Geochemistry and origin of the Mirny field kimberlites,Siberia     

Agashev  Aleksey M.  Nakai  Shun&#;ichi  Serov  Ilya V.  Tolstov  Aleksander V.  Garanin  Konstantin V.  Kovalchuk  Oleg E. 《Mineralogy and Petrology》2018,112(2):597-608

Here we present new data from a systematic Sr, Nd, O, C isotope and geochemical study of kimberlites of Devonian age Mirny field that are located in the southernmost part of the Siberian diamondiferous province. Major and trace element compositions of the Mirny field kimberlites show a significant compositional variability both between pipes and within one diatreme. They are enriched in incompatible trace elements with La/Yb ratios in the range of (65–300). Initial Nd isotope ratios calculated back to the time of the Mirny field kimberlite emplacement (t = 360 ma) are depleted relative to the chondritic uniform reservoir (CHUR) model being 4 up to 6 ɛNd(t) units, suggesting an asthenospheric source for incompatible elements in kimberlites. Initial Sr isotope ratios are significantly variable, being in the range 0.70387–0.70845, indicating a complex source history and a strong influence of post-magmatic alteration. Four samples have almost identical initial Nd and Sr isotope compositions that are similar to the prevalent mantle (PREMA) reservoir. We propose that the source of the proto-kimberlite melt of the Mirny field kimberlites is the same as that for the majority of ocean island basalts (OIB). The source of the Mirny field kimberlites must possess three main features: It should be enriched with incompatible elements, be depleted in the major elements (Si, Al, Fe and Ti) and heavy rare earth elements (REE) and it should retain the asthenospheric Nd isotope composition. A two-stage model of kimberlite melt formation can fulfil those requirements. The intrusion of small bodies of this proto-kimberlite melt into lithospheric mantle forms a veined heterogeneously enriched source through fractional crystallization and metasomatism of adjacent peridotites. Re-melting of this source shortly after it was metasomatically enriched produced the kimberlite melt. The chemistry, mineralogy and diamond grade of each particular kimberlite are strongly dependent on the character of the heterogeneous source part from which they melted and ascended.

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Spatio‐Temporal Building Population Estimation for Highly Urbanized Areas Using GIS          下载免费PDF全文

Konstantin Greger 《Transactions in GIS》2015,19(1):129-150

Detailed population information is crucial for the micro‐scale modeling and analysis of human behavior in urban areas. Since it is not available on the basis of individual persons, it has become necessary to derive data from aggregated census data. A variety of approaches have been published in the past, yet they are not entirely suitable for use in the micro‐scale context of highly urbanized areas, due mainly to their broad spatial scale and missing temporal scale. Here we introduce an enhanced approach for the spatio‐temporal estimation of building populations in highly urbanized areas. It builds upon other estimation methodologies, but extends them by introducing multiple usage categories and the temporal dimension. This allows for a more realistic representation of human activities in highly urbanized areas and the fact that populations change over time as a result of these activities. The model makes use of a variety of micro‐scale data sets to operationalize the activities and their spatio‐temporal representations. The outcome of the model provides estimated population figures for all buildings at each time step and thereby reveals spatio‐temporal behavior patterns. It can be used in a variety of applications concerning the implications of human behavior in urban areas.  相似文献   

Recent variability in the Pacific western subarctic boundary currents and Sea of Okhotsk     

Konstantin A. Rogachev 《Progress in Oceanography》2000,47(2-4)

The objective of this research is to describe physical processes which are the cause of the recent variability of the Pacific western subarctic waters. Rapid thermohaline changes have occurred within the Oyashio and Kamchatka Current during the last decade. This variability has included a warming of the Kamchatka Current warm intermediate layer, but a cooling and freshening of the upper layer in the Oyashio and Sea of Okhotsk. The example presented here uses data obtained during the Canada/Russia INPOC and WOCE projects, as well as the new Russian studies with high resolution station grid.The possible physical mechanism that generated the upper layer freshening during the thermohaline transition is examined. Major components of the fresh water budget of the Okhotsk Sea are considered in order to describe the dramatic changes in salinity which have recently occurred in the Pacific subarctic. Significant changes in precipitation and other fresh water inputs are demonstrated. It is suggested that upper layer of the Oyashio and Kamchatka Current became cooler and fresher because of the export of cold, fresher waters from the Bering and Okhotsk seas. These waters from the marginal seas have cooled the bottom of the halocline, reducing evaporation and acting as a feedback that has kept the upper layer of the western subarctic boundary currents fresh. It is also shown that the outflow of the cold Sea of Okhotsk water has changed its path during this recent thermohaline transition.  相似文献   

