The geochemistry of sediments is primarily controlled by their provenances, and different tectonic settingshave distinctive provenance characteristics and sedimentary processes. So, it is possible to discriminate provenances,depositional environments and tectonic settings in the development of a sedimentary basin with the geochemistry of theclastic rocks. The analytical results of the present paper demonstrate that sediments in the Songliao prototype basin areenriched in silica (SiO2=66.48-80.51%), and their ΣREE are 30-130 times of that of chondrite with remarkable Euanomalies. In discriminating diagrams of Eu/Eu* vs ΣREE and (La/Yb)N vs ΣREE, most samples locate above the line Eu/Eu*=1, on the right of the line Eu/Eu*/ΣREE=1 and under the line La/Yb)N/ΣREE=1/8, which indicates that thedepositional environment of sediments in the basin was oxidizing. In addition, variations of MgO, TiO2, A12O3,FeO+Fe2O3, Na2O and CaO vs SiO2 reflect a tendency of increasing mineral maturity of sediments in the basin. Analysesalso show that the protolytes of the sediments in the basin were felsic igneous rocks, and the Songliao prototype basin wasin a tectonic setting of an island arc on an active continental margin, with violent sinistral strike-slip.