Wind dynamics and circumstellar extinction variations in the T Tauri star RY Tau

The wind interaction with the dusty environment of the classical T Tauri star RY Tau has been investigated. During two seasons from 2013 to 2015, we carried out a spectroscopicmonitoring of this star with simultaneous BV R photometry. A correlation between the stellar brightness and the radial velocity of the wind determined from the Hα and Na D line profiles has been found. The irregular stellar brightness variations are shown to be caused by extinction in a dusty disk wind at a distance of about 0.2 AU from the star. We hypothesize that the circumstellar extinction variations result from a cyclic rearrangement of the magnetosphere and coronal mass ejections, which affect the dusty disk wind near the inner boundary of the circumstellar disk.     

Late Pleistocene Catastrophic Landslide from the Balaganchik Ridge: Evidence from the Mitoga 2 Reference Section (Western Kamchatka)

Lithology and Mineral Resources - A new reference section of the Okhotsk seaside of Kamchatka in the Mitoga 2 River area is studied and dated for the first time (14C and 230Th/U). Sedimentary...     

Numerical Simulation of Seismic Wave Propagation in Coastal Zones

Doklady Earth Sciences - The problem of tsunami warning and the use of the grid-characteristic method developed for studying wave processes in heterogeneous media is addressed. A multilayer...     

Carbon,oxygen, and sulfur isotope compositions and model of the Silurian rock formation in northwestern Belarus

The paper describes the results of study of the Silurian clayey–carbonate rocks ranging from the Telychian Stage (Llandovery) to the Gorstian Stage (Ludlow) recovered by the Borehole Davtyuny 3k in northwestern Belarus. Rocks of the Sheinwoodian Stage demonstrate a positive excursion of δ¹³C with amplitude of 4.7‰, marking the Ireviken biotic event recorded in the global chemostratigraphic curve. Values of δ¹⁸O for the carbonate material in the studied section (25.5–29.2‰ SMOW) are close to those for Silurian rocks from the Baltic region, Scandinavia, Ukraine, Poland, and Canada. The whole section contains postsedimentary gypsum as nodules and the infilling of fissures and fenestrae. Values of δ³⁴S in gypsum (21.3–26.7‰ CDT) are close to those for the Silurian rocks on the Phanerozoic isotope plot. The formation of gypsum was related to a partial development of the supralittoral environment over the sublittoral and littoral clayey–carbonate substrate. The seawater accumulated in lowlands of the supralittoral plain after storms was intensely concentrated during arid conditions and accumulated in the clayey–carbonate sediment. The subsequent underground evaporation promoted the formation of gypsum as nodules in the unlithified sediments and the infilling of fissures and fenestrae in the lithified rocks.     

C, О, S,and Sr Isotope Geochemistry and Chemostratigraphy of Ordovician Sediments in the Moyero River Section,Northern Siberian Platform

The ⁸⁷Sr/⁸⁶Sr ratio in gypsum and limestones of the Ordovician section of the Moyero River decreases from the bottom upward from 0.7091?0.7095 in the Irbukli Formation (Nyaian Regional Stage, ~Lower Ordovician Tremadocian Stage) to 0.7080 in the upper part of the Dzherom Formation (Dolborian Regional Stage, ~Upper Ordovician Katian Stage), which is well consistent with biostratigraphic subdivision of the section and existing concept concerning the strontium isotope evolution of the World Ocean. The most characteristic feature of the carbon isotope curve is decrease of δ¹³С values in carbonates from weakly positive values (0.5…1.1‰) in the Irbukli Formation (Nyaian Regional Stage) to sharply negative values (–5.4...–5.8‰) in the middle part of the Kochakan Formation (top of the Kimaian Regional Stage, ~end of the Dapingian–base of the Darriwilian Stage). Increase of δ¹⁸О from 20?22‰ to 26?28‰, the negative correlation of δ¹³С and δ¹⁸О, and decrease of δ³⁴S in gypsum from 30?32‰ to 22?24‰ in this interval indicate that the ¹³С depletion of carbonates was not related to the sulfate reduction and oxidation of organic matter during diagenesis and that the negative δ¹³С excursion was of primary nature. The presence of negative δ¹³С anomalies at this stratigraphic level in Ordovician sections of the South and North America (Buggish et al., 2003; Edwards and Saltzman, 2014; McLaughlin et al., 2016) indicates the global or subglobal distribution of this event, which was possibly related to the emergence of the oldest ground vegetation. Against the general decrease of δ¹³С, the lower part of the section reveals three low-amplitude (1?2‰) positive excursions, the position of which in general confirms the existing correlation scheme of the Moyero River section with the international scale. The upper part of the section is characterized by the alternation of low-δ¹³С intervals (from–2 to–3‰) and brief positive excursions with amplitude of 0.5?1.3‰. The positive δ¹³С excursion terminating the Ordovician section of the Moyero River correlates with the δ¹³С excursion in the middle Katian Stage, while the δ¹³С excursion in the lower part of the Baksian Regional Stage correlates with the excursion marking the Katian–Sandbian boundary.     

