Endogenous geological processes include. Genetic classification of sedimentary rocks

Ministry of Education and Science of the Russian Federation

Federal Agency for Education

State educational institution of higher

professional education

"Ufa State Oil Technical University"
Department of Applied Ecology

1. THE CONCEPT OF PROCESSES……………………………………………………3

2. EXOGENOUS PROCESSES…………………………………………………..3

2.1 WEATHERING……………………………………………………...3

2.1.1PHYSICAL WEATHERING………………………….4

2.1.2 CHEMICAL WEATHERING………………………...5

2.2 GEOLOGICAL ACTIVITY OF THE WIND…………………………6

2.2.1 DEFLATION AND CORROSION…………………………………….7

2.2.2 TRANSFER……………………………………………………...8

2.2.3 ACCUMULATION AND ELOL DEPOSITS…………..8

^ 2.3 GEOLOGICAL ACTIVITIES OF THE SURFACE

FLOWING WATERS………………………………………………………………...9

2.4 GEOLOGICAL ACTIVITY OF GROUNDWATER…………… 10

2.5 GEOLOGICAL ACTIVITY OF GLACIERS………………. 12

2.6 GEOLOGICAL ACTIVITY OF THE OCEANS AND SEA…… 12

3. ENDOGENOUS PROCESSES…………………………………………………. thirteen

3.1 MAGMATISM…………………………………………………………. thirteen

3.2 METAMORPHISM……………………………………………………... 14

3.2.1 MAIN FACTORS OF METAMORPHISM……………. fourteen

3.2.2. FACIES OF METAMORPHISM…………………………………. fifteen

3.3 EARTHQUAKE……………………………………………………… 15

LIST OF USED LITERATURE……………………… 16

^ THE CONCEPT OF PROCESSES

Throughout its existence, the Earth has gone through a long series of changes. In essence, she was never the same as in the previous moment. It changes continuously. Its composition, physical condition, appearance, position in world space and relationship with other members of the solar system are changing.

Geology (Greek "geo" - earth, "logos" - teaching) is one of the most important sciences about the Earth. It is engaged in the study of the composition, structure, history of the development of the Earth and the processes occurring in its bowels and on the surface. Modern geology uses the latest achievements and methods of a number of natural sciences - mathematics, physics, chemistry, biology, geography.

The subject of direct study of geology is the earth's crust and the underlying solid layer of the upper mantle - the lithosphere (Greek "lithos" - stone), which is of paramount importance for the implementation of human life and activity.

One of the several main directions in geology is dynamic geology, which studies various geological processes, landforms, the relationship of rocks of different genesis, the nature of their occurrence and deformation. It is known that in the course of geological development there were multiple changes in the composition, state of matter, appearance of the Earth's surface and the structure of the earth's crust. These transformations are associated with various geological processes and their interaction.

Among them there are two groups:

1) endogenous (Greek "endos" - inside), or internal, associated with the thermal effects of the Earth, stresses arising in its bowels, with gravitational energy and its uneven distribution;

2) exogenous (Greek "exos" - outside, external), or external, causing significant changes in the surface and near-surface parts of the earth's crust. These changes are associated with the radiant energy of the Sun, the force of gravity, the continuous movement of water and air masses, the circulation of water on the surface and inside the earth's crust, with the vital activity of organisms, and other factors. All exogenous processes are closely related to endogenous ones, which reflects the complexity and unity of forces acting inside the Earth and on its surface. Geological processes modify the earth's crust and its surface, leading to the destruction and at the same time the creation of rocks. Exogenous processes are due to the action of gravity and solar energy, and endogenous processes are due to the influence of the internal heat of the Earth and gravity. All processes are interconnected, and their study makes it possible to use the method of actualism to understand the geological processes of the distant past.

^ 2. EXOGENOUS PROCESSES

The term "weathering", which is widely used in the literature, does not reflect the essence and complexity of the natural processes defined by this concept. The unfortunate term has led to the fact that researchers do not have unity in understanding it in essence. In any case, weathering should never be confused with the activity of the wind itself.

Weathering is a set of complex processes of qualitative and quantitative transformation of rocks and their constituent minerals, occurring under the influence of various agents acting on the surface of the earth, among which the main role is played by temperature fluctuations, freezing of water, acids, alkalis, carbon dioxide, the action of wind, organisms, etc. .d . Depending on the predominance of certain factors in a single and complex weathering process, two interrelated types are conventionally distinguished:

1) physical weathering; and 2) chemical weathering.
^ 2.1.1 PHYSICAL WEATHERING

In this type, the most important is temperature weathering, which is associated with daily and seasonal temperature fluctuations, which causes either heating or cooling of the surface part of the rocks. Under the conditions of the earth's surface, especially in deserts, daily temperature fluctuations are quite significant. So in the summer in the daytime, the rocks are heated to + 80 0 C, and at night their temperature drops to + 20 0 C. Due to the sharp difference in thermal conductivity, thermal expansion and compression coefficients and anisotropy of the thermal properties of the minerals that make up the rocks, certain stresses arise. In addition to alternating heating and cooling, uneven heating of rocks also has a destructive effect, which is associated with different thermal properties, color and size of the minerals that make up the rocks.

