Mechanism of the magnetic susceptibility enhancements of the Chinese loess

doi:10.1029/2004JB003249

	Mechanism of the magnetic susceptibility enhancements of the Chinese loess
	Liu, QS ; Jackson, MJ ; Banerjee, SK ; Maher, BA ; Deng, CL ; Pan, YX ; Zhu, RX
刊名	JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
	2004-12-24
卷号	109 期号:B12
关键词	Chinese loess magnetic susceptibility pedogenesis
ISSN号	2169-9313
DOI	10.1029/2004JB003249
文献子类	Article
英文摘要	Chinese loess/paleosol sequences have been regarded as excellent continental archives for encoding continuous paleoclimatic variations over the past 2.5 Myr. However, the mechanism for magnetic enhancements ( especially the low-field mass-specific magnetic susceptibility, chi) of Chinese paleosols is still not completely resolved. This study quantifies contributions of aeolian and pedogenic magnetic particles to the bulk magnetic properties of the Chinese loess/paleosols by using a magnetic extraction technique. Magnetic properties of magnetic separates ( extractable) and the corresponding residues (nonextractable) for five characteristic samples covering both loesses and paleosols were comprehensively investigated by hysteresis loops, frequency and low-temperature dependence of magnetic susceptibility, and interparametric ratios. Results show that (1) with moderate degrees of pedogenesis (chi < 10 x 10(-7) m(3) kg(-1)), chi is enhanced more by increased concentration of stable single domain (SD) magnetic particles than by viscous superparamagnetic (SP) particles. For more mature paleosols with chi > (10-12) x 10(-7) m(3) kg(-1), contributions of pedogenically related fine-grained pseudosingle-domain (PSD, similar to100 nm to several microns) particles become significant; ( 2) pedogenic particles have a narrow grain size distribution concentrated above the SP/SD threshold; and ( 3) anhysteretic remanent magnetization (ARM) is carried dominantly by SD grains. Moreover, we propose that only the nonextractable fraction of chi, saturation magnetization (M-s) and remanent magnetization (M-rs) show a strong relationship with the degree of pedogenesis. This new interpretation of magnetic enhancements helps us to retrieve more accurate and quantitative paleoclimatic signals recorded by the Chinese loess/paleosol sequences.
WOS关键词	ISOTHERMAL REMANENT MAGNETIZATION ; ACQUISITION CURVES ; LOESS/PALEOSOL SEQUENCES ; FREQUENCY-DEPENDENCE ; QUADRATURE SUSCEPTIBILITY ; PALEOSOL SEQUENCES ; RECORD ; MINERALS ; PLATEAU ; ORIGIN
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	AMER GEOPHYSICAL UNION
WOS记录号	WOS:000226028300004
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/79711]
专题	中国科学院地质与地球物理研究所
通讯作者	Liu, QS
作者单位	1.Univ Minnesota, Inst Rock Magnetism, Minneapolis, MN 55455 USA 2.Univ Minnesota, Dept Geol & Geophys, Minneapolis, MN 55455 USA 3.Chinese Acad Sci, Inst Geol & Geophys, Paleomagnetism Lab, Beijing 100029, Peoples R China 4.Univ Lancaster, Dept Geog, CEMP, Lancaster LA1 4YW, England
推荐引用方式 GB/T 7714	Liu, QS,Jackson, MJ,Banerjee, SK,et al. Mechanism of the magnetic susceptibility enhancements of the Chinese loess[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2004,109(B12).
APA	Liu, QS.,Jackson, MJ.,Banerjee, SK.,Maher, BA.,Deng, CL.,...&Zhu, RX.(2004).Mechanism of the magnetic susceptibility enhancements of the Chinese loess.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,109(B12).
MLA	Liu, QS,et al."Mechanism of the magnetic susceptibility enhancements of the Chinese loess".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 109.B12(2004).