植物硅酸体研究在黄土古气候恢复中的应用

地表植被对环境变化的响应最为敏感 ,沉积物中保存的各种植物残余是古环境研究的良好材料 ,植物硅酸体因其特有的物理化学性质 ,成为古气候信息的绝佳载体。在大量现代植物研究基础上 ,科学家们通过对第三纪以来各种沉积物中硅酸体组合的研究 ,较好地恢复了当时的古植被、古气候及其演化特征 ,在缺乏其它化石依据的黄土地层研究中表现更为突出。由于C3、C4 植物具有明显不同的环境适应性和同位素组成 ,地层中C3、C4 植物硅酸体相对含量和稳定同位素的研究也被成功地应用于古气候恢复中。在现代气候—植被类型和土壤植物硅酸体同位素研究基础上 ,利用数理统计方法 ,建立同位素指标与各种气候因子之间的数学关系 ,将为高分辨率黄土古气候定量研究开辟新的途径。

APPLICATION OF PHYTOLITH IN RECONSTRUCTION OF LOESSIAL PALEOCLIMATE

Response of surface vegetation to environmental change is very sensitive. Residues of many plants preserved in sediments are regarded as excellent material in paleoenvironment study, so phytolith is often regarded as a good carrier of paleoclimate information with its unique physical-chemical characters. On the basis of the study of many present plants, scientists have better reconstructed their paleovegetation, paleoclimate and evolution characters in terms of phytolith association in many Tertiary sediments, especially in loessial layers with no fossil proof. Due to C 3 and C 4 plants having very obvious differences in isotopic composition and environmental adaptation, studies of the relative content of phytolith in C 3 and C 4 plants and stable isotopes have also been employed in the paleoclimate reconstruction. On the basis of present climate-vegetation type and soil-phytolith isotope, the mathematical correlations between isotope parameters and many climate factors can be established by virtue of mathematical-physical statistics. Therefore new approaches to the quantitative high-resolution study on loessial paleoclimate will be found.