Sequence Stratigraphy and Onlap History of the Donets Basin, Ukraine: Insight into Carboniferous Icehouse Dynamics

The degree to which Permo-Carboniferous cyclothemic successions archive evidence for long-term variations in ice volume during the Late Paleozoic Ice Age is insufficiently resolved. Here we develop the sequence stratigraphy and onlap-offlap history for a 33-my interval of the Carboniferous using the U-Pb calibrated succession of the Donets Basin, Ukraine, in order to assess the relationship between sea-level, high-latitude changes in glacial extent, and climate. Integrated subsurface and outcrop data permit meter-scale correlation of 242 biostratigraphically constrained limestones and coals, and in turn individual cyclothems, across ~250 km of the Donets Basin. Rapid uniform subsidence and basinwide continuity of marker beds indicate Pennsylvanian deposition under relatively stable tectonic conditions. Three scales of sequences (avg. durations of ~140 ky, ~480 ky and 1.6 my) are recognized on the basis of stratigraphic stacking patterns and basinwide architecture of marine to terrestrial facies assemblages. The hierarchy of sequences and the geographic and stratigraphic positions of shifts in base-level sensitive facies across the Donets ramp permit the construction of an onlap-offlap history at a sub-400 ky scale. Major sea-level lowstands occur across the mid-Carboniferous boundary and during the early Moscovian. These lowstands coincide with glacial maxima inferred from high-latitude glacigenic deposits. The middle to late Pennsylvanian is characterized by a stepwise onlap, culminating in an earliest Gzhelian highstand, suggesting contraction of Carboniferous ice sheets prior to the initiation of Early Permian glaciation. The stratigraphic position of climate sensitive facies within individual Donets cyclothems indicates a turnover from seasonal sub-humid or semi-arid climate to everwet conditions during the late lowstand and maximum ice sheet accumulation. Comparison of the stratigraphic and aerial distribution of coals and evaporites in the Donets Basin with the onlap-offlap history further indicates everwet conditions during lowstands and inferred glacial maxima and drier climate during onlap and inferred ice sheet contraction at the intermediate (~0.8 to 1.6 my) and long (106 yr) time-scales. Taken together, the relationship between inferred climate and glacioeustasy suggests a likely teleconnection between high-latitude ice sheet behavior and low-latitude atmospheric dynamics

Experimental Studies for the VVER-440/213 Bubble Condenser System for Kola NPP at the Integral Test Facility BC V-213

In the frame of Tacis Project R2.01/99, which was running from 2003 to 2005, the bubble condenser system of Kola NPP (unit 3) was qualified at the integral test facility BC V-213. Three LB LOCA tests, two MSLB tests, and one SB LOCA test were performed. The appropriate test scenarios for BC V-213 test facility, modeling accidents in the Kola NPP unit 3, were determined with pretest calculations. Analysis of test results has shown that calculated initial conditions and test scenarios were properly reproduced in the tests. The detailed posttest analysis of the tests performed at BC V-213 test facility was aimed to validate the COCOSYS code for the calculation of thermohydraulic processes in the hermetic compartments and bubble condenser. After that the validated COCOSYS code was applied to NPP calculations for Kola NPP (unit 3). Results of Tacis R2.01/99 Project confirmed the bubble condenser functionality during large and small break LOCAs and MSLB accidents. Maximum loads were reached in the LB LOCA case. No condensation oscillations were observed

Chayandinskoye field is the project of new technologies implementation in East Siberia

Modern level of study of structure of Chayandinskoye oil and gas condensate field is characterized by implementation of 3D seismic survey, carried out using a rich azimuth seismic survey system with a fold of 240. Complex seismic and geological conditions within this part of Eastern Siberia dictate high requirements to quality of field 3D seismic operations. A geological section of an area of operations is characterized by Lower Proterozoic formations of crystalline basement and Vendian, Cambrian, Jurassic, Quaternary deposits of the sedimentary cover. The main role in structure of the sedimentary cover is played by clastic and carbonate deposits of Vendian and halogen-carbonate formations of Cambrian Period. Productive part of a section refers to Botuobinsk, Khamakin and Talakh suits and is characterized by a very complex structure of natural reservoirs. Study of productive section structure is caused by need to prepare a field for production drilling and its subsequent development. In order to reveal features of structure of productive part of a section in a region with complex seismic and geological conditions, migration is used up to the summation in the deep region. Wide-azimuth observation system is aimed to study the most important challenges of medium structure such as direction and nature of change in fracture, study of azimuthal anisotropy of velocity characteristics of section and identification of characteristics of elastic properties change. Base technologies to study anisotropy of geological section properties are adapted and introduced into seismic exploration technique. They are as follows: 1) a method based on study of geometric attributes; 2) azimuthal analysis of velocities; 3) azimuth AVO-analysis (AVAZ); 4) anisotropic inversion. Based on results of processing and complex interpretation of seismic data of MOGT-3D works at the Chayandinskoye oil and gas condensate field the most important information about geological structure of sedimentary cover deposits and productive section was obtained. That allowed to significantly clarifying concept of structure of productive formations and geological development of this area. It also allowed determining distribution of reservoirs and evaluating reserves with considered new built structural and tectonic model

Molecular epidemiological study of clinical cases of acute hepatitis E in Belarus

