Magnetism of loess-palaeosol formations in relation to soil-forming and sedimentary processes

Typical loess-palaeosol formations in the southern part of the Russian plain (Novaya Etuliya type section), in China and in Central Asia show the same pattern of magnetic susceptibility (MS) variations with enhanced signatures in soils compared to loesses. This behavior is well known to be caused by in situ forming fine grained magnetite (maghemite) of pedogenic origin. A different pattern of MS changes has been reported for Western Siberia and Alaska: high magnetic signatures in loesses and low ones in palaeosols. The highest MS values in the Belovo type section (Ob River) are connected with the sand and silt fractions and hence are due to sedimentary processes and terrigenous magnetic minerals. Low MS in palaeosols is related to gleisation. A more complex behaviour of ms changes is observed in the Precaucasus loess section at Otkaznoe. The palaeosols here show enhanced magnetic signatures whereas the loess horizons display largely variable magnetic signals due to changing detrital material influx. (C) 2000 Elsevier Science Ltd. All rights reserved.