The construction of density models of the Earth's crust and upper mantle along the system of profiles crossing Eurasia and North America, the Atlantic Ocean, and transition zones between continents ...and oceans, begun by the works of the authors of recent years, is continued. In the crust, they are plotted by velocity sections along DSS profiles. The calculated effect of the section in anomalous densities in relation to the normal platform mantle (minus 870 mGl) corresponds to the zero observed field (Bouguer anomalies on land and Fay anomalies on sea). This value is established experimentally on the East European platform, where the geological and geophysical knowledge is the maximum. In the upper mantle, the authors' ideas about deep processes are used. They are associated with variants of heat and mass transfer under various endogenous regimes. Based on the results of these processes, temperature distribution that distinguish the densities of mantle rocks in each region from platform ones was determined. The gravitational effects calculated for such anomalous models are summarized with the crustal ones. Regions with all types of endogenous regimes were studied: platforms, zones of recent activation, geosynclines and rifts of different ages, mid-ocean ridge, oceanic depressions, marginal trench, island arc, back-arc depression. The total has compared with the observed fields. In all previously studied regions, the obtained differences do not exceed those explained by the errors of observations and calculations. Thus, the construction of density models of the tectonosphere becomes one of the methods for verifying the used schemes of deep processes. In the regions covered by recent activation and in the transition zones between continents and oceans, the differences between the experimental and calculated data turned out to be the maximum. Therefore, the work was continued using other DSS profiles, mainly on the continental platforms. The result generally confirmed the previous one, revealing additional modeling problems associated with velocity cross sections of the earth's crust.
This article presents an analysis of the extent of the impact of deformations of the earth’s crust resulting from geophysical models on changes in the coordinates of Global Navigation Satellite ...System (GNSS) stations. The author presents the results of analyses of the spatial correlation coefficient of deformation components for the non-tidal atmospheric loading (NTAL), non-tidal ocean loading (NTOL) and hydrological loading (HYDRO) models of geophysical deformation. In addition, the author calculated the correlation coefficients between station’s coordinate series to determine whether the deformations of the earth’s crust have a more global, large-area (regional scale) or local-range (local scale) impact, limited to the nearest of stations. In addition to correlation coefficients, the author analysed the similarity in periodic components between station coordinates by calculating the coherence between them. The results of the analysis showed that for the height components (Up), we observe the global range of deformation models, and the NTAL deformation has the greatest influence on the change in them. The lack of correlation between coordinate signals for horizontal components may result from specific local conditions in the place of the station, low-resolution of geophysical models and small amplitudes of these signals in relation to noise. An analysis of the coherence coefficients showed that each station coordinates shows completely different periodic components in the North, East and Up directions.
This work presents findings of deep geological and geophysical studies, which have revealed new and often unexpected features of the structure of the Earth's crust and the upper mantle of the ...continents and oceans, not easily explainable by current geodynamic concepts. For example, deepwater drilling has shown the old age of the oceanic crust and its inhomogeneous composition. Seismic studies of long-range profiles with nuclear explosions and laboratory studies of mantle xenoliths at high pressures and temperatures have revealed that the advection of energy-intensive and geochemically active deep fluids is central to the formation of the upper mantle structure. A comprehensive analysis of these data provides a geodynamic model for the natural transformation of the upper mantle substance influenced by deep fluids and the formation of continents and oceans as a result of unevenly distributed degassing of the Earth. The global variability of the deep fluid advection intensity led to formation of two hemispheres: the Indo Atlantic Hemisphere where almost all continents are located and the Pacific Hemisphere that consists of oceans. This formation of the hemispheres can be explained by the specific features of the Earth's rotation in the Earth-Moon-Sun system. This work provides a review and analysis of these data and then offers a possible explanation based on an integrated geodynamic model.
•Deep drilling in oceans and seismic studies revealed unexpected lithosphere features.•The crust of oceans is old and subcontinental lithosphere was found in all oceans.•Lithosphere roots of continents are composed of depleted decreased density material.•Earth degassing with energy-intensive fluids transformed the upper mantle material.•Earth's rotation in the Earth-Moon-Sun system formed the oceanic Pacific Hemisphere.
