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黄土高原不同地区发育的黄土-古土壤序列在东亚冬、夏季风记录上存在一定的差异性,而目前的研究多集中在黄土高原腹地。本文以黄土高原东北缘北京邻区矾山剖面S_6～L_9段地层为研究对象,开展了详细的古地磁、岩石磁学、粒度及地球化学测试分析。结果表明:1)与黄土高原腹地典型剖面同时段地层相比,矾山黄土成壤程度偏低,所受夏季风的影响较黄土高原内部剖面偏弱;2)在黄土高原腹地L_8～S_8地层中广为记录的布容-松山地磁极性倒转界线(M/B)及其高频极性转换特征在该剖面并未被清晰地记录,却在“上粉砂层”—L_9的顶部记录了一个明显的正、反磁极性转换,而相对古强度参数均指示M/B可能应位于L_8的下部;3)该剖面L_9段地层记录了3个较稳定的正极性段落,推测可能是布容期重磁化的结果,而非短期地磁极性漂移;4)L_9下部约0.8m的地层记录了一段天然剩磁异常高值带,可能是瞬间极强磁场(如雷电)磁化的结果。
The loess-paleosol sequences developed in different areas of the Loess Plateau have some differences in the winter and summer monsoon records of East Asia. However, the present researches are mostly concentrated in the hinterland of the Loess Plateau. In this paper, the S_6 ~ L_9 sections of the Aoshan section in the northeastern margin of the Loess Plateau are studied, and detailed paleomagnetic, rock magnetic, granularity and geochemical tests are carried out. The results show that: 1) compared with the same period of the typical section in the hinterland of the Loess Plateau, the degree of formation of volcanic rocks in Loess Plateau is low, and the influence of summer monsoon is weaker than that in the Loess Plateau; 2) In the L8 ~ S8 stratum The broad record of cloth - Matsuyama geomagnetic polarity inversion boundary (M / B) and its high-frequency polarity conversion characteristics in the profile is not clearly recorded, but in the “silt layer ” - L_9 A significant positive and negative polarity transitions were recorded at the top, and the relative paleo-intensity parameters indicated that M / B might be located at the lower part of L_8. 3) Three stable positive polarity segments were recorded in the L_9 segment of the profile, Rather than short-term geomagnetic polarity drift; 4) about 0.8m below the L_9 formation records a high value band of natural residual anomaly, which may be the result of the magnetization of an extremely strong magnetic field (such as lightning) .