Quantifying ultrafine pedogenic magnetic particles in Chinese loess by monitoring viscous decay of superparamagnetism

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	Quantifying ultrafine pedogenic magnetic particles in Chinese loess by monitoring viscous decay of superparamagnetism
	Wang, XS (Wang, Xisheng); Lovlie, R (Lovlie, Reidar); Zhao, XY (Zhao, Xiangyu); Yang, ZY (Yang, Zhenyu); Jiang, FC (Jiang, Fuchu); Wang, SB (Wang, Shubing)
刊名	GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
	2010
卷号	11 页码:-
关键词	relaxometry superparamagnetism frequency-dependent susceptibility pedogenic ferromagnetic grains Chinese loess
ISSN号	1525-2027
英文摘要	We propose a new approach for quantifying pedogenically produced ultrafine (nanometer-scale) magnetic particles in Chinese loess. We have recorded the viscous decay (Delta t = 100 s) of imposed isothermal remanent magnetization (IRM) assumed to be selectively carried by superparamagnetic particles (J(v)). Application of viscosity measurements (relaxometry) to loess-paleosol sequences from the SE extremity of the Chinese Loess Plateau reveals that J(v) aptly reflects contributions of viscous superparamagnetic (SP) particles to the total remanence carried by an assemblage of magnetic particles. Time decay of J(v) can be determined with a higher resolution than the conventionally used frequency-dependent susceptibility (chi(fd)%) for characterizing the relative abundance of SP particles. The nearly logarithmic time decay of IRM implies a rather broad grain size distribution of pedogenic particles in Chinese loess that may range from a lower size limit of similar to 10 nm to an upper limit of similar to 40 nm with a prevalent grain size maximum of similar to 21-25 nm. Numerical calculations of the time dependence of IRM decay demonstrate that the actual contribution of fine-grained pedogenic magnetite/maghemite to the total remanence is at least twice as large as that estimated by both cfd% and our proposed J(v)% parameter. We therefore propose that determination of superparamagnetic contributions by the time dependence of IRM viscosity is a useful technique for tracking pedogenic processes and hence paleoclimatic conditions of Chinese loess.
学科主题	环境地质学
WOS关键词	FINE-GRAINED MAGNETITE ; TIME-DEPENDENT IRM ; PLATEAU ; SEDIMENTS ; ENHANCEMENT ; REMANENCE ; RECORD ; SOILS ; SUSCEPTIBILITY ; DISSOLUTION
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	AMER GEOPHYSICAL UNION
WOS记录号	WOS:000283074900002
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39229]
专题	中国地质调查局
作者单位	Nanjing Univ, Dept Earth Sci, Nanjing 210093, Peoples R China
推荐引用方式 GB/T 7714	Wang, XS ,Lovlie, R ,Zhao, XY ,et al. Quantifying ultrafine pedogenic magnetic particles in Chinese loess by monitoring viscous decay of superparamagnetism[J]. GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,2010,11:-.
APA	Wang, XS ,Lovlie, R ,Zhao, XY ,Yang, ZY ,Jiang, FC ,&Wang, SB .(2010).Quantifying ultrafine pedogenic magnetic particles in Chinese loess by monitoring viscous decay of superparamagnetism.GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,11,-.
MLA	Wang, XS ,et al."Quantifying ultrafine pedogenic magnetic particles in Chinese loess by monitoring viscous decay of superparamagnetism".GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS 11(2010):-.