The magnetic properties of loess and paleosol samples from the Chinese Loess Plateau spanning the last 22 million years

doi:10.1016/j.palaeo.2007.11.010

	The magnetic properties of loess and paleosol samples from the Chinese Loess Plateau spanning the last 22 million years
	Hao, Qingzhen 1,2; Oldfield, Frank 1; Bloemendal, Jan 1; Guo, Zhengtang 2
刊名	PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
	2008-04-14
卷号	260 期号:3-4 页码:389-404
关键词	loess environmental magnetism neogene palaeoenvironment China
ISSN号	0031-0182
DOI	10.1016/j.palaeo.2007.11.010
文献子类	Article
英文摘要	Magnetic measurements (susceptibility, isothermal and anhysteretic remanence, and quotients derived from these) are presented for a suite of loess and paleosol samples from sites on the Chinese Loess Plateau. The three sites, Xifeng, Dongwan and Qinan (QA-I), together span most of the last 22 million years. The results provide the first multi-parameter magnetic measurements from pre-Pleistocene loess/paleosol sequences that began accumulation in the early Miocene. Mass specific measurements have been corrected for carbonate concentrations which peak in the loess layers and range up to 57%. All the magnetic properties recorded indicate variability on both orbital and supra-orbital timescales. The changing magnetic properties allow the record to be divided into a sequence of eight sample groups that broadly parallel the main supra-orbital changes in magnetic susceptibility. The pre-Pleistocene parts of the record include intervals (mainly late Miocene and Pliocene) during which loess as well as paleosol layers are characterized by high values for properties such as frequency dependent susceptibility (chi(fd)), usually associated with strong weathering. Most of the Miocene record prior to 8.5 Ma, with the exception of a brief interval from ca. 14.4 to 15.9 Ma, shows reduced values for indicators of pedogenic ferrimagnetic concentrations in both the loess and paleosol layers, as well as a low amplitude of variability between loess and paleosol values. The palaeoenvironmental implications of this part of the sequence are unclear since they hinge on the type of model of pedogenic magnetic mineral formation adopted. High-field remanence measurements indicate that the coercivity of the antiferromagnetic minerals represented declined progressively throughout the whole period in both the loess and the paleosol samples, though there is no unambiguous evidence for long-term diagenetic alteration of the magnetic properties on timescales beyond the orbital ones that drive the loess/palcosol alternations. The present results suggest caution in applying existing climofunctions based on magnetic susceptibility to deposits spanning the whole of the last 22 Ma. (C) 2008 Elsevier B.V. All rights reserved.
WOS关键词	RED-EARTH FORMATION ; SOIL SEQUENCE ; GRAIN-SIZE ; PALEOCLIMATIC SIGNIFICANCE ; NATURAL GOETHITE ; NORTHERN CHINA ; ORIGIN ; SUSCEPTIBILITY ; QINAN ; PALAEOPRECIPITATION
WOS研究方向	Physical Geography ; Geology ; Paleontology
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000255474200007
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/69566]
专题	中国科学院地质与地球物理研究所
通讯作者	Oldfield, Frank
作者单位	1.Univ Liverpool, Dept Geog, Liverpool L69 7ZT, Merseyside, England 2.Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Hao, Qingzhen,Oldfield, Frank,Bloemendal, Jan,et al. The magnetic properties of loess and paleosol samples from the Chinese Loess Plateau spanning the last 22 million years[J]. PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY,2008,260(3-4):389-404.
APA	Hao, Qingzhen,Oldfield, Frank,Bloemendal, Jan,&Guo, Zhengtang.(2008).The magnetic properties of loess and paleosol samples from the Chinese Loess Plateau spanning the last 22 million years.PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY,260(3-4),389-404.
MLA	Hao, Qingzhen,et al."The magnetic properties of loess and paleosol samples from the Chinese Loess Plateau spanning the last 22 million years".PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY 260.3-4(2008):389-404.