The paper reports the first findings of a series of alkali carbonate, chloride, and sulfate minerals among the usual groundmass kimberlite minerals, such as olivine, phlogopite, monticellite, calcite, spinel-group minerals, perovskite, ilmenite, rutile, and apatite. The sample was collected from an unserpentinized coherent kimberlite dyke that crosscuts earlier volcaniclastic kimberlite in the central part of the Udachnaya-East pipe. This rock can be described as primary/original kimberlite that did not interact with external/internal hydrothermal fluids either during its formation or after its crystallization. At least three alkali-rich carbonates have been found, a previously unknown (and perhaps, a new one) Na-, Ca-, K-, and S-rich carbonate with the calculated empirical formula (Na,K)6Ca4(CO3,SO4)7, shortite Na2Ca2(CO3)3, and nyerereite (Na,K)2Ca(CO3)2. Chlorides in this kimberlite are halite NaCl and sylvite KCl, and the sulfate is aphthitalite K3Na(SO4)2. The content of the Na-Ca-K-S-rich carbonate in the rock is ~15 vol %, that of shortite and halite is ≤5 vol % each, and those of sylvite and aphthitalite are ≤1 vol %. All alkali-rich minerals are of late magmatic origin. This follows from that (i) the studied kimberlite does not contain any secondary water-rich minerals of hydrothermal transformation of the rocks, such as serpentine, chlorite or iowaite; and (ii) crystalline inclusions of such usual kimberlite minerals as olivine, phlogopite, monticellite, calcite, spinel, perovskite, and apatite were found within Na-Ca-K-S-rich carbonate and halite. This publication expands the list of minerals of magmatic origin identified in the groundmass of worldwide kimberlites by at least three minerals: Na-Ca-K-S-rich (new?) carbonate, sylvite, and aphthitalite. It is important to note that all alkali carbonates, chlorides, and sulfates are unstable during secondary hydrothermal alterations of kimberlites, and hence, these minerals cannot be found in serpentinized rocks.

The paper presents the results of studies of daughter olivine within secondary melt inclusions marking healed cracks in olivine macrocrysts from unserpentinized kimberlite from the Udachnaya-East pipe. Macrocrysts compose four olivine generations: core olivine (Ol1); olivine marking healed cracks (Ol2); daughter olivine of melt inclusions (Ol3); thin outer rims of olivine (Olr) around macrocryst cores. The relationship between different olivine generations and variations in its chemical composition indicate that macrocrystal cores (Ol1) are grains or grain fragments of disintegrated mantle rocks; melt inclusions and Ol2 were formed due to infiltration of kimberlite melts into the grain cracks. Crystallization of a hybrid melt of inclusions and formation of an extremely magnesian daughter olivine (Ol3) occurred later, at lower PT conditions. Among the daughter minerals in the melt inclusions, in addition to Ol3 there were identified alkaline carbonates, sulfates, chlorides, oxides, and sulfides. It has been shown that the daughter olivine of melt inclusions (Ol3) has high Mg# (97–98) content, high MnO (0.18–0.41 wt. %) and CaO (0.12–0.25 wt. %) concentrations, and low NiO (0.02–0.04 wt. %) contents. The ratios between the daughter minerals of the melt inclusions indicate that the hybrid melt from which extremely magnesian olivine was formed was alkaline carbonate or silicate-carbonate liquid with a low water content. Our study directly showed for the first time that almost pure forsterite is able to be crystallized from evolved kimberlite melts of carbonate or silicate-carbonate composition, which confirms the previously proposed model for the formation of extremely magnesian outer rims of olivine crystals from worldwide kimberlites during crystallization of evolved kimberlite melts of carbonate composition.

