Abstract:
The typical segment DGS1 in the Dishaogouwan section from the Salawusu River Valley of the southeast depression of the Mu Us Desert is selected to study climate changes during the Holocene. The analyse of the concentrations and characterizations of major elements-- SiO2、Al2O3、TOFE、CaO、MgO、K2O、Na2O、TiO2, along with the age determination show that the fluctuations of major elements exhibit differences in two different periods: from 1CS to 9P, the contents of Al2O3,TOFE , CaO, MgO, K2O, Na2O, TiO2 are more than those in the secondary loess, and they are less in the dune sands than those in the secondary loess; from 10LS to the bottom of the DGS1 segment, the contents of CaO and MgO show peaks in the lacustrine facies, especially, the high peak appears in the15LS, and other major elements display low values. Those studies suggest that the DGS1 segment is actually the weathering accumulation under the alternations of Asian winter and summer monsoons since the Holocene, which is the stratigraphical climate record. Besides, according to the CIA values and SiO2/(Al2O3 + TOFE) ratios, the Holocene climate recored by the major elements in the DGS1 can be divided into four periods:the ewarming period of the Early Holocene;Holocene heyday;the fluctuation period from the Megathermal to cold;and the cooling instability and desertification period.