The Climatic Evolution During The Holocene In The Baoji Region

Global climate change is a mutual impacting process between human activity and natural evolution. The aim of understanding the problem of global climate change is to study the variation of the modern environment. It is of importance to study the climate change in Holocene in terms, to know the formation of modern environment, to estimate the change of future global climate, to understand the sustainable development of resource and environment, because there are many mankind civilization completed in the period of Holocene, including the evolution from primitive human to modern human.To study the rule of the environment evolution of Holocene, it is required to find the records of the information of the climate change. As proved by the recent scientific practice, the loess geologic stratum is comparable with both deep-sea deposit and Polar ice-caps in term of recording the information of paleoclimate. In China, the main related works on the study of climate changing in Holocene focus on the following areas, such as loess plateau, the boundary of desert and loess, the border area of desert and so on. Since the alternation is obvious in the sequence of loess and paleosol, the loess plateau becomes the optimal object to study the paleoclimate.After a detailed survey on the regional geography and geology, compared with the profile of tableland for Liujiayuan Village, Mei Country, Baoji, is selected as the research object. The sequence of loess and paleosoil of the profile of Liujiayuan Village has the following characters, completed records, clear borders and stable layers, and thus completed information of the change of climate and environment was recorded. The profile of Liujiayuan Village, was sampled, experimented, and analyzed in term of susceptibility. Referred to the granularity materials of the profile of Shenheyuan Village, Chanan Country, the experiment results of the profile of Liujiayuan Village is compared with the evolution rule of climate change of Holocene, and the characters of climate change of Liujiayuan Village, in the period of Holocene is concluded. Through comparing the changing characters of both susceptibility and granularity, we conclude that there are 5 stages included in the period of Holocene in term of the climate change; 1)10～8.2kaB.P.,This period is the climate transitional phase, where the summer wind is strengthened, and the climate turns warm and wet. However, since the effects of summer wind lags behind that of the winter wind, the temperature is warm and suitable, the precipitation is still little and the climate is dry.2)8.2～6.2kaB.P., This period is the stable stage of warm and moist of Holocene Megathermal. The summer winter reaches its most strength period, and the climate is warm and mois.3)6.2～ 4.6kaB.P.:The period is the stage of global climate deterioration. The characters of this stage includes:summer wind weaken, winter wind strengthen, temperature reduced and precipitation deduced.4)4.6～2.5kaB.P.:This period is the variation stage of cold and warm. The character of climate is complex.5)2.5kaB.P.～Present:This period is the stage of climate turning cold. Impacted by the global climate change, the characters of this stage includes: climate deterioration, summer wind weaken, winter wind strengthen, temperature reduced and precipitation deduced. The cooling points are 8200kaB.P.,6200ka B.P.,4600kaB.P..