Variable shape of magnetic hysteresis loops in the Chinese loess-paleosol sequence
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概要
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Shape of magnetic hysteresis loops of the Chinese loess-paleosol sequence is variable with low-field susceptibility and is weakly constricted in samples with intermediate susceptibility (-1.0 × 10-6 m3/kg). The analyses of the hysteresis loops show that both low- (ferrimagnetic) and high-coercivity (antiferromagnetic) components are present and the ferrimagnetic component dominate the magnetic characteristics. The ratio of ferrimagnetic over antiferromagnetic minerals (S ratio) and the superparamagnetic fraction increase with increasing susceptibility. Neither simple two-component mixtures of ferrimagnetic and antiferromagnetic minerals nor of single-domain and superparamagnetic grains fully explain the constricted hysteresis loops. We interpret the variation of the loop shape with susceptibility in the following way. When the ratio of the ferrimagnetic to antiferromagnetic contribution is relatively low (low susceptibility), the broad loop is controlled by lithogenic ferrimagnetic and antiferromagnetic minerals. For samples with intermediate susceptibility values, constricted shape originates from an addition of a broad loop from the lithogenic fraction and a narrow loop from a pedogenic fraction with high superparamagnetic content. Then with further susceptibility increase, the constricted shape almost disappears and the loop is dominated by the pedogenic fraction. The variation of hysteresis loop shape with susceptibility can be a useful indicator of the degree of pedogenesis for loess-paleosol samples.
- 公益社団法人 日本地震学会、地球電磁気・地球惑星圏学会 、特定非営利活動法人 日本火山学会、日本測地学会、日本惑星科学会の論文
著者
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Torii Masayuki
Division Of Earth And Planetary Sciences Graduate School Of Science Kyoto University
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Fukuma Koji
Division Of Earth And Planetary Sciences Graduate School Of Science Kyoto University
関連論文
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- Variable shape of magnetic hysteresis loops in the Chinese loess-paleosol sequence
- Variable shape of magnetic hysteresis loops in the Chinese loess-paleosol sequence