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黄土高原地区已建立多个表土低频磁化率-气候转换函数,为黄土古气候定量重建提供了关键方法。但是表土磁化率变化的气候控制因素的系统研究尚未开展;同时,低频磁化率部分受到沉积作用的影响,需要寻找气候意义更明确的指标。我们系统采集了黄土高原及周边地区的表土样品,运用相关、回归和因子分析等方法,研究了不同气候要素及其季节变化对表土磁化率和频率磁化率的控制作用。结果显示,湿度是控制黄土高原表土磁化率的主要因素,温度的影响相对较小;降水的季节分配也有影响,月降水变率较小的地区磁化率较高。在此基础上,选择反映成壤磁性颗粒组分的频率磁化率,建立了频率磁化率-年均降水量的转换函数,为黄土古气候定量估算提供了新的途径。
Loess Plateau has established a number of topsoil low frequency magnetic susceptibility - climate conversion function, which provides a key method for the quantitative reconstruction of paleoclimate in the Loess Plateau. However, systematic studies on climatic control factors of surface magnetic susceptibility changes have not yet been carried out. At the same time, the low frequency magnetic susceptibility is partly affected by sedimentation, and a more definite indicator of climatic significance needs to be found. We systematically collected topsoil samples from the Loess Plateau and its surrounding areas and studied the control effects of different climatic elements and seasonal variations on the susceptibility and frequency susceptibility of topsoil by using correlation, regression and factor analysis methods. The results show that humidity is the main factor to control the magnetic susceptibility of the surface soil in the Loess Plateau, and the influence of temperature is relatively small. The seasonal distribution of precipitation is also affected. The magnetic susceptibility is high in the areas with small monthly precipitation variability. On this basis, the frequency-dependent magnetic susceptibility of magnetite particles is selected, and the conversion function of frequency-magnetic susceptibility-annual average precipitation is established, which provides a new way for the quantitative estimation of pale-paleoclimate.