Geomagnetic secular variations 0–12 kyr as recorded by sediments from Lake Moreno (southern Argentina)

Data from paleomagnetic and sedimentological studies carried out on four cores from the bottom sediments of Lake Moreno (southern Argentina) were integrated with data obtained by Creer et al., Geophys. J. R. Astron. Soc., 74 (1983), 109 . Within-lake correlations are based on the magnetic susceptibility and intensity of remanent magnetization. The individual measurements were stacked and transformed to a time-scale to produce type-curves. The secular variation of the geomagnetic field was studied using spectral analysis and precession analysis of the magnetic vector. The spectrum obtained from spectral analysis shows major peaks at periodicities of about 1500, 2400, 3300, and 6200 yr for inclination data and major peaks at periodicities of about 1200, 2300, and 3500 yr for declination data. In order to test the stability of the obtained periodicities, spectral analysis was applied to every 6000 yr time span at intervals of 500 yr for both records. Both clockwise and counterclockwise precession of the geomagnetic vector is evident from analysis of the VGP path plots, with a preponderance of clockwise.