The protolith nature of diamondiferous metamorphic rocks of the Kokchetav Massif     

Vladislav Shatsky  Emil Jagoutz  Olga Kozmenko  Alexey Ragozin  Sergei Skuzovatov  Nikolai Sobolev 《《地质学报》英文版》2018,92(Z1):173-173

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Early Cambrian magmatism in the northeastern Siberian Craton (Olenek Uplift)     

A. I. Kiselev  B. B. Kochnev  V. V. Yarmolyuk  K. N. Egorov 《Doklady Earth Sciences》2015,465(2):1218-1223

The Vendian–Lower Cambrian tectonomagmatic activation took place in the northeastern Siberian Craton, within the Olenek Uplift and in the Kharaulakh segment of the Verkhoyansk fold-and-thrust belt (the lower reaches of the Lena River). The Early Paleozoic volcanic activity in the Olenek Uplift is expressed in the form of basitic diatremes, small basaltic covers, and doleritic dikes and sills intruding and covering the Upper Vendian carbonate deposits. The material specificity of the Lower Cambrian basites and their mantle sources, jointly with the Vendian–Cambrian sedimentation history, gives reason to consider the Lower Cambrian riftogenesis and the associated magmatism as a consequence of the plume–lithosphere interaction in the northeastern Siberian Craton.  相似文献   

Sicilian serpentinite xenoliths containing abiotic organics with nanodiamond clusters as key model for prebiotic processes     

Sergei K.Simakov  Vittorio Scribano  Nikolai N.Mel’Nik  Germana Barone 《地学前缘(英文版)》2021,12(1):255-263

Rock fragments from the deepest parts of a buried hydrothermal system belonging to the Mesozoic Tethys Ocean entered as xenoliths in a Miocenic diatreme,hence brought to the surface,in the Hyblean Plateau(Sicily).Some xenoliths consist of strongly serpentinized ultramafic rocks bearing blebs of abiotic organic matter,where clusters of amorphous carbon nanoparticles,including nanodiamonds,are immersed.Such an occurrence conjures up established hypotheses that diamond surfaces are suitable catalytic platforms stimulating the assemblage of complex bio-organic molecules relevant to the emergence of life on Earth.The appearance of bio-organic molecules under primitive Earth conditions is one of the major unsolved questions on the origin of life.Here we report new micro-Raman spectra on blebs of abiotic organic matter from a selected xenolith.Diamond bands were related to hydrogenated nanocrystalline diamonds,with size of nearly 1-1.6 nm,formed from organics at low pressures and temperatures.In particular,diamond surfaces can give rise to crystalline interfacial water layers that may have played a fundamental role in the early biosphere evolution as a good medium for rapidly transporting positive charges in the form of hydrated protons.Nowadays,proton gradients in alkaline hydrothermal vents along oceanic ridges are generally viewed as key pre-biotic factors.In general,serpentinites span the entire geological record,including prebiotic times.These hydrous ultramafic rocks often display evidence of abiotic carbon species,both organic and inorganic,including nanodiamonds,being also capable to give rise to chemiosmotic processes and proton gradients necessary to the organisms,such as the"Last Universal Common Ancestor"(LUCA),in the prebiotic Earth.  相似文献   

A novel probe for point injections in groundwater monitoring wells     

Fahrmeier  Nikolai  Goeppert  Nadine  Goldscheider  Nico 《Hydrogeology Journal》2022,30(3):1021-1029

Hydrogeology Journal - Groundwater monitoring wells or boreholes often show complex flow behaviors that are essential to understand for the characterization of aquifer systems. In karst or...  相似文献   

Photographic observations of visual double stars at Pulkovo: Digitization,measurement, and calibration     

I. S. Izmailov  E. A. Roshchina  A. A. Kiselev  T. P. Kiseleva  O. A. Kalinichenko  O. P. Bykov  O. V. Kiyaeva  L. G. Romanenko  N. A. Shakht  K. L. Maslennikov  T. A. Vasil’eva 《Astronomy Letters》2016,42(1):41-54

We present the results of determining the relative positions of 359 pairs of stars. More than 6000 photographic plates were obtained in 1960–2007 at the 26-inch refractor of the Pulkovo Observatory. The plates have been digitized with a Canon EOS 5D Mark II digital camera and a long-focus Jupiter 21M lens; the scalewas 21 μm/pixel. Themeasurements have been calibrated using a template digitized with the Belgian high-precision ROB Digitizer. The results have been thoroughly investigated for systematic errors. We have studied the scale of the 26-inch refractor and revealed its temperature and time dependences. The application of a new digitization, measurement, and calibration technique has allowed the accuracy to be increased compared to the past measurements. The single-exposure measurement accuracy is within the range from 2 to 70 mas, on average, 28 mas in both coordinates. The errors of the yearly mean positions are, on average, 8.7 mas in the angular separation and 0.05?. in the position angle.  相似文献   