Kaapvaal lamproites (aka orangeites) are a group of volatile-rich (H2O, CO2), micaceous, ultrapotassic igneous rocks that are unique to the Kaapvaal craton in southern Africa. However, the composition of the melts that give rise to these rocks remains poorly understood due to overprinting effects of contamination by mantle and crustal material, volatile exsolution, fractional crystallisation and post-magmatic alteration. Consequently, this lack of reliable data on the initial composition of the Kaapvaal lamproite melts hampers our understanding of their source, petrogenesis and ascent mechanisms.Olivine is a common mineral comprising the Kaapvaal lamproites that has both xenocrystic (i.e., mantle) and magmatic origins. Multiphase inclusions (melt/fluid) entrapped within olivine have been consistently demonstrated as an effective tool for gaining fundamental insights into the composition and evolution of melts that produce both kimberlites and lamproites, prior to processes, such as eruption, devolatization and syn-/post-magmatic alteration.In this study, multiphase inclusions of both secondary and pseudosecondary origin hosted in olivine from a Kaapvaal lamproite (Silvery Home, South Africa) provide novel insights into the composition of the melt(s) that initially transported olivine to the surface and then crystallised after emplacement to form the lamproite groundmass. The inclusions in our study contain daughter mineral assemblages consisting of diverse Ca-Mg carbonates, including K-, Na-, Ba-, and Sr-bearing varieties, moderate K-rich silicates (phlogopite, tetraferriphlogopite), and subordinate oxides, phosphates, sulphides, sulphates, and halides. Based on these daughter mineral assemblages, we suggest that the composition of the melt entrapped by olivine was SiO2-poor, Ca-Mg carbonate-rich and contained elevated concentrations of K, Na, Ba, Sr, P and Cl. The mineral and reconstructed melt compositions are in stark contrast to the mineral association of the groundmass and the bulk-rock composition of the Silvery Home lamproite, respectively. We suggest that alkali-/alkali-earth carbonates, phosphates, sulphides, sulphates, and halides represented a potentially significant, or even dominant, component of the melt that crystallised the Silvery Home lamproite but were likely removed by degassing and/or interaction with syn-/post-magmatic fluids. We show that olivine-hosted multiphase inclusions from the Silvery Home lamproite share many compositional similarities to melt inclusions hosted in olivine from kimberlites but are distinct from ‘classic’ cratonic olivine lamproites worldwide.

This paper describes secondary crystallized melt inclusions trapped in magnesiochromite of lherzolite xenolith from the V. Grib kimberlite pipe (Arkhangelsk diamondiferous province). It is shown that the inclusions are microportions of melt related to magmatism, which was further formed this pipe. Daughter minerals assemblage of inclusions in magnesiochromite contain Na‒K‒Ca-, Na‒Mg-, Ca‒Mg-, Mg-, and Ca-bearing carbonates; Na–Mg carbonates with additional PO _4^3 - , Cl–, and SO _4^2 - anions; chlorides; sulfate; phosphate; and silicate. The mineral assemblage of daughter phases, the amount of carbonates (77 vol

Garnet grains in mantle-derived peridotite xenoliths from kimberlites are surrounded by fine-grained aggregate of epigenetic minerals known as kelyphite. Existing models propose different kelyphite formation mechanisms. To test these models, we studied kelyphite around garnet grains in an unaltered lherzolite xenolith from the unique unserpentinised kimberlite from the Udachnaya pipe (Siberian Craton). Kelyphite consists of spinel, ortho- and clinopyroxenes, amphibole, phlogopite, sodalite, olivine, and magnetite. The absence of chlorite and serpentine in the studied intact kelyphite, but commonly found in kelyphite in other kimberlite-hosted peridotite xenoliths, suggests that they were likely a result of post-magmatic alteration. The comparison of the P-T stability fields of the minerals with the mantle residence P-T position of the investigated lherzolite (1350 degrees C, 6.4 GPa, similar to 200-km depth) indicates that the kelyphite was formed during xenolith transport to the surface (and subsequent cooling during pipe emplacement). Previously, the solid-phase reaction between garnet and olivine was considered the main kelyphite formation process in kimberlite-borne peridotite xenoliths. Based on the petrographic observations and bulk chemical data for kelyphite shells, we showed that this reaction is not suitable. As kelyphite is enriched in alkalis and incompatible trace elements, the participation of an external melt in kelyphite formation is required. Several lines of evidence discussed in this article demonstrate that kelyphite was formed exclusively by the reaction between garnet and kimberlite melt infiltrating the xenolith during ascent. We showed that even a water-poor kimberlite melt contains sufficient H2O to form the observed amounts of amphibole and phlogopite in kelyphite.