Rocks can be multi-mineral and single-mineral. Multi-mineral rocks are exposed to the greatest destruction as a result of the process of thermal weathering.

The process of thermal weathering, which causes mechanical disintegration of rocks, is especially characteristic of extra-arid and nival landscapes with a continental climate and a non-leaching type of moisture regime. This is especially evident in desert areas, where the amount of precipitation is in the range of 100-250 mm / year (with colossal evaporation) and a sharp amplitude of daily temperatures is observed on the rock surface unprotected by vegetation. Under these conditions, minerals, especially dark-colored ones, are heated to temperatures exceeding the air temperature, which causes the disintegration of rocks and clastic weathering products are formed on a consolidated undisturbed substrate. In deserts, peeling, or desquamation (lat. "desquamare" - to remove scales) is observed, when scales or thick plates parallel to the surface peel off from the smooth surface of rocks with significant temperature fluctuations. This process can be especially well traced on separate blocks, boulders. Intense physical (mechanical) weathering occurs in areas with severe climatic conditions (in polar and subpolar countries) with the presence of permafrost, due to its excessive surface moisture. Under these conditions, weathering is mainly associated with the wedging action of freezing water in cracks and with other physical and mechanical processes associated with ice formation. Temperature fluctuations in the surface horizons of rocks, especially strong supercooling in winter, lead to volumetric gradient stress and the formation of frost cracks, which are subsequently developed by freezing water in them. It is well known that when water freezes, it increases in volume by more than 9% (P. A. Shumsky, 1954). As a result, pressure develops on the walls of large cracks, causing a large wedging stress, crushing of rocks and the formation of predominantly blocky material. Such weathering is sometimes called frost weathering. The root system of growing trees also has a wedging effect on rocks. A variety of burrowing animals also perform mechanical work. In conclusion, it should be said that purely physical weathering leads to the fragmentation of rocks, to mechanical destruction without changing their mineralogical and chemical composition.

^ 2.1.2 CHEMICAL WEATHERING

Simultaneously with physical weathering, in areas with a leaching type of moistening regime, there are also processes of chemical change with the formation of new minerals. During the mechanical disintegration of dense rocks, macrocracks are formed, which contributes to the penetration of water and gas into them and, in addition, increases the reaction surface of weathered rocks. This creates conditions for the activation of chemical and biogeochemical reactions. The penetration of water or the degree of moisture not only determines the transformation of rocks, but also determines the migration of the most mobile chemical components. This is especially pronounced in humid tropical zones, where high humidity, high thermal conditions and rich forest vegetation are combined. The latter has a huge biomass and a significant decline. This mass of dying organic matter is transformed and processed by microorganisms, resulting in large quantities of aggressive organic acids (solutions). A high concentration of hydrogen ions in acidic solutions contributes to the most intensive chemical transformation of rocks, the extraction of cations from the crystal lattices of minerals and their involvement in migration.

Chemical weathering processes include oxidation, hydration, dissolution, and hydrolysis.

Oxidation. It proceeds especially intensively in minerals containing iron. An example is the oxidation of magnetite, which passes into a more stable form - hematite (Fe 2 0 4 Fe 2 0 3). Such transformations have been ascertained in the ancient weathering crust of the KMA, where rich hematite ores are mined. Iron sulfides undergo intense oxidation (often together with hydration). So, for example, you can imagine the weathering of pyrite:

FeS 2 + mO 2 + nH 2 O FeS0 4 Fe 2 (SO 4) Fe 2 O 3. nH 2 O

Limonite (brown ironstone)

In some deposits of sulfide and other iron ores, "brown-iron hats" are observed, consisting of oxidized and hydrated weathering products. Air and water in ionized form break down ferruginous silicates and convert ferrous iron into ferric iron.

Hydration. Under the influence of water, hydration of minerals occurs, i.e. fixing water molecules on the surface of individual sections of the crystal structure of the mineral. An example of hydration is the transition of anhydrite to gypsum: anhydrite-CaSO 4 +2H 2 O CaSO 4 . 2H 2 0 - gypsum. Hydrogoethite is also a hydrated variety: goethite - FeOOH + nH 2 O FeOH. nH 2 O - hydrogoethite.

The process of hydration is also observed in more complex minerals - silicates.

Dissolution. Many compounds are characterized by a certain degree of solubility. Their dissolution occurs under the action of water flowing down the surface of rocks and seeping through cracks and pores into the depths. The acceleration of dissolution processes is facilitated by a high concentration of hydrogen ions and the content of O 2 , CO 2 and organic acids in water. Of the chemical compounds, chlorides - halite (common salt), sylvin, etc. - have the best solubility. In second place are sulfates - anhydrite and gypsum. In third place are carbonates - limestones and dolomites. In the process of dissolution of these rocks, in a number of places, various karst forms are formed on the surface and in depth.

