Proverbs and sayings about May HORIZONTALLY: 2. May will deceive - in ... will leave.4 ....
Endogenous processes - geological processes associated with the energy arising in the bowels of the Earth. Endogenous processes include tectonic movements of the earth's crust, magmatism, metamorphism, seismic and tectonic processes. The main sources of energy for endogenous processes are heat and the redistribution of material in the Earth's interior in terms of density (gravitational differentiation). These are the processes of internal dynamics: they occur as a result of the influence of internal, in relation to the Earth, energy sources. The deep heat of the Earth, according to most scientists, is predominantly of radioactive origin. A certain amount of heat is also released during gravitational differentiation. The continuous generation of heat in the bowels of the Earth leads to the formation of its flow to the surface (heat flow). At some depths in the bowels of the Earth, with a favorable combination of material composition, temperature, and pressure, foci and layers of partial melting may arise. Such a layer in the upper mantle is the asthenosphere - the main source of magma formation; convection currents can arise in it, which serve as a presumed cause of vertical and horizontal movements in the lithosphere. Convection also occurs on the scale of the entire mantle|mantle, possibly separately in the lower and upper mantle, in one way or another leading to large horizontal displacements of lithospheric plates. The cooling of the latter leads to vertical subsidence (plate tectonics). In the zones of volcanic belts of island arcs and continental margins, the main magma chambers in the mantle are associated with superdeep inclined faults (the Wadati-Zavaritsky-Benioff seismic focal zones) extending under them from the ocean side (approximately to a depth of 700 km). Under the influence of a heat flow or directly the heat brought by rising deep magma, the so-called crustal magma chambers arise in the earth's crust itself; reaching the near-surface parts of the crust, magma intrudes into them in the form of intrusions of various shapes (plutons) or pours out to the surface, forming volcanoes. Gravitational differentiation led to the stratification of the Earth into geospheres of different densities. On the surface of the Earth, it also manifests itself in the form of tectonic movements, which, in turn, lead to tectonic deformations of the rocks of the earth's crust and upper mantle; the accumulation and subsequent discharge of tectonic stresses along active faults lead to earthquakes. Both types of deep processes are closely related: radioactive heat, by lowering the viscosity of the material, promotes its differentiation, and the latter accelerates the removal of heat to the surface. It is assumed that the combination of these processes leads to uneven transport of heat and light matter to the surface in time, which, in turn, can explain the presence of tectonomagmatic cycles in the history of the earth's crust. Spatial irregularities of the same deep processes are used to explain the division of the earth's crust into more or less geologically active regions, for example, into geosynclines and platforms. The formation of the Earth's relief and the formation of many important minerals are associated with endogenous processes.
Exogenous- geological processes caused by energy sources external to the Earth (mainly solar radiation) in combination with gravity. Electromagnetic phenomena occur on the surface and in the near-surface zone of the earth's crust in the form of its mechanical and physicochemical interactions with the hydrosphere and atmosphere. These include: weathering, geological activity wind (eolian processes, deflation), flowing surface and groundwater (erosion, Denudation), lakes and swamps, waters of the seas and oceans (Abrasia), glaciers (Exaration). The main forms of manifestation of E. p. on the surface of the Earth: destruction rocks and chemical transformation of the minerals composing them (physical, chemical, organic weathering); removal and transfer of loosened and soluble products of destruction of rocks by water, wind and glaciers; deposition (accumulation) of these products in the form of sediments on land or at the bottom of water basins and their gradual transformation into sedimentary rocks (sedimentogenesis, diagenesis, Catagenesis). Electromagnetic fields, in combination with endogenous processes, are involved in the formation of the earth's topography and in the formation of sedimentary rock masses and associated mineral deposits. Thus, for example, under conditions of manifestation of specific processes of weathering and sedimentation, ores of aluminum (bauxite), iron, nickel, etc. are formed; placers of gold and diamonds are formed as a result of selective deposition of minerals by water flows; under conditions favorable to the accumulation of organic matter and sedimentary rock strata enriched with it, combustible minerals arise.
| 7-Chemical and mineral composition of the earth's crust | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The composition of the earth's crust includes all known chemical elements. But they are distributed unevenly. The most common are 8 elements (oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium), which make up 99.03% of the total weight of the earth's crust; the remaining elements (the majority) account for only 0.97%, i.e., less than 1%. In nature, due to geochemical processes, significant accumulations of a chemical element are often formed and its deposits appear, while other elements are in a dispersed state. That is why some elements that make up a small percentage of the earth's crust, such as gold, find practical application, while other elements that are more widely distributed in the earth's crust, such as gallium (it is contained in the earth's crust almost twice more than gold), do not find wide application, although they have very valuable qualities (gallium is used to make solar photovoltaic cells used in space shipbuilding). "Rare" in our understanding of vanadium in the earth's crust contains more than "common" copper, but it does not form large accumulations. Radium in the earth's crust contains tens of millions of tons, but it is in a dispersed form and therefore represents a "rare" element. The total reserves of uranium are in the trillions of tons, but it is dispersed and rarely forms deposits. The chemical elements that make up the earth's crust are not always in a free state. For the most part, they form natural chemical compounds - minerals; A mineral is a component of a rock formed as a result of physical and chemical processes that have taken place and are taking place inside the Earth and on its surface. A mineral is a substance of a certain atomic, ionic, or molecular structure, stable at certain temperatures and pressures. Currently, some minerals are also obtained artificially. The vast majority are solid, crystalline substances (quartz, etc.). There are liquid minerals (native mercury) and gaseous (methane). As free chemical elements, or, as they are called, native, there are gold, copper, silver, platinum, carbon (diamond and graphite), sulfur and some others. Such chemical elements as molybdenum, tungsten, aluminum, silicon and many others are found in nature only in the form of compounds with other elements. A person extracts the chemical elements he needs from natural compounds, which serve as an ore for obtaining these elements. Thus, minerals or rocks are called ore, from which pure chemical elements (metals and non-metals) can be extracted industrially. Minerals are mostly found in the earth's crust together, in groups, forming large natural regular accumulations, the so-called rocks. Rocks are called mineral aggregates, consisting of several minerals, or large accumulations of them. So, for example, the rock granite consists of three main minerals: quartz, feldspar and mica. The exception is rocks that are composed of a single mineral, such as marble, which is composed of calcite. Minerals and rocks that are used and can be used in national economy are called minerals. Among the minerals, there are metallic ones, from which metals are extracted, non-metallic ones, used as building stone, ceramic raw materials, raw materials for chemical industry, mineral fertilizers, etc., fossil fuels - coal, oil, combustible gases, oil shale, peat. Mineral accumulations containing useful components in quantities sufficient for their economically profitable extraction represent mineral deposits. 8- The prevalence of chemical elements in the earth's crust
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9- General information about minerals
Mineral(from late Latin "minera" - ore) - a natural solid with a certain chemical composition, physical properties and crystal structure, formed as a result of natural physical and chemical processes and is integral part Earth's crust, rocks, ores, meteorites and other planets solar system. Mineralogy is the study of minerals.
The term "mineral" means a solid natural inorganic crystalline substance. But sometimes it is considered in an unjustifiably extended context, referring to minerals some organic, amorphous and other natural products, in particular some rocks, which in the strict sense cannot be classified as minerals.
· Minerals are also considered some natural substances, which are liquids under normal conditions (for example, native mercury, which comes to a crystalline state at a lower temperature). Water, on the contrary, is not classified as a mineral, considering it as a liquid state (melt) of the mineral ice.
· Some organic substances - oil, asphalt, bitumen - are often erroneously classified as minerals.
Some minerals are in an amorphous state and do not have a crystalline structure. This applies mainly to the so-called. metamict minerals that have the external form of crystals, but are in an amorphous, glassy state due to the destruction of their original crystal lattice under the influence of hard radioactive radiation of the radioactive elements (U, Th, etc.) included in their composition. There are clearly crystalline, amorphous minerals - metacolloids (for example, opal, leschatellerite, etc.) and metamict minerals that have the external form of crystals, but are in an amorphous, glassy state.
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Origin and early history of the development of the earth
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Origin and early history of the Earth
The formation of the planet Earth. The process of formation of each of the planets of the solar system had its own characteristics. Our planet was born about 5 billion years at a distance of 150 million km from the Sun. When falling
Internal structure
The Earth, like other terrestrial planets, has a layered internal structure. It consists of solid silicate shells (crust, extremely viscous mantle), and metallic
Atmosphere, hydrosphere, biosphere of the Earth
The atmosphere is the gaseous envelope that surrounds a celestial body. Its characteristics depend on the size, mass, temperature, rotation speed and chemical composition of a given celestial body, and that
COMPOSITION OF THE ATMOSPHERE
In the high layers of the atmosphere, the composition of the air changes under the influence of hard radiation from the Sun, which leads to the breakdown of oxygen molecules into atoms. Atomic oxygen is the main component
Thermal regime of the Earth
Internal heat of the Earth. The thermal regime of the Earth consists of two types: external heat received in the form solar radiation, and internal, emerging in the bowels of the planet. The sun gives the earth a huge
Chemical composition of magma
Magma contains almost all the chemical elements of the periodic table, including: Si, Al, Fe, Ca, Mg, K, Ti, Na, as well as various volatile components (carbon oxides, hydrogen sulfide, hydrogen
Varieties of magma
Basaltic - (basic) magma, apparently, has a greater distribution. It contains about 50% silica, aluminum, calcium, jelly are present in significant amounts.
Mineral genesis
Minerals can form under different conditions, in different parts of the earth's crust. Some of them are formed from molten magma, which can solidify both at depth and on the surface during volcanoes.
Endogenous processes
Endogenous processes of mineral formation, as a rule, are associated with the intrusion into the earth's crust and solidification of incandescent underground melts, called magmas. At the same time, endogenous mineral formation
Exogenous processes
exogenous processes proceed under completely different conditions than the processes of endogenous mineral formation. Exogenous mineral formation leads to the physical and chemical decomposition of whatever
Metamorphic processes
No matter how the rocks are formed and no matter how stable and durable they are, getting into other conditions, they begin to change. Rocks formed as a result of changes in the composition of silt
The internal structure of minerals
According to the internal structure, minerals are divided into crystalline (kitchen salt) and amorphous (opal). In minerals with a crystalline structure elementary particles(atoms, molecules) disperse
Physical
The definition of minerals is carried out by physical properties, which are determined by the material composition and structure of the crystal lattice of the mineral. This is the color of the mineral and its powder, luster, transparent
Sulfides in nature
Under natural conditions, sulfur occurs mainly in two valence states of the S2 anion, which forms S2- sulfides, and the S6+ cation, which is included in the sulfate
Description
This group includes fluorine, chloride and very rare bromine and iodine compounds. Fluorine compounds (fluorides), genetically associated with magmatic activity, they are sublimates
Properties
Trivalent anions 3−, 3−, and 3− have relatively large sizes; therefore, the most stable
Genesis
As for the conditions for the formation of numerous minerals belonging to this class, it should be said that the vast majority of them, especially aqueous compounds, are associated with exogenous processes.
