Hermannjahnite,CuZn(SO4)2, a new mineral with chalcocyanite derivative structure from the Naboko scoria cone of the 2012–2013 fissure eruption at Tolbachik volcano,Kamchatka, Russia     

Siidra  Oleg I.  Nazarchuk  Evgeny V.  Agakhanov  Atali A.  Lukina  Evgeniya A.  Zaitsev  Anatoly N.  Turner  Rick  Filatov  Stanislav K.  Pekov  Igor V.  Karpov  Gennady A.  Yapaskurt  Vasiliy O. 《Mineralogy and Petrology》2018,112(1):123-134

Mineralogy and Petrology - A new mineral hermannjahnite, ideally CuZn(SO4)2, was found in the sublimates of Saranchinaitovaya fumarole, Naboko scoria cone, where the recent Fissure Tolbachik...  相似文献   

The distribution of late-Quaternary woody taxa in northern Eurasia: evidence from a new macrofossil database     

Heather A. Binney  Katherine J. Willis  Mary E. Edwards  Shonil A. Bhagwat  Patricia M. Anderson  Andrei A. Andreev  Maarten Blaauw  Freddy Damblon  Paul Haesaerts  Frank Kienast  Konstantin V. Kremenetski  Sergey K. Krivonogov  Anatoly V. Lozhkin  Glen M. MacDonald  Elena Y. Novenko  Pirita Oksanen  Tatiana V. Sapelko  Minna Väliranta  Ludmila Vazhenina 《Quaternary Science Reviews》2009,28(23-24):2445-2464

We present a database of late-Quaternary plant macrofossil records for northern Eurasia (from 23° to 180°E and 46° to 76°N) comprising 281 localities, over 2300 samples and over 13,000 individual records. Samples are individually radiocarbon dated or are assigned ages via age models fitted to sequences of calibrated radiocarbon dates within a section. Tree species characteristic of modern northern forests (e.g. Picea, Larix, tree-Betula) are recorded at least intermittently from prior to the last glacial maximum (LGM), through the LGM and Lateglacial, to the Holocene, and some records locate trees close to the limits of the Scandinavian ice sheet, supporting the hypothesis that some taxa persisted in northern refugia during the last glacial cycle. Northern trees show differing spatio-temporal patterns across Siberia: deciduous trees were widespread in the Lateglacial, with individuals occurring across much of their contemporary ranges, while evergreen conifers expanded northwards to their range limits in the Holocene.  相似文献   

Forest or no forest: implications of the vegetation record for climatic stability in Western Beringia during Oxygen Isotope Stage 3     

Anatoly V. Lozhkin  Patricia M. Anderson 《Quaternary Science Reviews》2011,30(17-18):2160-2181

Two conflicting stratigraphic schemes describe the Siberian Karginskii interstade (Oxygen Isotope Stage 3 equivalent) as having: 1) relatively stable climate with environments more similar to the full glaciation; or 2) variable climate with landscapes that more closely approximate contemporary ones. New data from continuous lake cores and a nearly continuous section from western Beringia (WB) suggest that both schemes are valid. Herb-dominated communities, possibly with isolated populations of Larix, characterized northern WB with only a slight shift from relatively warm to cool summers during the mid-interstade. In contrast, herb and shrub tundra, steppe, forest-tundra, and modern Larix forest occurred at various times in areas of southern WB, suggesting greater climatic instability. A thermal optimum is evident in the south during the mid-interstade, with modern vegetation in southeastern WB and Larix forest-tundra in the southwest. Variations in Pinus pumila pollen indicate summer warm/winter dry and summer warm/winter wet conditions in southeastern WB. These fluctuations contrast to other areas of WB, where summers and probably winters were consistently arid. Although the interstade presents a unique interval within the Late Pleistocene, paleodata and paleoclimatic models suggest that changes in marine conditions, including sea level, were likely key drivers in the regional climate history.  相似文献   

Inertinite-rich Tertiary coals from the Zeya–Bureya Basin, Far Eastern Russia     

Peter J. Crosdale  Anatoly P. Sorokin  Ken J. Woolfe  David I. M. Macdonald 《International Journal of Coal Geology》2002,51(4)