Hydrolysis. During the weathering of silicates and aluminosilicates, hydrolysis is of great importance, in which the structure of crystalline minerals is destroyed due to the action of water and ions dissolved in it and is replaced by a new one that is significantly different from the original and inherent in newly formed supergene minerals. In this process, the following occurs: 1) the frame structure of feldspars turns into a layered one, characteristic of newly formed clay supergene minerals; 2) removal from the crystal lattice of feldspars of soluble compounds of strong bases (K, Na, Ca), which, interacting with CO 2, form true solutions of bicarbonates and carbonates (K 2 CO 3, Na 2 CO 3, CaCO 3). Under the conditions of the flushing regime, carbonates and bicarbonates are carried out of the place of their formation. In a dry climate, they remain in place, form films of various thicknesses in places, or fall out at a shallow depth from the surface (carbonatization occurs); 3) partial removal of silica; 4) addition of hydroxyl ions.

The hydrolysis process proceeds in stages with the sequential appearance of several minerals. So, during the hypergene transformation of feldspars, hydromicas arise, which then turn into minerals of the kaolinite or haloysite group:

K (K, H 3 O) A1 2 (OH) 2 [A1Si 3 O 10]. H 2 O Al 4 (OH) 8

Orthoclase hydromica kaolinite

In temperate climatic zones, kaolinite is quite stable, and as a result of its accumulation in weathering processes, kaolin deposits are formed. But in a humid tropical climate, further decomposition of kaolinite to free oxides and hydroxides can occur:

Al 4 (OH) 8 Al (OH) 3 + SiO 2. nH2O

hydrargillite

Thus, aluminum oxides and hydroxides are formed, which are an integral part of aluminum ore - bauxites.

During the weathering of mafic rocks and especially volcanic tuffs, along with hydromicas, montmorillonites (Al 2 Mg 3) (OH) 2 * nH 2 O and the high-alumina mineral beidellite A1 2 (OH) 2 [A1Si 3 О 10 ]nН 2 O. Weathering of ultramafic rocks (ultrabasites) produces nontronites, or ferruginous montmorillonites (FeAl 2)(OH) 2 . nH 2 O. Under conditions of significant atmospheric humidification, nontronite is destroyed, and oxides and hydroxides of iron (the phenomenon of nontronite scalding) and aluminum are formed.
^ 2.2. GEOLOGICAL WIND ACTIVITY

Winds are constantly blowing on the earth's surface. The speed, strength and direction of the winds are different. Often they are hurricane-like.

Wind is one of the most important exogenous factors that transform the Earth's topography and form specific deposits. This activity is most clearly manifested in deserts, which occupy about 20% of the surface of the continents, where strong winds are combined with a small amount of precipitation (annual amount does not exceed 100-200 mm/year); sharp fluctuations in temperature, sometimes reaching 50 o and above, which contributes to intensive weathering processes; lack or sparse vegetation.

The wind does a lot of geological work: the destruction of the earth's surface (blowing, or deflation, turning or corrosion), the transfer of destruction products and the deposition (accumulation) of these products in the form of accumulations of various shapes. All processes caused by the activity of the wind, the forms of relief and deposits created by them are called aeolian (Eol in ancient Greek mythology is the god of the winds).
^

2.2.1. deflation and corrasion

Deflation is the blowing and waving of loose particles of rocks (mainly sandy and dusty) by the wind. The well-known desert researcher B. A. Fedorovich distinguishes two types of deflation: areal and local.

Areal deflation is observed both within bedrocks subject to intense weathering processes, and especially on surfaces composed of river, sea, hydroglacial sands and other loose deposits. In hard fissured rocky rocks, the wind penetrates all cracks and blows loose weathering products out of them.

The surface of deserts in places of development of various detrital material as a result of deflation is gradually cleared of sandy and finer-earth particles (carried out by the wind) and only coarse fragments remain in place - stony and gravelly material. Areal deflation sometimes manifests itself in the arid steppe regions of various countries, where strong drying winds periodically arise - “dry winds”, which blow out plowed soils, transferring a large number of its particles over long distances.

Local deflation manifests itself in separate relief depressions. Many researchers use deflation to explain the origin of some large deep drainless basins in the deserts of Central Asia, Arabia and North Africa, the bottom of which in places is lowered many tens and even a few hundreds of meters below the level of the World Ocean.

Corrosion is the mechanical processing of exposed rocks by the wind with the help of solid particles carried by it - turning, grinding, drilling, etc.

