TO STRATIGRAPHY AND GEODYNAMICS ZILAIR SEDIMENTS IN THE SOUTHERN URALS

2021 ◽  
Vol 0 (3) ◽  
pp. 77-88
Author(s):  
T.T. KAZANTSEVA ◽  

It is known that the upper shell of our planet is the earth's crust, which is different in composition on the continents and in the oceans. The composition of the continental crust is predominantly sialic, and the oceanic one is simatic. The capacity of the first is within 35-70 km, the second is close to 5-12. The formation of any type of the earth's crust is determined by the participation of specific geological processes, causal relationships of matter and geodynamics, which is justified by researchers on the basis of well-proven facts and judgments. The concepts used must be specific, in accordance with well-known definitions, such as: stratigraphy is a branch of geology that studies «the formation of rocks in their primary spatial relationships», and geodynamics is «a branch of geology that studies the forces and processes in the crust, mantle and core of the Earth, deep and surface movements of masses in time and space» [1]. The use of the conceptual framework and the study of numerous facts allow us to confidently identify the sequence of connections and the reasons for the relationship.

Author(s):  
Maksim Nesterenko ◽  
Oksana Kapustina ◽  
Sergey Nikiforov

The article presents the results of the analysis of the impact of field development on the geody-namic state and seismic activity of the earth's crust of the Southern Urals, were compared in field development, anthropogenic changes in the bowels of district fields with the level of seismic ac-tivity, correlation between indicators of development of deposits and the parameters of the seis-mic activity of the earth's crust and the statistical analysis of the seismic regime of the area de-posits of hydrocarbon raw materials. Correlation analysis of field development indicators and seismic activity parameters revealed an almost linear relationship (r>0.9) between reservoir pres-sure and the number of events (including low-energy pulse events) and a close relationship be-tween the average debit and the number of events. A model of the seismic activity of hydrocar-bon deposits in the Southern Urals is constructed in the form of a set of graphs of the frequency of seismic events and changes in their angle of inclination. The constructed model indicates a change in the nature of seismic activity in the subsurface of the field area, which consists in a de-crease in the energy of events and an increase in their number. The cyclical nature of seismic ac-tivity on the territory of the Orenburg oil and gas condensate field (OOGCF) is revealed. Current-ly, there is an accumulation of stress associated with the continued drop in reservoir pressure during the field operation and natural tectonic processes against the background of a decrease in the rate of hydrocarbon production. Reducing production volumes at OOGCF does not reduce the man-made load on the Earth's crust, but reduces the rate of stress accumulation. This leads to a decrease in the energy of seismic events and an increase in their number (taking into account the pulses).


1883 ◽  
Vol 10 (6) ◽  
pp. 241-252
Author(s):  
W. O. Crosby

The theory of the origin of continents and ocean-basins developed during the last third of a century, chiefly by Prof. Dana, and commonly known as Prof. Dana’s theory, is now accepted by many geologists. The main points in this theory, as gathered from the latest expression of Prof. Dana’s views, are the following:1— The earth, superficially at least, is, and was originally, before it had a solid crust, of unlike composition on different sides. This heterogeneity caused a corresponding difference in heat-conductivity. The more rapidly conducting areas cooled fastest and were the first to become covered with a solid crust. Solidification is attended by contraction; and therefore the newly formed crust must have been heavier than the liquid immediately beneath it. As a consequence, it broke up and sank until it reached a liquid stratum of the same specific gravity as itself; and afterwards the process of crusting and sinking went on until a solid crust was built up from this point to the surface. Through the continued escape of heat this primitive crust is thickened, and is still thickening by additions to its lower surface. These first formed portions of the crust became, and will always continue to be, the continents. The remainder of the earth’s surface was still liquid, after the solidification of the continental areas was well advanced; and, of course, as long as it continued liquid, its surface was level with that of the crust-areas. Finally, it became the theatre of a similar process of crusting and sinking, and at last permanently froze over. Now the main point is that the contraction of this inter-continental crust during its formation caused its surface to sink below that of the continents; and the depressions thus developed became the future ocean-basins, which, like the continents, are necessarily of a permanent character. Indeed, it is a plain deduction from Prof. Dana’s theory that the existing continents and oceans are as old as the earth’s crust; and that during the course of geological time the continents have become constantly wider and the oceans deeper.


