摘要
本文对宝鸡黄土剖面250万年的磁化率时间系列进行了频谱分析,结果表明:地球轨道三要素(偏心率、倾斜轴、岁差)的40万年、10万年、4万年和2万年的准周期成分在黄土沉积中有明显反映。
Magnetic Susceptibility measurement was conducted at every 10cm interval in Baoji section, a 160m thick loess deposit in southern Loess Plateau. An independent time scale was developed under paleomagnetic and TL controls by assumjing a constant deposition rate for every loess-paleosol formation. The 1600 susceptibility data were then plotted to the tim scale which has 2.5 Ma basai age from paleomagnetic measurement. Fourier analysis of the susceptibility time sefies shows strong spectral peaks near quasi-periods of 400,000, 100,000, 40,000 and 20,000 years, coinciding with the astronomical theory of paleoclimate. According to theoretical computation, the 400,000 and 100,000 years quasiperiodic oscillations are forced by change of the eccentricity of the Earth's orbit, 40,000 years period by the obliquity of the ecliptic and 20,000 years period by the longitude of perihelion with respect to the moving vernal point. The climatic perildicity recorded in the loess section is a function of the time interval considered ;the 0-0.8Ma sector is dominated by the quasi-100,000 years period, the 0.8-1.6Ma interval by 40,000 years cycles and the 1.6- 2.5Ma span again by 100,000 years period.
出处
《地质科学》
CAS
CSCD
北大核心
1992年第A12期270-278,共9页
Chinese Journal of Geology(Scientia Geologica Sinica)