Sand particles are lifted by the wind to different heights, but their greatest concentration is in the lower surface parts of the air flow (up to 1.0-2.0 m). Strong long-lasting impacts of sand on the lower parts of the rocky ledges undermine and, as it were, undercut them, and they become thinner in comparison with the overlying ones. This is also facilitated by weathering processes that break the solidity of the rock, which is accompanied by the rapid removal of destruction products. Thus, the interplay of deflation, sand transport, corrosion, and weathering give rocks in deserts their distinctive shape.

Academician V. A. Obruchev in 1906 discovered in Dzungaria, bordering on Eastern Kazakhstan, a whole “eolian city”, consisting of bizarre structures and figures created in sandstones and variegated clays as a result of desert weathering, deflation and corrosion. If pebbles or small fragments of hard rocks are encountered along the path of sand movement, they are worn out, polished along one or more flat edges. With a sufficiently long exposure to wind-blown sand, pebbles and debris form eolian polyhedra or trihedrons with shiny polished edges and relatively sharp ribs between them (Fig. 5.2). It should also be noted that corrosion and deflation are also manifested on the horizontal clay surface of deserts, where, with steady winds of one direction, sand jets form separate long furrows or trenches from tens of centimeters to a few meters deep, separated by parallel, irregularly shaped ridges. Such formations in China are called yardangs.

2.2.2 TRANSFER

When moving, the wind captures sandy and dusty particles and transfers them to various distances. The transfer is carried out either spasmodically, or by rolling them along the bottom, or in a suspended state. The difference in transport depends on the size of the particles, the wind speed and the degree of its turbulence. With winds up to 7 m/s, about 90% of sand particles are transported in a layer of 5-10 cm from the Earth's surface, with strong winds (15-20 m/s), sand rises by several meters. Storm winds and hurricanes raise sand tens of meters in height and roll even pebbles and flat gravel with a diameter of up to 3-5 cm or more. The process of moving sand grains is carried out in the form of jumps or jumps at a steep angle from several centimeters to several meters along curved trajectories. When they land, they hit and break other sand grains, which are involved in a jerky movement, or saltation (Latin "saltacio" - jump). So there is a continuous process of moving many sand grains.

2.2.3 ACCUMULATION AND EOLIS

Simultaneously with difflation and transport, accumulation occurs, resulting in the formation of eolian continental deposits. Sands and loesses stand out among them.

Eolian sands are distinguished by significant sorting, good roundness, and a matte grain surface. These are predominantly fine-grained sands, the grain size of which is 0.25-0.1 mm.

The most common mineral in them is quartz, but there are other stable minerals (feldspars, etc.). Less resistant minerals, such as micas, are abraded and carried away during eolian processing. The color of eolian sands is different, most often light yellow, sometimes yellowish brown, and sometimes reddish (during deflation of red earth weathering crusts). In the deposited eolian sands, sloping or criss-crossing layering is observed, indicating the direction of their transportation.

Eolian loess (German "loess" - zheltozem) is a peculiar genetic type of continental deposits. It is formed during the accumulation of suspended silt particles carried by the wind outside the deserts and into their marginal parts, and into mountainous areas. A characteristic set of signs of loess is:

1) composition by silty particles of predominantly silty dimension - from 0.05 to 0.005 mm (more than 50%) with a subordinate value of clay and fine sandy fractions and the almost complete absence of larger particles;

2) lack of layering and uniformity throughout the thickness;

3) the presence of finely dispersed calcium carbonate and calcareous concretions;

4) diversity of mineral composition (quartz, feldspar, hornblende, mica, etc.);

5) permeation of loess with numerous short vertical tubular macropores;

6) increased overall porosity, reaching 50-60% in some places, which indicates undercompaction;

7) subsidence under load and when moistened;

8) columnar vertical separation in natural outcrops, which may be due to the angularity of the forms of mineral grains, providing strong adhesion. The loess thickness ranges from a few to 100 m or more.

Particularly large thicknesses are noted in China, the formation of which by some researchers is assumed due to the removal of dust material from the deserts of Central Asia.

^
2.3 GEOLOGICAL ACTIVITIES OF SURFACE FLOWING WATER

Groundwater and temporary streams of atmospheric precipitation, flowing down the ravine and gullies, are collected in permanent water flows - rivers. Full-flowing rivers do a lot of geological work - the destruction of rocks (erosion), the transfer and deposition (accumulation) of destruction products.

Erosion is carried out by the dynamic action of water on rocks. In addition, the river flow abrades the rocks with debris carried by the water, and the debris themselves are destroyed and destroy the bed of the stream by friction when rolling. At the same time, water has a dissolving effect on rocks.

There are two types of erosion:

1) bottom, or deep, aimed at cutting the river flow into the depth;

2) lateral, leading to erosion of the banks and, in general, to the expansion of the valley.

