Keywords: 
• Linxia Basin /
• Neogene /
• red clay /
• grain-size composition /
• paleoenvironment

Abstract: The Linxia basin is situated in the northeastern part of the Qinghai-Tibet Plateau, and it is a flexural basin bounded by mountains. The weathering and erosion materials that come from Plateau can be deposited in the Basin in the first place, the sediments of the basin completely record the history of the climatic changes brought by the up lift of the Qinghai-Tibet Plateau. Therefore, the sediments of the Linxia basin can sensitively indicate the up lifting processes of the Qinghai-Tibet Plateau and the climatic changes in a short period of time. Analytic consequences of the grain-size composition and the magnetic suscep tibility of the Neogene Red Clay in Linxia basin show: Since 8.2 Ma, climatic changes undergo Asian aridification periodic evolution and east Asian wintermonsoon secular reinforcement processes. During 8.2～7.4Ma, east Asian winter monsoon begins to form in this area, early stage Asian aridification results in the formation of eolian dust source, Neogene Red Clay begins to deposit in the basin, especially, aridity or semiaridity grassland environment and /or grassland environment with less forest offer favorable background for the Red Clay deposits. The east Asian winter monsoon that is gradually strengthened begins to influence the Loess Plateau in the east part of the Liupan mountain ( 7.4 ～6.8Ma), then, mass accumulations of the Red Clay start to deposit in the loess plateau. Meanwhile, the climate of the basin transforms semiaridification into semihumidity. From 6.8 Ma to 6.0Ma, the climate and the tectonics are fairly stable.During 5.9 ～5.3Ma, climatic changes undergo a period of small scope changes between the winter and summer monsoon intensity in Linxia basin, it indicates a dry wet and dry cool climatic environment. Between5.3Ma and 4.8Ma, the east Asia winter monsoon system prevails, aridification is the strongest in the basin evolution history from 8.2Ma to 4.0 Ma, climatic characteristics is cool and dry. The summer monsoon begins to strengthen and the climate becomeswarm and humid (4.8～4.0Ma). After 4.0Ma B. P, the Qinghai-Tibet Plateau begins to strongly up lift again, which results in the deposits of massive gravel conglomeration named Jishi Formation in the Linxia Basin.