Subpolar Urals Research Articles

The first find of Pd-telluride (Merenskyite) in placer gold of the Subpolar Urals and its forecasting significance

The first find of Pd-telluride (Merenskyite) in placer gold of the Subpolar Urals and its forecasting significance

New species of stromatoporoidea from the Upper Ordovician and Silurian of the Subpolar Urals

Stromatoporoidea are widespread in the Upper Ordovician and Silurian beds of the Kozhim River (western slope of the Subpolar Urals). Five new species Cystostroma prodigiosum sp. nov., Stylostroma flabellatum sp. nov., Labechiina arguta sp. nov., Ecclimadictyon faveolatum sp. nov., and Araneosustroma astroplexum sp. nov. are described.

New data on the age of subalkaline magmatism at the eastern margin of the east European paleocontinent and estimation of the rate of longitudinal opening of the early Paleozoic rift

Subalkaline igneous rocks are widespread in the Main Ural Fault Zone as a chain of dikes and minor intrusions that crosscut the Ordovician sequences deposited at the eastern (Uralian) margin of the East European paleocontinent (Fig. 1). In the Polar Urals, the subalkaline rocks belong to the Paipudyn rhyolite complex, the Manitanyrd trachybasalt–trachyrhyolite complex, and the Pozhem rhyolite complex. In the Subpolar and northern Urals, they occur in the Bol’shepatoka and Malinovka trachyrhyolite complexes. The Verkhneserebryanka trachybasalt–trachyte complex, the Vaganovka gabbro–syenite complex, the Kordonokamenka alkali granite complex, and the Belokamenka syenite complex are recognized in the central Urals. Most of these complexes are still poorly characterized in terms of petrography, geochemistry, and reliable isotopic dating. The age of some complexes is based only on random K–Ar determinations of wholerock samples. These complexes are attributed to tectonomagmatic reactivation in the Ordovician, Carboniferous, and Triassic–Jurassic.

On the taxonomy of the Paleozoic red algae of the family Ungdarellaceae

The history of the genus Ungdarella and the family Ungdarellaceae is discussed. Data on thallus morphology in members of the family are analyzed. Three new genera, Ungdarelloides, Urtasimella, and Suundukella, and a new species of the genus Ungdarella, U. mitchaelensis sp. nov., are described. The type localities of these taxa are briefly outlined. All these taxa come from Middle Carboniferous carbonate rocks of the Subpolar and Southern Ural Mountains.

Givetian deepwater sediments in the western slope of the Subpolar Urals

Givetian deepwater sediments in the western slope of the Subpolar Urals

New species of syringoporids from Eifelian deposits of the Subpolar Ural Mountains

A high diversity of tabulate corals in Eifelian deposits of the Syv“yu River basin (Subpolar Urals) is reported for the first time. Most of the corals are represented by colonies of syringoporids. Five new species Syringopora parva sp. nov., S. insueta sp. nov., S. indecora sp. nov., Tetraporinus syvjuensis sp. nov., and Armalites serotinus sp. nov. are described.

Rodent communities in the sub-polar Ural mountains

Distribution of the rodent communities in the Sub-polar Urals is analysed. This part of the range, between 64° and 66°N, includes the highest peaks, is very scarcely settled and has been rarely studied. However, the area is interesting for biogeography, being a border zone separating European and Siberian lowland faunas. Comparison of results with those from expeditions undertaken in 1927 and in 1972, allows to evaluate changing trends in the local rodent communities, and to relate these trends to changes in the environmental conditions. The results help to emphasize the barrier role played by Sub-polar Urals for the species of rodents inhabiting both sides of the range, and also show the shifting of southern rodent forms northwards, or the moving upwards of other lowland species. This could be seen as an additional evidence of current climate warming trends.

Isotopic signals from late Jurassic–early Cretaceous (Volgian–Valanginian) sub-Arctic belemnites, Yatria River, Western Siberia

This contribution presents the first detailed oxygen and carbon isotope record from the latest Jurassic–early Cretaceous interval of the Yatria River, subpolar Urals, Siberia. Isotopic compositions have been determined on well-preserved belemnite samples from the genera Lagonibelus , Cylindroteuthis and Acroteuthis . These new data indicate a shift to lower temperatures from the late Volgian into the late Valanginian, with some warmer phases recognized within the Ryazanian and earliest Valanginian. The lowest temperatures of the late Valanginian, consistent with subfreezing polar temperatures, are coincident with an inferred eustatic sea-level fall. A late Valanginian positive shift in carbon isotopes correlates with the carbon isotope excursion recorded from Tethyan successions. The most positive carbon isotope values correspond to the most positive oxygen isotope values (and hence lowest palaeotemperatures). In the absence of widespread Valanginian organic-rich black shale deposition, the carbon isotope excursion may point to increased storage of organic carbon in coastal areas and/or enhanced preservation within stratified waters in high-latitude basins. At these higher latitudes, where rates of weathering were presumably much lower because of the prevalent cold climate, the isotopic data may point to pulses of productivity being brought about by increased riverine nutrient transfer and also by nutrients being released by the melting of ice. The correlation between positive carbon isotopes and cool climates may indicate the effectiveness of these high-latitude carbon sinks and their ability to draw down atmospheric CO 2 , resulting in an ‘inverse greenhouse’ effect.

Structure and Depositional Environments of Lower to Upper Permian Boundary Sediments in the Kozhim River Section (Subpolar Urals)

It is established that the boundary between the Kozhim (P1) and Kozhim Rudnik (P2) formations in the Kozhim River section is drawn inside a member, about 100 m thick, composed of six lithocycles of similar structure. They reveal a general upsection coarsening of clastic material and incorporate six to ten layers. Based on the analysis of repeating combinations of genetic parameters (granulometric composition, structures, taphocoenoses, and others), we have recognized and described seven units of complete ideal lithocycles in the studied section. Evidently, each cycle was produced by processes related to the accumulation and burial of deltaic fans. The geohistorical rank of the boundary between the Kozhim (P1) and Kozhim Rudnik (P2) formations is very low and does not fit any significant boundary of the evolution of depositional environment in paleobasin. The revealed surfaces of intraformational washouts and hiatuses, as well as the wide range of facies changes, which significantly controls the composition of organic remains, do not support the proposition to establish here the global stratotype point for the lower boundary of the Upper Permian.

Argon and helium isotopes and the main fluid components in the quartz crystals from the subpolar ural

Argon and helium isotopes and the main fluid components in the quartz crystals from the subpolar ural

The age of relief in northern, subpolar and polar Urals

Reexamination of geological data available for the Northern, Subpolar and Polar Urals indicate that the relief of the area, originally considered to be ancient, is much younger in age. The absence of weathered crusts, Neogene deposits and other indirect evidence suggest a regional uplift of the area during the Neogene. -- IGR Staff.

Discovery of a Diplochone (Rugosa) in the Silurian of the Subpolar Urals

Diplochone kozhimica n. sp. is described from deposits of Ludlow age in the northern Urals. One of the described specimens grew on the surface of a colony of Squameofavosites sp. The morphologic effects on the rugose coral include basal processes that extend into the tabulate corallites, a broad, enlarged base, and stereoplasmic thickening of skeletal elements. — W. A. Oliver, Jr..