Geologicheskii Vestnik

Post-volcanic deformation structures of pyrite deposits of the Magnitogorsk megazone of the Southern Urals are characterized. The main research method was the structural-paragenetic analysis of tectonic disturbances, which included the study of morphogenetic features of folded and fault structures, the study of fault kinematics based on the analysis of small structural forms and tectonophysical reconstructions of paleostress fields. Based on the research results, the pyrite deposits of the megazone are divided into two groups. The first of them unites deposits in the formation of deformation structures of which thrust deformations play a leading role, and the second – shear deformations. Thrust parageneses include suture anticlines (Uchaly, New Uchaly deposits) and thrusts (Balta-Тau, Buribai, Bakr-Uzyak deposits, etc.). Suture anticlines are isoclinal folds complicated in the axial zone by longitudinal upthrusts, and on the wings by additional associated folds formed by ore bodies. A mechanism for the formation of additional associated folds is proposed. Thrusts have a predominantly scaly structure. In their hanging wings, pyrite deposits are often crushed into anticline drag folds. The deposits of the first group also exhibit late strike-slip dislocations. They do not exert a significant influence on the general structure of the deposits. Strike-slip parageneses are represented by two types of structures: 1) strike-slip faults with feathering ruptures (deposits and ore occurrences of the Kontrolny Group) and 2) secondary thrusts and reverse faults of large strike-slip zones that developed in the Late Paleozoic under transpression conditions (deposits and ore occurrences of the Aleksandrinsky ore region – Sabanovo, Babarykino, Aleksandrinsky). It is shown that the tectonic structures of the Magnitogorsk megazone pyrite deposits are collisional formations of the Late Paleozoic age.

Southern Urals, pyrite deposits, deformation structures, anticlines, thrusts, transpressive shifts

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