Selected Tertiary coals from the Zeya–Buryea Basin, Far Eastern Russia, were investigated for aspects of their coal type, rank, depositional environment and post-depositional history. The coals have been examined in outcrop (lithotype logging), microscopically (maceral, reflectance and fluorescence), and geochemically (proximate analysis).Two laterally extensive coal-bearing horizons occur: one of Palaeocene age and the other of early Miocene age. The Palaeocene coals were investigated in active open-cut mines at Raichikhinsk and Yerkovtsi and the early Miocene deposit in an abandoned open-cut mine at Cergeyevka.Palaeocene coals at Raichikhinsk and Yerkovtsi were indistinguishable from each other macroscopically, microscopically, and geochemically. The deposits were sufficiently coalified that brightness logging could be undertaken. Dull coals, with numerous fusainous wisps, were dominant. Four dulling-up sequences, which represent stacked peat deposits, were observed at Raichikhinsk. At Yerkovtsi, only a small section of the middle of the seam, which was mostly dull and muddy coal, was investigated. Petrographically, these coals were dominated by inertinite group macerals, which is unusual in non-Gondwanan coals and rare in the Tertiary. Rank classification was problematic with volatile matter (VM) content of vitrain (daf), macroscopic appearance, and microscopic textures suggesting subbituminous B rank, but carbon content, moisture content and specific energy indicating a lignite rank.Notwithstanding complications of rank, estimates of the maximum-range burial depths were calculated. Taking the VM (daf) content of vitrain as 48%, burial depth estimates range from 900 m for a high geothermal gradient and long heating time to a maximum of 3300 m for a low geothermal gradient and short heating time. These estimates are maxima as the coal rank may be lower than implied by the VM.The Cergeyevka deposit is a soft brown coal. Limited sampling of the upper-most portion indicated a high moisture content (75% daf) and an unusual, hydrogen-rich geochemistry. Lack of identifiable liptinites using either reflected light or fluorescence microscopy suggested a significant bituminite component. Otherwise, the coals appear to be typical for the Tertiary. An estimate of 125 m maximum burial depth was obtained using the bed-moisture content of the coal, which is around the present burial depth.Comparison of present-day thicknesses with inferred burial depths suggests that at least 500 m of section is missing between the Palaeocene coals and the early Miocene coals.Palaeoenvironmental considerations suggest that fire played a significant role in the accumulation of the peats at Raichikhinsk and Yerkovtsi. At Cergeyevka, peat accumulation ended by drowning of the mire.Two tuff beds were recognised within the seam at Raichikhinsk and one in the seam at Yerkovtsi. Correlation of the tuff beds is uncertain but they should prove useful in regional coal seam correlation and interpreting coal depositional environments. Geochemical analysis by XRF was complicated by high loss-on-ignition (LOI) values. Despite extensive alteration, an acid igneous source is implied from the presence of free quartz and TiO₂/Al₂O₃ ratios of 0.02 to 0.05.  相似文献   

Precise geochronology of phoscorites and carbonatites:: The critical role of U-series disequilibrium in age interpretations     

Yuri Amelin  Anatoly N Zaitsev 《Geochimica et cosmochimica acta》2002,66(13):2399-2419