Structural types of silicates
The structural structure of all silicates is based on a close bond between silicon and oxygen; this relationship comes from the crystal chemical principle, namely, from the ratio of the radii of the Si ions (0.39Å) and O (
Structure, texture, forms of occurrence of rocks
Structure - 1. for igneous and metasomatic rocks, a set of features of the rock, due to the degree of crystallinity, size and shape of crystals, the way they
ROCK POSITION FORMS
Forms of occurrence of igneous rocks differ significantly for rocks formed at a certain depth (intrusive) and rocks erupted on the surface (effusive). Basic functions
Carbonatites
Carbonatites are endogenous accumulations of calcite, dolomite and other carbonates, spatially and genetically associated with ultrabasic alkaline intrusions of the central type,
Forms of occurrence of intrusive rocks
The intrusion of magma into various rocks that make up the earth's crust leads to the formation of intrusive bodies (intrusives, intrusive massifs, plutons). Depending on how they interact
Composition of metamorphic rocks
The chemical composition of metamorphic rocks is diverse and depends primarily on the composition of the original ones. However, the composition may differ from the composition of the original rocks, since in the process of metamorphism
The structure of metamorphic rocks.
The structures and textures of metamorphic rocks arise during recrystallization in the solid state of primary sedimentary and igneous rocks under the influence of lithostatic pressure, temp.
Forms of occurrence of metamorphic rocks
Since the initial material of metamorphic rocks is sedimentary and igneous rocks, their forms of occurrence must coincide with the forms of occurrence of these rocks. So based on sedimentary rocks
Hypergenesis and weathering crust
HYPERGENESIS - (from hyper ... and "genesis"), a set of processes of chemical and physical transformation of mineral substances in the upper parts of the earth's crust and on its surface (at low temperatures
Fossils
Fossils (lat. Fossilis - fossil) - fossil remains of organisms or traces of their vital activity belonging to previous geological eras. Detected by humans at
Geological Survey
Geological survey - One of the main methods for studying the geological structure of the upper parts of the earth's crust of any area and identifying its prospects for mineral cheese
Grabens, ramps, rifts.
A graben (German "graben" - to dig) is a structure bounded on both sides by faults. (Fig. 3, 4). Uz
Geological history of the development of the Earth
Material from Wikipedia - the free encyclopedia
Neoarchean era
Neoarchean - geological era, part of the Archean. Covers the time period from 2.8 to 2.5 billion years ago. The period is determined only chronometrically, the geological layer of earth rocks is not distinguished. So
Paleoproterozoic era
Paleoproterozoic - a geological era, part of the Proterozoic, which began 2.5 billion years ago and ended 1.6 billion years ago. At this time, the first stabilization of the continents occurs. At that time
Neoproterozoic era
Neoproterozoic - geochronological era (the last era of the Proterozoic), which began 1000 million years ago and ended 542 million years ago. From a geological point of view, it is characterized by the collapse of the ancient su
Ediacaran period
Ediacarus - the last geological period Neoproterozoic, Proterozoic, and the entire Precambrian, just before the Cambrian. It lasted approximately from 635 to 542 million years BC. e. The name of the period formed
Phanerozoic eon
Phanerozoic eon - a geological eon that began ~ 542 million years ago and continues in our time, the time of "explicit" life. The beginning of the Phanerozoic eon is considered to be the Cambrian period, when the p
Palaeozoic
Paleozoic era, Paleozoic, PZ - geological era of the ancient life of the planet Earth. The oldest era in the Phanerozoic eon follows the Neoproterozoic era, followed by the Mesozoic era. Paleozoic
Carboniferous period
The Carboniferous period, abbreviated Carboniferous (C) - the geological period in the Upper Paleozoic 359.2 ± 2.5-299 ± 0.8 million years ago. Named for its strong
Mesozoic era
Mesozoic - a period of time in the geological history of the Earth from 251 million to 65 million years ago, one of the three eras of the Phanerozoic. It was first identified in 1841 by the British geologist John Phillips. Mesozoic - the era of those
Cenozoic era
Cenozoic (Cenozoic era) - an era in the geological history of the Earth with a length of 65.5 million years, starting from the great extinction of species at the end of the Cretaceous period to the present
Paleocene epoch
Paleocene - geological epoch of the Paleogene period. This is the first epoch of the Paleogene followed by the Eocene. The Paleocene covers the period from 66.5 to 55.8 million years ago. Paleocene begins tertiary
Pliocene Epoch
The Pliocene is an epoch of the Neogene period that began 5.332 million years ago and ended 2.588 million years ago. The Pliocene epoch is preceded by the Miocene epoch, and the follower of
Quaternary period
Quaternary period, or anthropogen - geological period, modern stage history of the Earth, ends with the Cenozoic. It began 2.6 million years ago and continues to this day. This is the shortest geological
Pleistocene Epoch
Pleistocene - the most numerous and καινός - new, modern) - the era of the Quaternary period, which began 2.588 million years ago and ended 11.7 thousand years ago
Mineral reserves
(mineral resources) - the amount of mineral raw materials and organic minerals in the bowels of the Earth, on its surface, at the bottom of reservoirs and in the volume of surface and groundwater. Reserves of useful
Reserve valuation
The amount of reserves is estimated based on geological exploration data in relation to existing production technologies. These data allow you to calculate the volume of bodies of minerals, and when multiplying the volume
Stock categories
According to the degree of reliability of the determination of reserves, they are divided into categories. V Russian Federation there is a classification of mineral reserves with their division into four categories: A, B, C1
Balance and off-balance reserves
Mineral reserves, according to their suitability for use in the national economy, are divided into balance and off-balance. Balance reserves include such mineral reserves, which
OPERATIONAL INTELLIGENCE
EXPLOITATIONAL EXPLORATION - the stage of exploration work carried out in the process of developing a deposit. Planned and carried out in conjunction with plans for the development of mining operations, ahead of stoping
Exploration of mineral deposits
Exploration of mineral deposits (geological exploration) - a set of studies and work carried out in order to identify and evaluate mineral reserves
Age of rocks
The relative age of rocks is the determination of which rocks formed earlier and which rocks later. The stratigraphic method is based on the fact that the age of the layer at normal bedding
Balance reserves
BALANCE RESERVES OF MINERALS - a group of mineral reserves, the use of which is economically feasible with the progressive technology existing or mastered by the industry and
Folded dislocations
Plicative disturbances (from lat. plico - I add) - disturbances in the primary occurrence of rocks (that is, the actual dislocation)), which lead to the occurrence of bends in rocks of various ma
Forecast resources
FORECAST RESOURCES - the possible amount of minerals in geologically poorly studied areas of the earth and hydrosphere. Inferred resources are estimated based on general geological predictions.
Geological sections and methods for their construction
GEOLOGICAL SECTION, geological profile - a vertical section of the earth's crust from the surface to the depth. Geological sections are compiled according to geological maps, data of geological observations and
Ecological crises in the history of the earth
The ecological crisis is a tense state of relations between humanity and nature, characterized by a mismatch between the development of productive forces and production relations in people
Geological development of continents and oceanic depressions
According to the hypothesis of the primacy of the oceans, the earth's crust of the oceanic type arose even before the formation of the oxygen-nitrogen atmosphere and covered the entire globe. The primary crust consisted of basic magmas
Endogenous are internal processes; exogenous - external, surface, for them the source of energy is the energy of the Sun and gravity (the gravitational field of the Earth).
Endogenous processes include:
Magmatism (from the word magma) is the process associated with the birth, movement and transformation of magma into igneous rock;
Tectonics (tectonic movements) - any mechanical movements of the earth's crust - uplifts, lowerings, horizontal movements, etc.;
Earthquakes - are the result of tectonic movements, but are usually considered independently;
Metamorphism - processes that lead to a change in the composition, structure of rocks inside the Earth with a change in physico-chemical parameters (pressure, temperature, etc.).
Exogenous processes include processes occurring on the surface or near it, changing the face of the Earth and associated with the activity of the atmosphere, hydrosphere and biosphere:
weathering (hypergenesis);
Geological wind activity;
Geological activity of flowing waters;
Geological activity of groundwater;
Geological activity of snow, ice, permafrost;
Geological activity of the seas, lakes, swamps;
Geological activity of man.
Endogenous processes create irregularities in the Earth's surface. The largest of them are created by tectonic movements. With downward movements (lowering) of sections of the earth's crust, depressions of large lakes, seas, and oceans arise. With the upward movements (uplift) of individual sections of the earth's crust, mountain uplifts, mountainous countries and entire continents arise.
Exogenous processes destroy the elevated areas of the earth's surface and tend to fill the resulting depressions. Thus, the relief of the Earth is an arena of a never-ending struggle between endogenous and exogenous forces, and the manifestation, confrontation of these forces is impossible without each other. Such an inseparable connection is called dialectical.
Denudation and penepelnization
Denudation is the process of destruction of rocks on the surface of the Earth, accompanied by the removal of the destroyed mass. Naturally, denudation leads to a lowering of the raised areas of the relief (Figure 4).
Figure 4 - Scheme of lowering the relief in the process of denudation: 1 - initial surface, 2 - surface after denudation
As a result of denudation, all new portions of rocks, previously covered from the impact of overlying masses, are exposed to exogenous processes and destruction.
In limited areas, denudation occurs most often as a result of the activity of any of the external factors: river erosion, marine abrasion, etc. Vast spaces are lowered under the combined influence of many external geodynamic processes. The denudation of mountainous countries proceeds the faster, the higher they are, and can reach a speed of 5-6 cm per year for the highest ranges (Caucasus, Alps). On the plains, the rate of denudation is much lower (fractions of millimeters per year), and in some places it is replaced by the accumulation of precipitation. Approximate calculations show that mountainous countries gradually decrease when denudation overcomes tectonic uplift, and in their place hilly plains - peneplens, as they are commonly called, can appear, and the time required for this is from 20 to 50 million years. The same calculations show that for the complete destruction of the continents, assuming the termination of the action of tectonic forces, it will take 200-250 million years. Continents can collapse to the level of ocean waters. Below this level, denudation processes practically stop: the ocean level is taken as the denudation limit.
Independent - local - levels of denudation can exist on the continents, as a rule, this is the level of large drainless depressions (Caspian, Aral, Dead Sea).
Plutonism and volcanism
Magmatism refers to phenomena associated with the formation, change in composition and movement of magma from the bowels of the Earth to its surface.
Magma is a natural high-temperature melt, formed as separate chambers in the lithosphere and upper mantle (mainly in the asthenosphere). The main reason for the melting of matter and the emergence of magma chambers in the lithosphere is an increase in temperature. The rise of magma and its breakthrough into the overlying horizons occur as a result of the so-called density inversion, in which foci of a less dense, but mobile melt appear inside the lithosphere. Thus, magmatism is a deep process caused by the thermal and gravitational fields of the Earth.
