Biostratigraphy versus isotope geochronology: Testing the Urals island arc model

Formation of the Urals volcanic-hosted massive sulphide (VHMS) deposits is considered to be related with the intra-oceanic stage of island arc(s) development in the Upper Ordovician–Middle Devonian based on the biostratigraphic record of ore-hosting sedimentary rocks. However, the direct Re-Os dating of four known VHMS systems in the Urals gives significantly younger Re-Os isochron ages ranging from 355 ± 15 Ma up to 366 ± 2 Ma. To address this discrepancy, we performed SHRIMP U-Pb dating on zircons extracted from rhyodacites (Eifelian biostratigraphic age of 393–388 Ma) from the footwall of the Alexandrinka VHMS deposit which has a Re-Os isochron age of sulphides of 355 ± 15 Ma. New 206Pb/238U mean age of 374 ± 3 Ma (MSWD = 1.4 and probability = 0.11) is considered to be the crystallisation age of the host volcanic rock. This age is ca. 15 Ma younger than the Eifelian (393–388 Ma) biostratigraphic age and overlaps the Frasnian–Famennian boundary (372 ± 2 Ma), characterised by the final stages of Magnitogorsk Arc – East European continent collision. Such an inconsistency with geochronological age may be due to a reburial of conodonts during resedimentation as a result of erosion of older rocks in younger sedimentary sequences

Silurian to Carboniferous Re-Os molybdenite ages of the Kalinovskoe, Mikheevskoe and Talitsa Cu-Mo porphyry deposits in the Urals: implications for geodynamic setting

The Urals can be regarded as a significant Cu-Mo-porphyry province, hosting over 30 porphyry deposits. Although their geological structure and ore-forming processes have been studied in great detail, uncertainty remains about their age and related geotectonic setting. In this contribution we report for the first time the Re-Os dating of molybdenites from three Cu-Mo porphyry deposits, namely Kalinovskoe, Mikheevskoe and Talitsa. Three molybdenite samples from the Kalinovskoe deposit yield Silurian Re-Os ages ranging from 427.1 Ma to 431.7 Ma (mean 429.8 ± 4.8 Ma; 2σ standard deviation), and a Re–Os isochron age of 430.7 ± 1.3 Ma (MSWD = 0.63), which coincides with previous U-Pb zircon dating of ore-hosting diorites from the same ore field (427 ± 6 Ma). The molybdenite from the Mikheevskoe deposit gives Re-Os ages of 357.8 ± 1.8 Ma and 356.1 ± 1.4 Ma (mean 357.0 ± 2.4 Ma; Carboniferous/Tournaisian), which corresponds to previous U-Pb dating of zircons from the diorite hosting porphyry deposit (356 ± 6 Ma). The molybdenite from Talitsa Mo-porphyry deposit yields the youngest Re-Os ages of 298.3 ± 1.3 and 299.9 ± 2.9 Ma (mean 299.1 ± 2.3 Ma) at Carboniferous-Permian boundary. Thus, the studied Cu and Mo porphyry deposits are not synchronous and belong to distinct tectonic events of the Urals

EFFICIENCY OF THE INVESTMENT MARKET IN RUSSIA (BY THE EXAMPLE OF LLC "COMPANY BKS")

Статья посвящена инвестиционному рынку в России. В статье данный вопрос будет рассматриваться на примере брокерской организации ООО «Компания БКС». В статье освещен анализ рисков финансового рынка и инвестиционных компаний и причины их возникновения, а также методы управления брокерскими рисками, которые уже хорошо изучены, но остаются эффективными по сей день. Актуальность темы исследования. В наши дни люди проявляются всё больший интерес к инвестициям, это влечет за собой появление новых организаций, занимающихся брокерской деятельность и предоставляющих услуги инвестиционного консультанта. Брокерские организации помогают физическим и юридическим лицам найти направления для выгодного вложения капитала, минимизировать финансовые риски, увеличить оборот капитала, а также оптимально его распределить. Помимо вышеперечисленных преимуществ работы брокерских организаций, любая инвестиционная компания также тесно связана со сложной системой рисков и вынуждена ежедневно искать пути для их минимизации и ликвидации. Цель статьи заключается в выявлении рисков инвестиционных компаний и их анализ. В данной статье рассмотрена деятельность брокерской организации, ее основные задачи, статистика инвестиционных продуктов, которые пользуются особой популярностью среди клиентов, основные риски компании и методы их предотвращения, а также проведен краткий анализ эффективности компании и динамики основных финансовых показателей за последние три года. На основании полученных данных делается вывод о том, что основные риски компании зависят не только от собственных усилий управляющих, но и прежде всего от внешних факторов, определяемых рыночной конъюнктурой, на которые крайне сложно оказать влияние.The article is devoted to the investment market in Russia. In the article this issue will be considered on the example of the brokerage organization "BKS Company LLC". The article highlights the analysis of financial market risks and investment companies and their causes, as well as methods of brokerage risk management, which have already been well studied, but remain effective to this day. Topicality of the research theme. These days, people are increasingly interested in investments, it entails the emergence of new organizations engaged in brokerage activities and providing investment advisory services. Brokerage organizations help physical and juridical persons to find directions for profitable investment of capital, to minimize financial risks, to increase the capital turnover, as well as optimally distribute it. Besides above-mentioned advantages of brokerage organizations, any investment company is also closely connected with a complex system of risks and has to look for ways to minimize and liquidate them every day. The purpose of this article is to identify the risks of investment companies and their analysis. In this article the activity of a brokerage company, its main tasks, statistics of investment products which are especially popular among clients, main risks of the company and methods of their prevention, and also the brief analysis of company efficiency and dynamics of main financial indicators for last three years are considered. Based on the data obtained, the conclusion is made that the main risks of the company depend not only on the managers' own efforts, but primarily on external factors determined by the market conditions, which are extremely difficult to influence

