Geomagnetic Secular Variations 0-12000 Yr. As Recorded By Sediments from Moreno Lake (South Argentina)

GOGORZA, C.S.G.; SINITO, A.M.; DI TOMMASO, I.; VILAS, J.F.; CREER, K.M.; NUÑEZ, H.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

Elsevier

Lugar: Amsterdam; Año: 2000 vol. 13 p. 627 - 645

0895-9811

Abstract Paleomagnetic and sedimentological studies carried out on four cores from the bottom sediments of Moreno lake (southwestern Argentina) are described. The data obtained by Creer et al. (1983b) are integrated with the new results. Within-lake correlation was 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 (SV) 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 years for inclination data and major peaks at periodicities of about 1200, 2300 and 3500 years for declination data. In order to test the stability of the obtained periodicities, spectral analysis has been 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 VGP path plots with preponderance of clockwise sense.