Depending on the nature of the movement of magma, magmatism is distinguished as intrusive and effusive. During intrusive magmatism (plutonism), magma does not reach the earth's surface, but actively intrudes into the enclosing overlying rocks, partially melting them, and solidifies in cracks and cavities of the crust. With effusive magmatism (volcanism), magma reaches the Earth's surface through a supply channel, where it forms volcanoes of various types, and freezes on the surface. In both cases, when the melt solidifies, igneous rocks are formed. Temperatures of magmatic melts located inside the earth's crust, judging by experimental data and study results mineral composition igneous rocks are in the range of 700-1100°C. The measured temperatures of magmas erupted on the surface, in most cases, fluctuate in the range of 900-1100°C, occasionally reaching 1350°C. The higher temperature of terrestrial melts is due to the fact that they undergo oxidation processes under the influence of atmospheric oxygen.
In terms of chemical composition, magma is a complex multicomponent system formed mainly by silica SiO2 and substances chemically equivalent to silicates of Al, Na, K, Ca. The predominant component of magma is silica. In nature, there are several types of magmas that differ in chemical composition. The composition of magmas depends on the composition of the material, due to the melting of which they are formed. However, during the rise of magma, partial melting and dissolution of the host rocks of the earth's crust, or their assimilation occurs; while its primary composition changes. Thus, the composition of magmas changes in the course of both their intrusion into the upper horizons of the crust and crystallization. At great depths, magmas in the dissolved state contain volatile components - water and gas vapors (H2S, H2, CO2, HCl, etc.). high pressures their content can reach 12%. They are chemically very active, mobile substances and are retained in magma only due to high external pressure.
In the process of magma rising to the surface, as temperatures and pressures decrease, the system breaks up into two phases - melt and gases. If the movement of magma is slow, its crystallization begins in the process of ascent, and then it turns into a three-phase system: gases, melt and mineral crystals floating in it. Further cooling of the magma leads to the transition of the entire melt into a solid phase and to the formation of igneous rock. In this case, volatile components are released, the main part of which is removed along the cracks surrounding the magma chamber, or directly into the atmosphere in the event of an outpouring of magma on the surface. In the hardened rock, only an insignificant part of the gas phase is preserved in the form of tiny inclusions in mineral grains. Thus, the composition of the original magma determines the composition of the main, rock-forming minerals of the formed rock, but is not strictly identical to it in terms of the content of volatile components.
Geological processes are divided into endogenous and exogenous.
Endogenous processes - geological processes associated with the energy that occurs in the bowels of the Earth. These include tectonic movements of the earth's crust, magmatism, rock metamorphism, and seismic activity. The main sources of energy for endogenous processes are heat and gravitational instability - the redistribution of material in the Earth's interior in terms of density (gravitational differentiation).
Endogenous processes include:
- - tectonic - diverse in direction and intensity of the movement of the earth's crust, causing its deformation (collapse into folds) or rupture of layers;
- - seismic - associated with earthquakes;
- - magmatic - associated with magmatic activity;
- - volcanic - associated with volcanic activity;
- - metamorphic - the process of transformation of rocks under the influence of pressure and temperature without the introduction or removal of chemical components;
- - skarn - metasomatic mineral and rock formation as a result of exposure to various rocks (mainly limestones and dolomites) of high-temperature solutions containing Fe, M?, Ca, 81, Al and other substances with a wide participation of volatile components (water , carbon dioxide, C1, B, C, etc.), and in a wide range of temperatures and pressures during the general evolution of solutions as the temperature decreases from alkaline to acidic;
- - greisen - metasomatic alteration of granite rocks under the influence of gases released from the cooling magma with the transformation of feldspars into light micas;
- - hydrothermal - deposits of metal ores (Au, Cu, Pb, Sn, XV, etc.) and non-metallic minerals (talc, asbestos, etc.), the formation of which is associated with the deposition or redeposition of ore matter from hot deep aqueous solutions, often associated with magma chambers cooling in the earth's crust.
Tectonic movements- mechanical movements of the earth's crust, caused by forces acting in it and mainly in the earth's mantle, and leading to deformation of the rocks that make up the crust. Tectonic movements are associated, as a rule, with a change in the chemical composition, phase state (mineral composition) and the internal structure of rocks undergoing deformation. Tectonic movements simultaneously cover very large areas.
Geodetic measurements show that almost the entire surface of the Earth is continuously in motion, however, the speed of tectonic movements is small, varies from hundredths to a few tens of millimeters per year, and only the accumulation of these movements during a very long (tens to hundreds of million years) geological time leads to to large total displacements of individual sections of the earth's crust.
The American geologist G. Gilbert proposed (1890), and the German geologist X. Stille developed (1919) a classification of tectonic movements with their division into epeirogenic, expressed in prolonged uplifts and subsidence of large areas of the earth's surface, and orogeny, manifested episodically (orogenic phases) in certain zones by the formation of folds and ruptures and leading to the formation of mountain structures. This classification is still used, but its main drawback is the combination of two fundamentally different processes in the concept of orogeny - folding and rupture formation, on the one hand, and mountain building, on the other. Other classifications have been proposed. One of them (domestic geologists A.P. Karpinsky, M.M. Tetyaev and others) provided for the allocation oscillatory folds and discontinuous tectonic movements, another (German geologist E. Harman and Dutch scientist R. W. van Bemmelen) - undation (wave) and undulation (folded) tectonic movements. It became clear that tectonic movements are very diverse both in the form of manifestation and in the depth of origin, and also, obviously, in the mechanism and causes of occurrence.
According to another principle, tectonic movements were divided by M.V. Lomonosov into slow (secular) and fast. Fast movements are associated with earthquakes and, as a rule, are distinguished by high speed, several orders of magnitude higher than the speed of slow movements. Displacements of the earth's surface during earthquakes amount to several meters, sometimes more than 10 m. However, such displacements appear sporadically.
The subdivision of tectonic movements into vertical (radial)) and horizontal (tangential), although it is largely conditional, since these movements are interconnected and pass one into another. Therefore, it is more correct to speak of tectonic movements with a predominant vertical or horizontal component. The prevailing vertical movements cause the rise and fall of the earth's surface, including the formation of mountain structures. They are the main reason for the accumulation of thick layers of sedimentary rocks in the oceans and seas, and partly on land. Horizontal movements are most clearly manifested in the formation of large shifts of individual blocks of the earth's crust relative to others with an amplitude of hundreds and even thousands of kilometers, in their thrusts with an amplitude of hundreds of kilometers, as well as in the formation of oceanic depressions thousands of kilometers wide as a result of the separation of blocks of continental crust.
Tectonic movements are distinguished by a certain periodicity or unevenness, which is expressed in changes in sign and (or) speed in time. Relatively short-period vertical movements with a frequent change of sign (reversible) are called oscillatory. Horizontal movements usually retain their direction for a long time and are irreversible. Oscillatory tectonic movements are likely to cause transgressions and regressions sea, the formation of sea and river terraces.
By the time of manifestation, the latest tectonic movements are distinguished, which are directly reflected in the modern relief of the Earth and therefore are recognized not only by geological, but also by geomorphological methods, and modern tectonic movements, which are also studied by geodetic methods (re-leveling, etc.). They are the subject of research in modern tectonics.
The tectonic movements of the remote geological past are established by the distribution of transgressions and regressions of the ocean, by the total thickness (thickness) of accumulated sedimentary deposits, by the distribution of their facies and sources of clastic material carried in the depression. In this way, the vertical component of the movement of the upper layers of the earth's crust or the surface of a consolidated basement located under the sedimentary cover is determined. The level of the World Ocean is used as a benchmark, which is considered almost constant, with possible deviations of up to 50-100 m during melting or the formation of glaciers, as well as more significant - up to several hundred meters as a result of a change in the capacity of oceanic depressions during their growth and the formation of mid-ocean basins. ridges.
Large horizontal displacements, which are not recognized by all scientists, are established both from geological data, by graphic straightening of folds and restoring thrust rock strata in their original position, and on the basis of studying the remanent magnetization of rocks and changes in paleoclimate. It is believed that with a sufficient amount of paleomagnetic and geological data, it is possible to restore the former location of the continents and oceans and determine the speed and direction of movements that occurred in subsequent times, for example, from the end of the Paleozoic era.
The rate of horizontal movements is determined by supporters of mobilism by the width of the newly formed oceans (Atlantic, Indian), by paleomagnetic data indicating changes in latitude and orientation with respect to the meridians, and by the width of magnetic anomaly bands of various signs formed during the growth of the ocean floor, which are compared with the duration of epochs. different polarity of the earth's magnetic field. These estimates, as well as the rate of modern horizontal movements, measured by geodetic methods in rifts (East Africa), folded areas (Japan, Tajikistan) and in strike slips (California), are 0.1-10 cm/g. Over millions of years, the speed of horizontal movements changes slightly, the direction remains almost constant.
Vertical movements, on the contrary, have a variable, oscillatory character. Repeated levelings show that the rate of subsidence or uplift on the plains usually does not exceed 0.5 cm/year, while the rise in mountainous areas (for example, in the Caucasus) reaches 2 cm/year. At the same time, the average rates of vertical tectonic movements determined for large time intervals (for example, over tens of millions of years) do not exceed 0.1 cm/year in mobile belts and 0.01 cm/year on platforms. This difference in velocities measured over short and long periods of time indicates that only the integral result of secular vertical movements is recorded in geological structures, which accumulates when oscillations of the opposite sign are summed.
The similarity of tectonic movements repeating on the same tectonic structures, allows us to speak about the inherited nature of vertical tectonic movements. Tectonic movements usually do not include the movement of rocks in the near-surface zone (tens of meters from the surface), caused by violations of their gravitational balance under the influence of exogenous (external) geological processes, as well as periodic rises and falls of the earth's surface, due to solid tides of the Earth due to the attraction of the Moon and Sun. It is disputable to attribute to tectonic movements processes associated with the restoration of isostatic equilibrium, for example, uplifts during the reduction of large ice sheets such as the Antarctic or Greenland. The movements of the earth's crust caused by the activity of volcanoes are of a local nature. The causes of tectonic movements have not yet been reliably established; various assumptions have been made in this regard.
According to a number of scientists, deep tectonic movements are caused by a system of large convection currents covering the upper and middle layers of the Earth's mantle. Such currents are apparently associated with the expansion of the earth's crust in the oceans and compression in folded areas, above those zones where the approach and subsidence of counter currents occurs. Other scientists (V. V. Belousov) deny the existence of closed convection currents in the mantle, but allow the rise of the mantle heated in the lower parts and lighter products of its differentiation, causing upward vertical movements of the crust. The cooling of these masses causes it to sink. At the same time, no significant significance is attached to horizontal movements, and they are considered derivatives of vertical ones. When elucidating the nature of movements and deformations of the earth's crust, some researchers assign a certain role to stresses arising in connection with changes in the speed of the earth's rotation, while others consider them too insignificant.
