Systematic study of hydrogen incorporation into Fe-free wadsleyite     

Konstantin D. Litasov  Anton Shatskiy  Eiji Ohtani  Tomoo Katsura 《Physics and Chemistry of Minerals》2011,38(1):75-84

The H₂O content of wadsleyite were measured in a wide pressure (13–20 GPa) and temperature range (1,200–1,900°C) using FTIR method. We confirmed significant decrease of the H₂O content of wadsleyite with increasing temperature and reported first systematic data for temperature interval of 1,400–1,900°C. Wadsleyite contains 0.37–0.55 wt% H₂O at 1,600°C, which may be close to its water storage capacity along average mantle geotherm in the transition zone. Accordingly, water storage capacity of the average mantle in the transition zone may be estimated as 0.2–0.3 wt% H₂O. The H₂O contents of wadsleyite at 1,800–1,900°C are 0.22–0.39 wt%, indicating that it can store significant amount of water even under the hot mantle environments. Temperature dependence of the H₂O content of wadsleyite can be described by exponential equation C_{\textH2 \textO} = 6 3 7.0 7 \texte ^{- 0.00 4 8T} , C_{{{\text{H}}_{2} {\text{O}}}} = 6 3 7.0 7 {\text{e}}^{ - 0.00 4 8T} , where T is in °C. This equation is valid for temperature range 1,200–2,100°C with the coefficient of determination R ² = 0.954. Temperature dependence of H₂O partition coefficient between wadsleyite and forsterite (D _wd/fo) is complex. According to our data apparent D_wd/fo decreases with increasing temperature from D _wd/fo = 4–5 at 1,200°C, reaches a minimum of D _wd/fo = 2.0 at 1,400–1,500°C, and then again increases to D _wd/fo = 4–6 at 1,700–1,900°C.  相似文献   

The mass,orbit, and tidal evolution of the Quaoar–Weywot system     

Wesley C. Fraser  Konstantin Batygin  Michael E. Brown  Antonin Bouchez 《Icarus》2013,222(1):357-363

Here we present new adaptive optics observations of the Quaoar–Weywot system. With these new observations we determine an improved system orbit. Due to a 0.39 day alias that exists in available observations, four possible orbital solutions are available with periods of ～11.6, ～12.0, ～12.4, and ～12.8 days. From the possible orbital solutions, system masses of 1.3–1.5 ± 0.1 × 10²¹ kg are found. These observations provide an updated density for Quaoar of 2.7–5.0 g cm^?3. In all cases, Weywot’s orbit is eccentric, with possible values ～0.13–0.16. We present a reanalysis of the tidal orbital evolution of the Quaoar–Weywot system. We have found that Weywot has probably evolved to a state of synchronous rotation, and has likely preserved its initial inclination over the age of the Solar System. We find that for plausible values of the effective tidal dissipation factor tides produce a very slow evolution of Weywot’s eccentricity and semi-major axis. Accordingly, it appears that Weywot’s eccentricity likely did not tidally evolve to its current value from an initially circular orbit. Rather, it seems that some other mechanism has raised its eccentricity post-formation, or Weywot formed with a non-negligible eccentricity.  相似文献   

Flood hazard and risk assessment in Russia     

Andrei Shalikovskiy  Konstantin Kurganovich 《Natural Hazards》2017,88(1):133-147

Flood risk assessment is usually performed by application of sophisticated mathematical models of river flow. However, there are cases when it is required to assess the risk in the lack of data conditions or a limited time available. In such cases, it is advisable to use some simplifications, which provide reliable results faster. This study proposes a hybrid approach to the flood risk assessment combining quantitative and qualitative indicators. The article describes various methods to assess the flood risk, such as likelihood of flooding, magnitude of the flood, average annual damage, maximum damage and expectation of damage. The authors examined special cases of calculation of the mathematical expectation of harm and zoning in the corresponding indicators. This approach is designed for the conditions of the Russian Federation, but it can be adapted for other regions. It is based on the use of two types of risk maps. The first type of maps is intended to define the mathematical expectation of damage zones for reference building with possibility of risk calculation for other buildings using multiple factors. The second type of maps is designed for the purposes of land use regulation for floodplains based on a priori statistical estimates of flood risk.  相似文献   

