The relevance of research. The Early Devonian stage of formation of the Magnitogorsk island-arc system remains poorly understood, despite the long history of research and rather large amount of data obtained. This stage corresponds to Lochkovian-Lower Emsian volcanoclastic, carbonate and siliceous rocks, widespread in the north of the West-Magnitogorsk zone. They are located in the zone of the Main Ural Fault and are therefore subject to secondary changes, and their sections have a fragmentary structure. Volcanoclastic rocks, the most widely spread, have not been studied. Their study and the study of facies relationships between them allows us to reconstruct the situation of sedimentation of the early Devonian basin and to detail the history of the development of the Magnitogorsk island arc system at the initial stage of its formation. The main aim of this work is to identify the sources of demolition and sedimentation environments of the Lower Devonian volcaniclastic deposits of the West-Magnitogorsk zone of the Southern Urals. Methods. Reconstruction of accumulation environments was carried out on the basis of studying structural and texture features, mineralogical-petrographic and lithogeochemical composition of volcaniclastic rocks and correlation of Lower Devonian deposits by biostratigraphic data. The results obtained were compared with the data of leading researchers on modern sedimentation environments. Results. The Lower Devonian volcaniclastic deposits of the West-Magnitogorsk zone of the Southern Urals are turbidites and debris. They are composed mainly of pyroclastic and volcanic-terrigenous material of basalt and andesibasalt composition. It is shown that their accumulation took place in the proximal and distal part of the island arc. Deposits of the Itlibanskay and Mansurovskay strata were accumulated in the distal part, in the proximal – the Uskulskay and the Ryskuzhinskay strata. The formation of the Magnitogorsk island-arc system could begin in the early-ems time or even earlier.