In the initial stages of the development of the river, bottom erosion prevails, which tends to develop an equilibrium profile in relation to the base of erosion - the level of the basin into which it flows. The basis of erosion determines the development of the entire river system - the main river with its tributaries of different orders. The initial profile on which the river is laid is usually characterized by various irregularities created before the formation of the valley. Such irregularities can be due to various factors: the presence of outcrops in the riverbed of rocks that are heterogeneous in terms of stability (lithological factor); lakes on the way of the river (climatic factor); structural forms - various folds, breaks, their combination (tectonic factor) and other forms. As the equilibrium profile develops and the channel slope decreases, bottom erosion gradually weakens and lateral erosion begins to affect more and more, aimed at washing away the banks and expanding the valley. This is especially evident during periods of floods, when the speed and degree of turbulence of the flow movement increase sharply, especially in the core part, which causes transverse circulation. The resulting eddy movements of water in the bottom layer contribute to active erosion of the bottom in the core part of the channel, and part of the bottom sediments is carried to the shore. The accumulation of sediments leads to a distortion of the shape of the cross section of the channel, the straightness of the flow is disturbed, as a result of which the core of the flow is displaced to one of the banks. The increased washing away of one bank and the accumulation of sediments on the other begins, which causes the formation of a bend in the river. Such primary bends, gradually developing, turn into bends that play a large role in the formation of river valleys.

Rivers carry a large amount of clastic material of various sizes - from fine silt particles and sand to large debris. Its transfer is carried out by dragging (rolling) along the bottom of the largest fragments and in a suspended state of sandy, silty and finer particles. Carried debris further enhances deep erosion. They are, as it were, erosive tools that crush, destroy, grind the rocks that make up the bottom of the channel, but they themselves are crushed, abraded with the formation of sand, gravel, pebbles. Dragged along the bottom and suspended transported materials are called the solid runoff of rivers. In addition to clastic material, rivers also carry dissolved mineral compounds. In the river waters of humid areas, Ca and Mg carbonates predominate, which account for about 60% of the ion sink (O. A. Alekin). Fe and Mn compounds are found in small amounts, often forming colloidal solutions. In the river waters of arid regions, in addition to carbonates, chlorides and sulfates play a significant role.

Along with erosion and transfer of various material, its accumulation (deposition) also occurs. At the first stages of the development of the river, when erosion processes predominate, deposits that occur in places turn out to be unstable and, with an increase in the flow rate during floods, they are again captured by the flow and move downstream. But as the equilibrium profile develops and the valleys expand, permanent deposits are formed, called alluvial, or alluvium (Latin “alluvio” - alluvium, alluvium).
^

2.4. GEOLOGICAL ACTIVITY OF GROUNDWATER

Groundwater includes all water found in the pores and cracks of rocks. They are widespread in the earth's crust, and their study is of great importance in solving issues: water supply for settlements and industrial enterprises, hydraulic engineering, industrial and civil construction, land reclamation activities, resort and sanatorium business, etc.

The geological activity of underground waters is great. They are associated with karst processes in soluble rocks, slumping of earth masses along the slopes of ravines, rivers and seas, the destruction of mineral deposits and their formation in new places, the removal of various compounds and heat from deep zones of the earth's crust.

Karst is a process of dissolution or leaching of fractured soluble rocks by underground and surface waters, as a result of which negative depression forms of relief are formed on the Earth's surface and various cavities, channels and caves in depth. For the first time, such widely developed processes were studied in detail on the coast of the Adriatic Sea, on the Karst plateau near Trieste, from which they got their name. Soluble rocks include salts, gypsum, limestone, dolomite, and chalk. In accordance with this, salt, gypsum and carbonate karst are distinguished. The carbonate karst is the most studied, which is associated with a significant areal distribution of limestones, dolomites, and chalk.

The necessary conditions for the development of karst are:

1) the presence of soluble rocks;

2) fracturing of rocks, providing the penetration of water;

3) dissolving power of water.
Surface karst forms include:

1) karr, or scars, small depressions in the form of ruts and furrows with a depth of several centimeters to 1-2 m;

2) ponors - vertical or inclined holes that go deep and absorb surface water;

3) karst funnels, which are most widespread both in mountainous regions and on the plains. Among them, according to the conditions of development, there are:

A) surface leaching funnels associated with the dissolving activity of meteoric waters;

B) sinkholes, formed by the collapse of the vaults of underground karst cavities;

4) large karst basins, at the bottom of which sinkholes can develop;

5) the largest karst forms - fields, well known in Yugoslavia and other regions;

6) karst wells and shafts, reaching depths of more than 1000 m in places and being, as it were, transitional to underground karst forms.

Underground karst forms include various channels and caves. The largest underground forms are karst caves, representing a system of horizontal or several inclined channels, often branching intricately and forming huge halls or grottoes. Such an unevenness in the outlines, apparently, is due to the nature of the complex fracturing of the rocks, and possibly also the heterogeneity of the latter. There are many lakes at the bottom of a number of caves, underground watercourses (rivers) flow through other caves, which, when moving, produce not only a chemical effect (leaching), but also erosion (erosion). The presence of constant water flows in caves is often associated with the absorption of surface river runoff. In karst massifs, disappearing rivers (partially or completely), periodically disappearing lakes are known.