The study of geodynamic processes observed in the Earth's crust at densely populated and commercially developed areas in the east of Russia and China is of great importance for their sustainable ...development. The research results available show that not only natural, but also man-made geodynamic events associated with mining operations reflect the global geodynamic processes. Geodynamic events that occurred while mining in impact-hazardous areas allowed to identify some common features in the manifestation of natural and man-made geodynamic events in the eastern regions of Russia and China. Thus, both natural and disastrous technogenic geodynamic events (tectonic rock bursts, induced earthquakes, cracking on the earth's surface) have positional connection with the linear zones of earth's crust modern destruction (block boundaries and faults). Existing tectonic faults get re-activated during major geodynamic events, i.e. they get displaced in response to the mining operations. Areas hazardous for manifestation of geodynamic phenomena can be defined by geodynamic zoning method which can be used to draft the development programs for the eastern regions of Russia and China
Continuous data recorded on more than 1600 USArray seismic stations operating in the western and central US between 2006 and 2012 are used to map phase velocities of Love and Rayleigh waves at short ...periods (5–40 s) using a noise-correlation technique. Vertical and transverse records for all station pairs separated by less than 600 km are cross correlated in 4-h-long segments, and the resulting spectra are stacked for the time period of station operation. Dispersion curves are determined from the locations of zeros in the real component of the correlation spectra using a method based on that of Aki (1957). Phase-velocity maps expanded on a 0.25°-by-0.25° pixel grid are estimated by inversion of the phase-velocity measurements. Comparison with predicted phase-velocity maps based on the crustal model CRUST2.0 combined with the mantle model ND08 shows good agreement at the longer periods. Strong slow anomalies (>25%) in the short-period maps are geographically correlated with basins and regions of thick sedimentary cover. The strength of these anomalies is not well predicted by existing crustal-velocity models.
•An automated spectral method for noise tomography is presented.•The method is applied to USArray TA data for 2006 to 2012.•Phase-velocity maps for periods 5–40 s are determined.•Sedimentary basins are imaged as very slow anomalies.•The slowest anomalies are not well predicted by existing models of the crust.
Layered intrusions are fossilized mafic magma chambers in the Earth's crust. The pathways that led to crystallization and solidification of layered intrusions have been hotly debated as the growth ...model of primocrysts (the earliest-formed crystals) in mafic magma chambers remains enigmatic. In this study, we carried out high-resolution elemental mapping of mm-scale olivine primocrysts from the Sept Iles layered intrusion (Canada), the third largest one in the world, with a focus on phosphorus (P) zoning of olivine. Our results reveal that complex P zoning of olivine with intense dissolution textures is ubiquitous in the ∼4.7 km-thick Layered Series of the intrusion. The P-rich zones of olivine are featured with dendritic, hopper and sector-zoned patterns, which are attributed to significant magma undercooling. Thermal modeling based on a 1-D conductive cooling model suggests that initially hot parental magma intruding into cold country rocks would result in high degrees of undercooling (-ΔT >60 °C) in the margins (i.e., floor, roof and sidewalls) of magma chamber, facilitating rapid growth of dendritic olivine, which may be then spread within the magma chamber by dynamic convection and crucial to construct initial crystal framework of a solidifying magma chamber. Additionally, diffusion modeling based on the P gradients in olivine suggests a minimum cooling rate of 2.7 to 3.3×10−3 °C/year in the center of the intrusion, similar to the averaged cooling rate of other layered intrusions (e.g., Bushveld, Stillwater and Skaergaard) reported in previous studies. This indicates that rapid cooling (ca. 10−2 to 10−3 °C/year) at high temperature (>800 °C) may be predominant regardless of the size of magma chambers. Our study demonstrates that P zoning of olivine is powerful in decoding crystallization and thermal histories of mafic-ultramafic intrusions.
•Olivine shows complex P zoning throughout the Layered Series of Sept Iles intrusion.•Dendritic growth of olivine is ubiquitous in mafic magma chamber.•Dendritic olivine constructs initial crystal framework of magma chamber.•Olivine grains experienced dissolution-reprecipitation processes.•Diffusion modeling reveals rapid cooling of Sept Iles intrusion.
We present the first quality-controlled relative sea-level (RSL) database for the Russian Arctic coast from the Barents Sea in the west to Laptev Sea in the east (29–152oE and 63 to 81oN). The ...database consists of 385 sea-level index points and 249 limiting dates and spans 24 ka to present. Sea-level indicators are derived from multiple proxies, including isolation basins, raised beaches, glacial erratics, marine terraces, laidas (salt marshes), and deltaic salt marshes. Here, we calculate the indicative meanings for all indicators and evaluated possible elevation errors. We have estimated the ages and uncertainties of index points and limiting dates using the most recent calibration datasets.