Extreme aridity prior to lake expansion deciphered from facies evolution in the Miocene Ili Basin,south‐east Kazakhstan     

Konstantin Frisch  Silke Voigt  Thomas Voigt  Alexandra Hellwig  Verena Verestek  Yuki Weber 《Sedimentology》2019,66(5):1716-1745

Central Asia witnessed progressive aridification during the Miocene, commonly related to mountain uplift, the Paratethys retreat and global climate cooling. However, the formation of Miocene lakes in Central Asia seems to oppose drier conditions, suggesting that the precise timing, extent and forcing of the aridification is still not well constrained. This study presents a facies model for the alluvial–lacustrine part of the Middle to Late Miocene of the Ili Basin, obtained from two successions. The model enables the semi‐quantitative assessment of regional water level and salinity, and characterizes the control of water level on evaporite formation and diagenesis. Both the proximal Kendyrlisai and the distal Aktau successions show an overall increase in water availability from dry mudflat deposits to lacustrine sedimentation with a transitional playa phase. Increasing evaporation rates outpaced the water supply and caused groundwater salinization. Subsequent lake expansion coincided with a basin‐wide desalinization and required a shift to a positive water budget. A climatic control of the hydrological evolution is inferred due to abrupt salinization and a minor tectonic influence. The long‐term water accumulation is probably related to the hydrological closure of the basin in the early Middle Miocene (15·3 Ma). Starting at 14·3 Ma, the step‐wise salinization occurred simultaneously with the global cooling of the Miocene Climate Transition. The Miocene Climate Transition led to extreme aridity in the Ili Basin, highlighted by the early diagenetic formation of displacive anhydrite in the basin centre. The expansion of the freshwater lake (12·7 to 11·5 Ma) was possibly promoted by lower evaporation rates due to decreasing air temperatures in the Ili Basin after the Miocene Climate Transition. The extreme aridity in the Ili Basin is interpreted as a continental counterpart to the Badenian Salinity Crisis in the Central Paratethys. This emphasizes the role of atmospheric forcing on evaporite sedimentation across Eurasia during the Middle Miocene.  相似文献   

The Mg-carbonate-Fe interaction:Implication for the fate of subducted carbonates and formation of diamond in the lower mantle     

Naira S.Martirosyan  Konstantin D.Litasov  Sergey S.Lobanov  Alexander F.Goncharov  Anton Shatskiy  Hiroaki Ohfuji  Vitali Prakapenka 《地学前缘(英文版)》2019,10(4):1449-1458

The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe^0 system at 70-150 GPa and 800-2600 Kin a laser-heated diamond anvil cell.Using in situ synchrotro n X-ray diffraction and ex situ transmission electron microscopy we show that the reduction of Mg-carbonate can be exemplified by:6 MgCO3+19 Fe=8 FeO+10(Mg0.6Fe^0.4)O+Fe7 C3+3 C.The presented results suggest that the interaction of carbonates with Fe^0 or Fe^0-bearing rocks can produce Fe-carbide and diamond,which can accumulate in the D"region,depending on its carbon to Fe ratio.Due to the sluggish kinetics of the transformation,diamond can remain metastable at the core-mantle boundary(CMB)unless it is in a direct contact with Fe-metal.In addition,it can be remobilized by redox melting accompanying the generation of mantle plumes.  相似文献   

Impact-generated dust clouds around planetary satellites: spherically symmetric case     

Alexander V. Krivov  Miodrag Srem?evi?Frank Spahn  Valeri V Dikarev  Konstantin V Kholshevnikov 《Planetary and Space Science》2003,51(3):251-269

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Beitrag zur Kenntnis der Blaualgenvegetation der Thermen von Baden und Leukerbad (Schweiz)     

Konstantin Anagnostidis  Alfons Zehnder 《Aquatic Sciences - Research Across Boundaries》1964,26(1):170-176