Relevance. The frequency of occurrence of anamnestic antibodies to the hepatitis E virus (HEV) in the general population of the Republic of Belarus is 7.3%, which is clearly not consistent with the low incidence of hepatitis E (HE). Most of primary HEV infections remain undiagnosed. The intensive epidemic process of HEV in the Belarusian population is hidden. Conducting epidemiological studies, including genotyping of HEV sequences isolated on the territory of the republic, makes it possible to more accurately characterize the sources of HEV infection and the mechanisms of its transmission. Aim molecular epidemiological study of two cases of acute hepatitis E detected in patients from Belarus. Materials and methods. During 20212022, samples of biological material were obtained from two patients undergoing treatment with an established diagnosis of acute hepatitis E. Serum samples were tested to detect antibodies to HEV using enzyme immunoassay, HEV RNA was detected in fecal samples using nested RT-PCR. The nucleotide sequence was determined by an automatic sequencer using the Sanger method. Analysis of nucleotide sequences, their genotyping, and calculation of evolutionary distances were performed using MEGA X software. Results. The HEV sequence isolated from a pregnant woman who had an epidemiological episode of alimentary contact with raw pork meat is clustered into a common phylogenetic clade with HEV sequence obtained from the patient from Belarus with a history of kidney transplantation and HEV sequences isolated from a domestic pigs. The HEV sequence isolated from a patient with a history of travel to Pakistan belongs to the HEV genotype 1 and joins a clade of HEV sequences isolated in Pakistan, India, Nepal and Mongolia

Solutions of Gross-Pitaevskii equations beyond the hydrodynamic approximation: Application to the vortex problem

We develop the multiscale technique to describe excitations of a Bose-Einstein condensate (BEC) whose characteristic scales are comparable with the healing length, thus going beyond the conventional hydrodynamical approximation. As an application of the theory we derive approximate explicit vortex and other solutions. The dynamical stability of the vortex is discussed on the basis of the mathematical framework developed here, the result being that its stability is granted at least up to times of the order of seconds, which is the condensate lifetime. Our analytical results are confirmed by the numerical simulations.Comment: To appear in Phys. Rev.

Global patterns in endemicity and vulnerability of soil fungi

Fungi are highly diverse organisms, which provide multiple ecosystem services. However, compared with charismatic animals and plants, the distribution patterns and conservation needs of fungi have been little explored. Here, we examined endemicity patterns, global change vulnerability and conservation priority areas for functional groups of soil fungi based on six global surveys using a high-resolution, long-read metabarcoding approach. We found that the endemicity of all fungi and most functional groups peaks in tropical habitats, including Amazonia, Yucatan, West-Central Africa, Sri Lanka, and New Caledonia, with a negligible island effect compared with plants and animals. We also found that fungi are predominantly vulnerable to drought, heat and land-cover change, particularly in dry tropical regions with high human population density. Fungal conservation areas of highest priority include herbaceous wetlands, tropical forests, and woodlands. We stress that more attention should be focused on the conservation of fungi, especially root symbiotic arbuscular mycorrhizal and ectomycorrhizal fungi in tropical regions as well as unicellular early-diverging groups and macrofungi in general. Given the low overlap between the endemicity of fungi and macroorganisms, but high conservation needs in both groups, detailed analyses on distribution and conservation requirements are warranted for other microorganisms and soil organisms

APPROACHES TO MODELING INTERFACING SURFACES WITH SPLINES

This article presents the results of the modelling interfacing surfaces with splines fit for further use in finite element engineering analysis. The process of modeling interfacing surfaces is divided into two levels based on the superposition principle: the level of modelling waviness and the level of modelling roughness

Usolka section (southern Urals, Russia): a potential candidate for GSSP to define the base of the Gzhelian Stage in the global chronostratigraphic scale

Conodont species Streptognathodus simulator Ellison, 1941 has been proposed recently to define the Kasimovian-Gzhelian boundary in the global chronostratigraphic scale.The species distributed globally and traditionally has been used as a marker of the base of the Gzhelian Stage in the type sections in Moscow Basin and Urals. Recent studies of conodont taxonomy and biostratigraphy in southern Urals have established the chronocline with ascendant and descendant to Streptognathodus simulator species. Usolka section proposed here as a potential candidate for the GSSP (Global Stratotype Section and Point) to define the global Gzhelian Stage at the FAD of the Streptognathodus simulator within the chronocline Streptognathodus praenuntius Chernykh, 2005 – St. simulator Ellison, 1941 – St. auritus Chernykh, 2005. The chronocline recovered within 2.7 m of beds 4 and 5 at the Usolka section, with all three species described and properly figured. No obvious interruptions in sedimentation are recorded within the Kasimovian-Gzhelian transition there. Several volcanic ash beds are present below and above the proposed boundary, making radiometric calibration highly possible in the near future. Mode of preservation of conodonts with a CAI of around 1.0–1.5 provides excellent basis for the geochemical studies. Accessibility presently is adequate, and this exposure will be improved and maintained permanently for interested scientists. Future access will be guaranteed by means of legislative action to create a scientific preserve

Usolka section (southern Urals, Russia): a potential candidate for GSSP to define the base of the Gzhelian Stage in the global chronostratigraphic scale

International audience(CE 9 octobre 2013, n° 359161, MJA (SELAFA), au Lebon ; AJDA 2013. 2002 ; D. 2014. 2136, obs. D. R. Martin et H. Synvet