Strong tidal currents over two shallow banks in the western subarctic Pacific     

Konstantin Rogachev  Natalia Shlyk 《Ocean Dynamics》2018,68(9):1093-1107

The south-flowing waters of the Kamchatka and Oyashio currents are key components of the western subarctic Pacific gyre. The dissipation of tidal energy in shallow and coastal regions of these currents and the attendant mixing are the important processes that affect the upper layer temperature and salinity. Examples of the impact of tidal currents on water temperature and salinity are the persistent tide-driven mixing around the Kashevarov and Kruzenshtern banks. The Kruzenshtern Bank is a shallow submarine bank stretching along the eastern continental slope of the Kuril Islands with the minimum depth of 86 m. Surface drifters observations are used to determine the characteristics of tidal currents and the circulation over these banks. New software that allows more versatility in the harmonic analysis is used for drifter’s data. The two banks have similar features. The variations in current velocities are dominated by the diurnal signals. The K₁ and O₁ tidal ellipses over the banks are the largest and clockwise. The enhanced tidal currents suggest that the formation of cold and saline water in summer is due to mixing of water column over the banks with intermediate waters. Variations of tidal ellipses over the bank may explain the formation of polynya at the western end of the Kashevarov Bank. We found that the 18.6-year lunar nodal cycle is a significant characteristic of salinity variation at the temperature minimum in the eddies eastward of the Boussole Strait over the period 1990–2015.  相似文献   

Evidence of short-term groundwater recharge signal propagation from the Andes to the central Atacama Desert: a singular spectrum analysis approach   总被引：2，自引：2，他引：0  

Konstantin W. Scheihing 《水文科学杂志》2018,63(8):1255-1261

The effect of pressure-driven groundwater recharge signal propagation in the Andean-Atacamenian environment is investigated by assessing a record of 15 years of water table fluctuations of an unconfined–confined aquifer system. Based on a singular spectrum analysis of water table time series, it is shown that, in the given case, groundwater levels in the central Atacama Desert are hydraulically controlled by two distant recharge areas associated with the Andes. The maximum observed range of the pressure signal propagation is ~50 km over an elevation difference of more than 3000 m at a lag of ~25 months. Several findings indicate that an often-cited study misinterpreted a water level rise at the same site as an in-situ alluvial fan recharge. Thus, the effect’s impact on groundwater dynamics in complex aquifer systems can easily be overlooked. Singular spectrum analysis could be of use to investigate pressure effects at hydrologically comparable sites.  相似文献   

Effects of metallic system components on marine electromagnetic loop data     

Konstantin Reeck  Hendrik Müller  Sebastian Hölz  Amir Haroon  Katrin Schwalenberg  Marion Jegen 《Geophysical Prospecting》2020,68(7):2254-2270

