论文部分内容阅读
通过对甘肃灵台晚新生代红粘土 -黄土 -古土壤序列的磁化率测量和频率磁化率分析 ,发现红粘土及黄土 -古土壤的磁化率和频率磁化率存有良好的正相关关系 ,表明两套沉积在成壤过程中由生物作用或化学作用而形成的超顺磁性矿物含量 ,对磁化率和频率磁化率增大有重要的贡献。相比磁化率而言 ,受影响因素较少的频率磁化率变化 ,反映了不同气候条件下形成的超顺磁粒级铁磁性矿物的相对含量 ,能更真实、敏感地记录不同时间尺度的古气候波动。灵台红粘土 -黄土 -古土壤序列的频率磁化率在 2 .6MaBP前后不同的变率特征 ,揭示了大冰期来临前后黄土高原的冷暖、干湿反差产生了显著变化 ,而与此相关的冬、夏季风变迁则表现出不同的组合特征
Through the magnetic susceptibility measurement and frequency susceptibility analysis of Late Cenozoic red clay-loess-paleosol sequence in Lingtai of Gansu Province, it is found that there is a good positive correlation between magnetic susceptibility and frequency magnetic susceptibility of red clay and loess-paleosol, indicating that two The superparamagnetic minerals formed by biological action or chemical action during sedimentation in the sediments have an important contribution to the increase of magnetic susceptibility and frequency magnetic susceptibility. Compared with the susceptibility, the change of frequency susceptibility with less affected factors reflects the relative content of superparamagnetic ferromagnetic minerals formed under different climatic conditions, and can more truly and sensitively record ancient Climate fluctuations. The different rates of frequency susceptibility of the Lingtai red clay-loess-paleosol sequence around 2.6 Ma BP reveal that the warm and cold contrast of the Loess Plateau before and after the Great Ice Age had a significant change. However, Summer monsoon changes show different combination characteristics