西安白鹿塬全新世黄土剖面磁化率的古气候特征

PALAEOCLIMATE CHARACTER OF SUSCEPTIBILITY OF HOLOCENE LOESS SECTION IN XI'AN BAI LUYUAN

对西安地区全新世以来的环境演变特征进行了系统研究,建立了该地区全新世以来黄土-古土壤沉积的年代序列,揭示其反映的东亚冬、夏季风变迁规律,为预测西安地区乃至中国和全球未来环境的发展趋势提供依据。通过对西安白鹿塬刘家坡典型剖面全新世黄土-古土壤地层的岩性描述、地层划分和对比,结合泾阳县新庄村AMS14C的年代测定和其他学者的测年数据,建立了该地区全新世以来黄土沉积的年代序列。根据磁化率气候替代指标显示的曲线特征,阐述了这一替代指标在剖面上的变化规律,探讨了该黄土剖面所反映的东亚冬、夏季风强弱变化特点,详细分析了西安地区全新世以来环境变化的特征和规律,进而将该剖面磁化率曲线特征与其他学者根据孢粉谱建立的温度曲线对比,对西安地区全新世以来古气候的阶段性进行了详细分析和论证,将西安地区10000a以来的气候演变划分为7个阶段。

Studying the characteristics of environment evolution in Xi＇an area during the Holocene,establishing loess-palaeosol sedimentary age sequence, revealing the regularity of changes in the East Asian winter and summer monsoon,and providing a basis for Xi＇an area,China and the global to predict future environment development trends is the work we did during the present study. Loess deposition age sequence during the Holocene in the study region is established through description of rock character of loess-palaeosol strata ,by the partition and contrast of strata in typical sections in Liu Jiapo Village of Xi＇an Bai Luyuan , and with the combination of age measuring of AMS^14 C in Xin Zhuang Village of Jing Yang County and other scholars＇testing data. According to the curve characters expressed by substitution indication of climate of susceptibility, we can expound the changing regularity of this substitution indication in the section. At the same time ,we can explore the strength changes of winter and summer monsoons in East Asian reflected by the loess section , demonstrate and minutely analyze the characters and laws of environment changes in Xi＇an area during the Holocene. And then the susceptibility curve of this section is compared with temperature curve of sporopollen spectrum established by other scholars. At the same time , on the basis of careful analysis and verification of the palaeoclimate stages during the Holocene in Xi ＇ an area , 7 climate stages during nearly 10 000 years in Xi＇an area can be raised.