| Abstract:The decrease of the Earth′s rotating speed implies its expansion during its rotation, which is consistent with the expansion of the universe indicated by the red-shift phenomenon. Radiogenic energy of radioactive materials in the Earth has led to the formation of the asthenoshphere and the fluid outer core. The joint action of the inertia difference of different layers during the earth′s rotation and the existence of fluid layers leads to the inter-layered gliding. The outer layers would rotate slower than the inner layers. As the Earth moves eastward, the inner layers which rotate faster would move eastward, resulting in sinistral shearing, because of its larger inertia. That is to say, the lower mantle beneath the asthenosphere would rotate faster eastward relative to the lithosphere, while the inner core beneath the liquid outer core would rotate faster eastward relative to the outer core. Due to the shearing between layers and heating of mass by radiogenic energy, the convection of mantle materials occurs within the asthenosphere. The convection of fluid materials is also considered to occur within the outer core. The expansion of the rotating Earth is the foundation of geodynamics. The movement of continental plates, such as the beak-up and dispersion of Gondwanaland including the southward drifting of Antarctic continent should be related to this expansion. The break-up of Gondwanaland took place during the transitional period when the speed of the earth′s rotation changed from slow deceleration in Jurassic to fast deceleration in Late Cretaceous. Since Cretaceous, along with the rapid slowing-down of the earth′s rotation, Gondwanaland has gradually broken up and dispersed. In other words, the break-up of Gondwanaland took place in the transitional period from Jurassic when the Earth slowly expanded to Late Cretaceous when the Earth rapidly expanded. Since then, fragments of Gondwanaland have dispersed and drifted to their present places respectively along with the rapid expansion of the Earth. The inclination angle of the earth′s axis ε, the tidal torque and the precession of quinox are important factors of geodynamics. Among them, changes in inclination of the Earth′s axis ε might have a long-period influence in geologic time. Since Jurassic, the inclination angle of the Earth's axis ε has changed from nearly vertical (about 10 degrees) to less tilting (23 degrees or so). The break-up of Gondwanaland might have just taken place in this background. Moreover, in consideration of the attraction of the sun for the earth during the revolution of the Earth around the sun, the change in inclination of the earth′s axis from nearly vertical to less tilting directions would obviously favor the southward drift of Antarctic continent to its present place. |