We present the results of a comparative study of several geochronometer minerals (baddeleyite, zircon, apatite, phlogopite and tetraferriphlogopite) and isotopic systems (U-Pb, Th-Pb and Rb-Sr) from phoscorites (magnetite-forsterite-apatite-calcite rocks) and carbonatites of the Kovdor ultramafic-alkaline-carbonatite massif, Kola Peninsula, Russia. Uranium, thorium and their decay products are extremely fractionated by minerals that crystallise from carbonatite and phoscorite magma. We obtain high-precision ages from different chronometers, compare their accuracy, and evaluate the role of geochronological pitfalls of initial radioactive disequilibrium, differential migration of radiogenic isotopes, and inaccurate decay constants.Apatite yielded concordant U-Th-Pb ages between 376 and 380 Ma. The accuracy of the apatite ²³⁸U-²⁰⁶Pb ages is, however, compromised by uncertainty in the amount of radiogenic ²⁰⁶Pb produced from initial excess ²³⁰Th. The ²³⁵U-²⁰⁷Pb ages are relatively imprecise due to large common Pb correction and the uncertainty in the initial Pb isotopic composition. The Th-Pb system yields a more precise age of 376.4 ± 0.6 Ma.Zircon from two carbonatite samples is characterised by moderate to low U contents, high Th contents, and very high Th/U ratios up to 9000. The ²⁰⁶Pb*/²³⁸U systems in the zircon are strongly affected by the presence of excess ²⁰⁶Pb*, produced by decay of initial ²³⁰Th. The ²⁰⁸Pb*/²³²Th ages of zircon from both carbonatite samples are uniform and yield a weighted average of 377.52 ± 0.94 Ma.Baddeleyite U-Pb analyses are 3 to 6% normally discordant and have variable ²⁰⁷Pb*/²⁰⁶Pb* apparent ages. Eleven alteration-free baddeleyite fractions from three samples with no evidence for Pb loss yield uniform ²⁰⁶Pb*/²³⁸U ages with a weighted average of 378.54±0.23 Ma (378.64 Ma after correction for initial ²³⁰Th deficiency), which we consider the best estimate for age of the phoscorite-carbonatite body of the Kovdor massif. The ²⁰⁶Pb*/²³⁸U ages of baddeleyite fractions from five other samples spread between 378.5 and 373 Ma, indicating a variable lead loss up to 1.5%. The anomalously old ²⁰⁷Pb/²³⁵U and ²⁰⁷Pb/²⁰⁶Pb ages are consistent with the presence of excess radiogenic ²⁰⁷Pb* in the baddeleyite. We interpret this as a result of preferential partitioning of ²³¹Pa to baddeleyite.Fifteen phlogopite and tetraferriphlogopite fractions from five carbonatite and phoscorite samples yielded precise Rb-Sr isochron age of 372.2 ± 1.5 Ma, which is 5 to 7 m.y. younger than our best estimate based on U-Th-Pb age values. This difference is unlikely to be a result of the disturbance or late closure of Rb-Sr system in phlogopite, but rather suggests that the accepted decay constant of ⁸⁷Rb is too high.Comparative study of multiple geochronometer minerals from the Kovdor massif has revealed an exceptional complexity of isotopic systems. Reliable ages can be understood through systematic analysis of possible sources of distortion. No single geochronometer is sufficiently reliable in these rocks. Th-Pb and Rb-Sr can be a very useful supplement to U-Pb geochronometry, but the routine use of these geochronometers together will require more precise and accurate determination of decay constants for ²³²Th and ⁸⁷Rb.  相似文献   

Late Cretaceous palaeomagnetic results from Sikhote Alin, far eastern Russia: tectonic implications for the eastern margin of the Mongolia Block   总被引：3，自引：0，他引：3  

Yo-ichiro Otofuji  Takaaki Matsuda  Ryo Enami  Koji Uno  Katsuhiko Nishihama  Nadir Halim  Li Su  Haider Zaman  Ruslan G. Kulinich  Petr S. Zimin  Anatoly P. Matunin  Vladimir G. Sakhno 《Geophysical Journal International》2003,152(1):202-214

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Dolomite-calcite textures in early carbonatites of the Kovdor ore deposit,Kola peninsula,Russia: their genesis and application for calcite-dolomite geothermometry     

Anatoly Zaitsev  Ludmila Polezhaeva 《Contributions to Mineralogy and Petrology》1994,115(3):339-344

In early calcite carbonatites of the Kovdor ore deposit four morphological types of dolomite are represented. In the first type, dolomite microcrystals occur as lamellae enclosed by optically continuous calcite. In the second, dolomite microcrystals occur as segmented rods, plates and xenomorphic grains, enclosed by optically discontinuous calcite, and in the third, dolomite is represented by grains of various morphologies, situated along calcite grain boundaries. The fourth type of dolomite occurs as a fine-grained aggregate, which develops along grain boundaries and cleavage cracks of calcite. From microscopic, scanning electron microscope and microprobe studies of these different types of dolomite microcrystals, as well as the calcite associated with them, it can be concluded that the first type of dolomite was exsolved from magnesian calcite during cooling. The second, and the third types of dolomite microcrystals were formed by recrystallization. The fourth type of dolomite was formed by metasomatic dolomitization. As the result of these two processes-recrystallization and metasomatic dolomitization-early dolomite microcrystals seldom occur. The composition of the early-formed primary magnesian calcite yielded temperatures of exsolution of dolomite from magnesian calcite between 665 and 700°C.  相似文献   

