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Morozov Alexey N. Vaganova Natalya V. Konechnaya Yana V. Asming Vladimir E. Dulentsova Ludmila G. Evtyugina Zinaida A. 《Journal of Seismology》2021,25(5):1171-1188
Journal of Seismology - A permanent seismic station was for the first time installed on Severnaya Zemlya in the Russian Arctic. This made it possible to record low-magnitude earthquakes occurring... 相似文献
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A review of the modern state of the lunar libration theory is presented. A significant progress in the lunar investigation is achieved due to the simultaneous processing of results of the satellite Doppler tracing and of the lunar laser ranging. The data evidencing existence of a small iron core in the Moon are discussed. In this connection, the further development of the theory of rotation of the Moon presents the study of internal structure and dynamics of a lunar body. A model of a two-layer Moon can have a very advanced application to explain some observed phenomena and to be as a first approach in the modelling of internal processes determining the lunar rotation. 相似文献
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IrinaP.Solovova Theodoros Ntaflos Andrei Girnis Natalya N.Kononkova Vyacheslav V.Akinin 《岩石学报》2007,23(1):83-92
Melt and fluid inclusions were studied in the minerals of Cenozoic olivine melanephelinites from the Chukchi Peninsula, Russia.The rock contain several generations of olivine phenocrysts varying in composition at mg=0.88～0.77.The phenocrysts bear fluid and melt inclusions recording various stages of melt crystallization in volcanic conduits and shallow magma chambers.Primary fluid inclusions are CO_2-dominated with a density of up to O.93 g/cm~3.All fluid inclusions are partially leaked,which is indicated by haloes of tiny fluid bubbles around large fluid inclusions in minerals.Melt inclusions contain various daughter crystals,which were completely resorbed in thermometric experiments at about 1230℃.Assuming that this temperature corresponds to the entrapment conditions of the CO_2 fluid inclusions,the minimum pressure of the beginning of magma degassing is estimated as 800MPa.Variations in the compositions of homogenized silicate melt inclusions indicate that olivine was the earliest crystalline phase followed by clinopyroxene,nepheline and orthoclase.This sequence is in agreement with the mineralogy of the rocks.The melts are strongly enriched in incompatible trace elements and volatiles(in addition to CO_2,high C1,F,and S contents were detected).There are some differences between the compositions of melts trapped in minerals from different samples.Variations in SiO_2,FeO,and incompatible element contents are probably related to melt generations at various levels in a homogeneous mantle reservoir. 相似文献
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The Institute of Biology investigations of morphological diversity of bacteriae with the aid of electronic microscopy are used for the purposes of ecological monitoring. The results obtained allow to recommend this method to be widely applied.It has been demonstrated that for oligotrophic lake Baikal microflora consists mainly from ultra-microscopic cocci. Where the river Selenga inflows into Baikal morphological diversity of bacteriae is much wider. Bacterioplankton of Irkutsk reservoir by morphological characteristics is very similar to one of lake Baikal In meso-eutrophic Bratsh reservoir bacteriuplankton is more morphologically diversified. There are flexibacteriae, vibrios. Caulobacter sp. cells occurring in its water body.In the places of waste waters'' income to river. Angara morphological diversity of bacteriae is high and various forms with projections etc. can be observed. 相似文献
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Noa Ohana-Levi Tarin Paz-Kagan Natalya Panov Aviva Peeters Asaf Tsoar 《地理信息系统科学与遥感》2019,56(3):362-387
Land-use changes as a result of residential development often lead to degradation and alter vegetation cover (VC). Although these are worldwide phenomena, sufficient knowledge about anthropogenic effects caused by various populated areas in dryland ecosystems is lacking. This study explored anthropogenic development in rural areas and its effects on the conservation of protected areas in drylands, focusing on the change in VC, the reasons, extent, and the drivers of change. We propose a novel framework for exploring VC change (VCC) as a function of environmental and human-driven factors including different types of populated areas in drylands. As a case study, we used a 30-year time series of Landsat satellite images over the arid region of Israel to analyze spatiotemporal VCC. The temporal analysis involved the Contextual Mann-Kendall significance test and spatial analysis to model clustering of VCC. A Gradient Boosted Regression machine learning algorithm was applied to study the relative influence of environmental and human-driven factors on VCC. In addition, we used ANOVA to examine differences between the effects of three types of populated areas on the spatiotemporal trends of VC. The results show that the most influential environmental variable on VCC was elevation (relative contribution of 17%), followed by slope (14.8%) and distance from populated areas (14.6%). Moreover, different types of populated areas affected VC differently with varying distances from residential centroids. The nature reserves increased VC positively and significantly, while livestock settlements had a negative effect. Change in vegetation was mostly confined to the stream network and occurred in lower elevations. The study demonstrates how different land-use practices alter the landscape in terms of VC and differ in their extents, patterns, and effects. With the expected growth in population and residential development worldwide, the proposed framework may assist conservation managements and policy makers in minimizing environmental degradation in drylands. 相似文献