The deep heat of the Earth is predominantly of radioactive origin. The continuous generation of heat in the bowels of the Earth leads to the formation of its flow directed to the surface. At some depths, with a favorable combination of material composition, temperature, and pressure, foci and layers of partial melting may appear. Such a layer in the upper mantle is the asthenosphere - the main source of magma formation; convection currents can arise in it, which serve as a presumed cause of vertical and horizontal movements of the lithosphere. In the zones of volcanic belts of island arcs and continental margins, the main chambers of magma are associated with superdeep inclined faults (the Zavaritsky-Benioff zones) extending under them from the ocean (approximately to a depth of 700 km). Under the influence of a heat flow or directly from the heat brought by rising deep magma, the so-called crustal magma chambers arise in the earth's crust itself; reaching the near-surface parts of the crust, magma intrudes into them in the form of intrusions of various shapes or pours out to the surface, forming volcanoes.
Gravitational differentiation led to the stratification of the Earth into geospheres of different density. On the surface of the Earth, it also manifests itself in the form of tectonic movements, which, in turn, lead to tectonic deformations of the rocks of the earth's crust and upper mantle. The accumulation and subsequent discharge of tectonic stresses along active faults lead to earthquakes.
Both types of deep processes are closely related: radioactive heat, by lowering the viscosity of the material, promotes its differentiation, and the latter accelerates the removal of heat to the surface. It is assumed that the combination of these processes leads to non-uniformity in time of the removal of heat and light matter to the surface, which, in turn, can be explained by the presence of tectonomagmatic cycles in the history of the earth's crust.
Tectonic cycles(stages) - large (more than 100 million years) periods of the geological history of the Earth, characterized by a certain sequence of tectonic and general geological events. They are most clearly manifested in the mobile areas of the Earth, where the cycle begins with subsidence of the earth's crust with the formation of deep sea basins, the accumulation of thick layers of sediments, underwater volcanism, and the formation of basic and ultrabasic intrusive-magmatic rocks. Island arcs appear, andesitic volcanism manifests itself, the sea basin is divided into smaller ones, and fold-thrust deformations begin. Then there is the formation of folded and folded-cover mountain structures, bordered and separated by advanced (marginal, foothill) and intermountain troughs, which are filled with mountain destruction products - maupasses. This process is accompanied by regional metamorphism, granite formation, and liparitic-basaltic ground volcanic eruptions.
A similar sequence of events is also observed on the platforms: a change in continental conditions due to the transgression of the sea, and then again regression and the establishment of a continental regime with the formation of weathering crusts, with a corresponding change in the type of sediments - first continental, then lagoonal, often saline or coal-bearing, then marine clastic, in the middle of the cycle predominantly carbonate or siliceous, at the end again marine, lagoonal (salt) and continental (sometimes glacial).
Intense fold-and-thrust deformations and mountain building in some mobile zones often correspond to the formation of new subsidence zones in their rear and the formation of rift systems - aulacogens on platforms.
The average duration of tectonic cycles in the Phanerozoic is 150-180 Ma (in the Precambrian, tectonic cycles were apparently longer). Along with such cycles, larger ones are sometimes distinguished - megacycles (megastages) - lasting hundreds of millions of years. In Europe, partly in North America and Asia, the following cycles were established in the Late Precambrian and Phanerozoic: Grenville (Middle Riphean); Baikal (Late Riphean-Vendian); Caledonian (Cambrian-Devonian); Hercynian (Devonian-Permian); Cimmerian or Mesozoic (Triassic-Jurassic); alpine (Cretaceous-Cenozoic).
The original schematic representation of tectonic cycles as being strictly synchronous on the scale of the entire planet, repeating everywhere and differing in the same complex of phenomena, is still rightly disputed. In fact, the end of one and the beginning of another cycle often turn out to be synchronous (in different, often adjacent regions). In each individual mobile system, usually one or two cycles are most fully expressed, immediately preceding its transformation into a folded system. mountain system, and the earlier ones are distinguished by the incompleteness of the set of phenomena characteristic of them, which sometimes merge with each other. On the scale of the entire history of the Earth, tectonic cyclicity acts only as a complication of its general directed development. Separate cycles form the stages of megacycles, and they, in turn, are major stages in the history of the Earth as a whole. The reasons for the cyclicity have not yet been established. Assumptions are made about the periodic accumulation of heat and an increase in the heat flow emanating from the deep bowels of the Earth, about the cycles of rise or circulation (convection) of the products of differentiation of the mantle substance, etc.
Spatial irregularities of the same deep processes are used to explain the division of the earth's crust into more or less geologically active regions, for example, into mountain-folded areas and platforms.
The formation of the Earth's relief and the formation of many important minerals are associated with endogenous processes.
Exogenous processes - geological processes caused by energy sources external to the Earth (mainly solar radiation) in combination with gravity. Exogenous processes occur on the surface and in the near-surface zone of the earth's crust in the form of its mechanical and physico-chemical interaction with the hydrosphere and atmosphere. These include sedimentation and the formation of deposits of sedimentary minerals, weathering, geological activity of the wind (eolian processes, deflation), flowing surface and ground waters (erosion, denudation), lakes and swamps, waters of the seas and oceans (abrasion), glaciers (exaration) .
Exogenous processes include different types of weathering in the form destruction:
- - deflationary - blowing, turning and grinding of rocks with mineral particles carried by the wind;
- - mudflows - formation and movement of mud or mud-rock flows;
- - erosion - erosion of soils and rocks by water flows;
or different processes accumulation rainfall:
- - alluvial - deposits of rivers in the form of sand, pebbles, conglomerates;
- - deluvial - the movement of weathering products of rocks down the slope under the influence of gravity, rain and melt water;
- - colluvial - displacement of slope debris under the influence of gravity;
- - landslide - separation of land masses and rocks and their movement along the slope under the influence of gravity;
- - sediment-forming - precipitation from water, air (in calm areas) or on slopes under the action of gravity;
- - proluvial - movement of products of destruction of rocks by temporary flows and their deposition at the foot of the mountains, often in the form of alluvial fans;
- - ore-forming - accumulation of ore substance under the action of different reasons: native gold - as a result of precipitation from water streams, aluminum oxides - precipitation from aqueous solutions, etc.;
- - eluvial - products of destruction of rocks remain at the place of their formation.
Weathering- the process of destruction and change of rocks in the conditions of the earth's surface as a result of the mechanical and chemical effects of the atmosphere, ground and surface waters and organisms. According to the nature of the environment in which weathering occurs, it can be atmospheric and underwater. By the nature of the impact of weathering on rocks, there are physical weathering, leading only to the mechanical disintegration of the rock into fragments; chemical weathering, in which the chemical composition of the rock changes with the formation of minerals that are more stable in the conditions of the earth's surface; organic (biological) weathering, reduced to mechanical fragmentation or chemical change of the rock as a result of the vital activity of organisms. A specific type of weathering is soil formation, in which biological factors play a particularly active role. Weathering of rocks occurs under the influence of water (atmospheric precipitation and groundwater), carbon dioxide and oxygen, water vapor, atmospheric and ground air, seasonal and daily temperature fluctuations, vital activity of macro- and microorganisms and their decomposition products. The speed and degree of weathering, the thickness of the resulting weathering products and their composition, in addition to the listed agents, are also affected by the topography and geological structure of the area, the composition and structure of parent rocks. The vast majority of physical and chemical weathering processes (oxidation, sorption, hydration, coagulation) occur with the release of energy. Usually, the types of weathering act simultaneously, but depending on the climate, one or another of them predominates.
Physical weathering occurs mainly in dry and hot climates and is associated with sharp fluctuations in the temperature of rocks when heated by sunlight (insolation) and subsequent cooling at night; a rapid change in the volume of the surface parts of the rocks leads to their cracking. In areas with frequent temperature fluctuations around 0 °C, mechanical destruction of rocks occurs under the influence of frost weathering; when the water that has penetrated into the cracks freezes, its volume increases and the rock breaks.
Chemical and organic types of weathering are characteristic mainly of layers with a humid climate. The main factors of chemical weathering are air and especially water containing salts, acids and alkalis. Aqueous solutions circulating in the rock mass, in addition to simple dissolution, are also capable of producing complex chemical changes.
The physical and chemical processes of weathering occur in close relationship with the development and vital activity of animals and plants and the action of their decay products after death. The most favorable conditions for the formation and preservation of weathering products (minerals) are the conditions of a tropical or subtropical climate and slight erosional dissection of the relief. At the same time, the thickness of rocks that have undergone weathering is characterized (in the direction from top to bottom) by geochemical zoning, expressed by a complex of minerals characteristic of each zone. The latter are formed as a result of successive processes: the disintegration of rocks under the influence of physical weathering, leaching of bases, hydration, hydrolysis and oxidation. These processes often go up to the complete decomposition of primary minerals, up to the formation of free oxides and hydroxides.
Depending on the degree of acidity - alkalinity of the environment, as well as the participation of biogenic factors, minerals of various chemical compositions are formed: from stable in an alkaline environment (in the lower horizons) to stable in an acidic or neutral environment (in the upper horizons). The diversity of weathering products represented by various minerals is determined by the composition of minerals in primary rocks. For example, on ultrabasic rocks (serpentinites), the upper zone is represented by rocks in the cracks of which carbonates (magnesite, dolomite) are formed. This is followed by horizons of carbonatization (calcite, dolomite, aragonite), hydrolysis, which is associated with the formation of nontronite and the accumulation of nickel (Niu up to 2.5%), silicification (quartz, opal, chalcedony). The zone of final hydrolysis and oxidation is composed of hydrogoethite (ocherous), goethite, magnetite, manganese oxides and hydroxides (nickel- and cobalt-containing). Weathering processes are associated with large deposits of nickel, cobalt, magnesite and naturally alloyed iron ores.
In those cases where weathering products do not remain at the site of their formation, but are carried away from the surface of weathered rocks by water or wind, peculiar relief forms often arise, depending both on the nature of weathering and on the properties of rocks, in which the process, as it were, manifests and emphasizes the features of their structure (Fig. 15).
Rice. 15.
Russia (TSB).
Igneous rocks (granites, diabases, etc.) are characterized by massive rounded forms of weathering; for layered sedimentary and metamorphic - stepped (cornices, niches, etc.). The heterogeneity of rocks and the unequal resistance of their various sections against weathering leads to the formation of remnants in the form of isolated mountains, pillars (Fig. 16), towers, etc.
In a humid climate, on inclined surfaces of homogeneous, relatively easily water-soluble rocks, such as limestone, flowing water corrodes irregular shape depressions separated by sharp protrusions and ridges, resulting in an uneven surface known as carr.
Rice. sixteen.
the Yenisei River near Krasnoyarsk (TSB).
In the process of regeneration of residual weathering products, many soluble compounds are formed, which are carried away by groundwater into water basins and enter into the composition of dissolved salts or precipitate. Weathering processes lead to the formation of various sedimentary rocks and many minerals: kaolins, ocher, refractory clays, sands, ores of iron, aluminum, manganese, nickel, cobalt, placers of gold, platinum, etc., oxidation zones of pyrite deposits with their minerals and others
Deflation(from late lat. With1 e/1 aio- blowing, blowing off) - waving, destruction of rocks and soils under the influence of wind, accompanied by the transfer and grinding of torn off particles. Deflation is especially strong in deserts, in those parts of them from which prevailing winds blow (for example, in the southern part of the Karakum desert). The combination of deflation and physical weathering processes leads to the formation of chiseled rocks of bizarre shape in the form of towers, columns, obelisks, etc.
soil erosion- destruction of soil by water and wind, movement of destruction products and their redeposition.
