TECTONIC CLIMATE RESPONSE IN THE GEOMORPHOLOGY OF THE WEIHE RIVER VALLEY AROUND BAOJI, SHAANXI PROVINCE

There have been developed five stages of terraces, formed in 1.2MaBP, 0.8MaBP, 0.5MaBP, 0.13MaBP, 0.009MaBP, respectively, in the Weihe river around Baoji, Shaaxi Province.Each of these stages is considered to be the response to the corresponding large up lifting and consequent climatic changes during the rising of Qingzang Plateau's since middle period of early Pleistocene, witnessing tectonic climatic cycles and subcycles of a period of about 0.4Ma and 0.1Ma.Such scale tectonic climatic cycles well agrees with the astroclimatic circles recorded by loess-paleosol sequence.This shows that there may be some causative relation between them. A knowledge of the relation will be helpful to the undertanding of the environmental evolution of the region.A preliminary discussion on the age of the passage of the Weihe river through the Longshan Mt.and the formation of a unified drainage system of it.