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Quantifying the grain size distribution of the pedogenic magnetic particles in Chinese loess and its significance for pedogenesis.

Liu, Qingsong S. and Torrent, Jose and Maher, Barbara A. and Yu, Yongjae and Deng, Chenglong L. and Zhu, Rixiang X. and Zhao, Xixi X. (2005) Quantifying the grain size distribution of the pedogenic magnetic particles in Chinese loess and its significance for pedogenesis. Journal of Geophysical Research: Solid Earth, 110 (B11). B11102. ISSN 2196-9356

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Abstract

Quaternary glacial/interglacial cycles have been imprinted on the Chinese loess/paleosol sequences through pedogenesis. In order to accurately decode the paleoclimatic signals carried by these pedogenic particles it is essential to quantify the pedogenically produced magnetic particles in terms of mineralogy as well as grain size distribution (GSD). To date, the GSD has not been accurately determined because of the dearth of available means for analyzing extremely fine grained (nanometer-scale) pedogenic magnetic particles. Using low-temperature techniques, we systematically investigated the temperature dependency of χ fd (defined as χ1Hz − χ10Hz, where χ1Hz and χ10Hz are AC magnetic susceptibility measured at 1 and 10 Hz, respectively) from two characteristic loess profiles, one located at the western Chinese Loess Plateau and the other in the central plateau. On the basis of Néel theory for a shape anisotropy dominant grain and experimental analysis at low temperatures, a quantitative GSD for pedogenic particles in Chinese loess/paleosols was constructed. We found that the dominant magnetic grain size lies just above the superparamagnetic/single-domain threshold (∼20–25 nm) and that the GSD is almost independent of the degree of pedogenesis. This observation agrees well with other constraints from previous studies. This new GSD model improves our understanding of the pedogenic processes in Chinese loess, enabling further explicit linkage of environmental magnetism to paleoclimate changes.

Item Type: Article
Journal or Publication Title: Journal of Geophysical Research: Solid Earth
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 23724
Deposited By: ep_ss_importer
Deposited On: 19 Feb 2009 16:25
Refereed?: Yes
Published?: Published
Last Modified: 17 Sep 2013 08:18
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/23724

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