Education eolian landforms occurs under the influence of wind mainly in areas with an arid climate (deserts, semi-deserts); It is also found along the shores of seas, lakes and rivers with a sparse vegetation cover that is not able to protect loose and weathered rocks of the substrate from the action of the wind. Most common accumulative and accumulative-deflationary forms, formed as a result of the movement and deposition of sand particles by the wind, as well as developed (deflationary) eolian landforms arising due to blowing (deflation) loose weathering products, destruction of rocks under the influence of dynamic impacts of the wind itself and especially under the impact of small particles carried by the wind in the wind-sand flow.
The shape and size of accumulative and accumulative-deflationary formations depend on the wind regime (strength, frequency, direction, structure of the wind flow) that prevailed in the area and acted in the past, on the saturation of the wind sand flow with sand particles, the degree of connectivity of the loose substrate with vegetation, on moisture and other factors, as well as the nature of the underlying relief. The greatest influence on the appearance of eolian landforms in sandy deserts is exerted by active winds, acting similarly to a water flow with turbulent motion of the medium near a solid surface. For medium- and fine-grained dry sand (with a grain diameter of 0.5-0.25 mm), the minimum active wind speed is 4 m/s. Accumulative and deflationary-accumulative forms, as a rule, move in accordance with the seasonally dominant wind direction: progressively with the annual impact of active winds of one or close directions; oscillatory and oscillatory-translationally, if the directions of these winds change significantly during the year (to opposite, perpendicular, etc.). Particularly intensive (at a speed of up to several tens of meters per year) is the movement of bare sandy accumulative forms.
Accumulative and deflationary-accumulative eolian landforms of deserts are characterized by the simultaneous presence of superimposed forms of several categories of magnitudes: 1st category - wind ripples, height from fractions of a millimeter to 0.5 m, distance between crests from a few millimeters to 2.5 m; 2nd category - thyroid accumulations with a height of at least 40 cm; 3rd category - dunes up to 2-3 m high, connected in a ridge longitudinal to the winds or in a dune chain transverse to the winds; 4th category - dune relief up to 10-30 m high; 5th and 6th categories - large forms (up to 500 m high), formed mainly by ascending air currents. In the deserts of the temperate zone, where vegetation plays an important role, which restrains the work of the wind, relief formation is slower and the largest forms do not exceed 60–70 m; 20 m
Since the prevailing wind regime (trade wind, monsoon-breeze, cyclonic, etc.) and the strength of the loose substrate are primarily determined by zonal-geographical factors, accumulative and accumulative-deflationary eolian landforms are generally distributed zonally. According to the classification proposed by the geographer B. A. Fedorovich, bare, easily mobile sandy forms are characteristic mainly of tropical extra-arid deserts (Sahara, deserts of the Arabian Peninsula, Iran, Afghanistan, Takla-Makan); semi-overgrown, weakly mobile - mainly for extratropical deserts (deserts of Central Asia and Kazakhstan, Dzungaria, Mongolia, Australia); overgrown mostly immobile dune forms - for non-desert territories (mainly ancient glacial regions of Europe, Western Siberia, North America). A detailed classification of accumulative and deflationary-accumulative eolian landforms depending on the wind regime is given in the description of dunes and dunes.
Among the developed microforms (up to several tens of centimeters in diameter), the most common lattice or honeycomb rocks, composed mainly of terrigenous rocks; among forms of medium size (meters and tens of meters) - yardangs, hollows, boilers and blowing niches, bizarre rocks(mushroom, ring etc.), clusters of which often form entire aeolian "cities"; large developed forms (several kilometers across) include blowing basins and saline-deflationary depressions, formed under the combined action of intense processes of physicochemical (salt) weathering and deflation (including vast areas up to hundreds of kilometers; for example, the Karagie depression in Western Kazakhstan). A comprehensive study of eolian landforms, their morphology, origin, and dynamics is of great importance in the economic development of deserts.
Abrasion(from lat. ahayayu- scraping, shaving) - destruction by waves and surf of the shores of the seas, lakes and large reservoirs. The intensity of abrasion depends on the degree of wave action of the reservoir. The most important condition predetermining the abrasion development of the coast is a relatively steep angle of the initial slope (more than 1 °) of the coastal part of the bottom of the sea or lake. Abrasion creates an abrasion terrace, or bench, and an abrasion ledge, or cliff on the banks (Fig. 17). The sand, gravel, and pebbles formed as a result of the destruction of rocks can be involved in the processes of sediment movement and serve as material for coastal accumulative forms. Part of the material is carried by waves and currents to the foot of the abrasion underwater slope and forms a leaning accumulative terrace here. As the abrasion terrace expands, the abrasion gradually fades (because the shallow water zone expands, overcoming which the wave energy is spent) and, with the influx of sediments, can be replaced by accumulation. On the slopes of artificial reservoirs, the slopes of which were formed in the past by other, non-abrasive factors, the rate of abrasion is especially high - up to ten meters per year.
Rice. 17.
K - cliff; AT - abrasion terrace (bench); PAT - underwater accumulative terrace; SW - water level. The dotted line indicates the pre-abrasion relief (BSE).
Exaration(from late lat. ehagayo- plowing) - glacial plowing, the destruction of the rocks that make up its bed by the glacier, and the removal of destruction products (sloughs, boulders, pebbles, sand, clay, etc.) by a moving glacier. As a result of exaration, troughs, lake basins, “lamb foreheads”, “curly rocks”, glacial scars, and hatching appear. Along with the destruction of rocks, they are smoothed, polished and polished.
The main forms of manifestation of exogenous processes on the Earth's surface:
- - the destruction of rocks and the chemical transformation of the minerals that compose them (physical, chemical, organic weathering);
- - removal and transfer of loosened and soluble products of destruction of rocks by water, wind and glaciers;
- - deposition (accumulation) of these products in the form of sediments on land or at the bottom of water basins and their gradual transformation into sedimentary rocks as a result of successive processes of sedimentogenesis, diagenesis and catagenesis.
Exogenous processes in combination with endogenous ones are involved in the formation of the Earth's relief, in the formation of sedimentary rock strata and associated mineral deposits. For example, under conditions of manifestation of specific processes of weathering and sedimentation, ores of aluminum (bauxites), iron, nickel, etc. are formed; placers of gold and diamonds are formed as a result of selective deposition of minerals by water flows; under conditions conducive to the accumulation organic matter and strata of sedimentary rocks enriched with it, combustible minerals arise.
Endogenous disorders of the human psyche are a fairly common phenomenon today. For a number of factors, both adults and children can be exposed to this disease. Therefore, the issue of this disease is relevant and requires our close attention.
In world history there are sad examples of people falling ill with the strongest psychopathic ailments. Because of this "ailment" in the first centuries of our era, a huge number of people died, entire civilizations disappeared. In those days, the reason for this was the loss of people's trust in the authorities, the change of ideologies, religious views and beliefs. People, not wanting to live, committed suicide, women had abortions, abandoned their children, generally stopped creating families. In science, this deliberate popular extinction, associated with the hatred of one's own life, was called "endogenous psychosis of the 2nd-3rd centuries." It was a mass psychogenic pathology in people who had lost the meaning of life.
A similar situation developed in Byzantium before the collapse. The Byzantine people, after the conclusion of the union, felt the betrayal of their faith, their worldview on the part of the authorities. People in Byzantium at this time succumbed to mass pessimism. The men became chronic alcoholics. A terrible depopulation began. In Byzantium at the end of the 14th century, only 25 out of 150 well-known intellectuals and intellectuals created their own families.
All this led in Byzantium to a serious destruction of the normal mental state of people, which brought the great empire very close to its "decline".
Psychoses. Their types
Psychosis is a clear disorder of the mental state and mental activity of a person, which is accompanied by the appearance of hallucinations, changes in consciousness, inappropriate behavior, disorganization of the personality.
There are many types of psychotic illnesses. Their classification according to such a feature as origin is based on two types: endogenous and exogenous species.
Endogenous disorders of consciousness are caused by factors of internal influence: somatic or mental illness, age-related pathologies. Such deviations in the psyche develop gradually. The cause of exogenous deviations from the normal consciousness of a person are external factors: mental trauma resulting from the negative impact on a person of stressful situations, the transfer of infectious diseases, serious intoxication. Exogenous psychosis today very often becomes a consequence of chronic alcoholism.
Exogenous psychoses are considered the main source of the acute form of a psychopathic illness, which forms suddenly and very rapidly.
In addition to acute exogenous mental disorders, there are acute endogenous psychoses and acute organic (disorders of brain activity, consisting in damage to brain cells due to injuries or tumors) psychotic abnormalities. Their distinguishing feature lies in the sudden and very rapid development. They are temporary, not chronic. Also, a person with impaired consciousness in an acute form may experience relapses. Acute endogenous psychoses and other acute forms respond well to treatment, it is only important to diagnose psychosis in time and start treating it immediately. Timely therapy, first of all, is necessary due to the fact that with a deviation over time, the adequacy of a person and his ability to control the situation are increasingly reduced, this can lead to the appearance of processes that are already irreversible for the psyche.
endogenous psychosis. Causes, symptoms
Endogenous psychosis is a pathology of human consciousness, in which the patient experiences irritability, nervousness, delusional states and hallucinations, memory problems caused by internal processes occurring in the human body.
These forms include:
- paranoia;
- schizophrenia;
- Genuine epilepsy;
- affective states, etc.
Determine the causes of this disorder in each specific person hard. They may be:
- somatic (bodily) diseases: cardiovascular, nervous, respiratory, endocrine systems, etc.;
- genetic predisposition;
- another mental disorder (for example, Alzheimer's disease - the death of brain neurons, oligophrenia);
- age changes.
In this case, the patient can observe the following symptoms:
- irritability;
- excessive sensitivity;
- loss of appetite and sleep disturbances;
- decreased efficiency, ability to concentrate;
- feeling of anxiety and fear;
- rave;
- disruptions in thinking, hallucinations;
- deep depression;
- inability to control their behavior.
Mental pathology caused by internal factors in children and adolescents
The close attention of parents and mandatory treatment from specialists require mental disorders in children and adolescents.
Psychosis in children may be accompanied by the appearance of illusions, strange behavior, unreasonable aggressiveness. A child with a disorder caused by internal factors often composes some incomprehensible words. He may have a delusional state, hallucinations may appear.
The sources of deviations here are very different. The main ones are taking medications for a long time, hormonal imbalance, high temperature.
Quite often in our time there are psychotic disorders in adolescents. However, it can be difficult for parents and even doctors to determine any deviations in a person at this age due to complex adolescent behavior. Therefore, if a pathology is suspected, it is necessary to contact a narrow-profile specialist.