Identification of sinkhole development mechanism based on a combined geophysical study in Nahal Hever South area (Dead Sea coast of Israel)   总被引：2，自引：0，他引：2  

Michael Ezersky  Anatoly Legchenko  Christian Camerlynck  Abdallah Al-Zoubi 《Environmental Geology》2009,58(5):1123-1141

Seismic refraction, magnetic resonance sounding (MRS), and the transient electromagnetic (TEM) method were applied to investigate the geological and hydrogeological conditions in the Nahal Hever South sinkhole development area at the Dead Sea (DS) coast of Israel. Microgravity and MRS results reliably reveal large karst cavity in the central part of investigated area. The map of the seismic velocity shows that sinkholes in Nahal Hever can be divided into two major groups: sinkholes close to the salt edge and sinkholes over compact salt formations between a few tens to a hundred meters from the major cavern. The present study shows that the formation of sinkholes of the first group is caused by soil collapsing into the cavern. In the area occupied by sinkholes of the second group, karst was not detected either by MRS or by seismic diffraction methods. TEM results reveal shallow clay layer saturated with DS brine underlain sinkholes of this group. It allows suggestion that the water drainage and intensive water circulation during rain events wash out fine rock particles from the unsaturated zone into the pre-existing cavern, initiating the formation of sinkholes of the second group. Karst development takes place at a very low bulk resistivity (<1 Ω m) of the DS aquifer, attesting to the fact that pores are filled with a highly saline solution. Refilling of the karstic cavities with collapsing and flushed soil slows down sinkhole development in the area. The sinkhole formation cycle at the site is estimated at 10 years. Sinkhole development throughout the studied area is triggered by a drop in the level of the DS, which reduces the head of the confined aquifer and the strength of the overlain sediments.

Abdallah Al-ZoubiEmail:

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Nonlinear interaction of broadband whistler waves with energetic electrons     

Anatoly Streltsov  Evgeny Mishin  Glenn Joyce 《Journal of Atmospheric and Solar》2009,71(8-9):897-904

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Characteristics of shallow gas hydrate in Okhotsk Sea   总被引：1，自引：0，他引：1  

LUAN XiWu  JIN YoungKeun  Anatoly OBZHIROV  YUE BaoJing Key Lab of Marine Geology  Environment  Institute of Oceanology  Chinese Academy of Sciences  Qingdao  China  Korea Polar Research Institute  KORDI  Incheon  -  Korea  V.I. Il’ichev Pacific Oceanological Institute of the Far Eastern Branch of Russian Academy of Sciences  Vladivostok  Russia 《中国科学D辑(英文版)》2008,51(3):415-421

Multidisciplinary field investigations were carried out in Okhotsk Sea by R/V Akademik M.A. Lavrentyev (LV) of the Russian Academy of Sciences (RAS) in May 2006, supported by funding agencies from Ko- rea, Russia, Japan and China. Geophysical data including echo-sounder, bottom profile, side-scan- sonar, and gravity core sample were obtained aimed to understand the characteristics and formation mechanism of shallow gas hydrates. Based on the geophysical data, we found that the methane flare detected by echo-sounder was the evidence of free gas in the sediment, while the dome structure de- tected by side-scan sonar and bottom profile was the root of gas venting. Gas hydrate retrieved from core on top of the dome structure which was interbedded as thin lamination or lenses with thickness varying from a few millimeters to 3 cm. Gas hydrate content in hydrate-bearing intervals visually amounted to 5%―30% of the sediment volume. This paper argued that gases in the sediment core were not all from gas hydrate decomposition during the gravity core lifting process, free gases must existed in the gas hydrate stability zone, and tectonic structure like dome structure in this paper was free gas central, gas hydrate formed only when gases over-saturated in this gas central, away from these struc- tures, gas hydrate could not form due to low gas concentration.  相似文献