Results of the Photometric Observations of the NEA (2100) Ra-Shalom During an Encounter in 2019     

Abdulloev  S. Kh.  Kiselev  N. N.  Shamsiddinov  Sh. Sh. 《Solar System Research》2021,55(5):398-401

Solar System Research - This paper presents the results of the photometric CCD observations of the NEA (2100) Ra-Shalom carried out on August 24–29, 2019, at the 1-m telescope of the Sanglokh...  相似文献   

Palaeoclimatic record from a loess–soil profile in northeastern Bulgaria—II. Correlation with global climatic events during the Pleistocene     

Diana Jordanova  & Nikolai Petersen 《Geophysical Journal International》1999,138(2):533-540

Magnetic susceptibility ( χ ) variations and the behaviour of the ratio of susceptibility to saturation magnetization ( χ/J _s ) along the loess/palaeosol section at Koriten (NE Bulgaria) are used to deduce climatic changes during the Pleistocene in southeastern Europe. A good correlation of susceptibility variations with the astronomically tuned oxygen isotope record from ODP site 677 enables us to propose a more precise dating of the upper part of the Bulgarian loess complex. Close correspondence between susceptibility and δ ^{1 8} O records demonstrates the global significance of the palaeoclimatic signal recorded, although differences in relative amplitudes of χ and χ/J _s and δ ^{1 8} O create difficulties in making quantitative estimates of the climatic humidity in the past. The role of local factors affecting the palaeoclimatic mineral magnetic record deduced from the profile studied in Bulgaria is discussed.  相似文献   

Influence of the Solar Activity Cycle on the Gasdynamic Structureof the Heliospheric Interface     

Nikolai Zaitsev 《Astrophysics and Space Science》2000,274(1-2):149-156

The effects of the 11 year solar activity cycle on the heliospheric plasma interface in the presence of neutral H-atoms have been investigated. Our calculations show that nonstationary processes of such kind lead to1) a decrease of the mean interstellar plasma density in the interface;2) a sequence of shocks and rarefaction waves moving from the heliopause (HP)to the bow shock (BS); 3) an expansion of the region between the BS and HP;4) the TS excursion along the upwind direction is within 30%of the mean solar distance. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Long-Term Temperature Trends and Tree Growth in the Taymir Region of Northern Siberia   总被引：2，自引：0，他引：2  

Gordon C. Jacoby  Nikolai V. Lovelius  Oleg I. Shumilov  Oleg M. Raspopov  Juri M. Karbainov  David C. Frank 《Quaternary Research》2000,53(3):312

The northernmost conifers in the world are located well above the Arctic Circle in the Taymir region of northern Siberia and have been recording the thermal environment for centuries to millennia. The trees respond to temperatures beyond the narrow season of actual cambial cell division by means of root growth, photosynthesis, lignification of cell walls, and other biochemical processes. Data from annual tree-ring widths are used to reconstruct May–September mean temperatures for the past four centuries. These warm-season temperatures correlate with annual temperatures and indicate unusual warming in the 20th century. However, there is a loss of thermal response in ring widths since about 1970. Previously the warmer temperatures induced wider rings. Most major warming and cooling trends are in agreement with other high-latitude temperature reconstructions based on tree-ring analyses with some regional differences in timing of cooling in the late 18th century and of warming in the late 19th century.  相似文献   

Toward development of the 4Dvar data assimilation system in the Bering Sea： reconstruction of the mean dynamic ocean topography     

Gleb Panteleev  Dmitri Nechaev  Vladimir Luchin  Phyllis Stabeno  Nikolai Maximenko  Motoyoshi Ikeda 《极地研究(英文版)》2008,19(2):123-134

The Bering Sea circulation is derived as a variational inverse of hydrographic profiles（ temperature and salinity） , atmospheric climatologies and historical observation of ocean curents. The important result of this study is estimate of the mean climatological sea surface height （SSH） that can be used as a reference for satellite altimetry sea level anomaly data in the Bering Sea region. Numerical experiments reveal that, when combined with satellite altimetry, the obtained reference SSH effectively constrains a realistic reconstruction of the Amukta Pass circulation.  相似文献