The thick Cenozoic sedimentary sequence of the Linxia Basin contains abundant well-preserved mammalian fossils, which provide significant information on the paleoenvironmental processes and mammalian evolution associated with the uplift and expansion of the Tibetan Plateau. Ambiguous age estimations have been made for some coarse-grained sedimentary units in the basin, which have led to the misinterpretation of biostratigraphic and magnetostratigraphic age models. To resolve these issues, we present radiometric dating of three late Cenozoic sedimentary units ("Liushu", Hewangjia, and Jishi formations) in the eastern Linxia Basin using cosmogenic 26Al/10Be and 10Be/21Ne burial methods. isotope measurements for the upper "Liushu" Formation indicate a 10Be/21Ne burial age of 11.70 & PLUSMN; 0.17 Ma. This age is older than, but not contrary to, recently revised bio-magnetostratigraphic work. The 26Al/10Be burial age of the Hewangjia Formation is 3.06 (+0.36/-0.31) Ma and had been underestimated by post-burial muon production possibility, while the 26Al/10Be burial age of the Jishi Formation is 2.50 (+0.20/-0.18) Ma and had been overestimated due to inherited cosmogenic nuclides from recycled deposits. The new age from the Jishi Formation delays the initial deposition of conglomerates in the Linxia Basin to no earlier than 2.5 Ma and constrains an important episode of tectonic uplift of the northeastern Tibetan Plateau to 2.5-3.1 Ma. The age of the Equus fauna of Longdan is revised to the Early Quaternary (ca. 2.1-1.9 Ma). Our new age determinations significantly refine the terrestrial sequence chronology of the Linxia Basin and associated mammalian faunas of the late Miocene to the early Pleistocene.

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