Ks. Ivanov, MODERN STRUCTURE OF THE URALS AS A RESULT OF THE POSTPALEOZOIC EXTENSION OF THE EARTHS CRUST, Geologia i geofizika, 39(2), 1998, pp. 204-210
The Urals structure, as a whole, is the result of the post-Permian sub
latitudinal extension of the region. It is characterized by alternatin
g submeridional zones: synform zones made up of nonmetamorphosed volca
nogenic and sedimentary series and the antiform ones comprised of deep
metamorphic and intrusive complexes. The boundaries between these zon
es are large faults, which usually descend at angles of 30-50 degrees
to less metamorphosed rocks. These faults are mainly normal faults whi
ch appeared as a result of the Earth's crust extension, but not overth
rusts, as was considered earlier. These young faults developed primari
ly in tectonically weak zones of the older thrusts and detachment zone
s which were present between the upper (brittle) and middle (plastic)
crust. Exhumation of megablocks of the high-grade rocks formed in the
lower and middle crust occurred as a result of their uprise to the upp
er crust during the rupture and extension of the latter. The extension
began, evidently, in the Early Triassic. The South Urals structure al
ong the Kumertau-Nikolaevka profile is described. A new important tect
onic stage - post-collision extension - has been determined in the geo
logical history of the Urals.