Welcome to Geological Journal of China Universities ! Today is
Share:

J4

• Article • Previous Articles     Next Articles

Paleoclimatic Implication of Frequency Dependent Magnetic Susceptibility of Red Clay-Loess-Paleosol Sequences in the Lingtai Profile

SUN You-bin1, SUN Dong-huai2, AN Zhi-sheng3   

  1. 1. Institute of Earth Environment Research, Chinese Academy Sciences, Xi’an 710054; 2 Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071; 3. South China Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301
  • Received:2001-09-20 Revised:2001-09-20 Online:2001-09-20 Published:2001-09-20

Abstract: On the basis of rock magnetic properties, red clay has the similar composition of magnetic minerals as that of loess-palm sols sequences, and the magnetic susceptibility value is well correlated to the content of ultra-fine magnetic minerals Magnetic susceptibility of loess-paleosols has been regarded as a proxy index of summer monsoon intensity. However, there are different opinions about the paleoclimatic implications of magnetic susceptibility of red clay, Here we report the magnetic susceptibility and frequency dependent magnetic susceptibility measured for the late Cenozoic red clay-loess-paleosol sequences of the Lingtai profile in Gansu province. A positive correlation is observed between the magnetic susceptibility and frequency-dependent magnetic susceptibility, indicating that the content of ultra-fine magnetic minerals formed by bio-chemical processes has a great contribution to the increase of magnetic susceptibility and frequency-dependent magnetic susceptibility. Compared with the magnetic susceptibility, the frequency dependent magnetic susceptibility, which indicates the content of ultra-fine magnetic minerals formed under different climatic conditions, can reliably and sensitively record the paleoclimatic variations on different time-scales, and also can be used as a proxy index of pedogenic degree and summer monsoon intensity. The different variability of frequency dependent magnetic susceptibility before and after 2.6MaBP indicates the great change between the cold and warm, dry and humid climatic conditions on the Loess Plateau. Summer and winter monsoon variations show different combinations before and after the occurrence of major North Hemisphere G1aciations.