Ohne Zusammenfassung  相似文献   

On linking coefficient of two Keplerian orbits     

Konstantin V. Kholshevnikov  Nikolay N. Vassiliev 《Celestial Mechanics and Dynamical Astronomy》1999,75(1):67-74

We define a function of the set of pairs of Keplerian ellipses so that the sign of the function will be a topological invariant of their configuration. The sign is negative if and only if the related ellipses are linked. Two modifications of the coefficient which are more reliable in the case of closed to coplanar orbits are proposed. Explicit formulae representing the linking coefficients as functions of orbital elements are deduced. Extension in the case of unbounded orbits is obtained. We suggest different ways to use these coefficients for determining intersections of pairs of osculating Keplerian orbits. If we study dynamical behaviour of geometric configuration of pairs of Keplerian orbits, we can fix the moments of their intersections. These moments correspond exactly to the vanishing of linking coefficients. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Isocystis pallida—Blaualge oder hefeartiger Pilz?     

Konstantin Anagnostidis  Ragna Rathsack-Künzenbach 《Aquatic Sciences - Research Across Boundaries》1967,29(1):191-198

Zusammenfassung Die vonWoronichin [29] alsIsocystis pallida beschriebene Cyanophycee, welche vonAnagnostidis [1] h?ufig in griechischen Thermalquellen gefunden wurde, hatGeitler [17] zu den hefeartigen Pilzen der GattungTorulopsidosira gestellt. Diesen Organismus, den wir in verschiedenen Thermen reelm?ssig angetroffen haben, (Griechenland, Ungarn, Schweiz) untersuchten wir an Hand umfangreicher Materialproben. Statistische und zellphysiologische Versuche sowie systematische Vergleiche führten uns zu dem Ergebnis, diesen Organismus alsI. pallida (Woronich.) bei den Cyanophyten zu belassen, bis biochemische Resultate seine Zugeh?rigkeit zu den Blaualgen in Frage stellen sollten.

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Summary The blue-green alga described byWoronichin [29] asIsocystis pallida and often found byAnagnostidis [1] in Greek hot springs has been classified byGeitler [17] among yeast-like fungi of the genusTorulopsidosira. This organism was regularly found in various hot springs (Greece, Hungary, Switzerland). Statistical and cytological tests, as well as systematical comparisons, led us to conclude that it should be classified asI. pallida (Woronich.) among the Cyanophyta until biochemical results should give cause to doubt that it belongs to the blue-green algae.

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Evidence for Holocene environmental changes in the northern Fertile Crescent provided by pedogenic carbonate coatings   总被引：1，自引：0，他引：1  

Konstantin Pustovoytov  Klaus Schmidt  Heinrich Taubald 《Quaternary Research》2007,67(3):315-327

Holocene environmental changes in the northern Fertile Crescent remain poorly understood because of the scarcity of local proxy records in the region. In this study we investigated pedogenic (soil-formed) carbonate coatings on stones at the Pre-Pottery Neolithic site Göbekli Tepe as an indicator of local early-mid Holocene environmental changes. The ¹⁴C ages and stable isotopic composition of carbon and oxygen in thin (0.2–0.3 mm thick) pedogenic carbonate lamina indicate two main periods of coating formation: the early-Holocene (ca. 10000–6000 cal yr BP) and the mid-Holocene (ca. 6000–4000 cal yr BP). During the first period, there was an inverse relationship between δ¹³C and δ¹⁸O curves: a decrease in δ¹³C values coincide with an increase in δ¹⁸O values. For this period a trend towards higher temperatures is suggested. In the mid-Holocene, the mean rate of coating growth was 2–3 times higher than in the early Holocene. Both δ¹³C and δ¹⁸O reached their maximum values during this time and the direction of changes of the δ¹³C and δ¹⁸O curves became similar. The combination of data suggests that this period was the most humid in the Holocene and on average warmer than the early Holocene. At ca. 4000 cal yr BP secondary accumulation of carbonate ceased, presumably reflecting a shift to a more arid climate.  相似文献