| 摘要: |
| 运用最大熵谱方法,对若尔盖深钻800kaB.P.以来的有机碳同位素序列进行了频谱分析。结果表明:1)0-800kaB.P,该地区存在有准80ka、60ka、41ka和20ka的周期,其中41ka和20ka的周期与米氏计算的地倾角及岁差周期较一致;2)0-480kaB.P.,以100ka周期为主,其次为41ka和20ka,与米氏计算的各夭文周期相一致;3)480-800kaB.P.,出现有115ka、33ka、27ka和16ka各个周期,然而,准41ka和20ka周期消失。以上结果表明,在0-480kaB.P.,该地区气候主要受轨道驱动影响。而480-800kaB.P.,除了受轨道控制外还明显受构造作用影响。 |
| 关键词: 若尔盖盆地 天文周期 有机质δ13C 最大谱分析 |
| DOI：10.18307/1997.0303 |
| 分类号: |
| 基金项目:国家攀登项目(85-029-02-01) |
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| Frequency rhythms of the organic matter δ13C record in the core rh over the past 800ka |
|
Wu Jinglu
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Nanjing Institute of Geography and Limnology, CAS.Nanjing 210008
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| Abstract: |
| A 120-m-long core (33°54'N;102°33'E;altitude 3 400m) has been drilled at the center of Zoige Basin of the northeastern Tibetan Plateau. The sediment core RH reaches back to 826kaB. P. according to 14C ages and paleomaganetic stratigraghy. By analyzing environmental proxies for spore-pollen, ostrode.diatom, fosvsil pigments, hydrogen index, the δ13C values of organic matter and so on, the sequences of climatic evolution in this region over the past 820ka have been rebuilt. Compared organic matter δ13C with other proxies from the core RH.we found that the changes in δ13C of organic matter correspond well with that of other climatic proxies in the core RH, and can be mainly relative with the record from the deep-sea oxygen isotope, suggesting that the organic matter Sl3C in the core RH is a sensitive environmental proxy. By using maximum entropy method, in this paper, we present the revsults of the frequency rhythms recorded in the δ13C proxy in the sediment core RH over the past 800ka. The results showed that:(1) 0-800ka, existing quisc-periods of 80ka, 60ka, 41ka and 20ka, in which the periods of 41ka and 20ka are very close to those predicted by the Milankovitch theory. (2) 0-480ka.power spectra showed a dominant peak near lOOka and smaller peaks at the orbital periodicities of 41ka and 20ka; (3) 480-800ka B. P., discovering the dominant periods of 115ka, 33ka and 16ka, while the periods of 100ka, 41ka predicted by the Millankovitch theory vanished. All the results demonstrated that during 0-480ka B. P. the climatic changes in the region were controlled by orbital forcing, and for the past 480-800ka B. P. the periodicities had greatly regional characteristics affected by the regional constructal actions. Therefore.in this period.the climatic changes are not only influenced by orbital forcing but strongly controlled by the constructal actions. |
| Key words: Orbital-frequency rhythms organic matter δ13C maximum entropy method.Zoige Basin |
