Suchergebnisse

The article describes the geological structure of the Turgoyak granitoid massif (γϬС1–2ts), Urenga (RF2ur) and Uytash (RF3uš) suites. In the Late Vendian time the rocks first experienced regional metamorphism under the conditions of the cummingtonite-amphibolite facies at a temperature of 550–595 °C and a pressure of 250400 МПа, and then in local areas — diaftoresis (T=520530 °C and P=130170 МПа). During the formation of the Turgoyak massif (T=770810 °C and P=210250 МПа), the rocks of the Urengin and Uytash suites were subjected to contact metamorphism. This metamorphic processes made the black shale gold to remove from the black shale zone of the amphibole-hornfels facies and caused its redeposition within the albite-epidote-hornfly zone.

The article presents new data on the geology and petrogeochemistry of the Magnitogorsk, Nepljuevsk and Kanzafarov rock complexes. Their belonging to the gabbro-granite formation has been proved. These data give opportunity to combine the South Ural and Middle Ural segments of the Early Carboniferous subduction rift into a single submeridional structure. Its formation took place at the Devonian island arc rear basin. The arc was overthrusted on the western edge of the East Ural Rise during the collision stage of the Southern Urals development. The Cu-Mo specialization of granitoids of the Magnitogorsk and Nepljuevsk complexes has been established.

The paper presents materials on geology and geochemical specialization Riphean clastic rocks of Bashkirian meganticlinorium, including carbonaceous shales and conglomerates. In the last set high content of gold and platinum group elements, confined mainly to heavily dislocated zones. The conclusion is that the potentially ore-bearing zones in clastic sediments of the Bashkir meganticlinorium is a result of polygenic multistep processes, caused geodynamic development of the region in the Riphean-Vendian time.

The article describes the geological structure of the Sarsanginsky gabbro-diorite-plagiogranite complex located in the border zone of the Middle and South Urals. The formation of its massifs took place in the late Silurian time in the abyssal zone at depths of about 6,5–7,0 km. The temperature range of crystallization of granodiorites was 900–990 С, and for gabbro 1180–1280 С. The system pressure at this moment corresponded to 190–200 MPa. The gabbro that make up the massifs under consideration were formed under stretching conditions on the oceanic crust. In terms of petrogeochemical features, they correspond to rocks at the base of island arcs and belong to the ophiolite formation.

Geological structure and physic-chemical characteristics of the Stepninsky, Vandyshevsky, Biryukovsky and Uisky massives related to the Stepninsky monzogabbro-granosyenite-granite complex are described. A conclusion was made that the depth of crystallization of the granitoid massives changes in this row from hypabbyssal to hypabyssal-subsurface facies. It is shown that the intrusions of the complex belong to the intraplate type. At the early stage, the basicintermediate rocks of a deep-mantle genesis were formed, which can be regarded as a derivative of an individual plume; at the later stage they were changed by granites and leucogranites of the calc-alkaline type, formed as a result of anatexis of the lower crust. The rocks of the later stage have a rare-metal geochemical specialization.

The Siratur gold deposit is located in the northern part of the South Ural segment of the Main Ural Fault. Its ore zone is confined to the area of the tectonic junction of the serpentinite of the Nurali massif and the submeridional strip of carbonaceous schists of the Ordovician Polyakovka Formation. Its composition is widely represented basalts with chemical characteristics of the main effusive rocks of the mid-ocean ridges. In the black shale deposits of the Siratur deposit, gold ore mineralization is mainly represented by the gold-sulfide vein-disseminated type, and in the listwanite-beresite complex, gold-quartz-low-sulfide vein-streaked type. Microprobe studies of zolotins showed that gold in ores of the first type has a low-qality of 670–820, and in the second — 940–970. The deposit can be attributed to the polygenic and polychronous type.