Basin-To-Basin and Year-To-Year Variation of Temperature and Salinity Characteristics in the East Sea (Sea of Japan)

Analysis of CTD data from four CREAMS expeditions carried out in summers of 1993–1996 produces distinct T-S relationships for the western and eastern Japan Basin, the Ulleung Basin and the Yamato Basin. T-S characteristics are mainly determined by salinity as it changes its horizontal pattern in three layers, which are divided by isotherms of 5°C and 1°C; upper warm water, intermediate water and deep cold water. Upper warm water is most saline in the Ulleung Basin and the Yamato Basin. Salinity of intermediate water is the highest in the eastern Japan Basin. Deep cold water has the highest salinity in the Japan Basin. T-S curves in the western Japan Basin are characterized by a salinity jump around 1.2–1.4°C in the T-S plane, which was previously found off the east coast of Korea associated with the East Sea Intermediate Water (Cho and Kim, 1994). T-S curves for the Japan Basin undergo a large year-to-year variation for water warmer than 0.6°C, which occupies upper 400 m. It is postulated that the year-to-year variation in the Japan Basin is caused by convective overturning in winter. This revised version was published online in August 2006 with corrections to the Cover Date.     

Epithermal mineralization in the Kedon Paleozoic volcano-plutonic belt,Northeast Russia: Geochemical studies of Au–Ag mineralization

This paper is concerned with the geochemical features and conditions of generation for Paleozoic Au–Ag mineralization in the pre-accretionary Kedon (D_2-3) volcano-plutonic belt (KVB), which is situated within the Omolon cratonic terrane (Northeast Russia). We present new data on the compositions and concentrations of trace elements and rare-earth elements (REEs) in the host rocks and volcanogenic ores of epithermal Au–Ag fields. The ores are found to be enriched in a wide range of trace elements. The general features of the ores under study include a low level of REE concentrations, an obvious enrichment in light REEs, and considerable variations in europium anomalies, ranging from low negative to low- and strongly positive. Fluid inclusions were studied to show that the ore-forming solutions were hydrocarbonate potassium in composition. The mineral content of the fluid increases toward later, low-temperature phases of the mineralization. We found a tendency of potassium increasing from the earlier oreless quartz to productive quartz going to great depth, as well as a slow decrease in the concentrations of Na⁺, Ca⁺⁺, and Cl^–. The productive quartz shows direct correlation in Ag–K and a reverse correlation in Ag–Na. The results indicate andesite magmas and meteoric water as the most likely sources of the fluids that have formed epithermal Au–Ag ores in the KVB deposits.     

The Geochemistry of Volcanogenic Mineralization in the Northwestern Segment of the Pacific Ore Belt: Northeast Russia

This paper considers the geochemistry of volcanogenic mineralization in the northeastern segment of the Pacific Ore Belt (Northeast Russia). We give new evidence for the compositions and concentrations of trace and rare-earth elements (REE) in the ores of volcanogenic fields: Au-Ag epithermal (of various types and ages), Cu-Mo-Au porphyritic, Au-Bi related to granitoidal intrusions, Sn-Ag subvolcanic and kies polymetallic enriched in Au and Ag, as well as REEs in alkaline volcanic rocks. Geochemical signatures have been compiled for 17 formation types of volcanogenic fields. It was found that the ore-forming fluids in most fields belonged to an NaCl-H₂O hydrothermal system that was enriched in Cl relative to F; the values of Y/Ho in the ores of nearly all types correspond with the interval of ratios characteristic for present-day hydrothermal fluids in backarc basins; most of the ores that we studied had near-chondrite spectra with configurations similar to those of the REE spectra in volcanic rock sequences of the andesite-diorite series. Comparative analysis of REE spectra in the distribution of trace elements over classes of gold concentration shows synchronous enrichment of ores in similar sets of trace elements. The high Co/Ni ratio in volcanogenic ores probably reflects the superposition of a later magmatic fluid upon an earlier mineralization. Samples from ores of volcanogenic fields, except for Kuroko, show δCe and δEu varying from negative to mildly positive values, thus indicating low-oxidizing conditions during deposition. It was found for Au-Ag epithermal ores that they are enriched in a wide range of trace elements; they have low concentrations of REEs, the light REEs are more abundant than the heavy ones, and the Eu anomalies vary considerably from small negative to low and high positive values. The results provide evidence of an exhalation hydrothermal origin of the Khotoidokh field. It has been shown that the REEs in the ores of the Bol’shoe field are of the type that is most valuable to industry. The results can be used to deal with practical problems: determining the formation type and evaluating the industrial value of a field; detecting accessory components in ores; and discriminating between the types of geochemical anomalies (in rocks or in soil) and stray fluxes as to the potential of a field.     

