A correlation model for oscillations of the Earth’s pole with parametric perturbations

A differential correlation model for oscillations of the Earth’s pole is constructed. The model has gravitational-tidal, additive and parametric, slowly varying, harmonic (at the Chandler frequency and double this frequency), and random Gaussian, broadband perturbations. Special attention is paid to the analysis of trends and the amplitude-frequency characteristics of stochastic oscillations of the Earth’s pole. Numerical simulations show that first-approximation equations can be used to estimate the correlation characteristics of oscillations of the Earth’s pole to within 10%. The results of the model are compared with the results of statistical modeling of oscillations at the Chandler frequency. The model represents a base of informational resources for analytical modeling of the motion of the Earth’s pole over intervals of three to five years.     

Lunar surface mineralogy using hyperspectral data: Implications for primordial crust in the Earth–Moon system

Mineralogy of the Lunar surface provides important clues for understanding the composition and evolution of the primordial crust in the Earth–Moon system. The primary rock forming minerals on the Moon such as pyroxene, olivine and plagioclase are potential tools to evaluate the Lunar Magma Ocean (LMO) hypothesis. Here we use the data from Moon Mineralogy Mapper (M³) onboard the Chandrayaan-1 project of India, which provides Visible/Near Infra Red (NIR) spectral data (hyperspectral data) of the Lunar surface to gain insights on the surface mineralogy. Band shaping and spectral profiling methods are used for identifying minerals in five sites: the Moscoviense basin, Orientale basin, Apollo basin, Wegener crater-highland, and Hertzsprung basin. The common presence of plagioclase in these sites is in conformity with the anorthositic composition of the Lunar crust. Pyroxenes, olivine and Fe-Mg-spinel from the sample sites indicate the presence of gabbroic and basaltic components. The compositional difference in pyroxenes suggests magmatic differentiation on the Lunar surface. Olivine contains OH/H₂O band, indicating hydrous phase in the primordial magmas.     

Some improved methods for modeling the Earth’s polar motion

Some improved methods for modeling the motions of the Earth’s pole determined by gravitational-tidal, fluctuating-dissipative perturbations occurring on various time scales are presented. The main attention is paid to dynamical linear-regression models and dynamical filtering models, which take into account dynamical measurement errors. Computer simulations of the oscillatory motion of the Earth’s pole for 1995–2010 are also presented.     

The Earth’s magnetic field history for the past 400 Myr

Published and new data on the Earth’s past magnetic field have been interpreted in terms of its links with the frequency of magnetic polarity reversals and with tectonic events such as plume-related eruptions and rifting. The paleointensity and reversal frequency variations show an antiphase correlation between 0 and 160 Ma, and the same tendency likely holds for the past 400 Myr. The geomagnetic field intensity averaged over geological ages (stages) appears to evolve in a linearly increasing trend while its variations increase proportionally in amplitude and change in structure. Both paleointensity and reversal frequency patterns correlate with rifting and eruption events. In periods of high rifting activity, the geomagnetic field increases (15 to 30%) and the reversals become about 40% less frequent. Large eruption events between 0 and 150 Ma have been preceded by notable changes in magnetic intensity which decreases and then increases, the lead being most often within a few million years.     

Accounting for the influence of the Earth’s sphericity in three-dimensional density modelling

A method for transformation of the three-dimensional regional “flat” density models of the Earth’s crust and upper mantle to the “spherical” models and vice versa is proposed. A computation algorithm and a method of meaningful comparison of the vertical component of the gravity field of both models are presented.     

Development of tomographic technology for the Earth’s crust in the shelf regions

On the basis of experimental data obtained during a comprehensive experiment in Vityaz Bay of the Sea of Japan using onshore laser strainmeters and a low-frequency hydroacoustic emitter generating complex phase-manipulated signals with a central frequency of 33 Hz, we developed the basic principles of contactless tomography of the Earth’s crust in the shelf regions of various seas, including those covered by ice, making it possible to determine efficiently the structure and composition of the upper Earth’s crust under seas.

     

Development of methods for constructing models for intra-year irregularity in the Earth’s rotation

The development of methods for the construction of stochastic, dynamical models for intra-year irregularity of the Earth’s rotation is considered. A correlational model based on harmonically additive and parametrically random, colored and broadband, gravitational-tidal perturbations from the Sun and Moon is developed. One-dimensional and multi-dimensional characteristic functions are found for the case of Gaussian and non-Gaussian colored and broadband fluctuations in the irregularity of the Earth’s rotation. Examples of computer modeling of the irregularity in the Earth’s rotation based on a priori and a posteriori IERS data are presented.     

Equation of state of magnesite for the conditions of the Earth’s lower mantle

A semiempirical equation of state was derived for magnesite under the thermodynamic conditions of the Earth’s mantle. Within experimental uncertainties, it is consistent with thermochemical, ultrasonic, X-ray, and shock-wave data at temperatures from 15 K to the melting point and pressures of up to 100–130 GPa. The following values were recommended for the isothermal bulk modulus and its pressure derivative: K _T = 111.71 GPa and K′ = 4.08. Thermodynamic analysis showed that magnesite does not decompose to periclase and CO₂ under the thermodynamic conditions of the Earth’s lower mantle and outer core.     

Analytical Conditions for the Formation of Arctic Amplification in the Earth’s Climate System

Doklady Earth Sciences - Analytical conditions for estimating the contribution of various internal and external factors to the formation of Arctic (polar) amplification under warming of the...     

