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运用小波分析与传统谱分析技术相结合的手段,对典型季风系统交互作用的青藏高原与黄土高原过渡带-甘肃陇南万象洞WX40D石笋616个碳同位素时间序列进行了周期谱演化分析。结果表明:在23-28.3kaB.P期间,石笋碳同位素记录的小波变换系数波谱在频率域尺度其主要的变化周期为120年,200年,并隐约表现出300年和600年的周期;小波变换实部时频分析图显示清晰的能量集中中心有10个,分别为1(23613,197)、2(24000,220)、3(24298,300)、4(25354,222)、5(25565,95)、6(26239,606)、7(26792,115)、8(27085,116)、9(27388,136)、10(27853,177),表明石笋碳同位素记录的古植被演化在该时间段具有明显的5次转变。小波实部过程线分析表明万象洞石笋在末次冰期晚期存在多尺度的变化特征,大尺度的周期变化嵌套小尺度的周期变化。
Using the combination of wavelet analysis and traditional spectral analysis techniques, the periodic spectral evolution of 616 carbon isotope time series of the WX40D stalagmite in the Wanxiang Cave of Longnan in the transitional zone of the Qinghai-Tibet Plateau and the typical plateau monsoon system was analyzed. The results show that the wavelet transform coefficient spectrum of stalagmite carbon isotope recorded from 23-28.3 kaB.P has the main period of change in frequency domain scale of 120 years and 200 years and the period of 300 and 600 years. Time-frequency analysis of the real part of the transform shows that there are 10 clear energy concentration centers with 1 (23613,197), 2 (24000,220), 3 (24298,300), 4 (25354,222), 5 (25565 (95), 6 (26239,606), 7 (26792,115), 8 (27085,116), 9 (27388,136), 10 (27853,177), indicating that the evolution of palaeo- Time period has obvious five changes. The wavelet analysis of the real part of the process shows that the stalagmite at the Wanxiang Cave existed multi-scale changes during the last glacial ice age, while the large-scale periodic variations nested the small-scale periodic changes.