The Climatic Evolution During The Holocene In The Western Of Guanzhong Region

The most prominent and important feature of Quaternary is the emergence and development of human. The natural environment is the basis for human life. Evolution of climate and environment is directly related to human development. Holocene is a recent period. Because of its climate change is closely related with the modern environment, it plays an important role in the study of paleoclimate and environment.This issue researched the western of Guanzhong region which is located in the Loess Plateau. The Holocene loess-paleosol sequence of this area realistically records and reflects the evolution of climate and environment in the geological period.On the basis of comprehensive field inspection, the subject made a serious division, lithological description and morphological observation on the Holocene loess stratum in loess plateau of Wangzhang of Baoji. By analyzed magnetic susceptibility, sampling and experiment of the section in loess plateau of Wangzhang of Baoji, combined with size analysis of the section in Yubaotou village of Chang'an and compared to the sections of other authors, this issue dicussed the loess-paleosol sedimentary sequence, sedimentary law,rate of sedimentation and characteristics of East Asian monsoon evolution in this area,then reconstructed the change sequence of climate and environment during Holocene in the western of Guanzhong, and further revealed the variation rule of climate and environmental during Holocene in the region.Through the contrast of research section and reference section, two sections in surrounding area and five sections in other areas, combined with previous studies,and clarified the Holocene climate in the region what was fluctuating.In the early,middle and late periods,it changed characterized by warming from the cold, warm and humid, dry and cool. According to the analysis, the change of Holocene climate in the region is divided into seven stages:10000～8700 aB.P. (dry and cold turn to warm and humid),8700～8100 aB.P. (short-term fluctuations in the cold),8100～6000aB. P. (relatively warm and humid),6000-4500aB.P. (warm and humid),4500～3100aB.P. (climate fluctuates dramatically),3100～1700 aB.P. (warm turn to cold),1700 aB. P.～nowadays (dry and cool). The duration of Megathermal of Holocene in the region is 8700～3100 aB.P.. Climate has also fluctuated in this period.It can be divided into four stages.This is consistent with the rule of climate change which is reflected in sections in other areas of Guanzhong region. During the Megathermal, 8600-8300aB.P.,5700 aB.P.,5300 aB.P.,4000 aB.P. significant cooling events had wider impact.It plays a underniable impact in the development of human civilization.