Porphyry deposits of the Urals: geological framework and metallogeny

Most of the Cu (± Mo,Au) porphyry and porphyry-related deposits of the Urals are located in the Tagil-Magnitogorsk, East-Uralian Volcanic and Trans-Uralian volcanic arc megaterranes. They are related to subduction zones of different ages: (1) Silurian westward subduction: Cu-porphyry deposits of the Birgilda-Tomino ore cluster (Birgilda, Tomino, and Kalinovskoe) and the Zeleny Dol Cu-porphyry deposit; (2) Devonian Magnitogorsk eastward subduction and the subsequent collision with the East European plate: deposits and occurrences are located in the Tagil (skarn-porphyry Gumeshevskoe etc.) and Magnitogorsk terranes (Cu-porphyry Salavat and Voznesenskoe, Mo-porphyry Verkhne-Uralskoe, Au-porphyry Yubileinoe etc.), and probably in the Alapaevsk-Techa terrane (occurrences of the Alapayevsk-Sukhoy Log cluster); (3) Late-Devonian to Carboniferous subduction: deposits located in the Trans-Uralian megaterrane. This includes Late-Devonian to Early Carboniferous Mikheevskoe Cu-porphyry and Tarutino Cu skarn-porphyry, Carboniferous deposits of the Alexandrov volcanic arc terrane (Bataly, Varvarinskoe) and Early Carboniferous deposits formed dew to eastward subduction under the Kazakh continent (Benkala, etc.).(4) Continent-continent collision in Late Carboniferous produced the Talitsa Mo-porphyry deposit located in the East Uralian megaterrane. Porphyry mineralization of the Magnitogorsk megaterrane shows an evolving relationship from gabbro-diorite and quartz diorite in the Middle Devonian (Gumeshevskoe, Salavat, Voznesenskoe) to granodiorite-plagiogranodiorite in the Late Devonian (Yubileinoe Au-porphyry) and finally to granodiorite in the Carboniferous (Talitsa Mo-porphyry) with a progressive increase in total REE, Rb and Sr contents. This corresponds to the evolution of the Magnitogorsk terrane from a volcanic arc which gave place to an arc-continent collision in the Famennian

Erratum to: Crustal Source of Pb and S at the Yubileynoe Porphyry Gold Deposit (Southern Urals, Kazakhstan): High Precision Pb–Pb and δ³⁴S Data (Geology of Ore Deposits, (2021), 63, 3, (173-184), 10.1134/S107570152103003X)

An Erratum to this paper has been published: https://doi.org/10.1134/S1075701521300012

Crustal Source of Pb and S at the Yubileynoe Porphyry Gold Deposit (Southern Urals, Kazakhstan): High Precision Pb–Pb and δ³⁴S Data

Abstract: The Yubileinoe large gold deposit, located at the southern end of the Magnitogorsk megazone, is the only known representative of the Au–porphyry systems in the Southern Urals. It is genetically related to granitoids formed in a suprasubduction setting under mature oceanic island arc environment/setting. The obtained isotope (Pb–Pb and δ34S) data indicate the input of mineral-forming components into the Au–porphyry system of the deposit, mainly from granitoid melts, confirming a common source of ore material and ore-bearing granitoids. The geochemical and isotopic characteristics of granitoids indicate the leading role in their genesis of the crustal source, which is considered Late Precambrian continental crust