MODERN STRUCTURE OF THE URALS AS A RESULT OF THE POST-PALEOZOIC EXTENSION OF THE EARTH’S CRUST Available to Purchase

The Urals structure as a whole is the result of the post-Permian sublatitudinal extension of the region. It is characterized by alternating submeridional zones: synform zones made up of nonmetamorphosed volcanogenic and sedimentary series and antiform zones composed of deep metamorphic and intrusive complexes. These zones are bordered by large faults, which usually dip at 30–50° beneath less metamorphosed rocks. These features are mainly normal faults, rather than overthrusts, as was considered earlier. These young faults were caused by the Earth’s crust extension and developed primarily in tectonically weak zones of the older thrusts and detachment zones which were present between the upper (brittle) and middle (plastic) crust. Exhumation of megablocks of rocks formed in the lower and middle crust was a result of their rise to the upper crust up to the time of its rupture and extension. The extension began, evidently, in the Early Triassic. The South Urals structure along the Kumertau-Nikolaevka profile is described. A new important tectonic stage – postcollision extension – has been determined in the geological history of the Urals.