The 1.80–1.74-Ga gabbro–anorthosite–rapakivi Korosten Pluton in the Ukrainian Shield: a 3-D geophysical reconstruction of deep structure

The deep structure of the gabbro–anorthosite–rapakivi granite (“AMCG-type”) Korosten Pluton (KP) in the northwestern Ukrainian Shield was studied by 3-D modelling of the gravity and magnetic fields together with previous seismic data. The KP occupies an area of ca. 12,500 km² and comprises several layered gabbro-anorthositic intrusions enveloped by large volumes of rapakivi-type granitoids. Between 1.80 and 1.74 Ga, the emplacement of mafic and associated granitoid melts took place in several pulses. The 3-D geophysical reconstruction included: (a) modelling of the density distribution in the crust using the observed Bouguer anomaly field constrained by seismic data on Moho depth, and (b) modelling of the magnetic anomaly field in order to outline rock domains of various magnetisation, size and shape in the upper and lower crust. The density modelling was referred to three depth levels of 0 to 5, 5 to 18, and 18 km to Moho, respectively. The 3-D reconstruction demonstrates close links between the subsurface geology of the KP and the structure of the lower crust. The existence of a non-magnetic body with anomalously high seismic velocity and density is documented. Most plausibly, it represents a gabbroic stock (a parent magma chamber) with a vertical extent of ca. 20 km, penetrating the entire lower crust. This stock has a half-cylindrical shape and a diameter of ca. 90 km. It appears to be connected with a crust–mantle transitional lens previously discovered by EUROBRIDGE seismic profiling. The position of the stock relative to the subsurface outlines of the KP is somewhat asymmetric. This may be due to a connection between the magmatism and sets of opposite-dipping faults initially developed during late Palaeoproterozoic collisional deformation in the Sarmatian crustal segment. Continuing movements and disturbances of the upper mantle and the lower crust during post-collisional tectonic events between 1.80 and 1.74 Ga may account for the long-lived, recurrent AMCG magmatism.     

Steady-state double layer structures in the interstellar medium

A one-dimensional, self consistent theoretical model is constructed for double layers in a thermodynamically nonequilibrium astrophysical plasma. A steady state is maintained by an asymmetry in the fluxes from both sides. The range of possible values of the parameters is determined.     

Geodetic Rotation of Neptune’s Satellites

Solar System Research - The paper considers the most significant relativistic effects in the rotational dynamics of Neptune’s satellites (Triton (N1), Naiad (N3), Thalassa (N4), Despina (N5),...     

Construction of the semi-analytical and numerical solutions to the problem of rotational motion of the moon

New high-precision, semianalytical and numerical solutions to the problem of the rotational motion of the Moon are obtained, for use in the long 418.9-year time frame. The dynamics of the rotational motion of the Moon is studied numerically using the Rodrigues-Hamilton parameters, relative to the fixed ecliptic for the epoch J2000. The results of the numerical solution to the problem under study are compared with a compiled semianalytical theory of Moon rotation (SMR). The initial conditions for the numerical integration have been taken from the SMR. The comparative discrepancies derived from the comparison between the numerical solutions and the SMR do not exceed 1.5″ on the time-scale of 418.9 yr. The investigation of the comparative discrepancies between the numerical and semianalytical solutions is performed using the least squares and spectral analysis methods in the Newtonian case. All the periodic terms describing the behavior of the comparative discrepancies are interpreted as the corrections to the semianalytical SMR theory. As a result, the series are constructed to describe the rotation of the Moon (MRS2010) in the time interval under study. The numerical solution for the Moon’s rotation has been obtained anew, with new initial conditions calculated using MRS2010. The discrepancies between the new numerical solution and MRS2010 do not exceed 20 arc milliseconds on the time-scale of 418.9 years. The results of the comparison suggest that that the MRS2010 series describe the rotation of the Moon more correctly than the SMR series.     

Methods for reconstructing harmonic functions from the magnetic field ΔT and V.N. Strakhov’s function ΔS: A review

We give an overview of the methods designed for reconstructing close-to-harmonic functions from the magnetic field ΔT. The formula of Yu.P. Tafeev is refined. It is shown that this refined formula directly leads to the relation derived by V.M. Gordin and his colleagues that allows isolating the harmonic component in the function ΔT. V.N. Strakhov’s linearized representation of the function ΔT is immediately derived from the main approximate Tafeev formula for Q ΔT. The experience of using Strakhov’s ΔS function in the interpretation of the magnetic anomaly ΔT generated by the Krivoi Rog structure is described. It is noted that the problem of reconstructing the corresponding harmonic functions from the data of magnetic and gravity surveys has much in common. The specific features of measuring the magnetic field H and magnetic induction B in the material media are considered, and the physical interpretation of these fields is presented.     

Consideration of Relativistic Effects in the Rotation of Mars and its Satellites

Solar System Research - This study is dedicated to the consideration of the relativistic effects (geodetic precession and nutation that make up the geodetic rotation) in the rotation of Mars and...     

Paleomagnetic and tectonophysical evidence of geodynamics of Sarmatia in the Devonian (based on the example of the Ukrainian shield)

As a result of paleomagnetic investigations the positions of Devonian magmatic complexes of the Ukrainian shield (Sarmatia) in the tropical latitudes of the Southern Hemisphere in the Late Devonian were reconstructed. The moderate-temperature magnetization components in complexes of different ages of the Ukrainian Shield and recorded manifestations of the Devonian tectonomagmatic events were determined.     

Effects of climate change and extreme events on forest communities in the European North

The European north is increasingly affected by changes in climate and climate variability. These changes and their causes are global in scope but specific impacts vary considerably between different regions. Recent incidents and events show that forest-resource based regions have difficulties in alleviating adverse effects of these changes. Also, the future socio-economic impact is to date unexplored. Norrbotten in Sweden, Lappi in Finland and Arkhangelsk oblast in Russia are regions that differ significantly in terms of their socio-economic characteristics and capacities. A modified employment multiplier model is used to predict future changes. Scenarios of changing forest resources provide quantitative estimations of the sensitivity of regional employment. These estimates are used to assess and discuss the adaptive capacities of the regions. Results show that Arkhangelsk oblast is more vulnerable to climate variability than Norrbotten and Lappi. This is due to the continued dependency on natural resources in combination with different capacities to counteract negative effects or to take advantage of the opportunities offered by climate change in this region.     

Relativistic Effect of Geodetic Precession in the Rotation of Dwarf Planets and Asteroids of the Solar System

Solar System Research - Geodetic precession is the most significant relativistic effect in the rotation of celestial bodies. In this work, for the first time, this relativistic effect is determined...