Core rotational dynamics and geological events
A study of Earth's fluid core oscillations induced by lunar-solar tidal forces, together with tidal secular deceleration of Earth's axial rotation, shows that the rotational eigenfrequency of the fluid core and some solar tidal waves were in resonance around 3.0 x 10(9), 1.8 x 10(9), and 3 x 10(8) years ago. The associated viscomagnetic frictional power at the core boundaries may be converted into heat and would destabilize the D" thermal layer, leading to the generation of deep-mantle plumes, and would also increase the temperature at the fluid core boundaries, perturbing the core dynamo process. Such phenomena could account for large-scale episodes of continental crust formation, the generation of flood basalts, and abrupt changes in geomagnetic reversal frequency.
Greff-Lefftz
M
Department of Geomagnetism and Paleomagnetism, Institut de Physique du Globe de Paris, 4 place Jussieu, 75252 Paris 05, France. Ecole et Observatoire des Sciences de la Terre, 5 rue R. Descartes, 67084 Strasbourg, France.
Legros
H