Electromagnetic loop systems rely on the use of non-conductive materials near the sensor to minimize bias effects superimposed on measured data. For marine sensors, rigidity, compactness and ease of platform handling are essential. Thus, commonly a compromise between rigid, cost-effective and non-conductive materials (e.g. stainless steel versus fibreglass composites) needs to be found. For systems dedicated to controlled-source electromagnetic measurements, a spatial separation between critical system components and sensors may be feasible, whereas compact multi-sensor platforms, remotely operated vehicles and autonomous unmanned vehicles require the use of electrically conductive components near the sensor. While data analysis and geological interpretations benefit vastly from each added instrument and multidisciplinary approaches, this introduces a systematic and platform-immanent bias in the measured electromagnetic data. In this scope, we present two comparable case studies targeting loop-source electromagnetic applications in both time and frequency domains: the time-domain system trades the compact design for a clear separation of 15 m between an upper fibreglass frame, holding most critical titanium system components, and a lower frame with its coil and receivers. In case of the frequency-domain profiler, the compact and rigid design is achieved by a circular fibreglass platform, carrying the transmitting and receiving coils, as well as several titanium housings and instruments. In this study, we analyse and quantify the quasi-static influence of conductive objects on time- and frequency-domain coil systems by applying an analytically and experimentally verified 3D finite element model. Moreover, we present calibration and optimization procedures to minimize bias inherent in the measured data. The numerical experiments do not only show the significance of the bias on the inversion results, but also the efficiency of a system calibration against the analytically calculated response of a known environment. The remaining bias after calibration is a time/frequency-dependent function of seafloor conductivity, which doubles the commonly estimated noise floor from 1% to 2%, decreasing the sensitivity and resolution of the devices. By optimizing size and position of critical conductive system components (e.g. titanium housings) and/or modifying the transmitter/receiver geometry, we significantly reduce the effect of this residual bias on the inversion results as demonstrated by 3D modelling. These procedures motivate the opportunity to design dedicated, compact, low-bias platforms and provide a solution for autonomous and remotely steered designs by minimizing their effect on the sensitivity of the controlled-source electromagnetic sensor.  相似文献   

Strong Tidal Mixing and Ventilation of Cold Intermediate Water at Kashevarov Bank, Sea of Okhotsk   总被引：1，自引：0，他引：1  

Konstantin A. Rogachev  Eddy C. Carmack  Alexandr S. Salomatin 《Journal of Oceanography》2000,56(4):439-447

Tidal mixing at the Kashevarov Bank, Sea of Okhotsk, has been investigated using observations of bottom pressure and currents. The tides are dominated by the diurnal constituents. The water motion over the Bank is predominantly controlled by strong diurnal tidal currents, which bring cold water on the bank from its source, a cold intermediate layer. The temperature fluctuations are about 1.2°C at the southern edge of the bank. The maximum observed velocity is about 164 cm/s at the top of the bank. A superposition of the original diurnal constituents K₁ and O₁ reveals a strong fortnightly (M_f) variability of the current speed. Tidal-induced mixing is responsible for ventilation of the cold intermediate layer of the Sea of Okhotsk. Strong tidal mixing creates a well-defined tidally mixed front around the bank. This front acts like a barrier separating well-mixed water on the bank from stratified water on its flanks. There is a residual current of the order of 10 cm/s.  相似文献   

Non-linear inversion for the hydrostatic structure of the solar interior     

Konstantin Marchenkov  Ian Roxburgh  Sergei Vorontsov 《Monthly notices of the Royal Astronomical Society》2000,312(1):39-50

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New Taxa of Chrysomelidae (Insecta:Coleoptera)from Rovno Amber,Late Eocene   总被引：1，自引：1，他引：0  

Konstantin NADEIN  Evgeny PERKOVSKY 《《地质学报》英文版》2010,84(4):772-782

<正>Leaf beetles Chrysomelidae of Rovno amber,from the Late Eocene,are recorded and described. Chrysomelidae of Rovno amber are represented by three subfamilies:Galerucinae(Alticini),Chrysomelinae,and Eumolpinae.Two new genera and three new species of Alticini:Manobiomorpha Nadein,gen.nov.(type species Manobiomorpha eocenica Nadein,sp.nov.),Psyllototus Nadein,gen.nov.(type species Psyllototus progenitor Nadein,sp.nov.),and Crepidodera decolorata Nadein et Perkovsky,sp.nov.are described.A new chrysomeline genus and species Paleophaedon minutus Nadein gen.nov.et sp.nov.is described.Probable trophic association of Crepidodera decolorata sp.nov.,the taxonomic positions of Manobiomorpha gen.nov.and Psyllototus gen.nov., and the composition of leaf beetle faunas of Middle and Late Eocene of Europe are discussed.  相似文献   

Metric spaces of Keplerian orbits     

Konstantin V. Kholshevnikov 《Celestial Mechanics and Dynamical Astronomy》2008,100(3):169-179

Several metric spaces of Keplerian orbits and a set of their most important subspaces, as well as a factor space (not distinguishing orbits with the same longitudes of nodes and pericentres) are constructed. Topological and metric properties of them are established. Simple formulae to calculate the distance are deduced. Applications to a number of problems of Celestial Mechanics are discussed.  相似文献