The paper presents a comprehensive review of currently available data on melt inclusions entrapped in minerals of kimberlites of different age and different provenance in ancient cratons. The crystallized melt inclusions represent snapshots of kimberlite melts at different stages of their evolution. All of the inclusions are completely crystallized and consist of daughter minerals and shrinkage bubbles, which sometimes contain low-density CO2, but no aqueous fluids and quenched silicate glasses have been found so far. Although more than 60 mineral species have been identified among the daughter phases in the inclusions, all inclusions hosted in various minerals from different kimberlites have closely similar or even identical composition. The daughter minerals are various Na–K–Ca, Na–Ca, Na–Mg, K–Ca, Ca–Mg, Ca, Mg, and Na carbonates; Na–Mg and Na carbonates with additional anions Cl–, SO_4^2 - , and PO_4^3 - ; and alkali sulfates, chlorides, phosphates, sulfides, oxides, and silicates. Alkali carbonates, sulfates, and chlorides are usually absent from among the groundmass phases of most kimberlites sampled worldwide, except the Udachnaya-East kimberlite in Siberia. However, this mineral assemblage, in association with such widespread kimberlite minerals as olivine, micas, monticellite, spinel-group minerals, perovskite, rutile, ilmenite, calcite, and dolomite, is common in the crystallized melt inclusions in all studied kimberlites. Carbonates ( 30 to 85 vol

В работе предложены подходы к исследованию стохастических моделей вычислительных сетей из персональных компьютеров с помощью многосерверных систем обслуживания с избыточностью. Представлены перспективы и ограничения указанного подхода, а также возможные направления дальнейших исследований.

In this paper we study the extreme behavior of waiting time in steady-state GI/G/1 systems with Exponential-Pareto service times. We show that this distribution belongs to the subclass of subexponential distributions, that allows to apply known tail asymptotic for stationary waiting times via the equilibrium distribution of service times. We propose the expressions for the normalizing constants and derive the limiting distribution of waiting time maxima (Frechet-type distribution). Simulation results show that approximation by Frechet-type distribution works well for GI/G/2 systems as well.

<p>The generation of carbonate melts during low degree partial melting of a mantle rocks was experimentally and theoretically predicted, however now days there are few direct <em>in situ</em> observations of relicts such melts in the mantle rocks. Here, we present the first directly empirical evidence of existence of alkali-carbonate liquid in the lithospheric mantle beneath the East European<strong> </strong>craton.</p> <p>A xenolith of garnet lherzolite G1-25 from the V. Grib kimberlite pipe (Arkhangelsk diamondiferous province, East European platform) was studied. The estimated P-T parameters of the last mineral equilibrium of the xenolith are 33 kbar and 750° C, which corresponds to the depth of ~ 100 km.  Olivine grains of the xenolith contain a large number of inclusions that arranged in groups along the randomly oriented healed fractures. Size of the inclusions varies from 2 to 50 μm. There are subhedral, elongate and vermicular inclusions shapes.</p> <p>The melt inclusions are composed of different daughter minerals, up to 10 within one inclusion, and rare bubble/bubbles. Mineral assemblages of the inclusions were studied by Raman spectroscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy.</p> <p>The following mineral species were identified among daughter phases of melt inclusions: nyerereite (Na,K)<sub>2</sub>Ca(CO<sub>3</sub>)<sub>2</sub>, shortite Na<sub>2</sub>Ca<sub>2</sub>(CO<sub>3</sub>)<sub>3</sub>, gregoryite/natrite (Na,K,Ca)<sub>2</sub>CO<sub>3</sub>, eitelite Na<sub>2</sub>Mg(CO<sub>3</sub>)<sub>2</sub>, dolomite CaMg(CO<sub>3</sub>)<sub>2</sub>, calcite CaCO<sub>3</sub>, magnesite MgCO<sub>3</sub>, unidentified Ba-carbonate, bradleyite Na<sub>3</sub>Mg(PO<sub>4</sub>)(CO<sub>3</sub>), northupite Na<sub>3</sub>Mg(CO<sub>3</sub>)<sub>2</sub>Cl, burkeite Na<sub>6</sub>CO<sub>3</sub>(SO<sub>4</sub>)<sub>2</sub>, aphthitalite K<sub>3</sub>Na(SO<sub>4</sub>)<sub>2</sub>, arcanite K<sub>2</sub>SO<sub>4</sub>, halite NaCl, sylvite KCl, tetraferriphlogopite KMg<sub>3</sub>FeSi<sub>3</sub>O<sub>10</sub>(OH), an unidentified Fe-Ni-Cu- sulfide, Fe-Ti-Mg-spinel-group mineral (Fe,Mg)(Fe,Al,Ti)<sub>2</sub>O<sub>4</sub> and apatite Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(F,Cl,OH).</p> <p>Analysis of confocal Raman images (Raman-maps) and BSE images show that more than 55 vol. % of studied inclusions is consist of various carbonate minerals dominated (>70 %) by alkaline carbonates, which indicate that the melt preserved in the inclusions was an alkaline carbonate liquid. Also, the funds of numerous sulfates (8 vol.%), halides (4 vol.%), phosphates (3 vol.%) among daughter phases of inclusions indicate high concentrations of volatile components in the preserved melt.</p>

