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The carbonate contentinthe stratigraphy ofLoessandinlandlakesis a sensitiveindicatorof climatic changes.3 267 samplesintotal were collected at2 5 cm intervalsfrom a 80 m thicklacustrine deposits,spanning 2 35 Myr,in the Dongshanding section of Linxia Basin.Allthe samples were ana lyzed by using a standard Bascomb calcimeter.The variation of carbonate contents showsthatthere are two obvious cold humid eventsinthe early Pleistocene atabout2 28 Maand 1 8～1 75 Marespective ly.Duringthesetwoperiods,theclimate wascoldorcool.Theclimaticchange wasdominated byan ob vious41 000a periodicity.Theresultsalsoindicatethatinthe early period ofthe Quaternary,the mon soon climate had been established but was notverystable.
The carbonate content of the stratigraphy of Loess and inland lakesis a sensitive indicator of climatic changes.3 267 samples in total were collected at 2 5 cm intervals from a 80 m thicklacustrine deposits, spanning 2 35 Myr, in the Dongshanding section of Linxia Basin. All of the samples were ana lyzed by using a standard Bascomb calcimeter. The variation of carbonate contents showsthatthere are two significant cold humid eventsinthe early Pleistocene atabout2 28 Maand18 ~ 175 Marespective ly.Duringthesetwoperiods, theclimatewascoldorcool.Theclimaticchangewasdominated byan obious41000aperiodicity.Theresultsalsoindicatethatinthe earlyperiod ofthe Quaternary, the mon soon climate had been established but was notverystable.