摘要
对黄河三门峡北岸的山西平陆庙下、阳凹两个黄土剖面研究结果表明 ,S6、S1 的磁化率值较黄土高原明显偏高 ,S5～ S2 的磁化率值则相对偏低 ,L7～L2 的磁化率值也表现出较低值 ,与黄土高原内部 L9磁化率值相近。另外 ,S5～L5地层厚度较大。把两剖面磁化率曲线与曹村剖面黄土 -古土壤序列磁化率曲线、深海氧同位素曲线、北半球 6 5°N太阳辐射变化曲线进行对比后表明 ,两剖面磁化率曲线反映的气候变迁 ,在 0 .1 Ma尺度上与黄土高原内部基本相同 ,反映出与地球轨道要素变化控制的太阳辐射变化诱导的全球冰期 -间冰期气候旋回的一致性 ;但并不是简单的一一对应关系 ,表现在地层厚度较大、磁化率值相对较低。其原因可能有 4个 :一是粉尘堆积速率不同 ,二是受流水侵蚀 ,三是物质来源有别 ,四是局地的成壤条件差异。
In this paper,two loess profiles located in Pinglu,Shanxi north of Sanmenxia gorge of the Yellow River,have been studied. The magnetic susceptibility curves of Miaoxia and Yangwa profiles show that the susceptibility values of S 6 and S 1 are higher than that deposited in the corresponding period in the Loess Plateau,while the values of S 5~S 2 and L 7~L 2 are somewhat lower,being close to the susceptibility value of L 9 in the interior of the Loess Plateau. The thickness of strata of S 5~L 5 is greater than that of the Loess Plateau. A comparison with the curves of the magnetic susceptibility, δ 18 O in DSDP607 and V30 97,and mid month insolation 65°N for July of Caocun profile,shows that the climatic changes indicated by both Miaoxia and Yangwa profiles are close to the interior of the Loess Plateau at the scale of 10 5a. This fact may reflect its consistency with the global glacial cycle resulting from the variation in solar radiation controlled by variation in some elements of earth's orbit. But there is no simple correspondence between them as shown by the greater thicknesses of deposits and relatively lower susceptibility values. It may be caused by (1) different rate of dust accumulation,(2) water erosion,(3)different source materials and (4) variation in local soil forming conditions.
出处
《地质力学学报》
CSCD
2000年第4期27-36,共10页
Journal of Geomechanics
基金
国家重点基础研究专项经费资助!项目 (G19990 4340 1)
国家自然科学基金!项目 (4 9972 0 6 0 )
中国科学院"九五"重大项目! (KZ
