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  • 1
    Electronic Resource
    Electronic Resource
    Middle/Late Pleistocene relative palaeointensity of the geomagnetic field from lacustrine sediments, Lake Chewaucan, western United States (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 118 (1994), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Detailed palaeomagnetic and rock magnetic studies of a 15 m succession of Middle/Late Pleistocene lacustrine sediments from ancient Lake Chewaucan, southern Oregon, western United States, indicate that the remanence-bearing grains are sufficiently uniform to be applicable to relative palaeointensity studies. We have used ARM, SIRM and χ for normalization of the NRM. All three parameters give essentially identical results in their relative stratigraphic variations, which indicates that the normalizations efficiently remove the effects of variation in magnetic mineral concentration. Patterns in grain-size variation, as indicated by small-scale quasi-cyclic fluctuations in hysteresis parameters, may be due to environmental changes such as lake-level variation. However, these fluctuations are within the acceptable range of grain sizes for palaeointensity studies and cannot be correlated with any of the features of the normalized remanence record. We therefore conclude that the large-scale variations in the normalized remanence record are due to geomagnetic palaeointensity fluctuations. Parts of the normalized remanence record, where firm chronological constraints exist, may correlate with features of relative palaeointensity records from deep-sea sediments. Our results also confirm the observation that low geomagnetic field intensities dominate during geomagnetic excursions. Further studies of relative palaeointensity of the geomagnetic field may enable the development of an independent time-scale which would make possible the direct correlation of palaeoclimate records from deep-sea and continental environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1994.tb04678.x
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  • 2
    Electronic Resource
    Electronic Resource
    Pedogenic and lithogenic contributions to the magnetic susceptibility record of the Chinese loess/palaeosol sequence (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 122 (1995), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: We have studied the magnetic properties of 69 loess and palaeosol samples from the loess plateau in China. Our methodology involves the combination of differential dissolution of secondary iron oxides and oxyhydroxides using citrate-bicarbonate-dithionite (CBD) with measurements of magnetic parameters. Because most of these parameters are additive, we can use pre- and post-CBD values to determine the mineral magnetic properties of the CBD-soluble material. We can also calculate the partitioning of iron among various phases. Approximately two-thirds of the total iron in our samples exists as paramagnetic iron in silicate minerals. Anti-ferromagnetic material (haematite) constitutes almost all of the remainder. However, the magnetic susceptibility record of the loess/palaeosol sequence arises primarily from a small amount of iron in ferrimagnetic phases. This iron consists of a CBD-resistant component which represents multidomain grains inherited from the parent material of the loess, and a CBD-soluble component which represents grains near the superparamagnetic/single domain boundary. The first component appears in nearly uniform amounts throughout the loess column and is the dominant ferrimagnetic phase in the magnetically less-enhanced loess. Accumulation of the second component in the palaeosols gives rise to the magnetic susceptibility enhancement of the loess column. The magnetic properties of the CBD-soluble component indicate that it formed as a result of in situ pedogenesis, which confirms our earlier conclusion that the palaeoclimate record of the loess/palaeosol sequence at the sites that we have sampled is primarily a record of pedogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1995.tb03539.x
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  • 3
    Electronic Resource
    Electronic Resource
    Alternative to the geomagnetic self-reversing dynamo (1975)
    [s.l.] : Nature Publishing Group
    Nature 253 (1975), S. 707-708 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Schematic diagram of polarity states, a, States of a self-reversing dynamo; b, states based on a two-source model. Net field is the same in both cases. The foregoing analysis is appealing in that it avoids the com-plexities inherent in a self-reversing dynamo theory. First, a self reversal ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/253707a0
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  • 4
    Electronic Resource
    Electronic Resource
    An Ising model approach to the behavior of the Earth's magnetic field: A progress report (1996)
    Springer
    Surveys in geophysics 17 (1996), S. 225-228 
    Details
    ISSN: 1573-0956
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01908684
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  • 5
    Electronic Resource
    Electronic Resource
    15-Myr periodicity in the frequency of geomagnetic reversals since 100 Myr (1983)
    [s.l.] : Nature Publishing Group
    Nature 304 (1983), S. 328-330 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Our study of the frequency of reversals is based on two different time scales, each of which covers the past 100 Myr. The first, LA, is the time scale of Lowrie and Alvarez3 which contains 174 reversals. The second, LKC, is that of Labreque et al.4; this time scale differs slightly from LA in the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/304328a0
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  • 6
    Electronic Resource
    Electronic Resource
    Mantle plumes and hotspots (1983)
    [s.l.] : Nature Publishing Group
    Nature 304 (1983), S. 664-664 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] HARRISON AND LINDH1 have recently reported a new determination of the relative motion between the geomagnetic frame of reference and the hotspot frame of reference. While I do not disagree with their approach, I would like to point out that the hotspot frame of reference is not necessarily the same ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/304664a0
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  • 7
    Electronic Resource
    Electronic Resource
    15-Myr Periodicity in the frequency of geogmagnetic reversals since 100 Myr (reply) (1984)
    [s.l.] : Nature Publishing Group
    Nature 311 (1984), S. 396-396 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] MAZAUD ET AL. REPLY-McFadden suggests that our report of a 15-Myr periodicity in the frequency of geomagnetic reversals arises from our use of a fixed-length, rectangular window to determine the number of reversals per unit time. We are well aware that the use of such a window can introduce ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/311396b0
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