Core Rotational Dynamics and Geological Events
Marianne Greff-Lefftz,
1
Hilaire Legros
2
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 × 109, 1.8 × 109, and 3 × 108 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.
1 Department of Geomagnetism and
Paleomagnetism, Institut de Physique du Globe de Paris, 4 place
Jussieu, 75252 Paris 05, France.
2 Ecole et
Observatoire des Sciences de la Terre, 5 rue R. Descartes, 67084 Strasbourg, France.
