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.
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 article considers the geological structure of the Tash-Yarsky pyritepolymetallic deposit located in the northern part of the Magnitogorsky megazone near the large (about 300 km2) Akhunovsky granite massif. The petrographic study of the hornfelses made it possible to identify a number of mineral parageneses containing cordierite, garnet, and biotite, which are installed respectively from the massif contact at a distance no further than 0,6–0,8; 1,2–1,5 and 2,3–2,5 km. Based on the temperature dependence of the maximum iron content of sphalerite, high temperatures of metamorphism (500–610 °С) were obtained for ores. According to garnet-biotite and garnet-cordierite thermobarometers for rocks close to the massif, the transformation temperature is 720–750 °С, and the pressure is 8,9–9,1 kbar. With a distance of 700–850 m from the contact of granitoids, the temperature does not exceed 620–640 °C, and the pressure is 5,3–5,4 kbar; at a distance of 1,3 km, respectively — 550–560 °C and 4,6–4,7 kbar.
Реферат. На основе материалов по детальной минералогии и изотопно-геохимическим характерис-тикам магматических пород Шатакского комплекса разработана детальная модель его формирования. Показано, что генезис всего разнообразия магматических пород комплекса (пикритов, базальтов, риолитов) удовлетворяет условиям AFC (Assimilation Fractional Crystallization) процесса, заключаю-щегося в фракционировании ликвидусных фаз (оливин ± клинопироксен) и накоплении флюидной фазы в прикровельной части камеры/очага, с одной стороны, и ассимиляции вмещающих пород -с другой. Ключевые слова: Шатакский комплекс, Rb-Sr изотопна я система, Sm-Nd изотопная система, пикриты, базальты, риолиты, AFC-процесс, фракционирование, ассимиляция
MODEL OF ORIGIN OF MAGMATIC ROCKS OF THE SHATAK COMPLEX
S. G. Kovalev, S. I. Vysotsky, S. S. KovalevAbstract. Based on materials on detailed mineralogy and isotope-geochemical characteristics of igneous rocks of the Shatak Complex, a detailed model of its formation is given. It is shown that the origin of the diversity of igneous rocks (picrites, basalt, rhyolite) satisfies the conditions of AFC (Assimilation Fractional Crystallization) process that occurs as a fractionation of liquidus phases (olivine ± clinopyroxene) and an accumulation of a fluid phase in the upper part of the chamber on one side and assimilation host rocks on the other.
Аннотация. В статье рассмотрено геологическое строение Троицкой площади, расположенной в центральной части Зауральского поднятия. Особое внимание уделено городищенской, алексеевской, чулаксайской свитам, потаповской и комсомольской толщам, в пределах которых развиты углеродистые отложения, а также чебаркульско-казбаевскому и дружнинскому габбро-гипербазитовым комплексам. Все они опробованы на золото, серебро, платину, палладий, вольфрам и молибден. Установлено, что в черносланцевых образованиях городищенской свиты в долине
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