SCIENTIA GEOGRAPHICA SINICA ›› 2004, Vol. 24 ›› Issue (6): 693-697.doi: 10.13249/j.cnki.sgs.2004.06.693

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Paleohumidity Evolution in Loess Plateau Recorded by Organic Matter in Xifeng Loess Section

JIA Rong-Fen, PENG Xian-Zhi   

  1. State Key Lab of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, Guangdong 510640
  • Received:2003-08-20 Revised:2004-02-20 Online:2004-11-20 Published:2004-11-20

Abstract: Here pHC2-1 is hydrocarbon pyrolyzed at 300-500℃, which presents organic matter combined with organism residue in sample and correlated to supergene water, rain or other surface water in the area, pHC2-2 is hydrocarbon pyrolyzed at 500-600℃, which presents organic matter combined with special secondary carbonate and correlated to evaporation water. The calculated result shows that the paleohumidity is bigger in the paleosol layer than that in the adjacent loess layers. The range of paleohumidity in the section is 47%-80%, the highest is in S5-1, the secondary is in S1, the lowest is in L6, the secondary is in L4. The paleohumidity change of L2-S1-LI in Xifengg section could correlate with the same layers in Weinan section of Shaanxi Province, Which could compared with the results of mineral partial size, content of CaCO3, iron changes of Fe, as well as susceptibility used often in the research on loess section. The paleohimidity evolution in Xifeng section shows that during L6-L4 layers, the paleohumidity changed intensively, it means that the general circulation of atmosphere was very activity and may be reflect an event of hot-humidity or the climatic boundary of the dry and humid general circulations. After L4, special in L4-L2 layers, the amplitude of paleohumidity changes to gentle, and the trend of humidity to decrease, but since S2 the trend of the humidity have changed to increase.

CLC Number: 

  • P531