Coexistence analysis was applied to 23 species of mammal fossils from the Oligocene Hanjiajing Formation in the Lanzhou Basin, Gansu Province, for reconstructing the palaeoclimatic parameters: the mean annual temperature(MAT) was -2.8～14.4 ℃ (the median was 5.8 ℃); the mean temperature of the warmest month(MWT) was 8.0～27.5 ℃ (the median was 17.75 ℃) ,the mean temperature of the coldest month(CMT) was -4.4～- 14. 6 ℃ (the median was -9. 5 ℃); the difference of temperatures between the coldest and warmest months(DT) was 23. 1～26.2 ℃(the median was 24.65 ℃),the mean annual precipitation (MAP) was 74.8～492.2 mm(the median was 283.5 mm) ,the mean maximum monthly precipitation(MMaP) was 5. 8～93.5 mm(the median was 49.65 mm) and the mean minimum monthly precipitation (MMiP) was 0. 1～27.8 mm(the median was 13.95 mm)in the Lanzhou Basin. Our analysis showed that the climate of the Oligocene in Lanzhou Basin was colder and drier than in the present time and there was to some degree different from the palaeobotanical proofs. For mammal fossils,this approach needs to be further improved.%运用共存分析法对甘肃兰州盆地渐新统韩家井组的23种哺乳动物化石进行了分析,重建了该地区渐新世古气候各参数:年均温为-2.8～14.4℃(中值5.8℃),最热月均温为8.0～27.5℃(中值17.75℃),最冷月均温为-4.4～-14.6℃(中值-9.5℃),年较差为23.1～26.2℃(中值24.65℃),年均降水量为74.8～492.2 mm(中值283.5 mm),平均最大月降水量为5.8～93.5 mm(中值49.65 mm),平均最小月降水量为0.1～27.8 mm(中值13.95 mm).分析表明渐新世比现在兰州气候较冷、干燥,与古植物学的证据存在一定差异,将该方法用于动物化石研究中则还有待于进一步完善.
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