A GEOCHRONOLOGICAL STUDY OF THE SALAWUSU STRATA IN NORTH CHINA

Salawusu Formation in Salawusu river area is one of the standard sections of Late Pleistocene strata in North China.However,there are a lot of different views about the strata since the establishment of Salawusu Formation,especially in the aspects of sedimental facies,stratigraphic age and its climate significance.Here,by the stratigraphic subdivision and dating,the following recognitions can be gained:
1.Salawusu Formation is mainly composed of fluvial lacustrine sediments,which corresponds to the stage 5 of deep sea ¹⁸O and formed between about 140-70kaBP.Chengchuan Formation mainly consists of fossil aeolian sands with some lacustrine silty-clay in the middle part,which corresponds to the stages 2-4 of deep sea ¹⁸O and formed between 70-10 kaBP.Dagouwan Formation is composed of lacustrine sediments and black-paleosol,which formed in early middle period of Holocene with the warm-humid climate,Dishaogouwan Formation consists of sub-loess and aeolian sands,which represented the sedimentation in the cold-dry climate during the late Holocene.
2.As a fluvial-lacustrine sedimentary strata,Salawusu Formation is quite different form its overlying Chengchuan Formation whether in geochronolgy,lithology and sedimentary facies or in palaeontology.Chengchuan Formation and Malan Loess belong to heteropic deposits (sandy and loessic facies) formed contemporaneously under the same wind action.
3.As a fluvial-lacustrine-aeolian-sand sequence found at the Dishaogouwan profile in the Salawusu river area,its climatic records corresponding to that of loess and deep sea deposits,may be divided into 5 climatic periods.It suggests that the climatic change of this region during the last interglacial period is synchronous with that of the whole earth.