The Kangtuo Formation is the first deposited continental-face clastic rock after the early uplift of the Qinghai—Xizang(Tibet)) Plateau,the analysis of the provenance information and tectonic background of this strata is of positive significance for studying the evolution process of the Qiangtang Basin in the Cenozoic and the plateau uplift.In this study,we tested and analyzed the stratigraphy,lithological,geochemical and clay content features of the Kangtuo Formation in the Bandaohu area of the Qiangtang Basin,and studied its provenance characteristics and tectonic background.Methods: The X-ray fluorescence (XRF) and high-resolution inductively coupled plasma mass (HR-ICP-MS) are used to test the major and trace elements of the Paleogene Kangtuo Formation sandstones in the Bandaohu area;the X- ray diffraction (XRD) is used to test the clay mineral composition of the same samples.All the analysis are measured in the Analytical Laboratory,Beijing Research Institute of Uranium Geology,China.Results: For the Kangtuo Formation sandstones,SiO2 (58.22%~71.91%) and CaO (12.72%~21.47%) are the most abundant oxides;Al2O3(1. 08%~2.45%) and Fe2O3T(0.98~1.94) are the second most abundant oxides;while other oxides like Na2O,K2O,MnO,TiO2,P2O5 are fewer than 1%. Elements Si and Ca are obviously enriched and other elements are apparently depleted compared to UCC.The total rare earth element(ΣREE) contents of the Kangtuo Formation sandstones are (34.40~67.10)×10-6 (avg.47.90×10-6),which are fewer than that of the UCC and have a significant negative Eu anomaly.Conclusion: The CIA (69.57~80.81),CIW (81. 07~95.02) and PIA (77.32~93.96) values indicate that intensities of weathering in the source area were strong.The A—CN—K diagram and the low K2O contents of the samples suggest that no K-metasomatism occurred in these sandstones.The ratios of trace elements such as Th/U,Sc/Th, Rb/Sr are similar to those of the continental crust.considering the REE distribution mode of the Kangtuo Formation,we conclude that this formation may be formed during a rapid accumulating process and was close to its provenance.The ratios of TiO2/Zr,Co/Th,La/Sc,Th/Sc,Cr/Zr and the negative anomalies of δEu,δCe,combined with the discriminant diagrams,show that the provenance of the Kangtuo Formation mainly comes from felsic rocks.The La—Th—Sc,Th—Sc—Zr/10 and major element two-factor structural discriminant diagrams indicate that the source area is mainly a passive continental margin.Combined with basin evolution characteristics,the Kangtuo Formation of Bandaohu area may be formed in intracontinental sedimentary environment.