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土壤和前期研究表明黄土-红粘土序列的赤铁矿含量与环境密切相关,对气候的干湿变化非常敏感,气候越湿热,赤铁矿含量越高。本文研究表明黄土-红粘土样品漫反射光谱一阶导数曲线在555～575nm间的峰面积作为赤铁矿指数可以客观有效地指示赤铁矿含量的高低。通过黄土高原朝那剖面红粘土-黄土序列的系统漫反射光谱分析,建立了3Ma以来黄土高原赤铁矿含量变化记录,揭示赤铁矿含量在约2.5Ma,1.5Ma,0.6Ma和0.15Ma显著阶段性减小,指示了黄土高原阶段性变冷干的演化历史。
Soil and previous studies show that the hematite content of the loess-red clay series is closely related to the environment, sensitive to the climate changes in the wet and dry climate, the more humid the climate, the higher the hematite content. This study shows that the hematite content can be objectively and effectively indicated by the peak area of 555 ~ 575nm in the first derivative curve of the diffuse reflectance spectrum of loess-red clay samples as hematite index. Based on the systematic diffuse reflectance spectra of the red clay-loess sequence in the Chana section of the Loess Plateau, the records of hematite content in the Loess Plateau since 3Ma were established and the contents of hematite were found to be significant at about 2.5Ma, 1.5Ma, 0.6Ma and 0.15Ma The decrease of the stage indicates the evolution history of the stage cold-drying in the Loess Plateau.