ГЕОЛОГИЧЕСКОЕ СТРОЕНИЕ И ПЕТРОГЕОХИМИЧЕСКИЕ ОСОБЕННОСТИ КИРЯБИНСКОГО ГАББРО-ПИРОКСЕНИТОВОГО КОМПЛЕКСА (ЗОНА УРАЛТАУ)

In the article is discussed in detail the geological structure of Kiryabinsky gabbro-pyroxenite complex, which is composed of Kiryabinsky essentially gabbroic, Birsinsky and Abdulkasimovsky ultramafic massifs. Gabbro and ultramafic rocks are grouped into latitudinal band, spatially coincident with the zone of West-Uraltau thrust and bounded to the East of the Main Ural fault. Petrochemical appearance of intrusive bodies is defined by the ultramafic and mafic rocks. Ultramafic rocks are presented locally and consist of apoperidotite serpentinites and pyroxenites of Kiryabinsky massif and independent bodies of serpentinites of Birsinsky and Abdulkasimovsky massifs. All of them, despite their different structural position, find petrochemical community and belong to nonfeldspar normal petrochemical series of rocks with variables the quantitative ratios of olivine and pyroxene, which determined their predominant affiliation with the group of harzburgite-lherzolite rocks. Gabbroids of Kiryabinsky massif by total alkalinity and the value of Na/K relationship belong to the normal range of sodium and potassium natrium petrochemical series and close to the products of crystallization of tholeiitic magmas. They are very close to gabbro of ophiolite association and to gabbroids of modern mid ocean ridges. Based on the petro-geochemical materials of study, it can be assumed that the considered massifs of gabbro and serpentinitic ultramafic rocks are tectonically separated parts of a single dunite (harzburgite)-pyroxenite-gabbroic ophiolite complex formed in the junction zone of the Bashkirsky and Uraltausky meganticlinorium. In the Paleozoic in connection with orogenic movements in the Urals gabbro and ultramafic massifs were napped on the Riphean-Vendian median Uraltau mass from enclosing his Zilairsky and Magnitogorsky depressions. This conclusion is confirmed not only by the petro-geochemical similarity of hyperbasites of these related structures, but also by tectonic association of these magmatic bodies to the marginal faults of the thrust type, framing the west and east of the Uraltau zone.