DOI: 10.1016/j.palaeo.2012.11.016
论文题名: New insights into magnetic enhancement mechanism in Chinese paleosols
作者: Yang T. ; Hyodo M. ; Zhang S. ; Maeda M. ; Yang Z. ; Wu H. ; Li H.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2013
卷: 369 起始页码: 493
结束页码: 500
语种: 英语
英文关键词: Chinese loess
; Environmental magnetism
; Magnetic enhancement mechanism
; Pedogenesis
; Weathering process
英文摘要: Magnetic susceptibility of Chinese loess-paleosol sequences has been extensively used as a reliable paleoclimatic proxy for reconstruction of the Asian summer monsoon system, and its enhancement is usually attributed to neoformation of fine-grained ferrimagnetic particles via pedogenesis, but there is little understanding of either the formation process of such magnetic particles or their actual form and grain sizes. To investigate these problems, scanning electron microscope observations were conducted on magnetic extracts from pristine loess and strongly-pedogenic paleosol samples from Xifeng on the Chinese Loess Plateau. Both magnetic extracts commonly contained coarse-grained detrital magnetite with grain size ranging from a few μm to several tens of μm. However, the magnetic extract from the mature paleosol sample additionally included coarse silicate particles with ultrafine ferrimagnetic inclusions, while that from the pristine loess sample did not. The size of the ferrimagnetic inclusions mainly ranged from tens to hundreds of nanometers. The temperature-dependent susceptibility and hysteresis loops of the paleosol sample, combined with the stratigraphic variations of rock-magnetic parameters, showed that the pedogenic maghemite inclusions should be a potential contributor to magnetic enhancements in Chinese paleosols. The fine-grained ferrimagnetic inclusions have been pedogenically formed by weathering of coarse-grained Fe-bearing silicate minerals. Our proposed magnetic enhancement mechanism is consistent with the accepted rock magnetic result that magnetic enhancement in Chinese paleosols is caused by pedogenic maghemite grains in superparamagnetic and single-domain size regions. The presence of ultrafine ferrimagnetic grains as inclusions within coarse silicate particles is also consistent with Han and Jiang's (1999) significant experimental result that magnetic enhancement in Chinese paleosols is mainly contributed by the > 0.5 μm sediment fractions. © 2012 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69908
Appears in Collections: 过去全球变化的重建
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作者单位: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China; School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China; Research Center for Inland Seas, Kobe University, Kobe 657-8501, Japan; Natural Science Center for Basic Research and Development (N-BARD), Hiroshima University, Higashihiroshima 739-8526, Japan; Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China
Recommended Citation:
Yang T.,Hyodo M.,Zhang S.,et al. New insights into magnetic enhancement mechanism in Chinese paleosols[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2013-01-01,369