PERIODICITY OF MAGNETIC INTENSITIES IN MAGNETIC ANOMALY PROFILES - THE CRETACEOUS OF THE CENTRAL PACIFIC

Spectral analyses of long magnetic anomaly profiles of Cretaceous age in the Phoenix and Hawaiian lineations within the Pacific Basin show t wo to five non-harmonic wavelength peaks, with probabilities > 90 per cent, within the range of several tens to hundreds of kilometres for e ach profile. For each profile with four peak wavelengths, their ratios correlate strongly (r > 0.98) with the ratios for the Earth's orbital eccentricity periodicities for this time, and hence the profile peaks necessarily correlate with each other. These observations suggest tha t the magnetic anomaly signal is influenced by the Earth's changing or bital parameters, probably through their influence on the internal geo magnetic held. This implies that assumptions usually made to convert t he magnetic signal to the magnetization of the oceanic crust may be su spect. The observations, if confirmed, indicate that orbital periodici ties can assist in improving the age calibration of the global polarit y timescale and that the predicted orbital behaviour of the Earth is c onfirmed for the last 150 Ma.