The Numerical Simulation of Aerodynamics of the Frontal Aerodynamic Screen of ExoMars Project Descent Vehicle and the Analysis of Flow Pattern in the Base Area and Near Wake     

Babakov  A. V.  Finchenko  V. S. 《Solar System Research》2020,54(7):712-718

Solar System Research - Results of the numerical study of the flow past the frontal aerodynamic screen of the descent vehicle of the ExoMars project, the determination of aerodynamic...  相似文献   

Optical Spectroscopy of SRG/eROSITA Objects with 2.5-m Telescope at the Caucasus Mountain Observatory of the SAI MSU     

Dodin  A. V.  Potanin  S. A.  Shatsky  N. I.  Belinski  A. A.  Atapin  K. E.  Burlak  M. A.  Egorov  O. V.  Tatarnikov  A. M.  Postnov  K. A.  Belvedersky  M. I.  Burenin  R. A.  Gilfanov  M. R.  Medvedev  P. S.  Meshcheryakov  A. V.  Sazonov  S. Yu.  Khorunzhev  G. A.  Sunyaev  R. A. 《Astronomy Letters》2020,46(7):429-438

Astronomy Letters - Based on observations with the new transient double-beam spectrograph (TDS) at the 2.5-m telescope of the Caucasus Mountain Observatory of SAI MSU, we have determined the types...  相似文献   

LA‐ICP‐MS Pb isotope test of meteorite provenance: A terrestrial origin for Lovina     

Christopher R. J. Charles  Phil J. A. McCausland  Donald W. Davis 《Meteoritics & planetary science》2020,55(5):1093-1102

Lovina, classified as an ungrouped ataxite, is controversial and its identity as a meteorite has been questioned. In this work, we use Pb isotopes on targeted troilite nodules in Lovina as a test of its antiquity and provenance. Although precise ages cannot be obtained, LA‐ICP‐MS offers a rapid, straightforward procedure to establish the source of lead, whether ancient (meteoritic) or modern (terrestrial). For nine pristine, unweathered nodules in Lovina, we find a lead isotopic composition of: ²⁰⁶Pb/²⁰⁸Pb = 0.492 ± 0.003 (2σ, MSWD 0.79; 95%) and ²⁰⁷Pb/²⁰⁶Pb = 0.852 ± 0.003 (2σ, MSWD 1.09; 95%) with no detectable uranium. All lead compositions of the troilite fall in the range expected for modern environmental and mantle lead and are distinctly different from the primordial Canyon Diablo Troilite (CDT) composition of ancient meteoritic troilite. Although the origin of Lovina remains unknown, we conclude that lead in the Lovina troilite is unsupported by U decay and originated from a terrestrial source.  相似文献   

Terrestrial heat flow and lithospheric thermal structure in the Chagan Depression of the Yingen-Ejinaqi Basin,north central China     

Yinhui Zuo  Shu Jiang  Shihu Wu  Wei Xu  Jiong Zhang  Renpeng Feng  Meihua Yang  Yongshui Zhou  M. Santosh 《Basin Research》2020,32(6):1328-1346

The Chagan Depression in the Yingen-Ejinaqi Basin, located at the intersection of the Paleo-Asian Ocean and the Tethys Ocean domains is an important region to gain insights on terrestrial heat flow, lithospheric thermal structure and deep geodynamic processes. Here, we compute terrestrial heat flow values in the Chagan Depression using a large set of system steady-state temperature data from four representative wells and rock thermal conductivity. We also estimate the “thermal” lithospheric thickness, mantle heat flow, ratio of mantle heat flow to surface heat flow and Moho temperature to evaluate the regional tectonic framework and deep dynamics. The results show that the heat flow in the Chagan Depression ranges from 66.5 to 69.8 mW/m², with an average value of 68.3 ± 1.2 mW/m². The Chagan Depression is characterized by a thin “thermal” lithosphere, high mantle heat flow, and high Moho temperature, corresponding to the lithospheric thermal structure of “cold mantle and hot crust” type. We correlate the formation of the Yingen-Ejinaqi Basin to the Early Cretaceous and Cenozoic subduction of the western Pacific Plate and the Cenozoic multiple extrusions. Our results provide new insights into the thermal structure and dynamics of the lithospheric evolution in central China.  相似文献   

Sediment routing in the Zagros foreland basin: Drainage reorganization and a shift from axial to transverse sediment dispersal in the Kurdistan region of Iraq     

Renas I. Koshnaw  Brian K. Horton  Daniel F. Stockli  Douglas E. Barber  Mazin Y. Tamar-Agha 《Basin Research》2020,32(4):688-715

