西安地区约8500aBP来气候变化与风尘堆积

CLIMATE VARIABILITY AND EOLIAN DEPOSITS SINCE ABOUT 8500 YEARS AGO IN XI'AN

根据野外调查、土层厚度测定、室内粒度分析、CaCO3含量分析和微结构鉴定资料,研究了西安地区约8500aBP来气候变化与风尘堆积的变化。结果表明,西安地区全新世以来的气候与末次间冰期第1阶段气候相比具有频繁变化和变异特点;3100aBP以来风尘堆积与沙尘暴活动比75～10kaBP之间的末次冰期还要强,风尘堆积与沙尘暴活动强的原因主要是气候的变干。全新世黄土发育条件分析表明,黄土高原的黄土可以发育在冰期,也可以发育在与现代气候相近的间冰期,可以发育在冬季风占优势的气候条件下,也可以发育在冬、夏季风活动强度相近的条件下。全新世气候的不稳定性为预测未来长期气候变化带来了不确定性,深入研究全新世气候变异特点对预测未来长期气候变化具有非常重要的意义。

According to field investigation, soil thickness determination, indoor grain size analysis, CaCO3 content analysis and rnicrostructure identification, we know changes in climate and eolian deposits since about 8 500 years ago in Xi＇an. The data show that Holocene climate,compared with that in the first stage of last interglacial, had more frequent changes and variations. Compared with the last glacial which was 75 000-10 000 years ago, eolian deposits and sand storm activity since 3 100 aBP have been much stron- ger. The reason for this is the strong dry climate. The analysis of the development of loess in Holocene indicates that the loess in the Loess Plateau can develop under different climate conditions such as in glaci- ation, in interglacial stage, in winter monsoon and in summer monsoon whose activities were as strong as the winter monsoon behavior. According to the climate change forecast, future sand storm activity should be strengthened. Holocene climate variability will bring uncertainty to the long-term climate change pre- diction in future. Furthur study about the characteristics of climate variability in Holocene is of very important significance for long-term climate change prediction in future.