地球のリズムと多圏相互作用

地球惑星進化解明のためのアラユルリズム計画

抄録

Soon after the formation of the Earth by collisional accretion of planetesimals in the primordial solar nebular, its interior has been differentiated gravitationally to form the central metallic core, silicate mantle and crust, atmosphere and ocean. The sequence of differentiation was very rapid during the formation and subsequent early history, since the interior has been maintained hot by the heating of accretional energy, gravitational energy of core-mantle separation and energy released by the radioactive neclides. The differentiation and interactions between the core, mantle, crust, atmosphere and ocean has been continued throughout the Earth's history less effectively but still a significant way.
The mode of interactions between the subsystems of the Earth includes mass transfer (geochemical cycle), electromagnetic interaction, and mechanical interactions such as angular momentum exchange, tidal interaction and convective flows and plate motions. Since these interactions have been maintained by the energy of radioactive nuclides and solar energy, the Earth system can be regarded as disequilibrium dissipated system with highly non-linear behavior. Many rhythmical variations in the Earth environments such as climate change, sea level change, geomagnetic variation, plate velocities and orogeny, volcanic and seismic activities are expected to show signatures of the non-linear dissipative systems. Specifically we expect the period bifurcation phenomena revealed in many non-linear systems would exist in the rhythmical variations in the Earth's history.
Here we reviewed the spectrum structures of galactic motions, solar activities, orbital motions of the Earth and planets with special reference to the Milankovitch cycles, the Earth rotatonal variation, geomagnetic variations, variations in the atmosphere and ocean phenomena, climate change, meteoroid impact and mass extinciton episodes, and then revealed nature of multi-sphere interactions in the Earth's history in the frequency domain. Some future problem to explore the nature and mechanisms in the multi-sphere interaction and evolution of the Earth were discussed.