Variations in the Geomagnetic Field Intensity with Characteristic Times of Five and One Million Years

Resumo

Variations in the paleointensity of the geomagnetic field over the Middle Jurassic–Paleogene (167–20 Ma) interval has been studied. It has been found that the amplitudes of paleointensity variations changed cyclically. The characteristic times of these changes are estimated to be approximately five and one million years. The cycles found in the evolution of paleointensity are compared with the cycles of changes in the ocean level. It is shown that characteristic times of cyclical changes in the amplitudes of paleointensity variations (∼5 and 1 Ma) coincide with the mean duration of transgression-regression cycles (T-R cycles) of the second and third order of the Geologic Time Scale 2008 (GTS 08). Increases in the amplitudes of paleointensity variations occur generally during regressions of the World Ocean. The equal characteristic times and existence of the correlation between the transgression–regression cycles and variations in paleointensity provide evidence that they reflect the same planetary process.