About reasons of avalanche sedimentation of the Ulutau formation in the West-Magnitogorsk zone of the Southern Urals

The Ulutau Formation (Givetian-Early Frasnian) has a wide distribution in the West-Magnitogorsk zone in the Southern Urals. It consists of sends, gravelites, mixtites and cherts with total thickness from 800 till 2000 m. Detrital sediments were deposited with avalanche velocity by means of two agencies. The first agency was active mobilization of detrital material in volcanic zone of the Magnitogorsk island arc (explosions and erosion of ash and petrified volcanic and sedimentary rocks). The second one is sedimentary basin structure. It coursed concentration of sediments in deep water trough situated between active Magnitigorsk arc and extinct Irendyk arc.