九州台黄土剖面碳酸盐稳定同位素及其气候意义

The Carbonate Stable Carbon and Oxygen Isotopes of the Jiuzhoutai Loess Profile and Their Climaic Significance

The further stable isotopic research on loess and paleaosol of the Jiuzhoutai profile has revealed that the systematic variations of the carbonate stable carbon and oxygen .isotopes can be regarded as the recorder of climatic history during loess and paleaosol formation: when the climate condition is warmer and humid, the values of carbon isotope decrease but the values of oxygen isotope increase when the climate condition is colder and dry, the values ofthe carbon isotope decrease but the values of oxygen isotope increase. As far as the long cyclity of the time scale is concerned, there is no linear correspondence between the change of carbon and oxygen isotopes.The carbon and oxygen isotopic curve especially the carbon isotopic curve reconstructed show that during last 1.5 Ma, more clearly and importantly during last 1.3 Ma the climate condition in Lanzhou area has experienced several change from cold-dry to warm-humid changes and the amplitude is becoming bigger.