Year: 2024
Pages: 90-116
UDC: 553.41: 552.11
Number: 2
Type: scientific article
DOI: 10.31084/2619-0087/2024-2-8
Topic: ARTICLES AND PUBLICATIONS
Authors: Kosarev, Alexander M., Gorozhanin, Valery M., Gorozhanina, Elena N., Shafigullina, Gulnara T.
Sakmara structural zone, identified by L.S. Librovich in 1929 on the western slope of the Southern Urals, is a meridionally elongated lens-shaped, complex tectonic block located in the center of the Zilair synclinorium and limited from the west and east by regional faults. The goal is to clarify the structure, geological and paleogeographic history of the formation of complexes of different ages and different facies of the Sakmara zone. Based on an analysis of published and archival materials and our own observations, a study was carried out of the composition and structure of sedimentary and volcanogenic complexes in the northern part of this zone. It is shown that there is a stratigraphically complete section of sediments from the Cambrian to Famennian. From the point of view of strike-slip tectonics, the structural features of the northern part of the Sakmara zone have been explained. Paleogeographical and geodynamic reconstructions were carried out. The paleogeographic conditions for the formation of sediments from the Cambrian to the Upper Devonian correspond to the conditions of the marginal sea; the modern analogue of these settings can be the marginal seas of the South China sea region. The established sequence of geodynamic events in the development of the marginal marine basin reflects the complete Wilson cycle — from the opening of the marginal oceanic space during rifting in the Cambrian, Ordovician and Silurian to its closure through the mechanisms of subduction in the Silurian and Early-Middle Devonian and collision in the Late Devonian. Structurally, the Ordovician-Silurian and Devonian sediment complexes of the Sakmara zone are not allochthonous — thrown over from the Magnitogorsk zone and the MUF. The structure of the Sakmara zone is considered as a horstlike synstrike-slip “flower” structure, brought to the surface from under the Middle-Upper Paleozoic deposits of the Zilair synclinorium, as a result of lateral compression in the late collisional stage and reactivated at the neotectonic stage.
Ordovician, Silurian, Devonian, marginal sea, paleoocean, ophiolites, volcanic rocks, accretation complex, serpentinites, subduction, strike-slip faults