中χlf和χhf分别是在470 Hz和4700 Hz测量的χ），χlf和磁化率的无滞后-恢复-磁化（χARM）是线性相关的红粘土序列。这种线性相关性表明，红粘土中的成土磁性矿物与黄土-古土壤序列中的成土磁性矿物一样，具有较均匀的粒度分布，粒度大小与成土作用程度无关。然而，红粘土沉积物中的超顺磁性颗粒比上覆的黄土-古土壤沉积物中的超顺磁性颗粒略富集，如χfd和χlf之间的回归线的较高斜率所示。
Little is known about the mechanisms of magnetic susceptibility (χ) enhancement for the red‐clay sequence on the Chinese Loess Plateau (CLP), in comparison to the overlying loess‐paleosol sequence. Here we present a rock magnetic study of the red‐clay sediments from the central CLP. Our results show that frequency dependence of χ (χfd = χlf − χhf, where χlf and χhf are χ measured at 470 Hz and 4700 Hz, respectively), χlf, and susceptibility of anhysteretic‐remanent‐magnetization (χARM) are linearly correlated within the red‐clay sequence. This linear correlation indicates that the pedogenic magnetic minerals of the red‐clay have a rather uniform grain size distribution as in the loess‐paleosol sequence, and the grain size is independent of the degree of pedogenesis. Nevertheless, red‐clay sediments are slightly more enriched in superparamagnetic magnetic particles than the overlying loess‐paleosol sediments as indicated by the higher slope of the regression line between χfd and χlf.