Common Neoproterozoic–Early Paleozoic Evolution of Ore-Bearing Sedimentary Complexes in the Southern Siberian Craton

Doklady Earth Sciences - A comparison of the lithological–geochemical parameters for the deposits of the Dalnetaiga series of the Bodaibo synclinorium (the Buzhuikhta and Khomolkho...     

Minerals of the Bournonite–Seligmannite Series in Ore of the Beresitovoe Deposit,Upper Amur Region,Russia

New data are presented on segregations and compositions of bournonite-seligmannite series of minerals in gold-bearing veinlets of the Beresitovoe deposit located in the eastern part of the Mongolia–Okhotsk Orogenic Belt. It was established that these minerals represent a discrete series of stoichiometric solid compounds with As formula coefficients varying from 0.2 to 1.2. It is shown that minerals of this series are characteristic of ore deposits that undergo high-grade metamorphism, the P–T conditions of which are sufficient for melting of primary sulfides.     

New U-Pb isotopic data on the age of metamorphic and igneous rocks of the western margin of the Selenga-Stanovoi orogenic belt

New data on the isotopic age of zircons from metamorphic and igneous rocks are given for the Berezitovoe and Kirovskoe deposits located in the eastern margin of the Selenga-Stanovoi orogenic belt. The zircons were studied with the LA-ICP-MS method in the State Key Laboratory of Continental Dynamics, Northwestern University, Sian, Shansi province, People’s Republic of China. The results allowed us to reveal three age epochs in formation of the eastern part of the Selenga-Stanovoi orogenic belt (1.87 Ga; 380–330 Ma; 138–125 Ma), which have significant importance for understanding of the geological structure of the south-eastern framework of the North Asian craton.     

Tritium chain of the hydrogen cycle of thermonuclear reactions in the solar interior

The tritium chain of the hydrogen cycle on the Sun including the reactions ³He(e⁻, ν _e) ³H(p, γ)⁴He is considered. The flux of tritium neutrinos at a distance of 1 AU is 8.1 × 10⁴ cm⁻² s⁻¹. It exceeds the neutrino flux from the (hep)-reaction by one order of magnitude. The radial distribution of the yield of ³H neutrinos inside the Sun and their energy spectrum, which has the form of a line at an energy of 2.5–3.0 keV, have also been calculated. The flux of thermal tritium neutrinos is accompanied by a very weak flux of antineutrinos (∼10³ cm⁻² yr⁻¹) with an energy below 18.6 keV. These antineutrinos are produced in the URCA processes ³He ⇆ ³H.     

Isotopic (Sm–Nd,Pb–Pb,and δ<Superscript>34</Superscript>S) and Geochemical Characteristics of the Metasedimentary Rocks of the Baikal–Patom Belt (Northern Transbaikalia) and Evolution of the Sedimentary Basin in the Neoproterozoic

This paper reports the results of a detailed isotopic (Sm–Nd, Pb–Pb, and δ³⁴S) and geochemical studies of Neoproterozoic metasedimentary rocks from the Patom and Bodaibo domains of the Baikal–Patom belt (northern Transbaikalia). It was shown that the metasedimentary rocks of these domains are strongly variable in their geochemical and isotope geochemical characteristics. Regular variations in these characteristics were observed, and their correlation with the main stages of the evolution of the sedimentary paleobasin in the Neoproterozoic was established.     

The first discovery of platinum group minerals in black shale gold ores of the Degdekan deposit, Northeast Russia

The results of investigation of heavy fraction minerals from the Degdekan deposit hosted by the lower portion of stratified Mid Permian sediments are presented; the investigation was conducted via electron microscopy using a QEMSCAN hardware and software instrument equipped with a QUANTAX quantitative analysis system. The following mineral phases of platinoids have been detected for the first time: native osmium, rutheniridosmine, osmiridium, ruthenosmiridium, laurite, iridarsenite, and Ru, Os, and Ir arsenide.     

Methodology of the experimental study of the state of spent nuclear fuel on the bottom of arctic seas

A methodology of experimental simulation of the state of spent nuclear fuel that is situated on the sea bottom as a result of some catastrophes or dumping is developed. Data on long-term (more than 2000 days) experiments on the estimation of the ⁸⁵Kr and ¹³⁷Cs release rate from spent nuclear fuel (fragments of irradiated UO₂ pellets) were first obtained; these estimates prove the correctness of the hypothesis put forward by us in the early 1990s concerning an earlier ⁸⁵Kr release (by one order of magnitude higher than that of ¹³⁷Cs) as compared to other fission fragments in the case of the loss of integrity of a fuel containment as a result of corrosion on the sea bottom. The method and technique of the onboard ⁸⁵Kr and ¹³⁷Cs sampling and extraction (as well as the sampling of tritium, a product of triple ²³⁵U fission) and their radiometric analysis at coastal laboratories are developed. Priority data on the ⁸⁵Kr background in the bottom layers of the Barents and Kara Seas and the ¹³⁷Cs and ³H in these seas (state of 2003) are presented. Models necessary for the estimation of the dilution of the fission products of spent nuclear fuel and their transport on the bottom in accident and dumping regions are developed. An experimental method for the examination of the state of spent nuclear fuel on the sea bottom (1 expedition each 2–3 years) by the ⁸⁵Kr release into the environment (a leak tracer) is proposed; this release is an indicator of the destruction of a fuel containment and the release of products of spent nuclear fuel in the case of ²³⁵UO₂ corrosion in sea water.     

Evolution of the Kara Ore-Magmatic System (Eastern Transbaikalia,Russia): Experience in Applying Small-Scale Geochemical Survey

Geology of Ore Deposits - The article discusses a novel methodological approach to deciphering the evolution of ore-magmatic systems (OMS), based on the study of geochemical fields associated with...     

The first detailed δ13Соrg record in Permo-Triassic boundary deposits in the Kolyma–Omolon region (Northeast Asia)

Doklady Earth Sciences - We have obtained the first detailed δ13Сorg record in Permian-Triassic boundary sediments in deepwater facies in Northeast Asia (Kolyma–Omolon region,...     

Geochemical characteristics of sediments from Lake El’gygytgyn,Chukotka Peninsula,as indicators of climatic variations for the past 350 ka

This paper presents data on the inorganic geochemical characteristics of the sediments from Hole LZ1024 (Lake El’gygytgyn, Chukotka, 67°30′ N 172°08′ E). It is demonstrated how these data are associated with climatic variations during isotope stages 1–9. The sediments of the warm stages are characterized by elevated contents of SiO₂, CaO, Na₂O, K₂O, and Sr and low concentrations of TiO₂, Al₂O₃, MgO, and Fe₂O₃. It has been established that the geochemical parameters correlate with global climatic variations.