Tevelev, Arc. V., Tevelev Al. V., Okhapkina E.Y.

Modern (neotectonic) state of south part of the Eastern Urals follows extremely complex PZ-MZ evolution. Region that transsected by “Urseis ‘95” includes four principal recent morphological units: (1) Pre-Uralian foredeep (subsident margin of the East European platform), (2) mountain building of the Western and Central Urals (overprinted and uplifted platform margin); (3) East Uralian Plateau, (topographically smoothed and relatively low-level collage of oceanic, island arc and microcontinental terraines); (4) western margin of the West Siberian Deep (Trans-Uralian Paleozoic fold-thrust belt overlaid by post-rift MZ-KZ sediments). In fact, such a set of geomorphologic elements is a small-scale model on large continental subduction system, and that is suggesting an oblique subduction of the East European plate, development of the foredeep and transpressional folded and ‘crystalline’ zones as mostly high-level topographic elements, and appearance of inner plateau as some “back-arc” basin. Distribution of deep-seated reflectors inferred from URSEIS ‘95 (Knapp, et al., 1996), compatible with deep structure of the Alpine orogens supports this concept. Within the East Uralian plateau, the regional geomorphologic levels descent continuously eastward and beyond the Redutovo boundary zone the highest levels become buried. The river valleys here are separated into non-equilibrated chain of segments with individual style of development. The WE to ESE trending segments present wide domains of relative subsidence, but ENE segments are narrow, often V-shaped domains of relative uplifting. It may be evidence that their formation is under tectonic control. We suggest that domains of subsidence evolve as small strike-slip-related extensional basins (micro-pull-aparts). Morphological expression of those convergent strike-slip faults, compensating a component of ~WE compression, is domains of uplifting. Supposed quaternary strike-slip faults trend at the angle of ~ 15° to orientation of structurally expressed faults, having the same sense of motion, and can be determined as R-shears.