The Paleogeomagnetic Intensity Variation from 10Be Record in Chinese Loess
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摘要: 因受气候因素的强烈影响, 中国黄土10Be记录无法直接用于示踪地磁场变化, 需开展信号分离研究.针对黄土10Be示踪古地磁场的复杂性和存在的关键问题, 结合分离黄土10Be浓度所包含的气候因素和地磁场因素的数理分析方法发展历史, 分析了各种方法的优缺点.在原有方法的基础上, 引入主成分分析法对洛川和西峰2个黄土剖面的10Be记录进行主成分提取, 进一步剔除了残差中可能存在的少量气候因素、噪声等随机信号, 定量重建了130 ka以来的大气10Be产率, 与以往方法相比较取得了更优的结果.将主成分分析应用于复杂地质信号的分离, 将有助于解决地质或其他信号分离的难题.Abstract: The 10Be records in Chinese loess can't be used for tracing the paleogeomagnetic change because of the significant climate effect, so we need to do research on signal separation. The difficulties are summarized in the reconstruction of the paleogeomagnetic intensity by using the 10Be records in Chinese loess in this paper. Here we present the advantages and shortcomings in our methods used to separate climate effects and geomagnetic modulation effects from 10Be concentration. Based on these methods, principal component analysis (PCA) is used to extract the common signal of 10Be from Luochuan and Xifeng loess sections to further clear up the effect of the climate change, noise and other random signals, which we interpret as variations of the global 10Be production rate of the past 130 ka. The PCA method presented here may be facilitated to solve the difficulties in geological or other signal separation.
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Key words:
- loess /
- 10Be /
- paleogeomagnetic intensity /
- principal component analysis /
- magnetic susceptibility /
- climate change
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表 1 文中符号定义
Table 1. Nomenclature
符号 说明 [10Be]m 黄土测量10Be浓度 [10Be]D 10Be浓度粉尘组分 [10Be]p 10Be浓度降雨组分 SUSm 黄土磁化率测量值 SUSD 尘降磁化率估计值 SUSP 成壤磁化率 ΦD 粉尘通量 Pr 10Be产率 -
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