Geologicheskii Vestnik

The purpose of research is the petrographic description of the Frasnian greywackes of the western limb of the Khudolaz syncline located in the territory of the West Magnitogorsk zone, slightly south of the latitude of the Magnitogorsk. The research is based on descriptions of 130 thin sections. On the study area, fi ve debris complexes (bottom to top) were identifi ed: the upper part of the Ulutau Formation, the Mukasevo Formation, the Yalangas, Idash-Kuskarovo and Khudolaz lentils. Generation of clastic material proceeded with high tectonic activity. Signifi cant processing of detrital material in watercourses did not occur. The sandstones of the Ulutau Formation and the Yalangas lentil are tephra. Their formation is caused by explosions. The detrital rocks of the Idash-Kuskarovo lentil formed during the destruction of volcanogenic rocks of diff erent composition and degree of metamorphism. The sandstones of the Khudolaz lentil are classifi ed as terrigenous. They consist of debris of volcanogenic, sedimentary and metamorphic rocks. The detrital rocks of the Mukasevo Formation stand apart (they have not been studied purposefully). A large amount of clay matrix and quartz grains in their composition, their association with mudstones and shale is not characteristic of the Devonian detrital complexes of the West Magnitogorsk zone.

greywackes, petrography, the Ulutau Formation, the Mukasevo Formation, the Biyagoda Formation, the Zilair Formation, the Frasnian, deep-sea sandstones, turbidities

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