Modern statistics say that approximately 15% of adolescents need the help of a psychiatrist, 2% of young people are diagnosed with a psychotic disorder.
Symptoms of endogenous psychosis in adolescents differ little from the signs of the course of the disease in adults. But it is necessary to take into account the not fully formed teenage psyche, changes in the hormonal system. Pathological processes against the background of processes occurring with a person in adolescence can lead to the most sad consequences, up to the commission of suicide by a teenager.
Diagnosis and treatment of endogenous psychosis
The symptoms of different types of psychotic disorders are quite similar. In this regard, only a specialist (psychiatrist) after a thorough examination can determine the type of pathology in a patient caused precisely by factors of internal influence. Already at the first suspicious signs of a deviation in a person, first of all, his relatives and relatives, it is necessary to urgently consult a doctor and consult with him. The patient himself may not understand his condition. Self-treatment of endogenous psychosis is dangerous not only for health, but also for the life of the patient.
With the manifestation of an acute pathological form in a person, it is necessary for him to call an ambulance.
When confirming the diagnosis, the doctor prescribes a list of medicines to the patient. As a rule, the following drugs are used:
- sedatives (soothing);
- antidepressants (fighting depression and feelings of depression);
- tranquilizers (removing nervous tension, fatigue, relieving anxiety and fear), etc.
In addition to drug therapy, psychotherapy is also important. For each patient, individual techniques are used to cure him. For the successful recovery of the patient, it is important for the doctor to choose right ways therapy.
The duration of treatment for endogenous or exogenous psychosis may vary. It directly depends on at what stage of the course of the pathology the patient asked for help, how severely the disease is started. Subject to timely provision medical care healing can last for about two months. In a neglected case, the recovery process can stretch for a long, indefinite period.
Diagnosis and treatment of endogenous psychosis in the younger generation is not the same as in adults. When the first symptoms occur, the baby is examined by a number of specialists: a psychiatrist, an otolaryngologist, a neuropathologist, a speech therapist, and a psychologist. Diagnosis consists in a complete examination of the health of the little man, his mental, physical, speech development, doctors check his hearing, the level of development of thinking. For an even more detailed examination, the baby can be placed in a hospital. It happens that the roots of deviations in the psyche come from some other serious illness. In this regard, it is important not only to determine the child's psychogenic disorder, but also to identify the causes of the development of this disease.
Ways to cure small patients are different. Some children can recover after a few sessions with specialists, others need a fairly long observation. Most often, a child is prescribed psychotherapy, but sometimes only this method of dealing with endogenous psychosis is not enough. Then drugs are used. However, potent agents are used extremely rarely.
A special attitude and constant supervision of a psychotherapist is required by representatives of a younger age, in whom endogenous psychosis has developed against the background of severe stressful situations.
V modern world children's mental illnesses (including endogenous and exogenous psychoses) are successfully treated. Relapses in later life are minimized if young children and adolescents receive timely help from specialists, of course, provided that there are no severe psychological shocks.
Huge responsibility falls on the shoulders of relatives and friends of sick kids. Parents must comply with the medication regimen, proper nutrition, spend a lot of time with their child in the fresh air. It is very important that relatives do not treat the “flower of life” as an unbalanced person. The key to a speedy recovery of children is the unquestioning faith of parents in victory over the disease.
Endogenous psychoses are not uncommon today. However, you should not despair if you, a loved one or your offspring have been diagnosed with this. Psychotic disorders are successfully treated! It is only necessary to consult a doctor in time, follow the treatment and believe in recovery. Then the person will be able to live a full life again.
Questions
1.Endogenous and exogenous processes
Earthquake
.Physical properties of minerals
.Epeirogenic movements
.Bibliography
1. EXOGENOUS AND ENDOGENOUS PROCESSES
Exogenous processes - geological processes occurring on the surface of the Earth and in the uppermost parts of the earth's crust (weathering, erosion, glacier activity, etc.); are mainly due to the energy of solar radiation, gravity and vital activity of organisms.
Erosion (from Latin erosio - corrosive) - the destruction of rocks and soils by surface water flows and wind, which includes the separation and removal of fragments of material and is accompanied by their deposition.
Often, especially in foreign literature, erosion is understood as any destructive activity of geological forces, such as sea surf, glaciers, gravity; in this case, erosion is synonymous with denudation. However, there are also special terms for them: abrasion (wave erosion), exaration (glacial erosion), gravitational processes, solifluction, etc. The same term (deflation) is used in parallel with the concept of wind erosion, but the latter is much more common.
According to the rate of development, erosion is divided into normal and accelerated. Normal occurs always in the presence of any pronounced runoff, proceeds more slowly than soil formation and does not lead to a noticeable change in the level and shape of the earth's surface. Accelerated is faster than soil formation, leads to soil degradation and is accompanied by a noticeable change in relief. For reasons, natural and anthropogenic erosion are distinguished. It should be noted that anthropogenic erosion is not always accelerated, and vice versa.
The work of glaciers is the relief-forming activity of mountain and sheet glaciers, consisting in the capture of rock particles by a moving glacier, their transfer and deposition when ice melts.
Endogenous processes Endogenous processes are geological processes associated with the energy that arises in the depths of the solid Earth. Endogenous processes include tectonic processes, magmatism, metamorphism, and seismic activity.
Tectonic processes - the formation of faults and folds.
Magmatism is a term that combines effusive (volcanism) and intrusive (plutonism) processes in the development of folded and platform areas. Magmatism is understood as the totality of all geological processes, driving force which is magma and its derivatives.
Magmatism is a manifestation of the deep activity of the Earth; it is closely related to its development, thermal history and tectonic evolution.
Allocate magmatism:
geosynclinal
platform
oceanic
magmatism of activation areas
Depth of manifestation:
abyssal
hypabyssal
surface
According to the composition of magma:
ultrabasic
basic
alkaline
In the modern geological epoch, magmatism is especially developed within the Pacific geosynclinal belt, mid-ocean ridges, reef zones of Africa and the Mediterranean, etc. The formation of a large number of various mineral deposits is associated with magmatism.
Seismic activity is a quantitative measure of the seismic regime, determined by the average number of earthquake sources in a certain energy range that occur in the area under consideration for a certain observation time.
2. EARTHQUAKES
geological crust epeirogenic
The action of the internal forces of the Earth is most clearly manifested in the phenomenon of earthquakes, which are understood as tremors of the earth's crust caused by displacements of rocks in the bowels of the Earth.
Earthquakeis a fairly common phenomenon. It is observed in many parts of the continents, as well as at the bottom of the oceans and seas (in the latter case, they speak of a “seaquake”). The number of earthquakes on the globe reaches several hundred thousand a year, i.e., on average, one or two earthquakes occur per minute. The strength of the earthquake is different: most of them are captured only by highly sensitive instruments - seismographs, others are felt directly by a person. The number of the latter reaches two to three thousand a year, and they are distributed very unevenly - in some areas such strong earthquakes are very frequent, while in others they are unusually rare or even practically absent.
Earthquakes can be divided into endogenousassociated with the processes occurring in the depths of the Earth, and exogenous, depending on the processes occurring near the Earth's surface.
To endogenous earthquakesinclude volcanic earthquakes, caused by the processes of volcanic eruptions, and tectonic, due to the movement of matter in the deep bowels of the Earth.
To exogenous earthquakesinclude earthquakes occurring as a result of underground collapses associated with karst and some other phenomena, gas explosions, etc. Exogenous earthquakes can also be caused by processes occurring on the very surface of the Earth: rock falls, meteorite impacts, water falling from great heights and other phenomena, as well as factors associated with human activity (artificial explosions, machine operation, etc.).
Genetically, earthquakes can be classified as follows: natural
Endogenous: a) tectonic, b) volcanic. Exogenous: a) karst-landslide, b) atmospheric c) from the impact of waves, waterfalls, etc. Artificial
a) from explosions, b) from artillery fire, c) from artificial collapse of rocks, d) from transport, etc.
In the course of geology, only earthquakes associated with endogenous processes are considered.
In cases where strong earthquakes occur in densely populated areas, they cause great harm to humans. Earthquakes cannot be compared with any other natural phenomenon in terms of disasters caused to man. For example, in Japan, during the earthquake of September 1, 1923, which lasted only a few seconds, 128,266 houses were completely destroyed and 126,233 partially destroyed, about 800 ships perished, 142,807 people were killed and went missing. More than 100 thousand people were injured.
It is extremely difficult to describe the phenomenon of an earthquake, since the whole process lasts only a few seconds or minutes, and a person does not have time to perceive all the variety of changes that occur during this time in nature. Attention is usually fixed only on those colossal destructions that appear as a result of an earthquake.
Here is how M. Gorky describes the earthquake that occurred in Italy in 1908, which he witnessed: ... Startled and staggered, the buildings leaned, cracks snaked along their white walls like lightning and the walls crumbled, falling asleep narrow streets and people among them ... The underground rumble, the roar of stones, the screech of wood drown out cries for help, cries of madness. The earth is agitated like the sea, throwing palaces, shacks, temples, barracks, prisons, schools from its chest, destroying hundreds and thousands of women, children, rich and poor with each shudder. ".
As a result of this earthquake, the city of Messina and a number of other settlements.
The general sequence of all phenomena during an earthquake was studied by I. V. Mushketov during the largest Central Asian earthquake in Alma-Ata in 1887.
On May 27, 1887, in the evening, as eyewitnesses wrote, there were no signs of an earthquake, but domestic animals behaved restlessly, did not take food, were torn from a leash, etc. On the morning of May 28 at 4:35 an underground rumble was heard and quite strong push. The shaking lasted no more than a second. A few minutes later the rumble resumed, it resembled the muffled ringing of numerous powerful bells or the roar of passing heavy artillery. The rumble was followed by strong crushing blows: plaster fell in the houses, windows flew out, stoves collapsed, walls and ceilings fell: the streets were filled with gray dust. Massive stone buildings suffered the most. At the houses located along the meridian, the northern and southern walls fell out, while the western and eastern ones were preserved. For the first minute it seemed that the city no longer existed, that all the buildings were destroyed without exception. Blows and concussions, but less severe, continued throughout the day. Many damaged but previously standing houses fell from these weaker shocks.
Falls and cracks formed in the mountains, through which streams came to the surface in places underground water. Clay soil on the slopes of the mountains, already heavily moistened by rains, began to creep, blocking up the riverbeds. Caught up by the streams, all this mass of earth, rubble, boulders, in the form of dense mudflows, rushed to the foot of the mountains. One of these streams stretched for 10 km with a width of 0.5 km.
The destruction in Alma-Ata itself was enormous: out of 1,800 houses, only a few survived, but the number of human casualties was relatively small (332 people).
Numerous observations have shown that in the houses, first (a fraction of a second earlier), the southern walls collapsed, and then the northern ones, that the bells in the Intercession Church (in the northern part of the city) struck a few seconds after the destruction that occurred in the southern part of the city. All this testified that the center of the earthquake was located south of the city.