In the western Russian Arctic (Barents and White Seas), RSL was driven by glacial isostatic adjustment (GIA) due to deglaciation of the Eurasian ice sheet complex. For example, within the Baltic crystalline shield, RSL fell rapidly from 80 to 100 m at 11–12 ka to 15–25 m at ∼4–5 ka. In the Arctic Islands of Franz-Joseph Land and Novaya Zemlya, RSL gradually fell from 25 to 35 m at 9 ka to 5–10 m at 3 ka. The Timan coast and the Kara Sea shelf are characterized by constant RSL rise due to proglacial forebulge collapse; Yamal and the Gydan Peninsula and Novaya Zemlya are all marked by a high LGM position of RSL, followed by a lowstand and consequent rise to a late Holocene highstand of several meters. Data from the Laptev Sea coasts and shelf and the New Siberian Islands demonstrate post-LGM RSL rise with a Holocene highstand of up to 5–10 m, with scatter caused by differential tectonic movements along a diffuse lithospheric plate boundary. The collected database allowed to estimate and discuss the reasons of both spatial and temporal variability of RSL histories in different parts of the Russian Arctic.
•A database of post-glacial relative sea-level in the Russian Arctic was collected.•For the first time, both spatial and temporal uncertainties of RSL histories were estimated.•The main drivers of RSL variability were GIA, deglaciation patterns and vertical tectonic land motion.
This work presents the relationships between the measured present Earth crust movement and sedimentary cover feature indexes with the help of correlation and regressive analysis method. Indexes ...having the biggest impact on investigated nature processes have been distinguished while applying the incremental regression analysis. The research of correlative analysis coeffi cient‘s dependence on general correlative space has been performed. Forecast patterns of vertical Earth surface movement have been created and compared with the present ones with the help of regressive analysis method. Article in Lithuanian Dabartinių žemės plutos judesių Lietuvos pajūrio teritorijoje sąsajos su nuosėdinės dangos savybėmis Santrauka. Koreliacinės ir regresinės analizės metodais išnagrinėta išmatuotųjų dabartinių vertikaliųjų Žemės plutos judesių bei nuosėdinės dangos savybių sąsajos. Taikant atvirkštinės žingsninės regresijos analizę išskirti reikšmingiausieji tiriamų gamtinių procesų rodikliai. Atliktas koreliacinės analizės koeficientų priklausomybės bendrai koreliacinei erdvei tyrimas. Sudaryti bei su esamais palyginti regresinės analizės metodu prognozuojamų vertikaliųjų Žemės paviršiaus judesių modeliai. Reikšminiai žodžiai: vertikalieji Žemės plutos judesiai, teritorijos geologinė charakteristika, tiesinė regresinė analizė, žingsninė regresinė analizė, prognozuojamieji Žemės plutos judesiai.
It is accepted as a well-known fact that in different places on the Earth's crust, a similar anthropogenic impact causes a dissimilar response. Seismic zoning maps are not designed to predict such ...geodynamic hazards as rock bursts, induced earthquakes, reactivation of tectonic faults, etc., and therefore require careful adjustments in places of intense impact on the subsurface strata. In this regard, we consider the classification of the Earth's crustal areas according to the degree of geodynamic hazard, i.e. its potential geodynamic response to anthropogenic intervention. This classification is based on the concept that there exists a critically stressed layer within the Earth's crust. It is believed that such a critically stressed layer within the Earth's crust extends from the Earth's surface to a certain depth, and each point depends on the nature of the interaction between crustal blocks of different hierarchical levels.
From this perspective, anthropogenic impact, such as mining operations, represents a direct impact upon the critically stressed zone. We recognize the hypothesis that the thicker the critical stressed rock layer, the stronger the response might be to anthropogenic intervention, as it has more accumulated energy. Four categories of geodynamic threat have been found and mapped. To verify this classification, the manifestations of the geodynamic hazards were studied. The intensity of geodynamic hazard increased from the first area to the fourth area. The phenomenon of large induced seismic events with hypocenters at great depths is explained on the basis of this theory, and could be associated with anthropogenic impacts from the surface directly on the regional zone of the critically stressed rock massif. The approach can be used to assess the geodynamic consequences of human exposure to the Earth's crust.
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