Open AccessSpectral analysis of Quaternary palaeomagnetic data from British Columbia and its bearing on geomagnetic secular variation
Author(s) -
Oberg C. J.,
Evans M. E.
Publication year - 1977
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1977.tb04214.x
Subject(s) - earth's magnetic field , clockwise , geology , paleomagnetism , geomagnetic secular variation , geomagnetic pole , remanence , radiocarbon dating , excursion , secular variation , declination , magnetostratigraphy , dipole , paleontology , geophysics , geodesy , rotation (mathematics) , magnetic field , geomagnetic storm , geometry , physics , magnetization , mathematics , quantum mechanics , political science , law , astronomy
Palaeomagnetic results obtained from a 7‐m sedimentary sequence in southern British Columbia spanning approximately 9000 yr (˜ 22 000 to ˜31 000 yr BP based on radiocarbon dates) are reported and analysed. Remanence directions from 37 horizons spread throughout the section have been determined, and no evidence of the geomagnetic excursion observed at Lake Mungo, Australia (˜ 31 000–28 000 yr BP), or that observed at Mono Lake, California (25 000–24 000 yr BP) is present. However, regular oscillations in the remanence vectors are observed, and maximum entropy spectral analysis, after mapping the remanence directions on to the complex plane, reveals peaks at periods of approximately 2000 and 5000 yr. The 2000‐yr peak is associated with clockwise looping of the geomagnetic vector, and therefore most likely represents the time associated with one full cycle of the westward drift of the non‐dipole field. The 5000‐yr peak is associated with elliptical counterclockwise looping of the local geomagnetic vector and may be indicative of counterclockwise motion of the geomagnetic dipole axis.