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Details of the Early-Middle Frasnian boundary interval of the Pymvashor River section (Timan-Pechora Basin, Cis-Urals, in the far north of European Russia) are revealed by biostratigraphically constrained carbonate (d13Ccarb) and organic carbon (d13Corg) stable data. The studied interval corresponds to the lower part of the Domanik Formation, which consists of interbedded limestone and shale beds. Organic-rich black shale that lacks bioturbation and benthic organisms indicates an oxygen-depleted depositional environment. Detection of isorenieratene derivatives in organic matter indicates that anoxia was present in the photic zone during deposition. The Pymvashor River section contains d13Ccarb and d13Corg isotope records related to the Early-Middle Frasnian isotope Event. The similarity between the Cis-Uralian (this study) and the Chinese d13Ccarb and d13Corg oscillations, including the twostep pattern of the recorded major positive excursions, suggests a robust correlation of the Late Devonian Early-Middle Frasnian isotope Event and minor intra-event excursions. Magnitude of variations and values of d13Corg and d13Ccarb in the punctata Zone in the Pymvashor River section are minor than those observed in the North American, Polish, and Chinese successions. Such difference may reflect specific variation of the local environments. [ABSTRACT FROM AUTHOR]

The article offers information on the study based on the age and substance sources of the Ilmeno-Vishnevogorsky Alkaline Complex (IVC). It mentions that isochron method, a radiometric dating technique, was used for the dating of the main rock types of the IVC. It also adds that sources of substances for magmatic rocks and ores were established by using initial isotope characteristics of rocks and minerals of the IVC. It also adds that IVC has a source similar as that of ultra basic alkaline formation (UAC) source regarding the magma formation. It mentions of geochronological data that provides evidence that the IVC intruded rocks underwent significant transformations in the course of consolidation of the Ural Mountains.

The article focuses on the zones of paleospreading and crustal extension in the Ural Mountains, Russia runs from north to south through western Russia. It states that the fragments of the sheeted dyke complex extends with breaks over 60 kilometers in the eastern framework of the Revda massif, Urals Region, Russia. It mentions that these dykes are made of fine grained gabbrodolerites and porphyritic dolerites with plagioclase and hornblende phenocrysts, as well as less common aphyric and fine porphyritic varieties.

This study presents new compositional and S-Os isotope data for primary Ru-Os sulfides within a platinum-group mineral (PGM) assemblage from placer deposits associated with the Verkh-Neivinsk massif, which is part of the mantle ophiolite association of Middle Urals (Russia). The primary nature of Ru-Os sulfides represented by laurite (RuS2)–erlichmanite (OsS2) series is supported by occurrence of euhedral inclusions of high-Mg olivine (Fo92–94) that fall within the compositional range of mantle (primitive) olivine (Fo 88–93). The sulfur isotope signatures of Ru-Os sulfides reveal a range of δ34S values from 0.3 to 3.3‰, with a mean of 2.05‰ and a standard deviation of 0.86‰ (n = 18), implying that the sulfur derived from a subchondritic source. A range of sub-chondritic initial 187Os/188Os values defined for Ru-Os sulfides (0.1173–0.1278) are clearly indicative of derivation from a sub-chondritic source. Re-depletion (TRD) ages of the Verkh-Neivinsk Ru-Os sulfides are consistent with prolonged melt-extraction processes and likely multi-stage evolution of highly siderophile elements (HSE) within the upper mantle. A single radiogenic 187Os/188Os value of 0.13459 ± 0.00002 determined in the erlichmanite is indicative of a supra-chondritic source of HSE. This feature can be interpreted as evidence of a radiogenic crustal component associated with a subduction event or as an indication of an enriched mantle source. The mineralogical and Os-isotope data point to a high-temperature origin of the studied PGM and two contrasting sources for HSE in Ru-Os sulfides of the Verkh-Neivinsk massif. [ABSTRACT FROM AUTHOR]