MAIN URALIAN THRUST AND MAIN URALIAN NORMAL-FAULT - NON-EXTENSIONAL PALEOZOIC HIGH-P ROCK EXHUMATION, OBLIQUE COLLISION, AND NORMAL FAULTING IN THE SOUTHERN URALS

The crustal architecture of the Southern Urals is dominated by an orog enic wedge thrusted westward upon the subducted East European continen tal margin. The N-S trending wedge constitutes an antiformal stack com posed mainly of the high-P Maksyutov Complex, the overlying Suvanyak C omplex and the allochthonous synformal Zilair flysch further west. The se tectono-metamorphic: units are separated by tectonic contacts and r ecord discontinously decreasing metamorphic conditions from bottom to top. In the east, the E-dipping Main Uralian Normal Fault cross-cuts t he metamorphic: footwall and juxtaposes the non metamorphic Magnitogor sk island are. This syncollisional normal fault compensated crustal th ickening and exhumation of the high-P rocks. Orogenic shortening was a ccommodated by the Main Uralian Thrust, a W-vergent crustal-scale shea r zone at the base of the wedge. Geological investigations and reflect ion seismics (URSEIS '95) argue in favour of a geodynamic evolution in tegrating subduction and basal accretion of high-P rocks during sinist ral oblique thrusting along the Main Uralian Thrust and coeval normal- faulting along the Main Uralian Normal Fault.