柴达木盆地自然伽玛曲线记录的古气候变化对太阳辐射响应关系的对比研究

采用柴达木盆地达参1井自然伽玛(GR)曲线,建立了2 85MaBP以来的轨道调谐时标.对GR曲线、深海记录和黄土记录与太阳辐射曲线时频域的多维谱分析及奇异谱分析结果表明:达参1井GR曲线相对于太阳辐射的滞后时间短于深海及黄土记录3～4ka,GR曲线记录的岁差周期成分更为显著,且与太阳辐射在岁差周期上显示了更强的相关性.表明盆地古气候演化受到太阳辐射岁差周期强烈影响,具有低纬陆地记录的特征,而与深海记录和黄土记录受轨道倾斜周期和全球冰量变化的重要影响有别.

Paleoclimatic Change Derived from Natural Gamma-Logging Curve in Qaidam Basin and Its Relation to the Solar Insolation

The astronomical theory of climate has provided a very powerful means for developing accurate time-scales. Using orbital tuning methods, a millennial-resolution time scale of Dacan-1 core is established over the past 2.85 Ma for a 3200-meter-long logging curve of lake sediments in the Qaidam Basin, Western China. By analyzing multi-dimension spectra and singular spectrum of the logging curve and other climatic records from deep-sea ((δ¹⁸O) curve of ODP677, ODP659、ODP758 sites and ice volume simulated curve) and Chinese loess deposits (grain size of the Baoji loess-soil sequence), a significant difference of periodic features is found between the Qaidam record and the deep-sea, the loess deposits. The climatic change reflected in the time-domain spectrum of the Qaidam record lagged those in the deep-sea and loess deposits by 3～4 ka. Furthermore, frequency-domain analyses and combination of singular spectrum illustrate that the signal of processional domain in the Qaidam record stronger than that in other deep-sea and loess records. This suggests that long-term climate change in the basin has been strongly influenced by variation of the processional-scale orbital insolation, as previously discovered in the low-latitude climatic regime. Deep-sea records and loess records have been strongly influenced by obliquity cycle change. It is pointed that the processional cycles in the logging curve over the past 2.85 Ma are quite different from those in deep-sea and loess deposits.