Light Curves of the Type II-P Supernova SN 2017eaw: The First 200 Days

We present the results of our UBVRI photometry for the type II-P supernova SN 2017eaw in NGC6946 obtained fromMay 14 to December 7, 2017, at several telescopes, including the 2.5-m telescope at the CaucasusHigh-Altitude Observatory of the SAIMSU. The dates andmagnitudes atmaximumlight and the light-curve parameters have been determined. The color evolution, extinction, and peak luminosity of SN 2017eaw are discussed. The results of our preliminary radiation–gasdynamic simulations of its light curves with the STELLA code describe satisfactorily the UBVRI observational data.     

Structure of the Pre-Paleozoic Formation of the Central Ural Uplift in the Northern and Subpolar Urals and Its Relation with Gold Production

The Central Ural uplift occupies the near-Vodorazdelnaya part of the Urals. It is composed of metaterrigenous and metavolcanogenic Riphean–Vendian formations. Distributed folds, which formed in several stages, and various tectonic faults are widespread. The study of these structures in the areas located in the Northern and Subpolar Urals showed their lateral and temporal variability, which was reflected in the difference in morphology and nature of faulting. In the Vodorazdelnaya area of the Northern Urals, as a result of thrust–fold deformations, a complex fold structure of the sequence was formed, subsequently broken by two submeridional subparallel faults into blocks. In the Khalmerya area of the Subpolar Urals, there are several tectonic blocks bounded by gently eastward dipping and overlapping tectonic blocks that form a duplex structure. This series of thrust structures created a complex cover structure contrasting in composition and degree of deformation. Later, a northeastern strike-slip fault zone arose. The orientation of early isoclinal folds in the rocks indicates pressure from the northeast, during the formation of tectonic scales and sheets in the Precambrian basement. Then this pressure occurred from the southeast and the Lower Paleozoic sediments were involved in the thrust process. Differences in the features of the formation of structures apparently depend on the morphology of the eastern margin of the East European platform and the change in the vector of displacement of the thrust sheet. The movement of the thrust sheets within the continental margin occurred along the main surface of the fault, with which the thrust structures are articulated at depth. At the final stages, extended strike-slip-upthrust zones were established, which affected the distribution of he gold mineralization.

     

Photometric Evolution of the Orbital Light Curves of the Slow Nova V723 Cas

UBVRI photoelectric and CCD photometry of the slow nova V723 Cas obtained in the years 1995–2003 is presented. The evolution of light curves in 1-year intervals, folded with the orbital period 0.69326 days, shows an increase of the amplitude of the wave-like variations from 0.07 to 1.3 mag during the years 1997–2003. The fact that the shape and amplitude of the orbital light curves does not depend on wavelength is most probably related to the geometry of eclipses combined with the distribution of circumstellar matter in the system.     

Apsidal motion in the eclipsing binary GG Ori

High-precision WBVR photoelectric observations of the eclipsing binary GG Ori (B9.5V+B9.5V), which has an eccentric orbit (e=0.22), were carried out in 1988–2001 at the Moscow and high-altitude Tian-Shan Observatories of the Sternberg Astronomical Institute. The aim of these observations was investigation of the apsidal motion of the system. Analysis of the resulting 12-year series of observations enabled us for the first time to accurately (to within 11%) measure the rate of rotation of the orbit $\dot \omega _{obs} = 0.046 \pm 0.005^\circ /yr$ and to appreciably improve estimates of the photometric and absolute parameters. The observed value of $\dot \omega _{obs}$ is 28% higher than the theoretical prediction of $\dot \omega _{th} = \dot \omega _{cl} + \dot \omega _{rel} = 0.036 \pm 0.001^\circ /yr$ . The relativistic part of the apsidal motion in this system $\dot \omega _{rel}$ is a factor of 2.5 greater than the classical term $\dot \omega _{cl}$ due to the tidal and rotational deformations of the components. The interstellar extinction in the direction of the star (at a distance of r=425 pc) is very large (A _v =1.75 ^m ). A number of recently published results (in particular, the conclusion that the components of this eclipsing binary are young) are confirmed.     

Studying the mesoscale structure of inhomogeneities within the high-latitude stratosphere during the evolution of the circumpolar vortex on the basis of aircraft measurements

Mesoscale inhomogeneities in the fields of wind, temperature, and ozone concentrations have been studied on the basis of aircraft measurements performed within the international EUPLEX and RECONCILE projects in the northern polar region in the presence of the circumpolar vortex. Data have been obtained on the structure of turbulence inside and outside the circumpolar vortex. The zones of enhanced turbulence have been studied. The spectrum of coherence between ozone and wind velocity are found to have high values.