Most of the cracks in the houses were also inclined to the south, or rather to the southeast (170°) at an angle of 40-60°. Analyzing the direction of the cracks, I. V. Mushketov came to the conclusion that the source of the earthquake waves was located at a depth of 10-12 km, 15 km south of the city of Alma-Ata.
The deep center, or focus of an earthquake, is called the hypocenter. Vplan it is outlined as a rounded or oval area.
The area located on the surface The land above the hypocenter is calledepicenter . It is characterized by maximum destruction, and many objects here are shifted vertically (bounce), and the cracks in the houses are located very steeply, almost vertically.
The area of the epicenter of the Alma-Ata earthquake was determined at 288 km ² (36 *8 km), and the area where the earthquake was the strongest covered an area of 6000 km ². Such an area was called pleistoseist ("pleisto" - the largest and "seistos" - shaken).
The Alma-Ata earthquake lasted more than one day: after the shocks of May 28, 1887, shocks of lesser strength c. at intervals, first of several hours, and then of days. In just two years there were over 600 blows, more and more weakened.
In the history of the Earth, earthquakes have been described since large quantity shocks. So, for example, in 1870, aftershocks began in the province of Phokis in Greece, which continued for three years. In the first three days, shocks followed every 3 minutes, during the first five months there were about 500 thousand shocks, of which 300 had destructive power and followed each other with an average interval of 25 seconds. Over three years, more than 750 thousand strokes occurred in total.
Thus, an earthquake occurs not as a result of a single act occurring at depth, but as a result of some long-term developing process of the movement of matter in the inner parts of the globe.
Usually, an initial large shock is followed by a chain of smaller shocks, and this whole period can be called an earthquake period. All shocks of one period come from a common hypocenter, which can sometimes shift in the process of development, and therefore the epicenter also shifts.
This is clearly seen in a number of examples of Caucasian earthquakes, as well as an earthquake in the Ashgabat region, which occurred on October 6, 1948. The main shock followed at 01:12 without preliminary shocks and lasted 8-10 seconds. During this time, huge destruction occurred in the city and surrounding villages. One-story houses crumbled from raw bricks, and the roofs were covered with these piles of bricks, household utensils, etc. In more solidly built houses, separate walls, collapsed pipes and furnaces. It is interesting to note that round-shaped buildings (elevator, mosque, cathedral, etc.) withstood the shock better than ordinary quadrangular buildings.
The epicenter of the earthquake was located 25 km. southeast of Ashgabat, near the state farm "Karagaudan". The epicentral region turned out to be elongated in a northwestern direction. The hypocenter was located at a depth of 15-20 km. The pleistoseist region was 80 km long and 10 km wide. The period of the Ashgabat earthquake was long and consisted of many (more than 1000) shocks, the epicenters of which were located northwest of the main one within a narrow strip located in the foothills of the Kopet-Dag
The hypocenters of all these aftershocks were at the same shallow depth (about 20–30 km) as the hypocenter of the main shock.
Earthquake hypocenters can be located not only under the surface of the continents, but also under the bottom of the seas and oceans. During seaquakes, the destruction of coastal cities is also very significant and is accompanied by human casualties.
The strongest earthquake happened in 1775 in Portugal. The pleistoseist region of this earthquake covered a huge area; the epicenter was located under the bottom of the Bay of Biscay near the capital of Portugal, Lisbon, which suffered the most.
The first shock occurred on the afternoon of November 1 and was accompanied by a terrible roar. According to eyewitnesses, the earth rose up and down for a whole cubit. Houses fell with a terrible crash. The huge monastery on the mountain swayed so violently from side to side that it threatened to collapse every minute. The shocks lasted 8 minutes. A few hours later, the earthquake resumed.
The marble embankment collapsed and went under water. People and ships that stood near the shore were carried away into the formed water funnel. After the earthquake, the depth of the bay at the place of the embankment reached 200 m.
The sea receded at the beginning of the earthquake, but then a huge wave 26 m high hit the shore and flooded the coast to a width of 15 km. There were three such waves following one after another. What survived the earthquake was washed away and carried away to the sea. Only in the harbor of Lisbon, more than 300 ships were destroyed or damaged.
The waves of the Lisbon earthquake passed through the entire Atlantic Ocean: near Cadiz, their height reached 20 m, on the African coast, off the coast of Tangier and Morocco - 6 m, on the islands of Funchal and Madera - up to 5 m. The waves crossed the Atlantic Ocean and were felt off the coast America on the islands of Martinique, Barbados, Antigua, etc. During the Lisbon earthquake, more than 60 thousand people died.
Such waves quite often occur during seaquakes, they are called tsutsnas. The propagation speed of these waves ranges from 20 to 300 m / s depending on: the depth of the ocean; wave height reaches 30 m.
Drainage of the coast before a tsunami usually lasts several minutes and in exceptional cases reaches an hour. Tsunamis occur only during those seaquakes, when a certain part of the bottom sinks or rises.
The appearance of tsunamis and ebb waves is explained as follows. In the epicentral region, due to the deformation of the bottom, a pressure wave is formed that propagates upward. The sea in this place only strongly swells, short-term currents are formed on the surface, diverging in all directions, or “boil” with water tossing up to a height of up to 0.3 m. All this is accompanied by a hum. The pressure wave then transforms on the surface into tsunami waves that run in different directions. The ebb before the tsunami is explained by the fact that at first the water rushes into the underwater sinkhole, from which it is then pushed out into the epicentral region.
In the case when the epicenters are in densely populated areas, earthquakes bring great disasters. Especially destructive were the earthquakes of Japan, where 233 large earthquakes were recorded over 1500 years with the number of shocks exceeding 2 million.
Great disasters are caused by earthquakes in China. During the catastrophe on December 16, 1920, more than 200 thousand people died in the Kansu region, and the main cause of death was the collapse of dwellings dug in the loess. Earthquakes of exceptional magnitude have occurred in America. An earthquake in the Riobamba region in 1797 killed 40,000 people and destroyed 80% of the buildings. In 1812, the city of Caracas (Venezuela) was completely destroyed within 15 seconds. The city of Concepcion in Chile was repeatedly almost completely destroyed, the city of San Francisco was badly damaged in 1906. In Europe, the greatest destruction was observed after an earthquake in Sicily, where in 1693 50 villages were destroyed and more than 60 thousand people died.
On the territory of the USSR, the most destructive earthquakes were in the south of Central Asia, in the Crimea (1927) and in the Caucasus. The city of Shamakhi in Transcaucasia suffered especially often from earthquakes. It was destroyed in 1669, 1679, 1828, 1856, 1859, 1872, 1902. Until 1859, the city of Shamakhi was the provincial center of Eastern Transcaucasia, but because of the earthquake, the capital had to be moved to Baku. On fig. 173 shows the location of the epicenters of Shamakhi earthquakes. Just like in Turkmenistan, they are located along a certain line, elongated in a north-western direction.
During earthquakes, significant changes occur on the surface of the Earth, expressed in the formation of cracks, dips, folds, the uplift of individual sections on land, the formation of islands in the sea, etc. These disturbances, called seismic, often contribute to the formation of powerful collapses, screes, landslides, mudflows and mudflows in the mountains, the emergence of new sources, the cessation of old ones, the formation of mud hills, gas emissions, etc. Disturbances formed after earthquakes are called postseismic.
Phenomena. associated with earthquakes both on the surface of the Earth and in its bowels are called seismic phenomena. The science that studies seismic phenomena is called seismology.
3. PHYSICAL PROPERTIES OF MINERALS
Although the main characteristics of minerals (chemical composition and internal crystal structure) are established on the basis of chemical analyzes and X-ray diffraction, they are indirectly reflected in properties that are easily observed or measured. To diagnose most minerals, it is enough to determine their luster, color, cleavage, hardness, and density.
Shine(metallic, semi-metallic and non-metallic - diamond, glass, oily, waxy, silky, mother-of-pearl, etc.) is determined by the amount of light reflected from the surface of the mineral and depends on its refractive index. By transparency, minerals are divided into transparent, translucent, translucent in thin fragments and opaque. Quantitative determination of light refraction and light reflection is possible only under a microscope. Some opaque minerals reflect light strongly and have a metallic sheen. This is typical for ore minerals, for example, galena (lead mineral), chalcopyrite and bornite (copper minerals), argentite and acanthite (silver minerals). Most minerals absorb or transmit a significant portion of the light falling on them and have a non-metallic luster. Some minerals have a luster that transitions from metallic to non-metallic, which is called semi-metallic.
Minerals with non-metallic luster are usually light-colored, some of them are transparent. Often there are transparent quartz, gypsum and light mica. Other minerals (for example, milky white quartz) that transmit light, but through which objects cannot be clearly distinguished, are called translucent. Minerals containing metals differ from others in terms of light transmission. If light passes through a mineral, at least in the thinnest edges of the grains, then it is, as a rule, non-metallic; if the light does not pass, then it is ore. There are, however, exceptions: for example, light-colored sphalerite (zinc mineral) or cinnabar (mercury mineral) are often transparent or translucent.
Minerals differ in the qualitative characteristics of non-metallic luster. Clay has a dull earthy sheen. Quartz on the edges of crystals or on fracture surfaces is glassy, talc, which is divided into thin leaves along cleavage planes, is mother-of-pearl. Bright, sparkling, like a diamond, the brilliance is called diamond.
When light falls on a mineral with a non-metallic luster, it is partially reflected from the surface of the mineral, and partially refracted at this boundary. Each substance is characterized by a certain refractive index. Since this indicator can be measured with high accuracy, it is a very useful diagnostic feature of minerals.
The nature of the brilliance depends on the refractive index, and both of them depend on the chemical composition and crystal structure of the mineral. In general, transparent minerals containing heavy metal atoms are distinguished by high brilliance and a high refractive index. This group includes such common minerals as anglesite (lead sulfate), cassiterite (tin oxide) and titanite, or sphene (calcium and titanium silicate). Minerals composed of relatively light elements can also have high luster and a high refractive index if their atoms are closely packed and held together by strong chemical bonds. A striking example is diamond, which consists of only one light element, carbon. To a lesser extent, this is also true for the mineral corundum (Al 2O 3), the transparent colored varieties of which - ruby and sapphires - are precious stones. Although corundum is made up of light atoms of aluminum and oxygen, they are so tightly bound together that the mineral has a rather strong luster and a relatively high refractive index.
Some glosses (oily, waxy, matte, silky, etc.) depend on the state of the surface of the mineral or on the structure of the mineral aggregate; resinous luster is characteristic of many amorphous substances (including minerals containing radioactive elements uranium or thorium).
Color- a simple and convenient diagnostic feature. Examples are brass yellow pyrite (FeS 2), lead gray galena (PbS) and silvery white arsenopyrite (FeAsS 2). In other ore minerals with a metallic or semi-metallic luster, the characteristic color may be masked by the play of light in a thin surface film (tarnish). This is characteristic of most copper minerals, especially bornite, which is called "peacock ore" because of its iridescent blue-green tint, which quickly develops on a fresh fracture. However, other copper minerals are painted in well-known colors: malachite - in green, azurite - in blue.
