Climate Change in the Hydrometeorological Parameters of the Black and Azov Seas (1980–2020)

Oceanology - To study the nature of climate change in the hydrometeorological parameters of the Black and Azov Seas—surface air temperature (SAT), sea surface temperature (SST), ice cover,...     

Cobalt mineralization in the Altai–Sayan orogen: age and correlation with magmatism

The paper discusses the spatiotemporal and genetic relationships of hydrothermal Co mineralization in the Altai–Sayan orogen with mafic, alkaline mafic, and granitoid magmatism on the basis of isotopic, geochemical, and geochronological investigations. Four stages of Co mineralization have been distinguished for this region: Early Devonian (D₁), Late Devonian–Early Carboniferous (D₃–C₁), Permo-Triassic (P₂–T), and Early Cretaceous (K₁). They correspond to periods of large-scale mafic magmatism. Isotopic (Pb, Sr, He) and geochemical studies have shown that Co mineralization is genetically related to mafic and granitoid magmatism. Also, these studies have confirmed that Co deposits are formed with the participation of mantle fluids and are related to chambers of mafic and alkaline mafic melts. Besides, it has been found that ore originated both from magmatic sources and host rocks. A pulsed facies endogenic zonation has been established for Co deposits, Co-bearing ore clusters, and zones with high-temperature Co–As and low-temperature Ni–Co–As mineralization. It has been first established that ores at hydrothermal Co deposits are rich in Pt and Pd.     

A HED Laboratory Astrophysics Testbed Comes of Age: JET Deflection via Cross Winds

We present new data from High-Energy Density (HED) laboratory experiments designed to explore the interaction of a heavy hypersonic radiative jet with a cross wind. The jets are generated with the MAGPIE pulsed power machine where converging conical plasma flows are produced from a cylindrically symmetric array of inclined wires. Radiative hypersonic jets emerge from the convergence point. The cross wind is generated by ablation of a plastic foil via soft-X-rays from the plasma convergence region. Our experiments show that the jets are deflected by the action of the cross wind with the angle of deflection dependent on the proximity of the foil. Shocks within the jet beam are apparent in the data. Analysis of the data shows that the interaction of the jet and cross wind is collisional and therefore in the hydrodynamic regime. We consider the astrophysical relevance of these experiments applying published models of jet deflection developed for AGN and YSOs. We also present results of 3-D numerical simulations of jet deflection using a new astrophysical Adaptive Mesh Refinement code. These simulations show highly structured shocks occurring within the beam similar to what was observed in the experiments.     

An annular eclipse on May 31, 2003, observed in extreme ultraviolet

The CORONAS-F spacecraft crossed the zone of the ring solar eclipse three times on May 31, 2003. A considerable decrease in solar radiation was detected by the spacecraft instruments for these moments. The passages through the eclipse zone were registered by the VUSS instrument, which measured the shortwave solar radiation flux near the hydrogen Lyman alpha line, and by the DIFOS instrument, which was sensitive to infrared, visible, and near-ultraviolet radiation. The eclipse is also clearly seen in solar images obtained by the X-ray SPIRIT telescope. Some details of measurement results are discussed.     

Some features of sea ice formation in Antarctic coastal waters

Considered are the peculiarities of fast ice formation in the Antarctic coastal waters. It is noted that the fine-crystalline ice with the chaotic orientation of crystals is mainly developed in the surface layers of the ice cover as well as the ice formed due to the infiltration of the sea water and its subsequent freezing in the lower layers of the snow cover. It is demonstrated that under the conditions of coastal Antarctic, the lamination of the structure during the period of ice cover formation and its subsequent development is the result of heavy precipitation in the form of snow and the formation of the large amount of snow sludge and crystals of intrawater ice (frazil ice) on the open water. The main distinctive feature of the Antarctic sea ice is its seasonal stratification with the formation of the surface layer of recrystallized ice and underlying destructive layers including the water interlayer in the ice column. The provision of the safety of overice movement of machinery requires the development of methods of continuous remote control of the snow-ice stratum of the fast ice.     

Late Paleozoic alkali-granitic magmatism of Tuva and its relation to intraplate activity within the Siberian paleocontinent

Geological, petrologeochemical, and geochronological studies of the rocks from the Shivei alkali-granitic pluton were conducted. A pluton about 500 km² in area is a part of the larger (more than 30 000 km²) Kaakhem magmatic area. The data obtained allow us to characterize the magmatic complex of the Shivei pluton as a bimodal association with picrobasalts, subalkali basalts, and subalkali and alkali granitic rocks differentiated from syenites to leucogranites. The SHRIMP_II zircon dating from quartz syenites and alkali granites indicate the Permian age of the pluton (293.8 ± 3.8 Ma and 297.1 ± 3.8 Ma, respectively). Mafic-alkali-granitic associations similar in age and type, which are traced in the meridional direction along the Eastern Sayan toward the Siberian Platform, were distinguished as the Eastern Sayan zone of the Late Paleozoic alkaline magmatism. Its location corresponds to the western periphery of the Angaro-Vitim batholite and fits well into the zonal structure of the Barguzin magmatic province. We relate the geodynamic position of the Barguzin province with the mantle plume that was overlapped by the edge of the Siberian Pale-ocontinent in the course of its Paleozoic migration above the African hot spot.     

Formation of Working Surfaces in Radiatively Cooled Laboratory Jets

Whilst observations provide many examples of collimated outflows or jets from astrophysical bodies, there remain unresolved questions relating to their formation, propagation and stability. The ability to form scaled jets in the laboratory has provided many useful insights. Experiments (Lebedev et al.: 2002, ApJ 564, 113) using conical arrays of fine metallic wires on the MAGPIE generator (1MA in 240 ns) have produced radiatively cooled collimated jets in vacuum using the redirection of convergent flows by a conical shock. Here we present results of a jet produced by this method propagating through a photo-ionized, quasi-stationary gas cloud. A working surface is observed at the head of the jet. The velocity of this working surface is lower than the velocity of a jet tip in vacuum.     

New Paleomagnetic Data on Late Cretaceous Chukotka Volcanics: the Chukotka Block Probably Underwent Displacements Relative to the North American and Eurasian Plates after the Formation of the Okhotsk-Chukotka Volcanic Belt?

Izvestiya, Physics of the Solid Earth - Abstract—Paleomagnetic studies of several Late Cretaceous volcanic sections of the Okhotsk–Chukotka volcanic belt have been carried out in the...