Magnetic Susceptibility Features and Environmental Records of the Xiashu Loess in Zhenjiang, Jiangsu Province
Magnetic Susceptibility Features and Environmental Records of the Xiashu Loess in Zhenjiang, Jiangsu Province
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发表时间：
2002
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通讯作者：
Yang Da-yuan
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作者：
Yang Da-yuan
磁化率参数作为一种古气候代用指标，在北方黄土研究中得到广泛应用，本文将其应用于长江下游南部下蜀黄土的研究。在系统采样和测试的基础上，分析了江苏镇江下蜀黄土的磁化率特征及其气候意义。下蜀黄土磁化率曲线具有明显的旋回性，记录了长江下游中更新世以来7~8个大的气候旋回，与安徽、山东和北方地区风成沉积序列揭示的气候变化特征相似。磁化率特征表明，下蜀黄土沉积剖面不连续，地下水浸泡对磁化率背景值有明显影响。下蜀黄土S2层以来的磁化率记录与第7阶段以来的海相同位素记录吻合较好。本文首次在下蜀黄土记录中发现了对应于MIS 5a-5 b-5c-5d-5e的变化特征，但MS记录与MIS记录的变化细节存在一定差异。对比表明，下蜀黄土沉积区对地球仪200 a BP以来的古气候变化具有敏感的响应。另一方面，下蜀黄土记录的某些阶段的气候变化具有明显的区域性，这可能是地球仪气候变化和东亚季风气候变化双重作用的结果。镇江下蜀黄土剖面含有高精度的地球仪变化信息，这与其所处的地理位置、纬度位置和地形条件有关。
As a paleo-climatic proxy index, magnetic susceptibility (MS) parameter that has been widely used in loess studies of northern China, is applied in studies on the Xiashu loess in the south of lower reaches of the Yangtze River. On the basis of systematic sampling and measurement, the magnetic susceptibility features and their climatic implications of the Xiashu loess in Zhenjiang, Jiangsu province are analyzed in this paper. Magnetic susceptibility curve of the Xiashu loess is characterized by cycle, which records 7～8 large climatic cycles since Middle-Pleistocene in the lower reach of the Yangtze River and that is similar to the climatic change features disclosed by the aeolian deposition sequence in Anhui, Shandong and northern China. Magnetic susceptibility features indicate that the deposition section of the Xiashu loess is discontinuous and soaking by groundwater exerted an obvious influence on background value of the magnetic susceptibility. Magnetic susceptibility record of the Xiashu loess since S2 stratum coincides with marine isotope record since stage 7 perfectly. The change feature corresponding to MIS 5a-5b-5c-5d-5e is found in the Xiashu loess record for the first time in this paper, but the change details contain certain differences between MS record and MIS record. The comparison indicates that the area of the Xiashu loess deposition has given a sensitive response to globe paleo-climatic changes since about 200 a BP. On the other hand, the climate changes in some stages recorded by the Xiashu loess has regional characteristic obviously, which might be result of the dual effect of globe climate changes and East-Asia monsoon climate changes. The Xiashu loess section in Zhenjiang containing globe change information with high precision should be related to its geographic position, latitude location and landform conditions.