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  • 1 Paleomagnetic Laboratory, Eötvös Loránd Geophysical Institute, Budapest, Hungary
  • | 2 Department of Physical Geography, Eötvös Loránd University, Budapest, Hungary
  • | 3 Geological Institute of Hungary, Budapest, Hungary
  • | 4 H-1145, Budapest, Columbus u. 17-23, Hungary
  • | 5 H-1117, Budapest, Pázmány P. sétány 1/C, Hungary
  • | 6 H-1143, Budapest, Stefánia u. 14, Hungary
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Abstract

Four paleosol layers indicating wet and moderate periods and five loess layers indicating dry and cold climate were separated by different methods. The following climate cycle model, based on the development of the sediment sequence created by the influence of climatic, geologic and geomorphologic phenomena, was established by detailed paleomagnetic studies (e.g. anisotropy of magnetic susceptibility (AMS), isothermal remanent magnetization (IRM), frequency dependence of magnetic susceptibility (κFD), etc.):

  1. A well-foliated magnetic fabric predominantly built up by multi-domain ferromagnetic minerals (magnetite, maghemite) was developed during the semi-arid (350–400 mm/y) and cold loessification period of the Pleistocene. The magnetic fabric can reflect the direction of dust deposition and/or the paleoslope.
  2. The accumulation period of dust was followed by the more humid (650 mm/y) pedogenic period indicated by the enrichment of superparamagnetic minerals and by the disturbed or inverse magnetic fabric developed during pedogenesis by different processes (e.g. leaching and/or bioturbation).
  3. The third period following the pedogenic period is the humid erosional phase indicated by the finely layered reworked loess. The magnetic fabric built up by multi-domain ferro- and superparamagnetic minerals is characterized by better-aligned directions of principal susceptibilities than in the wind blown material. Sheet wash and other waterlogged surface processes appeared in the fabric of these layers. This process is possibly connected to sudden, rare yet significant events with high precipitation and absence of vegetation.
  4. The cycle was closed by the beginning of the next dust accumulation period.
  • J.R. Balsley A.F. Buddington 1960 Magnetic Susceptibility Anisotropy and Fabric of Some Adirondack Granites and Orthogneisses American Journal of Science 258-A 6 20.

    • Search Google Scholar
    • Export Citation
  • S. Cisowski 1981 Interacting vs. non-interacting single domain behaviour in natural and synthetic samples Physics of the Earth and Planetary Interiors 26 56 62.

    • Search Google Scholar
    • Export Citation
  • B.B. Ellwood J.H. Howard 1981 Magnetic fabric development in an experimentally produced barchan dune Journal of Sedimentology — Petrology 51 97 100.

    • Search Google Scholar
    • Export Citation
  • J. Eyre 1997 Frequency dependence of magnetic susceptibility for populations of single-domaingrains Geophysical Journal International 129 209 211.

    • Search Google Scholar
    • Export Citation
  • M.E. Evans F. Heller 1994 Magnetic enhancement and paleoclimate: study of a loess/paleosol couplet across the Loess Plateau of China Geophysical Journal International 117 257 264.

    • Search Google Scholar
    • Export Citation
  • T. Forster M.E. Evans F. Heller 1994 The frequency dependence of low field susceptibility in loess sediments Geophysical Journal International 118 636 642.

    • Search Google Scholar
    • Export Citation
  • T. Forster F. Heller 1997 Magnetic enhancement path in loess sediments from Tajikistan, China and Hungary Geophys. Res. Lett. 24 17 20.

    • Search Google Scholar
    • Export Citation
  • V. Jelinek 1981 Characterization of magnetic fabric of rocks Tectonophysics 79 63 67.

  • G. Kukla F. Heller X.M. Liu T.C. Xu T.S. Liu Z.S. An 1988 Pleistocene climate in China dated by magnetic susceptibility Geology 16 811 814.

    • Search Google Scholar
    • Export Citation
  • B. Maher R. Thompson 1995 Paleorainfall reconstruction from pedogenic magnetic susceptibility variations in the Chinese Loess and Paleosols Quaternary Research 44 383 391.

    • Search Google Scholar
    • Export Citation
  • X. Meng E. Derbyshire R.A. Kemp 1997 Origin of the magnetic susceptibility signal in Chinese loess Quaternary Science Reviews 16 833 839.

    • Search Google Scholar
    • Export Citation
  • T. Nagata 1961 Rock Magnetism Maruzen Tokyo.

  • C.G. Panaiotu E.C. Panaiotu A. Grama C. Necula 2001 Paleoclimatic record from loess-paleosol profile in south-eastern Romania Physics and Chemistry of the Earth 26/11–12 893 898.

    • Search Google Scholar
    • Export Citation
  • D.K. Potter A. Stephenson 1988 Single-domain particles in rocks and magnetic fabric analysis Geophysical Research Letters 15 1097 1100.

    • Search Google Scholar
    • Export Citation
  • A.I. Rees 1966 The effect of depositional slopes on the anisotropy of magnetic susceptibility of laboratory deposited sands Journal of Geology 74 856 867.

    • Search Google Scholar
    • Export Citation
  • A.I. Rees W.A. Woodal 1975 The magnetic fabric of some laboratory-deposited sediments Earth and Planetary Science Letters 25 121 130.

  • S.G. Robinson J.T.S. Sahota 2000 Rock-magnetic characterization of early, redoxomorphic diagenesis in turbidic sediments from the Madeira Abyssal Plain Sedimentology 47 367 394.

    • Search Google Scholar
    • Export Citation
  • F.D. Stacey G. Joplin J. Lindsay 1960 Magnetic Anisotropy and Fabric of Some Foliated Rock from S.E. Australia Geofiz. Pura. Appl. 47 30 40.

    • Search Google Scholar
    • Export Citation
  • D.H. Tarling F. Hrouda 1993 The Magnetic Anisotropy of Rock Chapman and Hall London, Glasgow, New York, Tokyo, Melbourne, Madras.

  • Thompson, R., M. Oldfield 1986: Environmental Magnetism. — London, Allen and Unwin. 227 p.

  • H.-U. Worm 1998 On the superparamagnetic-stable single domain transition for magnetite, and frequency dependence of susceptibility Geophysical Journal International 133 201 206.

    • Search Google Scholar
    • Export Citation
  • R. Zhu Q. Liu M.J. Jackson 2004 Paleoenvironmental significance of the magnetic fabric in Chinese loess-paleosols since the last interglacial (<130 ka) Earth and Planetary Science Letters 221 55 69.

    • Search Google Scholar
    • Export Citation
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