Abstract
The Paleozoic formations exposed to the West of the Main Uralian fault belonged to a passive margin of Balica. The margin formed in the Early Paleozoic as a result of break-up of a bigger continent. The rugged outline of the margin, with promontories and recesses, predetermined many features of the future Uralide foldbelt. Three stages of development of the margin are established: a rift stage; a passive stage; and a collisional stage. Late Cambrian to Early Ordovician rifting was followed by seafloor spreading and subsidence of the newly formed margin. The margin developed a typical topographic profile with a shelf, continental slope, and continental rise, whose facial zones can be recognised in the rocks of the Uralides. The passive margin stage was accompanied by weak tectonic activity, with rare, localised episodes of rifting. The accumulation of sediments was governed by subsidence and a strong dependence on sea-level changes. The change to the collisional stage can be recognised in the accumulation of greywacke flysch, which filled a deep-water basin and was deposited over the continental shelf. These collision-related processes were strongly diachronous, starting in the Late Devonian in the Southern Urals, and propagating northward, were they ended in Pay-Khoy as late as the Jurassic.
Published Version
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