Some non-metallic minerals are unmistakably recognized by the color due to the main chemical element (yellow - sulfur and black - dark gray - graphite, etc.). Many non-metallic minerals are composed of elements that do not provide them with a specific color, but they are known to have colored varieties, the color of which is due to the presence of impurities of chemical elements in small quantities, not comparable with the intensity of the color they cause. Such elements are called chromophores; their ions are distinguished by the selective absorption of light. For example, deep purple amethyst owes its color to an insignificant impurity of iron in quartz, and the deep green color of emerald is associated with a small content of chromium in beryl. The coloration of normally colorless minerals may appear due to defects in the crystal structure (due to unoccupied positions of atoms in the lattice or the entry of foreign ions), which can cause selective absorption of certain wavelengths in the white light spectrum. Then the minerals are painted in complementary colors. Rubies, sapphires and alexandrites owe their coloration to precisely such lighting effects.
Colorless minerals can be colored by mechanical inclusions. So, a thin disseminated dissemination of hematite gives quartz a red color, chlorite - green. Milky quartz is turbid with gas-liquid inclusions. Although the color of minerals is one of the most easily determined properties in the diagnosis of minerals, it must be used with caution, as it depends on many factors.
Despite the variability in the color of many minerals, the color of the mineral powder is very constant, and therefore is an important diagnostic feature. Usually, the color of the mineral powder is determined by the line (the so-called “line color”) that the mineral leaves if it is drawn over an unglazed porcelain plate (biscuit). For example, the mineral fluorite can be colored in different colors, but its line is always white.
Cleavage- very perfect, perfect, medium (clear), imperfect (obscure) and very imperfect - is expressed in the ability of minerals to split in certain directions. Fracture (smooth stepped, uneven, splintery, conchoidal, etc.) characterizes the surface of a mineral split that did not occur along cleavage. For example, quartz and tourmaline, whose fracture surface resembles a glass chip, have a conchoidal fracture. In other minerals, the fracture may be described as rough, jagged, or splintery. For many minerals, the characteristic is not a fracture, but cleavage. This means that they split along smooth planes that are directly related to their crystal structure. The bonding forces between the planes of the crystal lattice can be different depending on the crystallographic direction. If in some directions they are much larger than in others, then the mineral will split across the weakest bond. Since cleavage is always parallel to the atomic planes, it can be labeled with crystallographic directions. For example, halite (NaCl) has cube cleavage, i.e. three mutually perpendicular directions of a possible split. Cleavage is also characterized by the ease of manifestation and the quality of the resulting cleavage surface. Mica has a very perfect cleavage in one direction, i.e. easily splits into very thin leaves with a smooth shiny surface. Topaz has perfect cleavage in one direction. Minerals can have two, three, four or six cleavage directions, along which they are equally easy to crack, or several cleavage directions of varying degrees. Some minerals have no cleavage at all. Since cleavage as a manifestation of the internal structure of minerals is their invariable property, it serves as an important diagnostic feature.
Hardness- the resistance that the mineral provides when scratched. Hardness depends on the crystal structure: the more strongly the atoms in the structure of the mineral are bound together, the harder it is to scratch it. Talc and graphite are soft lamellar minerals built from layers of atoms linked together by very weak forces. They are greasy to the touch: when rubbing against the skin of the hand, the individual thinnest layers slip off. The hardest mineral is diamond, in which the carbon atoms are so tightly bound that it can only be scratched by another diamond. At the beginning of the 19th century Austrian mineralogist F. Moos arranged 10 minerals in order of increasing hardness. Since then, they have been used as standards for the relative hardness of minerals, the so-called. Mohs scale (Table 1)
Table 1. MOHS HARDNESS SCALE
MineralRelative hardnessTalc 1Gypsum 2 Calcite 3 Fluorite 4 Apatite 5 Orthoclase 6 Quartz 7 Topaz 8 Corundum 9 Diamond 10
To determine the hardness of a mineral, it is necessary to identify the hardest mineral that it can scratch. The hardness of the studied mineral will be greater than the hardness of the mineral scratched by it, but less than the hardness of the next mineral on the Mohs scale. Bond strengths can vary with crystallographic direction, and since hardness is a rough estimate of these forces, it can vary in different directions. This difference is usually small, with the exception of kyanite, which has a hardness of 5 in the direction parallel to the length of the crystal and 7 in the transverse direction.
For a less accurate determination of hardness, you can use the following, simpler, practical scale.
2-2.5 Thumbnail 3 Silver coin 3.5 Bronze coin 5.5-6 Penknife blade 5.5-6 Window glass 6.5-7 File
In mineralogical practice, it is also used to measure the absolute values of hardness (the so-called microhardness) using a sclerometer device, which is expressed in kg / mm2 .
Density.The mass of atoms of chemical elements varies from hydrogen (the lightest) to uranium (the heaviest). Other things being equal, the mass of a substance consisting of heavy atoms is greater than that of a substance consisting of light atoms. For example, two carbonates - aragonite and cerussite - have a similar internal structure, but aragonite contains light calcium atoms, and cerussite contains heavy lead atoms. As a result, the mass of cerussite exceeds the mass of aragonite of the same volume. The mass per unit volume of a mineral also depends on the packing density of the atoms. Calcite, like aragonite, is calcium carbonate, but in calcite the atoms are less tightly packed, because it has a lower mass per unit volume than aragonite. The relative mass, or density, depends on the chemical composition and internal structure. Density is the ratio of the mass of a substance to the mass of the same volume of water at 4 ° C. So, if the mass of a mineral is 4 g, and the mass of the same volume of water is 1 g, then the density of the mineral is 4. In mineralogy, it is customary to express density in g / cm3 .
Density is an important diagnostic feature of minerals and is easy to measure. The sample is first weighed in air and then in water. Since a sample immersed in water is subjected to an upward buoyancy force, its weight is less there than in air. The weight loss is equal to the weight of the water displaced. Thus, the density is determined by the ratio of the mass of the sample in air to the loss of its weight in water.
Pyro-electricity.Some minerals, such as tourmaline, calamine, etc., become electrified when heated or cooled. This phenomenon can be observed by pollinating a cooling mineral with a mixture of sulfur and red lead powders. In this case, sulfur covers the positively charged areas of the mineral surface, and red lead - areas with a negative charge.
Magnetism -this is the property of certain minerals to act on a magnetic needle or be attracted by a magnet. To determine the magnetism, a magnetic needle placed on a sharp tripod, or a magnetic horseshoe, a bar is used. It is also very convenient to use a magnetic needle or knife.
When testing for magnetism, three cases are possible:
a) when a mineral in its natural form (“by itself”) acts on a magnetic needle,
b) when the mineral becomes magnetic only after calcination in the reducing flame of a blowpipe
c) when the mineral neither before nor after calcination in a reducing flame exhibits magnetism. To ignite the reducing flame, you need to take small pieces of 2-3 mm in size.
Glow.Many minerals that do not glow by themselves begin to glow under certain special conditions.
There are phosphorescence, luminescence, thermoluminescence and triboluminescence of minerals. Phosphorescence is the ability of a mineral to glow after being exposed to certain rays (willemite). Luminescence - the ability to glow at the time of irradiation (scheelite when irradiated with ultraviolet and cathode beams, calcite, etc.). Thermoluminescence - glow when heated (fluorite, apatite).
Triboluminescence - glow at the moment of scratching with a needle or splitting (mica, corundum).
Radioactivity.Many minerals containing elements such as niobium, tantalum, zirconium, rare earths, uranium, thorium often have quite significant radioactivity, easily detectable even by household radiometers, which can serve as an important diagnostic feature.
To check for radioactivity, the background value is first measured and recorded, then the mineral is brought, possibly closer to the instrument's detector. An increase in readings by more than 10-15% can serve as an indicator of the radioactivity of the mineral.
Electrical conductivity.A number of minerals have significant electrical conductivity, which allows them to be unambiguously distinguished from similar minerals. Can be tested with a common household tester.
4. EPEIROGENIC MOVEMENTS OF THE EARTH'S CRUST
Epeirogenic movements- slow age-old uplifts and subsidences of the earth's crust, which do not cause changes in the primary occurrence of the layers. These vertical movements are oscillatory and reversible; uplift may be followed by a downturn. These movements include:
Modern, which are fixed in the memory of a person and can be measured instrumentally by re-leveling. The speed of modern oscillatory movements on average does not exceed 1-2 cm/year, and in mountainous areas it can reach 20 cm/year.
Neotectonic movements are movements for the Neogene-Quaternary time (25 million years). Fundamentally, they are no different from modern ones. Neotectonic movements are recorded in the modern relief and the main method of their study is geomorphological. The speed of their movement is an order of magnitude less, in mountainous areas - 1 cm / year; on the plains - 1 mm/year.
Ancient slow vertical movements are recorded in sections of sedimentary rocks. The rate of ancient oscillatory movements, according to scientists, is less than 0.001 mm/year.
Orogenic movementsoccur in two directions - horizontal and vertical. The first leads to the collapse of rocks and the formation of folds and overthrusts, i.e. to the reduction of the earth's surface. Vertical movements lead to the uplift of the area of manifestation of fold formation and the appearance of often mountain structures. Orogenic movements proceed much faster than oscillatory ones.
They are accompanied by active effusive and intrusive magmatism, as well as metamorphism. In recent decades, these movements are explained by the collision of large lithospheric plates, which move in a horizontal direction along the asthenospheric layer of the upper mantle.
TYPES OF TECTONIC FAULT
Types of tectonic disturbances
a - folded (plicate) forms;
In most cases, their formation is associated with compaction or compression of the Earth's matter. Folded disorders are morphologically divided into two main types: convex and concave. In the case of a horizontal cut, older layers are located in the core of the convex fold, and younger layers are located on the wings. Concave bends, on the contrary, have younger deposits in the core. In folds, convex wings are usually inclined laterally from the axial surface.
b - discontinuous (disjunctive) forms
Discontinuous tectonic disturbances are called such changes in which the continuity (integrity) of rocks is disturbed.
Faults are divided into two groups: faults without displacement of the rocks separated by them relative to each other and faults with displacement. The former are called tectonic cracks, or diaclases, the latter are called paraclases.
BIBLIOGRAPHY
1. Belousov V.V. Essays on the history of geology. At the origins of Earth science (geology until the end of the 18th century). - M., - 1993.
Vernadsky V.I. Selected works on the history of science. - M.: Nauka, - 1981.
Cookery A.S., Onoprienko V.I. Mineralogy: past, present, future. - Kiev: Naukova Dumka, - 1985.
Modern ideas of theoretical geology. - L .: Nedra, - 1984.
Khain V.E. The main problems of modern geology (geology on the threshold of the XXI century). - M.: Scientific world, 2003 ..
Khain V.E., Ryabukhin A.G. History and methodology of geological sciences. - M.: MGU, - 1996.
Hallem A. Great geological disputes. M.: Mir, 1985.