Various displacements of rocks that make up the steep coastal slopes of river valleys, lakes and seas are associated with the activity of underground and surface waters and other factors. Such gravitational displacements, in addition to screes and landslides, also include landslides. It is in landslide processes that groundwater plays an important role. Landslides are understood as large displacements of various rocks along the slope, spreading in certain areas to large spaces and depths. Landslides are often of a very complex structure; they can represent a series of blocks sliding down along slip planes with overturning of layers of displaced rocks towards the bedrock.

Landslide processes occur under the influence of many factors, which include:

1) a significant steepness of the coastal slopes and the formation of cracks on the side pressure;

2) washing away the banks by the river (Volga region and other rivers) or abrasion by the sea (Crimea, Caucasus), which increases the stress state of the slope and disturbs the existing balance;

3) a large amount of precipitation and an increase in the degree of watering of the rocks of the slope with both surface and ground waters. In a number of cases, landslides occur during or at the end of intense precipitation. Especially large landslides are caused by floods;

4) the influence of groundwater is determined by two factors - suffusion and hydrodynamic pressure. Suffusion, or undermining, caused by groundwater sources emerging on the slope, carrying out small particles of water-bearing rock and chemically soluble substances from the aquifer. As a result, this leads to loosening of the aquifer, which naturally causes instability of the higher part of the slope, and it slides; hydrodynamic pressure created by groundwater when it reaches the slope surface. This is especially evident when the water level in the river changes during floods, when river waters infiltrate into the sides of the valley and the groundwater level rises. The decline of hollow waters in the river is relatively fast, and the lowering of the groundwater level is relatively slow (lagging behind). As a result of such a gap between the levels of river and groundwater, the sloping part of the aquifer can be squeezed out, followed by the slumping of rocks located above;

5) the fall of rocks towards the river or the sea, especially if they contain clays, which, under the influence of water and weathering processes, acquire plastic properties;

6) anthropogenic impact on the slopes (artificial cutting of the slope and increase in its steepness, additional load on the slopes by the installation of various structures, destruction of beaches, deforestation, etc.).

Thus, in the complex of factors contributing to landslide processes, a significant and sometimes decisive role belongs to groundwater. In all cases, when deciding on the construction of certain structures near slopes, their stability is studied in detail, and measures are developed to combat landslides in each specific case. Special anti-landslide stations operate in a number of places.
^ 2.5. GEOLOGICAL ACTIVITY OF GLACIERS

Glaciers are a natural body of large size, consisting of crystalline ice formed on the surface of the earth as a result of the accumulation and subsequent transformation of solid atmospheric precipitation and in motion.

During the movement of glaciers, a number of interrelated geological processes are carried out:

1) destruction of rocks of the under-ice bed with the formation of clastic material of various shapes and sizes (from fine sand particles to large boulders);

2) the transfer of rock fragments on the surface and inside glaciers, as well as those frozen into the bottom parts of the ice or dragged along the bottom;

3) accumulation of clastic material, which takes place both during the movement of the glacier and during deglaciation. The whole complex of these processes and their results can be observed in mountain glaciers, especially where the glaciers previously extended for many kilometers beyond the modern boundaries. The destructive work of glaciers is called exaration (from the Latin "exaratio" - plowing). It manifests itself especially intensively at large thicknesses of ice, which create enormous pressure on the sub-ice bed. There is a capture and breaking out of various blocks of rocks, their crushing, wear.

Glaciers saturated with detrital material frozen into the bottom parts of the ice, when moving along the rocks, leave various strokes, scratches, furrows on their surface - glacial scars, which are oriented in the direction of the glacier movement.

Glaciers during their movement carry a huge amount of various detrital material, consisting mainly of products of supraglacial and subglacial weathering, as well as from fragments arising from the mechanical destruction of rocks by moving glaciers. All this clastic material that enters the body of the glacier, is carried and deposited by it is called moraine. Among the moving moraine material, surface (lateral and median), internal and bottom moraines are distinguished. The deposited material was called coastal and terminal moraines.

Coastal moraines are banks of clastic material located along the slopes of glacial valleys. End moraines are formed at the end of glaciers, where they completely melt.
^ 2.6. GEOLOGICAL ACTIVITY OF THE OCEANS AND SEA

It is known that the surface of the globe is 510 million km 2, of which about 361 million km 2, or 70.8%, is occupied by oceans and seas, and 149 million km 2, or 29.2%, is land. Thus, the area occupied by oceans and seas is almost 2.5 times the land area. In marine basins, as the seas and oceans are usually called, complex processes of vigorous destruction, movement of destruction products, sedimentation and the formation of various sedimentary rocks proceed from them.

The geological activity of the sea in the form of destruction of rocks, coasts and bottom is called abrasion. Abrasion processes are directly dependent on the characteristics of water movement, intensity and direction of blowing winds and currents.

