Modeling of freezing and melting hummocks on shelf of Sakhalin Island

In this paper, results of numerical experiments based on the one-dimensional thermodynamic model of hummock formations evolution, which has been developed by the authors, are analysed. This model has been used for computation of relative rates of freezing and melting of hummocks in typical conditions of the northeastern shelf of Sakhalin Island; then obtained values were compared with the plain sea ice cover parameters simulated by using climate and actual meteorological data. It is shown that obtained results well comply with observational data collected during expeditions in this region.     

Estimates of the maximum land-fast ice thickness probable once in 5, 10, 25, 50, and 100 years

Presented are the empirical, nonparametric (quantile), parametric, and randomized estimates of the maximum land-fast ice thickness in the Northern Caspian probable once in 5, 10, 25, 50, and 100 years. The annual maxima of the land-fast ice thickness for the 72-year period from 1937 to 2008 are computed using the one-dimensional thermodynamic model of the sea ice developed at Arctic and Antarctic Research Institute.     

Geological Position,Age, and Sources of the Tallai Gabbro–Diorite–Plagiogranite Pluton (Middle Vitim Highland)

Doklady Earth Sciences - The results of geochronological study (U–Pb SHRIMP-II) of zircons from granodiorites and plagiogranites of the main phase of the Tallai pluton of the...     

Formation of nano-and microspherules of minerals in ore deposits depending on depth of host rock occurrence

The cavitation and cavitation-ablation mechanisms of formation of mineral nano-and microspherules in hydrothermal fluids are considered. The formation conditions of nano-and microspherules were studied with regard to the depth of host rock occurrence on the basis of the theory describing the cavitation mechanism. It is shown that the temperature and pressure of hydrothermal fluid as functions of the depth of host rock occurrence may markedly affect the dimensions of cavitation bubbles, the temperature within them at the moment of greatest compression, and the time of bubble collapse in the fluid. the dimensions of nano-and microspherules produced by cavitation depend only slightly on the depth of host rock occurrence and are mainly controlled by the thermophysical properties of their constituents. Characteristic dimensions of nanospherules formed as a result of ablation from the surface of overheated material have been obtained.     

P/2010 TO20 LINEAR-Grauer: A comet in transition from Centaurs to the Jupiter family

The object P/2010 TO20 LINEAR-Grauer, discovered at a heliocentric distance of over 5 AU, and at first classified as a Trojan, is now believed to be a comet. This paper reports special observations of the object that have allowed a significant refinement of its orbit and investigation of its dynamic evolution. It is shown that P/2010 TO20 LINEAR-Grauer is not a Trojan yet demonstrates unusual dynamic features. In particular, the object moves in a temporary satellite orbit relative to Jupiter over the observation interval. The comet has been in the Hill sphere for about two years and has made one revolution around the planet. The jovicentric distance function has two minima, and the smallest distance is 0.075 AU. Our estimates show that, with a probability of 0.76, the comet is likely to move in a Jupiter family orbit with a perihelion distance of less than 2.5 AU. The average time for such a transition is around forty thousand years.     

Deglaciation history of Lake Ladoga (northwestern Russia) based on varved sediments

Lake Ladoga in northwestern Russia is Europe's largest lake. The postglacial history of the Ladoga basin is for the first time documented continuously with high temporal resolution in the upper 13.3 m of a sediment core (Co1309) from the northwestern part of the lake. We applied a multiproxy approach including radiographic imaging, (bio‐)geochemical and granulometric analyses. Age control was established combining radiocarbon dating with varve chronology, the latter anchored to a correlated radiocarbon age from a lake close by. The age‐depth model reveals the onset of glacial varve sedimentation at 13 910±140 cal. a BP, when Lake Ladoga was part of the Baltic Ice Lake. Linear extrapolation of published retreat rates of the Scandinavian Ice Sheet provides a formation age of the Luga moraine close to Lake Ladoga's southern shore of 14.5–15.9 cal. ka BP, older than previously assumed. Varve sedimentation covers the Bølling/Allerød interstadial, the Younger Dryas stadial and the Early Holocene. Varve‐thickness variations, conjoined with grain‐size and geochemical variations, inform about the relative position of the Scandinavian Ice Sheet and the climate during the deglaciation phase. The upper limit of the varved succession marks the change from glaciolacustrine to normal lacustrine sedimentation and post‐dates the drainage of the Baltic Ice Lake as well as the formation of the Salpausselkä II moraine north of Lake Ladoga, by c. 250 years. The Holocene sediment record is divided into three periods in the following order: (i) a lower transition zone between the Holocene boundary and c. 9.5 cal. ka BP, characterized by mostly massive sediments with low organic content, (ii) a phase with increased organic content from c. 9.5 to 4.5 cal. ka BP corresponding to the Holocene Thermal Maximum, and (iii) a phase with relatively stable sedimentation in a lacustrine environment from c. 4.5 cal. ka BP until present.     

Analysis of the light curves of BY Cam in the low accretion state at various beat phases

The results of observations of the asynchronous polar BY Cam in the low accretion state in 2004–2007 are presented. It is shown that the light curves depend on the beat phase and vary nonchaotically from cycle to cycle.     

Forecasting environmental contamination development in the coastal and water area of the Russian far east under the effect of the radiation factor and industrial anthropogenic load under conditions of catastrophes

Studies of seasonal variability (including the winter season) of the main hydrodynamic, sedimentation, physicochemical and other characteristics of the Chazhma Bay of the Sea of Japan, in the zone of the atomic submarine K-431 nuclear accident of 1985 that influence the radioecological state of the environment was carried out. The substance fluxes required for estimating radionuclide balance are defined based on the expedition survey of radioactivity of bottom sediments, sea water, and suspension in the epicenter of the accident and over the water area of the bay together with hydrophysical, sedimentation, and meteorological observations. Modern trace methods and 3D prognostic modeling of interaction of natural and anthropogenic processes of evolution of radioactive contamination of the bottom sediments in the zone of the atomic submarine accident are used; a new approach to estimating the maximum contamination of the marine environment is proposed.     

Calculation methods and the distribution of anthropogenic variations of pH values in the Pacific Subarctic

Common approaches were used to calculate the anthropogenic CO₂, equations were proposed to characterize anthropogenic variations in pH values (ΔpH_ant) in the Pacific Subarctic. For the treated area, the temporal and spatial ΔpH_ant variability was analyzed in 1986 and 2001–2004. From the ΔpH_ant values, the influence of pH variations on iron solubility in seawater was considered.     

富钴铁锰结壳的控矿要素和成矿过程——以西太平洋为例

以西太平洋海山的麦哲伦海山群和马尔库斯-威克海山群为例,研究了富钴铁锰结壳（富钴结壳）形成过程中地质要素和海洋要素的作用,重点分析了海山漂移和沉降、水道开合、最小含氧带（OMZ）、大洋环流,以及气候变化等要素对富钴结壳形成的控制作用。基于对麦哲伦海山和马尔库斯-威克海山结壳样品剖面Mn／Fe值曲线的综合研究,结合控矿要素和成矿背景分析,将该区白垩纪以来富钴结壳的成矿过程划分为五个阶段：（1）自垩纪-始新世,（2）始新世末-晚渐新期,（3）晚渐新期-中中新期早期,（4）中中新期早期晚中新期早期,（5）晚中新期早期-现代,其中（2）、（3）阶段有利于发育富钴结壳。