Geomagnetic secular variation in Late Weichselian Allerød sediments from Nr. Lyngby (Denmark)

Abstract

Palaeomagnetic measurements on 400 specimens from lake sediments exposed in the cliff of the classic Late Glacial Allerød site at Nørre Lyngby in North Jutland, Denmark, are presented. Two profiles in the 7 m sequence of sand, silt and gyttja, spanning the time interval between c. 12 000 and c. 10 700 BP show about 5 cycles in the declination and about 2 cycles in inclination. Secular variation features as observed at this site are also recognizable at sites in southern Sweden and Soviet Karelia. Comparisons with Holocene records indicate that the short time-scale behaviour (i.e. < 103 y) of the geomagnetic field appears to have been similar since 14 000 BP, i.e. for a period considerably longer than the timescale of the variations themselves, thus suggesting that this type of behaviour is a permanent feature of the geomagnetic field. These secular variation features may be useful in local as well as more regional stratigraphical correlations for the Late Glacial and Holocene on a much more detailed timescale than is obtained from the magnetic reversal timescale used for older materials.