过去2．5百万年间黄土与深海古气候变化周期的对比分析

过去２．５Ｍａ间宝鸡黄土粒度记录和深海氧同位素曲线的Ｆｏｕｒｉｅｒ功率谱分析结果表明：在１．６Ｍａ以上部分，两者的周期性相当一致；但在２．５-１．６Ｍａ时段，两者的周期记录差异很大．深海氧同位素曲线记录的全球大陆冰量变化周期以与地轴倾斜度有关的０．０４１Ｍａ为主，而黄土粒度曲线记录的内陆风力强度变化周期则以与偏心率有关的０．４Ｍａ和０．１Ｍａ为主．造成这种异同的原因是：在２．５-１．６Ｍａ时段，内陆风力强度变化主要受地球轨道变化驱动，而从１．６Ｍａ前开始，转而主要受全球大陆冰量变化驱动．

COMPARISON OF PALEOCLIMATIC VARIATION PERIODICITY BETWEEN LOESS AND OCEAN OVER THE PAST 2.5Ma

This paper presents Fourier power spectra of the grain-size time series at Baoji,regarded as a proxy of variations in winter monsoon strength and generated by employing orbital tuning approach developed by SPECMAP project,and the marine δ18O time series,regarded as an indicator of global continent ice volume,in order to make a comparison of paleoclimatic variation periodicity between loess and ocean over the past 2.5Ma. Results obtained indicate that periodicities of two records are similar by and large in the past 1.6Ma and considerably different in the interval of 2.5 to 1.6Ma B.P.In the latter interval the dominant period of global continent ice volume as indicated by the marine δ18O record is about 0.041Ma,related to the obliquity,but me dominant periods of variations in winter monsoon strangth as indicated by the grain-size record are about 0.4Ma and 0.1Ma,related to the eccentricity of the Earth’s orbit.