The main destructive work is done by: sea surf, and to a lesser extent various currents (coastal, bottom, tides).

^ ENDOGENIC PROCESSES

3.1.MAGMATISM

Igneous rocks, formed from a liquid melt - magma, play a huge role in the structure of the earth's crust. These rocks were formed in different ways. Their large volumes solidified at different depths, before reaching the surface, and had a strong effect on the host rocks by high temperature, hot solutions and gases. Thus, intrusive (lat. "intrusio" - I penetrate, introduce) bodies were formed. If magmatic melts burst to the surface, then volcanic eruptions occurred, which, depending on the composition of the magma, were calm or catastrophic. This type of magmatism is called effusive (lat. "effusio" - outpouring), which is not entirely accurate. Often, volcanic eruptions are explosive in nature, in which magma does not erupt, but explodes and finely divided crystals and frozen droplets of glass - melt fall onto the earth's surface. Such eruptions are called explosive (Latin "explosio" - to blow up). Therefore, speaking of magmatism (from the Greek "magma" - plastic, pasty, viscous mass), one should distinguish between intrusive processes associated with the formation and movement of magma below the Earth's surface, and volcanic processes due to the release of magma to the earth's surface. Both of these processes are inextricably linked, and the manifestation of one or the other of them depends on the depth and method of formation of magma, its temperature, the amount of dissolved gases, the geological structure of the area, the nature and speed of movements of the earth's crust, etc.

Allocate magmatism:

Geosynclinal

Platform

Oceanic

Magmatism of areas of activation
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.

If a liquid magmatic melt reaches the earth's surface, it erupts, the nature of which is determined by the composition of the melt, its temperature, pressure, concentration of volatile components, and other parameters. One of the most important causes of magma eruptions is its degassing. It is the gases contained in the melt that serve as the "driver" that causes the eruption. Depending on the amount of gases, their composition and temperature, they can be released from the magma relatively calmly, then an outpouring occurs - the effusion of lava flows. When the gases are separated quickly, the melt instantly boils and the magma is broken by expanding gas bubbles, causing a powerful explosive eruption - an explosion. If the magma is viscous and its temperature is low, then the melt is slowly squeezed out, squeezed out to the surface, and the magma is extruded.

Thus, the method and rate of separation of volatiles determine the three main forms of eruptions: effusive, explosive and extrusive. Volcanic products during eruptions are liquid, solid and gaseous.

Gaseous products or volatiles, as shown above, play a decisive role in volcanic eruptions and their composition is very complex and far from fully understood due to difficulties in determining the composition of the gas phase in magma located deep under the Earth's surface. According to direct measurements, various active volcanoes contain water vapor, carbon dioxide (CO 2), carbon monoxide (CO), nitrogen (N 2), sulfur dioxide (SO 2), sulfur oxide (III) (SO 3) among volatiles. , gaseous sulfur (S), hydrogen (H 2), ammonia (NH 3), hydrogen chloride (HCL), hydrogen fluoride (HF), hydrogen sulfide (H 2 S), methane (CH 4), boric acid (H 3 BO 2), chlorine (Cl), argon and others, although H 2 O and CO 2 predominate. There are alkali metal chlorides, as well as iron. The composition of gases and their concentration vary greatly within the same volcano from place to place and over time, they depend both on temperature and, in the most general form, on the degree of degassing of the mantle, i.e. on the type of earth's crust.

Liquid volcanic products are represented by lava - magma that has come to the surface and is already highly degassed. The term "lava" comes from the Latin word "laver" (wash, wash) and used to be called lava mud flows. The main properties of lava - chemical composition, viscosity, temperature, volatile content - determine the nature of effusive eruptions, the shape and extent of lava flows.

3.2.METAMORPHISM

Metamorphism (Greek metamorphoómai - undergoing transformation, transforming) is the process of solid-phase mineral and structural changes in rocks under the influence of temperature and pressure in the presence of fluid.

There are isochemical metamorphism, in which the chemical composition of the rock changes insignificantly, and non-isochemical metamorphism (metasomatosis), which is characterized by a noticeable change in the chemical composition of the rock, as a result of the transfer of components by the fluid.

According to the size of the distribution areas of metamorphic rocks, their structural position and the causes of metamorphism, the following are distinguished:

Regional metamorphism that affects large volumes of the earth's crust and is distributed over large areas

Ultra-high pressure metamorphism

Contact metamorphism is confined to igneous intrusions, and occurs from the heat of cooling magma.

Dynamo metamorphism occurs in fault zones, it is associated with significant deformation of rocks

Impact metamorphism, which occurs when a meteorite hits the surface of a planet
^ 3.2.1 MAIN FACTORS OF METAMORPHISM

The main factors of metamorphism are temperature, pressure and fluid.