In the northwestern sector of the Zagros foreland basin, axial fluvial systems initially delivered fine-grained sediments from northwestern source regions into a contiguous basin, and later transverse fluvial systems delivered coarse-grained sediments from northeastern sources into a structurally partitioned basin by fold-thrust deformation. Here we integrate sedimentologic, stratigraphic, palaeomagnetic and geochronologic data from the northwestern Zagros foreland basin to define the Neogene history of deposition and sediment routing in response to progressive advance of the Zagros fold-thrust belt. This study constrains the depositional environments, timing of deposition and provenance of nonmarine clastic deposits of the Injana (Upper Fars), Mukdadiya (Lower Bakhtiari) and Bai-Hasan (Upper Bakhtiari) Formations in the Kurdistan region of Iraq. Sediments of the Injana Formation (~12.4–7.75 Ma) were transported axially (orogen-parallel) from northwest to southeast by meandering and low-sinuosity channel belt system. In contrast, during deposition of the Mukdadiya Formation (~7.75–5 Ma), sediments were delivered transversely (orogen-perpendicular) from northeast to southwest by braided and low-sinuosity channel belt system in distributive fluvial megafans. By ~5 Ma, the northwestern Zagros foreland basin became partitioned by growth of the Mountain Front Flexure and considerable gravel was introduced in localized alluvial fans derived from growing topographic highs. Foredeep accumulation rates during deposition of the Injana, Mukdadiya and Bai-Hasan Formations averaged 350, 400 and 600 m/Myr respectively, suggesting accelerated accommodation generation in a rapidly subsiding basin governed by flexural subsidence. Detrital zircon U-Pb age spectra show that in addition to sources of Mesozoic-Cenozoic cover strata, the Injana Formation was derived chiefly from Palaeozoic-Precambrian (including Carboniferous and latest Neoproterozoic) strata in an axial position to the northwest, likely from the Bitlis-Puturge Massif and broader Eastern Anatolia. In contrast, the Mukdadiya and Bai-Hasan Formations yield distinctive Palaeogene U-Pb age peaks, particularly in the southeastern sector of the study region, consistent with transverse delivery from the arc-related terranes of the Walash and Naopurdan volcano-sedimentary groups (Gaveh-Rud domain?) and Urumieh-Dokhtar magmatic arc to the northeast. These temporal and spatial variations in stratigraphic framework, depositional environments, sediment routing and compositional provenance reveal a major drainage reorganization during Neogene shortening in the Zagros fold-thrust belt. Whereas axial fluvial systems initially dominated the foreland basin during early orogenesis in the Kurdistan region of Iraq, transverse fluvial systems were subsequently established and delivered major sediment volumes to the foreland as a consequence of the abrupt deformation advance and associated topographic growth in the Zagros.  相似文献   

The MIRS Microwave Radiometer–Spectrometer as the Basis for the Convergence Space Experiment     

Sadovsky  I. N.  Kuzmin  A. V.  Khapin  Yu. B.  Kozlova  T. O. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(12):1741-1750

Izvestiya, Atmospheric and Oceanic Physics - The MIRS microwave radiometer–spectrometer is described. The instrument is being developed using a conceptual design that was the first stage of...  相似文献   

Density Structure of the Lithosphere of the Sikhote-Alin Orogenic Belt     

Didenko  A. N.  Nosyrev  M. Yu. 《Doklady Earth Sciences》2020,492(2):446-450

Doklady Earth Sciences - For the first time, a detailed density 3D model of the lithosphere of the Sikhote-Alin orogenic belt to a depth of 130 km has been created. Two extended submeridional...  相似文献   

Restructuring of the Solar Magnetic Fields and Flare Activity Centers in Cycle 24     

A. V. Borovik  A. V. Mordvinov  E. M. Golubeva  A. A. Zhdanov 《Astronomy Reports》2020,64(6):540-546

The development of the solar magnetic activity in cycle 24 has been analyzed. It has been shown that the significant north–south asymmetry of magnetic activity was accompanied by the asynchronous reorganization of solar magnetic fields in the northern and southern hemispheres. The formation of unipolar magnetic regions after the decay of activity centers has been studied. The meridional transport of unipolar magnetic regions leading to changes in the zonal structure of the solar magnetic field has been shown. Long-lived centers of flare activity have been found to exist during the periods of magnetic field restructuring. The spatiotemporal analysis of the flare ensemble making it possible to diagnose non-stationary processes in the solar atmosphere has been shown.  相似文献   

Quantification of Hydrogen in Natural Diamond by Secondary Ion Mass Spectrometry (SIMS)     

Kaminsky  F. V.  Shilobreeva  S. N.  Ber  B. Ya.  Kazantsev  D. Yu. 《Doklady Earth Sciences》2020,494(1):699-703

Doklady Earth Sciences - The volumetric concentration of hydrogen in two Brazilian diamonds is determined using secondary ion mass spectrometry and implantation of hydrogen into an external...  相似文献   

Digital Elevation Models of the Bottom in the Operational Oceanography System     

Libina  N. V.  Nikiforov  S. L. 《Oceanology》2020,60(6):854-860

Oceanology - A new area of oceanography, operational oceanography, involves a comprehensive assessment and forecast of the variability of the state of the marine environment. This requires...  相似文献