The relevance. Diagrams that allow assuming the geodynamic position of sedimentary basins on the basis of lithochemical features of clastoliths have been used for many decades. At the same time, the possibility of using them to study tefrogenic sandstones is not clear, and the results are contradictory. The main aim of the research is a comparative analysis of the position on the most frequently used point diagrams corresponding to the composition of two groups of rocks – tefrogenic sandstones and volcanic rocks of their source. Objects of the research are tephrogenic greywackes of the Ulutau formation and volcanic rocks (from rhyolites to basalts) of the Urlada formation of the Magnitogorsk megazone of the Southern Urals. Age of Ulutau formation is the Givetian – Early Frasnian. Genetically greywackes are tephrogenic turbidites and debrites, formed in the deep-water depression located at the foot of the oceanic Magnitogorsk island arc. In the modern erosional slice the axial zone of the island arc corresponds to the volcanics of the Urlada formation. Methods. The comparison is based on the results of determination of the main elements content in the Ulutau formation greywackes (202 samples) and Urlada formation volcanics (202 samples). The comparison was made on the basis of the Meinard, Bhatia, Roser–Korsch and Verma–Armstrong-Altrin diagrams. Results. The analysis of the diagrams showed that the use of the low silica volcaniclastic greywackes (SiO₂<63 %) gives more realistic results. An exception in this case is the diagram (Fe₂O₃+MgO)–TiO₂: most of the points turned out to be outside of any fields. Hi-silica graywackes with (SiO₂>63 %) in many diagrams fall into the fields of oceanic island arcs, active and passive continental margins. The best results for Hi-silica rocks were obtained using the DF1–DF2 diagram and the modified Bhatia Al₂O₃/(CaO+Na₂O)–K₂O/Na₂O diagram. The fields of greywacke on the majority of diagrams coincide with the fields of volcanic rocks and are more compact compared to them, which is caused by the mixed composition of sandstones and low explosiveness of basalt melts. The results obtained are largely not consistent with the results of similar studies. Consequently, the conclusions obtained when constructing lithochemical geodynamic diagrams cannot be considered as the final ones and must be supplemented by other methods.