Study On The Paleoclimate Change In The Pengyang Section Over The Past 800, 000 Years

China loess plateau is an important area to research the global change of paleoclimate. It is at the crossing of monsoon circumfluence and westerly circumfluence, and closing to Qinghai-Tibet Plateau. China loess-paleosol sequence has been ranked one of the emphases in the study of PAGES.This paper measured the loess-paleosol sequence magnetic susceptibility, frequency magnetic susceptibility, calcium carbonate, pH and grain size in the Pengyang section, discussed the paleoclimate ecolvement from 800KaB.P., and forecasted the future climate evolvement. The result showed:(1) The four proxy records gives good indications of the past monsoon change. Magnetic susceptibility and frequency magnetic susceptibility are main approach to reveal the wet-warm period, the content of calcium carbonate and pH can indicate the rainfall, and in the grain size records, the content of coarse volume ( > 30μm) reveals the dry-cold period. (2)During the past 800 thousand years, there are five phases when the winter monsoon was strengthened, and four phases weakened. (3)Since 800 thousand yeaes, globle climate had nineteen cycles. Every cycle is a period that the climate changed from wet-warm to dry-cold. (4)Overlook the influnce of humen being, the climate will be drier and colder in the future. The summer monsoon will be weakened, and the winter minsoon will be strengthened.