Ubiquitous post-peak zircon in an eclogite from the Kumdy-Kol,Kokchetav UHP-HP Massif (Kazakhstan): Significance of exhumation-related zircon growth and modification in continental-subduction settings     

Sergei Yu. Skuzovatov  Vladislav S. Shatsky  Alexey L. Ragozin  Kuo-Lung Wang 《Island Arc》2021,30(1):e12385

U–Pb geochronological, trace-element and Lu–Hf isotopic studies have been made on zircons from ultrahigh-pressure (UHP) mafic eclogite from the Kumdy-Kol area, one of the diamond-facies domains of the Kokchetav Massif (northern Kazakhstan). The peak eclogitic assemblage equilibrated at > 900 °C, whereas the bulk sample composition displays light rare-earth element (LREE) and Th depletion evident of partial melting. Zircons from the eclogite are represented by exclusively newly formed metamorphic grains and have U–Pb age spread over 533–459 Ma, thus ranging from the time of peak subduction burial to that of the late post-orogenic collapse. The major zircon group with concordant age estimates have a concordia age of 508.1 ±4.4 Ma, which corresponds to exhumation of the eclogite-bearing UHP crustal slice to granulite- or amphibolite-facies depths. This may indicate potentially incoherent exhumation of different crustal blocks within a single Kumdy-Kol UHP domain. Model Hf isotopic characteristics of zircons (ε_Hf(t) +1.5 to +7.8, Neoproterozoic model Hf ages of 1.02–0.79 Ga) closely resemble the whole-rock values of the Kumdy-Kol eclogites and likely reflect in situ derivation of HFSE source for newly formed grains. The ages coupled with geochemical systematics of zircons confirm that predominantly late zircon growth occurred in Th–LREE-depleted eclogitic assemblage, that experienced incipient melting and monazite dissolution in melt at granulite-facies depths, followed by amphibolite-facies rehydration during late-stage exhumation-related retrogression.  相似文献   

The Role of Salinity in the Global Distribution of Surface Density Fluxes in the World Ocean Based on the Example of 2014     

Kukushkin  V. M.  Markina  M. Yu.  Gulev  S. K.  Dobrolyubov  S. A. 《Oceanology》2021,61(4):450-458

Oceanology - We have analyzed the dependence of the calculated magnitudes of buoyancy fluxes at the ocean surface on the various sources of information used about salinity based on the example of...  相似文献   

Comparison of Field and Satellite Data on the Total Cloudiness for the Atlantic Ocean in the Period 2004–2014     

Sinitsyn  A. V.  Gulev  S. K. 《Oceanology》2022,62(1):1-7

Oceanology - The aim of this study is to compare satellite measurements of the total cloudiness with visual observations of clouds. This makes it possible to compare “different...  相似文献   

Predictive modeling of the permafrost thermal regime in Russian railroad subgrade support systems     

Sergei Kudriavtcev  Tatiana Valtsev  Alexei Kazharskyi  Elena Goncharov  Iurii Berestianyi 《寒旱区科学》2013,5(4):0404-0407

The goal of a predictive thermotechnical calculation is to model the behavior of the top permafrost boundary under current operational conditions as well as increasing average annual air temperatures that results in degradation of the permafrost layer. Numerical modeling was used to assess the efficient application of construction measures to create sustainable operation of the railroad. The numerical modeling was carried out in the programming complex FEM-models developed by geotechnical engineers of St. Petersburg, Russia under Prof. V. M. Ulitsky’s guidance. The Termoground Program as a part of the FEM-models enables the research of freezing, heaving and thawing in different design solutions. Research was carried out in space resolution for a year cycle. The performed model has shown that the designing measures accepted for permafrost protection from retreat in the subgrade support were generally effective.  相似文献   

A. Omstedt: Guide to process based modeling of lakes and coastal seas     

Sergei Katsev 《Journal of Paleolimnology》2013,49(4):703-705

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Non-Fickian mass transport in fractured porous media     

Sergei A. Fomin  Vladimir A. ChugunovToshiyuki Hashida 《Advances in water resources》2011,34(2):205-214

The paper provides an introduction to fundamental concepts of mathematical modeling of mass transport in fractured porous heterogeneous rocks. Keeping aside many important factors that can affect mass transport in subsurface, our main concern is the multi-scale character of the rock formation, which is constituted by porous domains dissected by the network of fractures. Taking into account the well-documented fact that porous rocks can be considered as a fractal medium and assuming that sizes of pores vary significantly (i.e. have different characteristic scales), the fractional-order differential equations that model the anomalous diffusive mass transport in such type of domains are derived and justified analytically. Analytical solutions of some particular problems of anomalous diffusion in the fractal media of various geometries are obtained. Extending this approach to more complex situation when diffusion is accompanied by advection, solute transport in a fractured porous medium is modeled by the advection-dispersion equation with fractional time derivative. In the case of confined fractured porous aquifer, accounting for anomalous non-Fickian diffusion in the surrounding rock mass, the adopted approach leads to introduction of an additional fractional time derivative in the equation for solute transport. The closed-form solutions for concentrations in the aquifer and surrounding rocks are obtained for the arbitrary time-dependent source of contamination located in the inlet of the aquifer. Based on these solutions, different regimes of contamination of the aquifers with different physical properties can be readily modeled and analyzed.  相似文献   

Dust torus formed by particles ejected from a celestial body at an arbitrary point of its elliptic orbit     

Sergei A. Orlov  Konstantin V. Kholshevnikov 《Celestial Mechanics and Dynamical Astronomy》2013,116(1):35-52

Dust comnplexes make one of the components of the Solar System. The surface shape of a typical dust complex consisting of particles ejected by a celestial body is found analytically, under reasonable assumptions (the main one being the smallness of perturbations). Parametric equations of the surface are obtained. The main properties of the surface are established and studied. Singular points are found, and the topological type of the surface as a whole and in the vicinity of the singular points (one conic points and one constriction) is examined.  相似文献   

Nature of the X-ray Source in Supernova Remnant RCW103     

Sergei B. Popov 《Astrophysics and Space Science》2000,274(1-2):285-290

I discuss the nature of the compact X-ray source in the center of the supernova remnant RCW 103. Several models, based on the accretion onto a compact object are briefly discussed. I show that it is more likely that the central X-ray source is an accreting neutron star than an accreting black hole. I also argue that models of a disrupted binary system consisting of an old accreting neutron star and a new one observed as a 69-ms pulsar are most favored. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Reply to comment by F. H. Cornet on 'Large-scale in situ permeability tensor of rocks from induced microseismicity'     

Sergei A. Shapiro  Pascal Audigane  & Jean-Jacques Royer 《Geophysical Journal International》2000,140(2):470-473

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Millisecond and binary pulsars as nature's frequency standards II. The effects of low-frequency timing noise on residuals and measured parameters     

Sergei M. Kopeikin 《Monthly notices of the Royal Astronomical Society》1999,305(3):563-590

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