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  • 1
    Publication Date: 2017-04-04
    Description: We report mineral magnetic results from a 7.5 m loess sequence (150 samples) from the southernmost extremity of the Chinese loess plateau (which includes the last two glacial cycles). In this area the loess sediments experienced particularly intense weathering processes. The magnetic assemblage is dominated by a mixture of pseudo-single domain (PSD) and multidomain (MD) magnetite with associated superparamagnetic (SP) grains of either magnetite or maghemite in the paleosols and weathered loess horizons. All the rock magnetic parameters fluctuate in parallel with marine sediment δ18O data over the last 150Kyr, thus reflecting changing global paleoclimatic conditions. This relationship is also supported by the evidence of Milankovitch cycles in the magnetic susceptibility record. Paleorainfall estimates, when compared with other studies from the Chinese loess plateau, underline the (more) humid character of this region during the last ~130 kyr.
    Description: Published
    Description: 645-659
    Description: JCR Journal
    Description: reserved
    Keywords: magnetic mineralogy ; climatic cycles ; Loess ; China ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: We have conducted a detailed mineral magnetic study of loess unit 8 (L8) and paleosol unit 8 (S8) from three localities (Jingbian, Yichuan, and Duanjiapo) along a N-S transect in the Chinese loess plateau. As expected, the lowfield magnetic susceptibility (χ) has higher values in S8 and lower values in L8. Similarly, superparamagnetic particle concentrations increase in S8 with increasingly humid climates along the N-S transect, which suggests that pedogenic magnetic enhancement is related to climate. However, in S8 at Duanjiapo, χ is so low that there is no correlation between χ and the degree of pedogenesis in this loess-paleosol cycle. It therefore appears that χ is not consistently the most suitable indicator of paleoclimate in Chinese loess-paleosol sequences. Our results indicate that there are complexities in the mineral magnetic response to pedogenesis, which could invalidate interpretation of the χ record of Chinese loess-paleosol sequences in terms of paleoprecipitation.
    Description: Published
    Description: 4259-4262
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: N/A or not JCR
    Description: reserved
    Keywords: rock magnetism ; magnetic susceptibility ; Chinese loess/paleosol sequences ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    ISSN: 1432-0649
    Keywords: 42.70.Gz ; 42.30.Va ; 42.40.Kw ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have optically characterized the newly-developed photorefractive crystal KNSBN: Cu by two-wave coupling at visible and near-infrared wavelengths. The effective electrooptic coefficientsξ(k g)r 13 andξ(k g)r 33, the effective charge carrier densityN eff, the dark conductivityσ d, the product of mobility and electron-trap recombination timeμτ R, the formation and decay rate of index grating and the absorption coefficientα of the crystal were determined from visible to near-infrared wavelengths. Their wavelength dependences were also studied. It is interesting to notice that the KNSBN: Cu crystal has a very largeN eff and large gain coefficientΓ for ordinary ray (o-ray) in the visible region, and the photorefractive properties of the crystal are very different in the visible and near-infrared spectral regions.
    Type of Medium: Electronic Resource
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