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Nadezhda Alexandrovna Krivolutskaya Alexandr Vladimirovich Sobolev Sergey Grigor’evich Snisar Bronislav Iosiphovich Gongalskiy Dmitry Vladimirovich Kuzmin Folkmar Hauff Irina Nikolaevna Tushentsova Natalya Mikhailovna Svirskaya Natalya Nikolaevna Kononkova Tatyana B. Schlychkova 《Mineralium Deposita》2012,47(1-2):69-88
We report new data on the stratigraphy, mineralogy and geochemistry of the rocks and ores of the Maslovsky Pt–Cu–Ni sulfide deposit which is thought to be the southwestern extension of the Noril’sk 1 intrusion. Variations in the Ta/Nb ratio of the gabbro-dolerites hosting the sulfide mineralization and the compositions of their pyroxene and olivine indicate that these rocks were produced by two discrete magmatic pulses, which gave rise to the Northern and Southern Maslovsky intrusions that together host the Maslovsky deposit. The Northern intrusion is located inside the Tungusska sandstones and basalt of the Ivakinsky Formation. The Southern intrusion cuts through all of the lower units of the Siberian Trap tuff-lavas, including the Lower Nadezhdinsky Formation; demonstrating that the ore-bearing intrusions of the Noril’sk Complex post-date that unit. Rocks in both intrusions have low TiO2 and elevated MgO contents (average mean TiO2 <1 and MgO?=?12?wt.%) that are more primitive than the lavas of the Upper Formations of the Siberian Traps which suggests that the ore-bearing intrusions result from a separate magmatic event. Unusually high concentrations of both HREE (Dy+Yb+Er+Lu) and Y (up to 1.2 and 2.1?ppm, respectively) occur in olivines (Fo79.5 and 0.25% NiO) from picritic and taxitic gabbro-dolerites with disseminated sulfide mineralization. Thus accumulation of HREE, Y and Ni in the melts is correlated with the mineral potential of the intrusions. The TiO2 concentration in pyroxene has a strong negative correlation with the Mg# of both host mineral and Mg# of host rock. Sulfides from the Northern Maslovsky intrusion are predominantly chalcopyrite–pyrrhotite–pentlandite with subordinate and minor amounts of cubanite, bornite and millerite and a diverse assemblage of rare precious metal minerals including native metals (Au, Ag and Pd), Sn–Pd–Pt–Bi–Pb compounds and Fe–Pt alloys. Sulfides from the Southern Maslovsky intrusion have δ 34S?=?5–6‰ up to 10.8‰ in two samples whereas the country rock basalt have δ 34S?=?3–4‰, implying there was no in situ assimilation of surrounding rocks by magmas. 相似文献
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Alexander N. Krot Alan E. Rubin Natalya N. Kononkova 《Meteoritics & planetary science》1993,28(2):232-239
Abstract A 220 × 430 μm Mg-Al-chromite fragment in the Raguli H3.8 ordinary chondrite exhibits distinct optical and compositional zoning. The dark central region of the Mg-Al-chromite is enriched in MgO, Al2O3 and ZnO and depleted in TiO2, Cr2O3, FeO and MnO relative to the lighter outer region. A subhedral olivine grain attached to radiating euhedral ilmenites is present in the central region of the fragment. One of the ilmenite crystals contains a tiny grain (0.5 × 5.8 μm) of baddeleyite (ZrO2). Two end-member pyrophanite grains (MnTiO3) occur in the outer portion of the fragment This is the first occurrence of pyrophanite and baddeleyite in an ordinary chondrite. Although it is possible that the Mg-Al-chromite fragment was derived from an achondritic projectile of unusual composition, we offer two alternative models for its formation. These include (a) a multi-stage process involving nebular melting of a chromian-spinel chondrule that had accreted some olivine-bearing, Mn-rich material followed by metamorphism on the parent body, and (b) formation of the fragment on a metamorphosed parent body from an impact melt of a chromite-rich assemblage containing Mn-rich ilmenite. We favor the latter alternative. 相似文献
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A sequence of Late Holocene moraines on the foreland of the Mueller Glacier, Southern Alps, New Zealand, forms part of a local moraine‐age database used to establish a regional glacier chronology and subsequently to investigate potential intra‐hemispheric and global climate forcing mechanisms. We present new sedimentological and geomorphological evidence that a set of these moraine ridges, previously considered to represent individual advances, constitutes a single moraine complex (the ‘Mueller Memorial Moraine’) formed by supraglacial transport of a large volume of landslide debris to the glacier terminus. Because a moraine formed in this way is not necessarily associated with an advance triggered by a climate event, we question the palaeoclimatic significance of the Mueller Memorial Moraine, as well as that of other moraines in comparable settings. Our findings suggest that the mode of formation and glacio‐dynamical context of moraines whose ages contribute to existing palaeoclimate reconstructions need to be re‐examined in order to assess the reliability of these reconstructions. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
30.
Alexander N. Krot Nina I. Zaslavskay Michail I. Petaev Natalya N. Kononkova Gennady M. Kolesov Lydia D. Barsukova 《Meteoritics & planetary science》1992,27(4):465-466
Abstract— Sychevka is a relatively unweathered 65-kg iron meteorite that was found in Russia in 1988. The microstructure, mineralogy and bulk composition of Sychevka as revealed by optical microscopy, electron microprobe and instrumental neutron activation analysis indicate that this meteorite is a group-IIIAB medium octahedrite. Sychevka consists of (in vol%): kamacite (82.5), plessite (16), schreibersite (1.5), and rare grains of chromite and troilite. 相似文献