Element geochemistry characteristics of sediments are responses to the depositional environment. On the basis of field geological investigation,we studied the characteristics of trace and rare elements of the sedimentary rocks and probed into the features of paleoclimate,paleosalinity and redox conditions by analyzing the changes of the element components and ratios.The contents of Cu and Cs and the ratios of Rb/Sr and Sr/Cu as well obviously show that one humid-arid climate change event occurred during the deposition time of Sikouzi Formation,when the deposition entered into Qingshuiying Formation,the climate turned from arid to humid.The ratios of Sr/Ba and B/Ga reveal that the water during the period of Qingshuiying Formation contained a little less salinity than that of Sikouzi Formation except Shixiakou reservoir, where the salinity reached the peak.Also,the paleosalinity experienced an upward tendency during one specific period of Sikouzi Formation.The redox conditions of the sandstones and mudstones in Sikouzi Formation and Qingshuiying Formation were also investigated by means of element ratios of V/Cr,Ni/Co, U/Th and V/(V+Ni)as well asdeltaU,deltaCe,Ce/La and Ce_(anom) and also some trace element concentrations such as V,U,Ni,Zn and Cr.The results show that the sedimentary environment was oxidation environment during Sikouzi Formation while oxidation-lean oxidation environment during Qingshuiying Formation.