Breakthrough in the China’s Separation Technology for Extraction of Rare Earth Elements

Separation technology of rare earth elements （REEs）, as the critical step in the separation process, had long been fraught with technical difficulty. A research project conducted by Baotou Shibo Rare Earth Extraction ＆ Equipment Co. Ltd., Baotou REE Research Institute, and Baotou Steel ＆ REE Group Hi-Tech Co. Ltd （Inner Mongolia）, has successfully solved the problem using a centrifugal extractor and advanced techniques to achieve a key breakthrough.     

On the use of unmanned aerial vehicles for high-precision measurements of the Earth’s magnetic field

A brief account of the evolution of Russian airborne geomagnetics is given. It is shown that the development of aeromagnetic systems based on unmanned aerial vehicles (UAVs) is of great interest. This paper presents theoretical and experimental data that concern the development of the optimal UAV layout in order to create a UAV-based aeromagnetic survey system using a new-generation optically pumped quantum rubidium aeromagnetometer. The new UAV-based aeromagnetic system is planned for use for high-precision aeromagnetic surveying at low altitude (30 m and more) for geological, engineering, and environmental applications.     

Measurement of the difference in the Earth’s gravitational potentials with the help of a transportable quantum clock

The results of the Russia’s first ground-based experiment for determination of the difference in the Earth’s gravitational potentials on the basis of the measurement of the gravitational effect of the time delay with the help of a high-stability transportable atomic clock are provided. The reference atomic clock was placed in Moscow oblast, and a transportable quantum clock with an instability of 3 × 10^–15 was placed in the Caucasus Mountains, with a difference in height of the clocks of 1804 m. The measured difference in the gravitational potentials between the positions of the two quantum clocks was (182.0 ± 3.1)10²m²s^-2 at a relative measurement error of no more than 1.7%.     

Tectonic model of seismicity for the northeastern segment of the Amur Plate in the Earth’s two-phased rotation

The spatial distribution of the epicenters and hypocenters is analyzed for earthquakes of 2 ≤ M < 6 that occurred in the northeastern segment of the Amur Plate in two phases of changes in the angular speed of the Earth’s rotation. Groups of seismic events in the magnitude interval of 5 ≤ M < 6 are distinguished in the form of NE-trending seismic clusters regularly alternating along the plane of latitude. The seismic clusters are up to 1500 km long and 180–240 km wide and cover the seismic zones with different geodynamic and seismotectonic conditions of seismicity origination. In terms of the epicentral distributions for earthquakes with 2 ≤ M < 4, seismic activity zones are distinguished; these zones are seen as seimolineaments coupling the Tan Lu seismic zones and the eastern flanks of the latitudinal seismic zones. A scheme of distinguishing the compression and extension zones from the spatial clusters of earthquakes with 5 ≤ M < 6 in two phases of changes in the angular speed of the Earth’s rotation is proposed. This scheme satisfactorily agrees with the model of seismotectonic reconstructions of the compression–extension fields and axes.     

Lateral density inhomogeneities of the continental and oceanic lithosphere and their relationship with the Earth’s crust formation

This paper presents the results of the study of the free mantle surface (FMS) depth beneath continents and oceans. The reasons for the observed dependence of the FMS depth on the crustal thickness in the continental lithosphere are discussed. The influence of radial variations in the mantle’s density is evaluated. The calculations performed have indicated that the observed dependence of the FMS depth on the crustal thickness is caused mostly by lateral inhomogeneities in the lithospheric mantle, and the size of these inhomogeneities is proportional to the thickness of the crust. The origin of such inhomogeneities can be related to the process of continental crust formation.     

On thermochemical mantle plumes with an intermediate thermal power that erupt on the Earth’s surface

The relative plume thermal power Ka = N/N₁ is used (N is the thermal power transferred from the plume base to its conduit and N₁ is the thermal power transferred from the plume conduit into the surrounding mantle in the steady-state heat conduction regime). Thermochemical mantle plumes with small (Ka < 1.15) and intermediate (1.15 < Ka < 1.9) thermal powers are formed at the core–mantle boundary beneath cratons in the absence of horizontal free-convection mantle flows beneath them, or in the presence of weak horizontal mantle flows. Thermochemical plumes reach the Earth’s surface when their relative thermal power is Ka > 1.15. The thermal and hydrodynamical structure of the plume conduit ascending from the core–mantle interface to the level from which the magmatic melt erupts on the Earth’s surface is presented. The model of two-stage eruption of the melt from the plume conduit to the surface is considered. The critical height of the massif above the plume roof, at which the eruption conduit supplying magmatic melt to the surface forms, is determined. The volume of melt erupting through the eruption conduit to the surface is estimated. The dependence of depth Δx from which the melt is transported to the surface on the plume diameter for a kinematic viscosity of ν = 0.5–2 m²/s is presented. In the case when the value Δx is larger than the depth starting from which diamond is stable (150 km), the melt from the plume conduit can transport diamonds to the Earth’s surface. The melt flow in the eruption conduit is considered as a turbulent flow in a cylindrical duct. The velocity of the melt flow in the eruption conduit and the time for the melt to be transported to the surface from a depth of Δx = 150 km for a kinematic viscosity of the melt in the eruption conduit ν_v = 0.01–1 m²/s are determined. Tangential stress on the eruption conduit sidewall is estimated in cases of melt flow both in smooth and rough conduits.