0.4 Ma QUASI-PERIODIC TECTONICLIMATIC CYCLE AND ITS FORCING MECHANISM IN THE LAST 3 Ma

摘要

An evolution of the geologic environment is dually controlled by the tectonic movements and climatic changes. On the basis of both structural layers and geologic events, a study of the tectonoclimatic cycle dated back to 6.5 Ma BP by Wu Xihao et al. has recognized six major cycles: A, B, C, D, E, F from young to old, with a periodicity of over 1 Ma. Furthermore, the cycles which have a period of about 0.4 Ma have been subdivided for the major cycles A, B, C in the Loess Plateau. When comparing the phase relations between the tectonoclimatic cycles and the Earth's orbital eccentricity variation in the last 3 Ma , it can be found that there exists an amazing identity in time and the change is especially clear in the quasi-period of 0.4 Ma.