2014 ◽  
Vol 40 (2) ◽  
pp. 58-67
Author(s):  
Ruta Puziene ◽  
Asta Anikeniene ◽  
Gitana Karsokiene

In the research of vertical movements of the earth’s crust, examination of statistical correlations between the measured vertical movements of the earth’s crust and territorial geo-indexes is accomplished with the help of mathematical statistical analysis. Availability of the precise repeated levelling measuring data coupled with the preferred research methodology offer a chance to determine and predict recent vertical movements of the earth’s crust. For the inquiry into recent vertical movements of the earth’s crust, a Lithuanian class I vertical network levelling polygon was used. Drawing on measurements made in the polygon, vertical velocities of earth’s crust movements were calculated along the following levelling lines. For determining the relations shared by vertical movements of the earth’s crust and territorial geo-parameters, the following territory-defining parameters are accepted. Examination of the special qualities of relations shared by vertical movements of the earth’s crust and geo-parameters in the territory under research contributed to the computation of correlation matrices. Regression models are worked out taking into consideration only particular territory-defining geo-parameters, i.e. only those parameters which exhibit the following correlation coefficient value of the vertical earth’s crust movement velocity: r ≥ 0.50. A forecast of the velocities pertaining to vertical movements of the earth’s crust in the territory under examination was made with the application of regression models. Further in the process of this research, a map was compiled specifying the velocities of vertical movements of the earth’s crust in the territory. In the eastern part of this territory, the earth’s crust rises at a rate of up to 3 mm/year; while in the western part of it, the earth crust lowers at a rate of up to –1.5 mm/year. In order to pinpoint territories characterised by temperate and regular rising/lowering or intensive rising/lowering, a map of horizontal gradients of recent vertical earth crust movements in the territory enclosed by levelling polygon was compiled.


2015 ◽  
Vol 4 (2) ◽  
pp. 149-154 ◽  
Author(s):  
A. M. Prystai ◽  
V. O. Pronenko

Abstract. The study of the deep structure of the Earth's crust is of great interest for both applied (e.g. mineral exploration) and scientific research. For this the electromagnetic (EM) studies which enable one to construct the distribution of electrical conductivity in the Earth's crust are of great use. The most common method of EM exploration is magnetotelluric sounding (MT). This passive method of research uses a wide range of natural geomagnetic variations as a powerful source of electromagnetic induction in the Earth, producing telluric current variations there. It includes the measurements of variations of natural electric and magnetic fields in orthogonal directions at the surface of the Earth. By this, the measurements of electric fields are much more complicated metrological processes, and, namely, they limit the precision of MT prospecting. This is especially complicated at deep sounding when measurements of long periods are of interest. The increase in the accuracy of the electric field measurement can significantly improve the quality of MT data. Because of this, the development of a new version of an instrument for the measurements of electric fields at MT – both electric field sensors and the electrometer – with higher levels relative to the known instrument parameter level – was initiated. The paper deals with the peculiarities of this development and the results of experimental tests of the new sensors and electrometers included as a unit in the long-period magnetotelluric station LEMI-420 are given.


2018 ◽  
Author(s):  
C. Brenhin Keller

Earth’s unique continental crust represents the active interface between the deep earth and the surface earth system, and is crucial for the survival and diversification of life on Earth, both as a source for nutrients and a component in the silicate weathering feedback that stabilizes Earth’s equable climate on billion-year timescales. However, many open questions remain regarding the formation and secular temporal evolution of Earth’s crust – in part due to the extremely poorly-mixed nature of Earth’s continental crust such that compositional heterogeneity at any one point in geologic time typically dwarfs any systematic variation over time. New computational approaches enabled by the emergence of large, freely accessible geochemical datasets provide a way to see through this heterogeneity and extract quantitative information about underlying processes and variables that drive the evolution of Earth’s crust over geologic time.


