On comparative analysis of ophiolites in the South Urals and the North Caucasus
The unity of tectonic conditions and geodynamic regimes responsible for the formation and development of fold areas in the Urals and Caucasus during the pre-Mesozoic period is exemplified by one of the most important geological real units, that is the ophiolitic complex of the Kraka Mountains on the western slope of the South Urals and the Malka hyperbasite massif in the Bechasyn zone of the North Caucasus. Common characteristics of the geological structure include: miogeosynclinal type of both Precambrian and Paleozoic sections; structural combination of Silurian heterogeneous facies formed in various paleotectonic environments and differing in the intensity of their shearing along with isoclinal folding; tectonic style characterized by thrust sheets. Typical features of the ophiolitic complex in the South Urals and the North Caucasus are as follows: contrasting topography peculiar to hyperbasites and host rocks; prevailing harzburgite composition with subordinate lherzolites and dunites; high-degree serpentinization of all ultrabasic rocks; relatively thin hyperbasite bodies; tectonic interrelations with host rocks; identical stratigraphic range of underlying rocks from the Precambrian to the Middle Paleozoic inclusive; tectonically congruent dissimilar types of the Paleozoic section; identical geochronological periodization. These peculiarities are characteristic of the pre-Mesozoic both in the Bechasyn zone of the North Caucasus and the boundary zone between the Zilair Synclinorium and the Bashkir Anticlynorium in the South Urals. This is testimony to the unity of tectonic conditions in the course of their origin and development.