Queueing systems with multiserver customers anew attracted the attention of researchers due to a number of modern applications such as the supercomputers, storage and wireless transmission. In such a system, each customer requires a random number of servers simultaneously. The models are hardly analytically tractable even in simple cases due to the non-work-conserving property and huge state space. However, it is important for applications to capture more details of the system, such as the shared resources (e.g. memory). In this paper we address this problem by appropriate model modifications.

This report deals with the first mineralogical examination of secondary crystallized melt inclusions (CMIs) in healed cracks within olivine in a mantle peridotite xenolith from the V. Grib kimberlite pipe (Arkhangelsk diamondiferous province). In contrast to micro/nano-inclusions in diamonds, the studied CMIs are quite large (up to 50 µm), so that the mineral composition of the CMIs can be determined via conventional analytical approaches, e.g., Raman spectroscopy and scanning electron microscopy. Garnet peridotite is a coarse-grained mantle rock that equilibrates at 3.3 GPa and 750 °C (corresponding to a depth of ~100 km). The CMIs are therefore tiny snapshots of melt that existed in the shallow lithospheric mantle and were entrapped in olivine. In total, nineteen mineral species were identified among the daughter magmatic minerals of the CMIs. Various Na-K-Ca-, Na-Ca-, Na-Mg-, Ca-Mg-, Mg- and Ca-carbonates; Na-Mg-carbonates with the additional anions Cl−, SO42− and PO43−; alkali sulfates; chlorides; phosphates; sulfides; oxides; and silicates were established. Within the mineral assemblage, carbonates were predominant, with their abundance being more than 62 vol.%. The CMIs contained twelve alkali-rich minerals; nine of them were Na-bearing and showed bulk molar (Na + K)/Ca ≥ 1. The CMIs’ parental melt was an alkali-rich carbonate liquid that contained low amounts of SiO2 (≤9.6 wt%) and H2O (≤2.6 wt%). According to our estimates, the time of complete equilibration between olivine within the healed cracks and host olivine in the mantle at the calculated P-T parameters for the studied xenolith should be no more than several years. Based on this geologically short time span, a genetic link between the studied CMIs and the magmatism that formed the V. Grib kimberlite pipe is suggested.

Data centers can participate in demand-response schemes by reducing their demand, however, at the expense of the agreed-upon performance of their IT services defined by the SLAs. The successful application of such schemes necessitates a careful analysis so that the amount of degradation of the SLAs with respect to power savings can be quantified helping the data center operators to set up the optimal configuration. In this paper, we study and analyze a system consisting of a data center, its operator, and IT clients under the consideration of relaxed SLAs. For this purpose, we consider a data center system consisting of two heterogeneous pools of servers, where each server is modeled using the single-server system with a power-saving inactive state, non-zero (random) activation/deactivation times, and hot standby state. Making use of the distributional Little's Law, derive the steady-state performance (in terms of response time distribution) and average power demand and study the power-performance trade-off in an explicit way. Numerical results illustrate the model's theoretical properties, under different considerations of low, medium, and high workload utilization rates.

This paper reports the first discovery of zoned aragonite, a high-pressure CaCO3 polymorph, in a mantle xenolith from kimberlite. Aragonite is the most common epigenetic mineral in the studied xenolith and is located in the interstitial space, where it can occupy up to 80 vol