Author(s):  
Alex Maltman

We come now to the metamorphic rocks, the result of modifications to already existing rock. I’m well aware that this can all seem a bit mysterious. After all, no one has ever seen the changes take place; no one has ever witnessed a metamorphic rock form—the processes are imperceptibly slow, and they happen deep in the Earth’s crust, way out of sight. Why should these changes happen? Well, they are primarily driven by increases in pressure and temperature, so we begin with a look at these two factors. There are sites in the Earth’s crust where material becomes progressively buried. It happens, for example, where a tectonic plate is driving underneath another one, taking rocks ever deeper as it descends. It can happen in the central area of a plate that is stretching and sagging, allowing thick accumulations of sediment. It’s pretty self-evident that as buried material gets deeper, because of the growing weight of rocks above bearing down due to gravity, it becomes subjected to increasing burial pressure. Less intuitive, though, is the fact that this pressure acts on a volume of rock equally in all directions. Imagine a small volume of rock at depth. It’s bearing the weight of the rocks above it, and so it responds by trying to move downward and to spread out laterally. Of course, it can’t because it’s constrained all around by other volumes of rock that are trying to do exactly the same thing. And so the downward gravity is translated into an all-around pressure. It’s the same effect as diving down to the bottom of a swimming pool. You feel the increased pressure owing to the weight of water above, but you feel it equally in all directions. All-round pressure like this can cause things to change in volume, through changing their density, but it can’t change their shape. However, there can be another kind of pressure as well, and this does have direction, and it can cause change of shape. In the Earth, we call it tectonic stress. It comes about through heat-driven motions in the Earth, including the movement of tectonic plates.


2011 ◽  
Vol 2 (1) ◽  
pp. 139-160 ◽  
Author(s):  
J. G. Dyke ◽  
F. Gans ◽  
A. Kleidon

Abstract. Life has significantly altered the Earth's atmosphere, oceans and crust. To what extent has it also affected interior geological processes? To address this question, three models of geological processes are formulated: mantle convection, continental crust uplift and erosion and oceanic crust recycling. These processes are characterised as non-equilibrium thermodynamic systems. Their states of disequilibrium are maintained by the power generated from the dissipation of energy from the interior of the Earth. Altering the thickness of continental crust via weathering and erosion affects the upper mantle temperature which leads to changes in rates of oceanic crust recycling and consequently rates of outgassing of carbon dioxide into the atmosphere. Estimates for the power generated by various elements in the Earth system are shown. This includes, inter alia, surface life generation of 264 TW of power, much greater than those of geological processes such as mantle convection at 12 TW. This high power results from life's ability to harvest energy directly from the sun. Life need only utilise a small fraction of the generated free chemical energy for geochemical transformations at the surface, such as affecting rates of weathering and erosion of continental rocks, in order to affect interior, geological processes. Consequently when assessing the effects of life on Earth, and potentially any planet with a significant biosphere, dynamical models may be required that better capture the coupled nature of biologically-mediated surface and interior processes.


2018 ◽  
Vol 56 ◽  
pp. 02007 ◽  
Author(s):  
Andrian Batugin

Despite advances in rockburst studies, suddenness of major geodynamic events is reported in a number of cases. Phenomenological tectonophysical model is suggested to explain some geodynamics phenomena. Prof. Petukhov I.M. suggested a concept: the Earth crust's critical stress condition is developed due to horizontal compressive forces and entrains rock strata from the sub-surface to a certain depth. The conditions that induced earthquake in 2013 at Bachat coal field in south west Kuzbass are considered in terms of critical stress developed in the top layer of the Earth crust. Estimates show that the size of the critical stress zone, produced presumably by interaction of huge (over 100 km) crustal blocks is at least 10km. Whereas critical stress zone is located in the top part of Earth's crust, mining operations in the pit including blast operations was making a direct impact on this area. Shallow occurrence of critical stress area and its size can provide insight into why mining works brought about induced earthquake with hypocenter at the depth of several kilometers. The conclusion has been made that regional areas of critical stress within rock massif developed as a result of crustal blocks interaction create hazard medium for mining.


