CARBON, OXYGEN ISOTOPIC RECORDS ON CLIMATIC CHANGES IN THE CENTRAL LOESS PLATEAU SINCE 130KA B.P.
Chen Yun Li Zhenghua Ye Hao Wang Yuhai(Institute of Hydrogeology and Engineering Geology,Chinese Academy of Geological Sciences,Zhengding,050803,China)
Carbon,oxygen isotopic records show that at least 8 big climatic changes have takenplace in the central Loess Plateau since 130 ka B. K. During 130 75 ka B. P. environ-ment of the last interglacial period was prevalent in this region,under which climate waswarm and humid,and the first layer of paleosol(S_1)widely developed with two clear pe-dogeneses indicating two much warm and humid time stages.In about 75ka B. P. ,theplateau entered into the last glacial age,in which the first layer of loess(L_1)was deposit-ed. But around 60ka B. P. and 30ka B. P. ,each saw a relatively warm and humid climaticenvironment in the general background of dryness and coldness,each having one weakpedogenesis formed. Since about 10ka B. P. ,the region has been in the post-glacial e-poch.9-6ka B. P. was the climatic optimum of Holocene with the highest air tempera- ture;subsequently,air temperature began to drop and frequently fluctuated until now. On the whole,in the central Loess Plateau,paleoclimatic change since 130ka B. P. hasbeen with the concurrence of the global trend on the scale of ten-thousand year;on thesmaller time scale,however,it has its own obvious regional features.