Simulation,Design, and Control of the Thermal Regime of Deep Mines

Doklady Earth Sciences - The results of fundamental and applied research aimed at ensuring safe working conditions in terms of the thermal factor in the development of deep deposits of solid...     

On the Need for Accurate Monitoring of the Geomagnetic Field during Directional Drilling in the Russian Arctic

Izvestiya, Physics of the Solid Earth - Abstract—The readings of well magnetometers used in directional drilling may be distorted by geomagnetic storms and substorms. These distortions occur...     

First Data on the Geochemistry and Age of the Kontay Intrusion in Polar Siberia

The first ever comprehensive geochemical data on the Kontay intrusion, polar Siberia, demonstrate that the intrusion is profoundly differentiated and shows geochemical features typical of intraplate magmatism. The age of the intrusion is Early Paleozoic. The paper summarizes literature data regarded as circumstantial evidence that a large magmatic intraplate (perhaps, plume-related) province of Early Paleozoic age may occur in the northern part of the Siberian Platform, whose only component found as of now is the Kontay intrusion. The intrusion is demonstrated not to possess any precious-metal (Ag–Pd) ore potential, contrary to what was surmised previously.     

C, О, S,and Sr Isotope Geochemistry and Chemostratigraphy of Ordovician Sediments in the Moyero River Section,Northern Siberian Platform

The ⁸⁷Sr/⁸⁶Sr ratio in gypsum and limestones of the Ordovician section of the Moyero River decreases from the bottom upward from 0.7091?0.7095 in the Irbukli Formation (Nyaian Regional Stage, ~Lower Ordovician Tremadocian Stage) to 0.7080 in the upper part of the Dzherom Formation (Dolborian Regional Stage, ~Upper Ordovician Katian Stage), which is well consistent with biostratigraphic subdivision of the section and existing concept concerning the strontium isotope evolution of the World Ocean. The most characteristic feature of the carbon isotope curve is decrease of δ¹³С values in carbonates from weakly positive values (0.5…1.1‰) in the Irbukli Formation (Nyaian Regional Stage) to sharply negative values (–5.4...–5.8‰) in the middle part of the Kochakan Formation (top of the Kimaian Regional Stage, ~end of the Dapingian–base of the Darriwilian Stage). Increase of δ¹⁸О from 20?22‰ to 26?28‰, the negative correlation of δ¹³С and δ¹⁸О, and decrease of δ³⁴S in gypsum from 30?32‰ to 22?24‰ in this interval indicate that the ¹³С depletion of carbonates was not related to the sulfate reduction and oxidation of organic matter during diagenesis and that the negative δ¹³С excursion was of primary nature. The presence of negative δ¹³С anomalies at this stratigraphic level in Ordovician sections of the South and North America (Buggish et al., 2003; Edwards and Saltzman, 2014; McLaughlin et al., 2016) indicates the global or subglobal distribution of this event, which was possibly related to the emergence of the oldest ground vegetation. Against the general decrease of δ¹³С, the lower part of the section reveals three low-amplitude (1?2‰) positive excursions, the position of which in general confirms the existing correlation scheme of the Moyero River section with the international scale. The upper part of the section is characterized by the alternation of low-δ¹³С intervals (from–2 to–3‰) and brief positive excursions with amplitude of 0.5?1.3‰. The positive δ¹³С excursion terminating the Ordovician section of the Moyero River correlates with the δ¹³С excursion in the middle Katian Stage, while the δ¹³С excursion in the lower part of the Baksian Regional Stage correlates with the excursion marking the Katian–Sandbian boundary.     

Generation of superDreicer electric fields in the solar chromosphere

The electric field generation at the front of the current pulse, which originates in a coronal magnetic loop owing to the development of the Rayleigh–Taylor magnetic instability at loop footpoints, has been considered. During the τ_A ≈ l/V _A ≈ 5?25 s time (where l is the plasma plume height entering a magnetic loop as a result of the Rayleigh–Taylor instability), a disturbance related to the magnetic field tension B _?(r,t), “escapes” the instability region with the Alfvén velocity in this case. As a result, an electric current pulse I_z(z ? V _A t), at the front of which an induction magnetic field E _z, which is directed along the magnetic tube axis and can therefore accelerate particles, starts propagating along a magnetic loop with a characteristic scale of Δξ ≈ l. In the case of sufficiently large currents, when B _? ²/8π > p, an electric current pulse propagates nonlinearly, and a relatively large longitudinal electric field originates E _z ≈ 2I _z ³ V _A/c ⁴a²B_z ²l, which can be larger than the Dreicer field, depending on the electric current value.     

Particle Acceleration by Induced Electric Fields in Course of Electric Current Oscillations in Coronal Magnetic Loops

Geomagnetism and Aeronomy - A mechanism for acceleration of electrons driven by the oscillations of the electric current in solar magnetic loops is considered. The magnetic loop is presented as an...     

Experimental Model of the Formation of Nanophase Metallic Iron in the Lunar Regolith

Doklady Earth Sciences - One of the signs of “space weathering” on the Moon, including the effect of the solar wind and micrometeorite bombardment, is the formation of nanophase...     

Correcting for Cryoprecipitation in the Calibration of IR Channels of the MSU-MR Radiometer

Izvestiya, Atmospheric and Oceanic Physics - The presence of cryoprecipitation, which forms a thin film on the input windows of infrared (IR) detectors and distorts the signal, is a major issue in...     

The Mineral Composition of Rare-Metal Placers of the Lovozero Massif

Geology of Ore Deposits - The new original data on the mineralogy of the Sergevanskii section of the Revdinskaya placer of the Lovozero placer area are reported in the paper. Glacial and tectonic...