Research subject . Clinopyroxene xenocrysts from the heavy-mineral concentrates of 14 kimberlite bodies (western part of the field: Obnazhennaya, Rubin, Seraya, Vodorazdelnaya, Vtorogodnitsa, Antoshka; central part of the field: Sliudyanka, Skiff II; western part of the field: Irina, Noyabrskaya, Vechernyaya, Lyusya, Dianga and Zhila 79) of the Kuoika field (Yakutian diamondiferous province, Siberian craton). Aim . To reconstruct the mantle paleogeotherms Under the six kimberlite pipes (Vodorazdelnaya, Obnazhennaya, Vtorogodnitsa, Sliudyanka, Dianga, and Zhila 79) using two independent approaches. Materials and methods . The chemical composition of clinopyroxene xenocrysts was investigated and last equilibrium temperatures and pressures were estimated using single-crystal thermobarometry. The geothermal line fitting to the P-T data set was performed using two methods. The first method is based on the D. Hasterok and D.S. Champan model, and the second - on the D. McKenzie model. Results. The value of lithosphere thickness falls within the margin of error for the two methods, being also comparable with earlier reconstructions for the Vtorogodnitsa, Dyanga, and Obnazhennaya pipes. The obtained results indicate that, during the Mesozoic kimberlitic magmatism, the lithosphere thickness beneath the Kuoika field was about 200 km. Conclusion . The determined peculiarities of the chemical composition of clinopyroxene xenocrysts indicate heterogeneity of the lithospheric mantle composition. Different depths of transported mantle material for kimberlite pipes of the Kuoika field, which are coeval and are located a few km apart, may be related to peculiarities of kimberlite magma ascent to the surface and the presence of intermediate magma chambers. The eastern part of the Kuoika field contains more garnet and garnet-spinel peridotites compared to the central and western parts, which may indirectly indicate a greater diamondiferous potential of the eastern block, where the diamondiferous Dianga pipe is located. The absence of diamonds in other discovered pipes of the Kuoika field may be connected with the metasomatic enrichment of the lithospheric mantle in the area of the “diamond window”, which is confirmed by a large number of high-temperature clinopyroxenes at these depths.

Long-lived radioactive isotopes provide valuable information on the evolution of Earth's geological reservoirs. Coupled measurements of the 138La-138Ce and 147Sm-143Nd systems have attracted much interest, but some critical reservoirs, such as the deep continental crust, have yet to be investigated. To address this gap, we report Ce-Nd isotope measurements of 35 crustal samples from Canada, western Europe, and Siberia, with Archean to Phanerozoic ages. Most samples from western Europe and Siberia are interpreted to represent the deepest continental crust because of low SiO2 content (< 55 wt%) and generally mafic compositions. In contrast, Precambrian composites from the Canadian shield have highly felsic compositions (61–71 wt% SiO2) and represent the old upper continental crust. Xenoliths from the Massif Central (France) and samples from uplifted massifs in the Ivrea-Verbano zone (Italy) plot on the Ce-Nd mantle array. Precambrian Canadian composites and xenoliths from Udachnaya (Siberian Craton) plot to the left of the mantle array, with the Siberian samples farthest from the array. The La-Ce system yields a ca. 1.8 Ga age for the Siberian xenoliths, distinct from the ca. 2.7 Ga Sm-Nd errorchron age. The La-Ce system was most likely reset during a large-scale episode of delamination and rejuvenation of the Archean lower lithosphere established in Siberia. A change in the La/Ce ratio during this event explains an increasing deviation with time of the Ce-Nd isotopic composition of the Siberian deep crust from the mantle array. We introduce a new parameter (θ) to quantify the likelihood of any rock evolving away from the mantle array. It represents the angle between the evolution vector of a sample and the mantle array, and it is calculated from measured La/Ce and Sm/Nd ratios. Samples that plot to the right of the mantle array have θ > 0, whereas samples that plot to the left of the mantle array have θ < 0. The angle θ was used to compare our samples to a worldwide granulite compilation (1581 samples) because it is independent of the age and the initial isotopic composition of the samples. The majority of lower crust rocks have negative θ, suggesting they are prone to evolve to the left of the mantle array, but to a lesser extent than the Siberian samples that are characterized by the most negative θ values. Thus, the Siberian samples with the most unusual Ce-Nd isotopic compositions are the only group to plot close to the deep crust end-member calculated from classical mass-balance budget of the bulk silicate Earth. These results suggest that the lower crust sampled by Siberian xenoliths is only a minor component in the terrestrial deep crust. We use this database to estimate new parent/daughter ratios for the lower continental crust: 138La/142Ce = 0.00380 ±0.00007 and 147Sm/144Nd = 0.128 ±0.007. Measurements and models are finally reconciled when considering massive recycling of lower continental crust through Earth's history, totaling 3 to 4 present-day, continental crust masses.

The paper is dedicated to digitalization efficiency evaluation methods in view of regional economy. Existing methods are briefly summarized. A modified digital efficiency evaluation method adopted to aquaculture as one of the key fields in regional economy of the Republic of Karelia as well as Finland, is extensively studied by means of simulation based on the statistics of the sector, and optimal parameters of budget devoted to digitalization for various size enterprises are obtained by means of numerical study.