2001 ◽  
Vol 6 (4) ◽  
pp. 281-290
Author(s):  
E. V. Artyushkov

The upper part of the Earth—the lithospheric layer,∼100 km thick, is rigid. Segments of this spherical shell–lithospheric plates are drifting over a ductile asthenosphere. On the continents, the lithosphere includes the Earth's crust,∼40 km thick, which is underlain by peridotitic rocks of the mantle. In most areas, at depths∼20–40 km the continental crust is composed of basalts with density∼2900kg m−3. At temperature and pressure typical for this depth, basalts are metastable and should transform into another assemblage of minerals which corresponds to garnet granulites and eclogites with higher densities 3300–3600 kgm−3. The rate of this transformation is extremely low in dry rocks, and the associated contraction of basalts evolves during the time≥108a. To restore the Archimede's equilibrium, the crust subsides with a formation of sedimentary basins, up to 10–15 km deep.Volumes of hot mantle with a water-containing fluid emerge sometimes from a deep mantle to the base of the lithosphere. Fluids infiltrate into the crust through the mantle part of the lithosphere. They catalyze the reaction in the lower crust which results in rock contraction with a formation of deep water basins at the surface during∼106a. The major hydrocarbon basins of the world were formed in this way. Infiltration of fluids strongly reduces the viscosity of the lithosphere, which is evidenced by narrow-wavelength deformations of this layer. At times of softening of the mantle part of the lithosphere, it becomes convectively replaced by a hotter and lighter asthenosphere. This process has resulted in the formation of many mountain ranges and high plateaus during the last several millions of years. Softening of the whole lithospheric layer which is rigid under normal conditions allows its strong compressive and tensile deformations. At the epochs of compression, a large portion of dense eclogites that were formed from basalts in the lower crust sink deeply into the mantle. In some cases they carry down lighter blocks of granites and sedimentary rocks of the upper crust which delaminate from eclogitic blocks and emerge back to the crust. Such blocks of upper crustal rocks include diamonds and other minerals which were formed at a depth of 100–150 km.


2020 ◽  
Author(s):  
Bin Gong ◽  
Chun‘an Tang ◽  
Tiantian Chen ◽  
Zhanjie Qin ◽  
Hua Zhang

<p>Alternative cooling and warming have occurred many times in the history of Earth since its formation. In the meantime, active and quiescent periods of geological activity have also alternatively occurred in this same planet. When Earth became hotter, it shows widespread geological activities, such as LIPs, whereas during the colder stage, it became relatively quiet without too much magma activities. Although various models have been used to explain the trigger for each of these activities, there is no consensus about the fundamental relationships between the thermal cycles and episodically geological processes. The major energy sources for Earth after ~3.8 Ga include primordial heat left from the accretion, differentiation, and the radioactive decay of heat-producing elements. Surface tectonics and magmatism control the transport of heat from the interior to the surface and most surface tectonic features of Earth are the expression of their interior dynamics. Supercontinental breakup and aggregation have occurred for many times in the Earth history, accompanied by episodic cooling and warming on the Earth surface. This breakup and aggregation regime is known as plate tectonics and is characterized by high average surface heat flow fluctuations. Based on the thermodynamic principle, a thermodynamic equilibrium equation describing the earth’s thermal cycles is established. We realized that this thermal cycle may drive Earth itself to evolve, and is the fundamental reason for the periodicity or rhythmicity of geological events such as tectonic movements, orogenies, glacial periods and biological extinctions. Following this principle, we then introduced a project of Wall Chat to compile global data or evidences using a variety of literatures in Geology of early investigations of geological events to explore the relationship between geological events and Earth’s thermal cycles. The data includes the supercontinent cycle, tectonic movement, plate tectonics, extremely hot event, extremely cold event, evaporite, marine red bed, biological evolution and extinction, sea level fluctuation, etc. The Wall Chat reveals that most of the geological events have their relation to the Earth’s thermal cycles. We found that there may exist a good correlation between the occurrence of evaporites and marine red beds and the higher temperature periods, which then provides a new perspective to understand the triggering of these events. The Wall Chat also raises an interest and important question on why are the two Great Oxidation Events (GOE) both related to the two snowball events? We have several clear objectives for the future. First, we are currently cooperating with some of the related institutes of geology to obtain additional evidence data to fill in many of the gaps in the chat; targeted areas include Paleontology, Glaciology, evaporite and red beds. Second, to understand fully the relationship between thermal cycles and, at least, most of the great geological events. Such studies, when sufficiently constrained by event data, should lead to a greatly improved understanding of the earth evolution.</p>


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