Geochemical distinctive criteria of Lower and Middle Devonian volcaniclastic graywackes from Western Magnitogorsk zone of South Urals

Lower Devonian deposits, mainly represented by volcaniclastic greywackes, are widespread in the Western Magnitogorsk zone of South Urals. Their external features are similar to the Irendykskaya Formation greywackes. This led to the need to identify their differences in geochemical parameters. This problem was solved by the example of deposits of the Lower Devonian Ryskuzhinskaya Formation. Geochemicalsamplingwas conducted from the sections, which age was based on thefauna. The elemental composition was determined by XRF and ICP-MS. As a result, it was found that the greywackes from Ryskuzhinskaya formation have higher contents of U, Th, P2O5, LREE, Zr, Nb, Hf, Co, higher values of La/Y, Th/Zr, La/Yb, La/Co, La/Sc, Th/Co, Y/Co and lower values of Sc / Zr, Co / Zr, Co / Th, Th / Sc, Yb / Th.