The Effect of Seismic Deformation Mechanisms on Fluid Migration in the Accumulation Area of Gold Ore Concentrations

Doklady Earth Sciences - The mechanisms of paleodeformations during the time of fluid inflow into the accumulation area of gold ore concentrations were studied for two deposits. It was found that...     

Contamination of Tris(4-Chlorophenyl) Methane and Tris(4-Chlorophenyl) Methanol in Marine Mammals from Russia and Japan: Body Distribution, Bioaccumulation and Contamination Status

Four seal species (Phoca caspica, Phoca sibirica, Phoca hispida and Phoca largha) and one whale (Orcinus orca) from Russia and Japan were examined to determine the body distribution, bioaccumulation and contamination status of tris(4-chlorophenyl) methane (TCPMe) and tris(4-chlorophenyl) methanol (TCPMOH). Lipid normalized concentrations of TCPMe and TCPMOH were comparable in various organs and tissues, implying that their body distribution is followed to the lipid-dependent accumulation, similar to that for other organochlorines. The highest body burden of these compounds was found in the blubber. Bioaccumulation potential of TCPMe and TCPMOH was high and comparable to PCBs and DDTs. Relatively higher concentrations of TCPMe and TCPMOH were observed in Caspian seal than in other seal species examined. TCPMOH concentration in killer whale was the highest of the marine mammals examined. Another peak detected had similar mass spectrum to TCPMOH, however, at a different retention time, suggesting the presence of an isomer of TCPMOH.     

Erratum to: Sedimentary Basins of the East Siberian Sea and the Chukchi Sea and the Adjacent Area of the Amerasia Basin: Seismic Stratigraphy and Stages of Geological History

Geotectonics - erratum     

Carbon and Oxygen Isotopes and Formation Conditions of the Upper Famennian Shale-Bearing Rocks in the Pripyat Trough,Southern Belarus

The behavior of stable carbon and oxygen isotopes in carbonates during the deposition and diagenesis of sediments in the bioproductive Upper Famennian Pripyat Trough (southern Belarus) is discussed. Limestones and clayey limestones (Corg 0.92 ± 0.11%) are characterized by very low δ13C values (–9.6 ± 0.3‰). Parental sediments of these rocks were deposited in the shallow-water zone during slow downwarping episodes of the seafloor. Lithification of the sediments took place in oxidative conditions of the diagenesis zone. Organic matter was actively oxidized by free oxygen. Carbon dioxide with isotopically light organic carbon formed in this process was used during the crystallization of diagenetic carbonates that are visually indiscernible from the sedimentational variety. Marls, clayey marls, and carbonate-bearing clays (Corg 6.02 ± 0.80%) are characterized by δ13C values as high as –3.5 ± 0.6‰. In combustible shales (Corg >10%), δ13C value is ‒1.2 ± 0.6‰). The clayey rocks mark the episodes of sedimentation in relatively deep-water conditions that appear during the uncompensated sagging of the basin floor. The diagenetic zone with free oxygen was significantly decreased or absent at all. Here, oxygen of marine sulfates was the main or single oxidizer of organic matter (sulfate reduction). The sulfate oxygen is a weaker oxidizing agent than free oxygen. Therefore, much more organic matter was retained and fossilized in clayey rocks than in carbonate rocks. Organic carbon released during the sulfate reduction and mobilized later for the diagenetic carbonate formation was insufficient for the significant decrease of δ13C values relative to the marine carbonate standard. Isotopic composition of carbonate oxygen in the studied rocks is invariable and does not depend on the content of clay and organic matter. In these rocks, δ18O values are at the level (approximately –5‰) shown for the Famennian in the Global Chemostratigraphic Chart. This fact is consistent with the supposition that oxygen isotope composition of atmospheric precipitates, which influenced the rock formation via continental flow, is close to that of sea water in low latitudes where the territory of Belarus was located in the Late Devonian.