Abstract:
Paleomagnetic records can be a rich source of empirical data in characteristic time scales of tremendous interest to solar astronomers and verifiable theories on the earth’s evolution in its galactic environment. The record of magnetic polarity changes beyond phanerozoic (600 million years before present) is quite unreliable. However, phanerozoic polarity bias data can be analysed by sophisticated spectral techniques. The long term spectral structure of frequently reversing axial geocentric dipole field has been re-examined in this paper by Fourier Analysis, Walsh spectrum and Maximum Entropy Spectrum Methods to the available worldwide paleomagnetic measurements. The results of analysis of Mc Elhinny’s data suggest significant long term well-resolved geomagnetic reversals (GMR) periods of 285, 114, 63, 47 and 34 million years. The first and last periods in this sequence are significant at 99 percent confidence level. It is quite surprising to find that the 285 million year term corresponds well to the cosmic year. (Period of complete revolution of the solar system around the milky-way galactic centre).