With an increase in temperature, metamorphic reactions occur with the decomposition of water-containing phases (chlorites, micas, amphiboles). With an increase in pressure, reactions occur with a decrease in the volume of phases. At temperatures above 600 ˚С, partial melting of some rocks begins, melts are formed, which go to the upper horizons, leaving a refractory residue - restite.
Fluids are the volatile components of metamorphic systems. This is primarily water and carbon dioxide. Less often, oxygen, hydrogen, hydrocarbons, halogen compounds, and some others can play a role. In the presence of fluid, the stability region of many phases (especially those containing these volatile components) changes. In their presence, the melting of rocks begins at much lower temperatures.
^ 3.2.2. FACIES OF METAMORPHISM

Metamorphic rocks are very diverse. More than 20 minerals have been identified as rock-forming minerals. Rocks of similar composition, but formed under different thermodynamic conditions, may have completely different mineral compositions. The first researchers of metamorphic complexes found that several characteristic, widespread associations can be distinguished, which were formed under different thermodynamic conditions. The first division of metamorphic rocks according to the thermodynamic conditions of formation was made by Escola. In rocks of basalt composition, he identified green shales, epidote rocks, amphibolites, granulites, and eclogites. Subsequent studies have shown the logic and content of such a division.

3.3. EARTHQUAKES

An earthquake is any vibration of the earth's surface, caused by natural causes, among which the main importance belongs to tectonic processes. In some places, the earthquake occurs frequently and reaches great strength.

On the coasts, the sea recedes, exposing the bottom, and then a giant wave falls on the shore, sweeping away everything in its path, carrying the remains of buildings into the sea. Large earthquakes are accompanied by numerous casualties among the population, which perishes under the ruins of buildings, from fires, and finally, simply from the resulting panic. An earthquake is a disaster, a catastrophe, so huge efforts are spent on predicting possible seismic shocks, on seismically hazardous areas, on measures designed to make industrial and civil buildings earthquake-resistant, which leads to large additional costs in construction.

Any earthquake is a tectonic deformation of the earth's crust or upper mantle, occurring due to the fact that the accumulated stresses at some point exceeded the strength of the rocks in a given place. The discharge of these voltages causes seismic vibrations in the form of waves, which, having reached the earth's surface, produce destruction. The "trigger" that causes stress discharge may be, at first glance, the most insignificant, for example, the filling of a reservoir, a rapid change in atmospheric pressure, ocean tides, etc.

^ LIST OF USED LITERATURE

1. G. P. Gorshkov, A.F. Yakusheva General geology. Third edition. - Publishing House of Moscow University, 1973 - 589 pp.: ill.

2. N. V. Koronovsky, A. F. Yakusheva Fundamentals of Geology - 213 pp.: ill.

3. V.P. Ananiev, A.D. Potapov Engineering Geology. Third edition, revised and corrected. - M .: Higher school, 2005. - 575 p.: ill.

Endogenous processes:

Endogenous processes - geological processes associated with energy arising in the bowels 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, the driving force of 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.

Metamorphism is a process of solid-phase mineral and structural change of rocks under the influence of temperature and pressure in the presence of fluid.

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.

Exogenous 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, the force of gravity and the vital activity of organisms.

Erosion is 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.

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. The accelerated one goes 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.

Interactions:

The relief is formed as a result of the interaction of endogenous and exogenous processes.

21. Physical weathering of rocks:

Physical weathering of rocks is the process of mechanical fragmentation of rocks without changing the chemical composition of the minerals that form them.

Physical weathering actively proceeds with large fluctuations in daily and seasonal temperatures, for example, in hot deserts, where the soil surface sometimes heats up to 60 - 70 ° C, and cools down to almost 0 ° C at night.

The process of destruction is enhanced by condensation and freezing of water in the cracks of rocks, because, freezing, the water expands and presses against the walls with great force.

In a dry climate, a similar role is played by salts that crystallize in the cracks of rocks. Thus, the calcium salt CaSO4, turning into gypsum (CaSO4 - 2H2O), increases in volume by 33%. As a result, individual fragments begin to fall off from the rock, broken by a network of cracks, and over time, its surface may undergo complete mechanical destruction, which favors chemical weathering.

22. Chemical weathering of rocks:

Chemical weathering is the process of chemical change of rocks and minerals and the formation of new, simpler compounds as a result of dissolution, hydrolysis, hydration and oxidation reactions. The most important factors in chemical weathering are water, carbon dioxide and oxygen. Water acts as an active solvent of rocks and minerals, and carbon dioxide dissolved in water enhances the destructive effect of water. The main chemical reaction of water with minerals of igneous rocks - hydrolysis - leads to the replacement of cations of alkaline and alkaline earth elements of the crystal lattice with hydrogen ions of dissociated water molecules. Hydration is also associated with the activity of water - the chemical process of adding water to minerals. As a result of the reaction, the surface of minerals is destroyed, which in turn enhances their interaction with the surrounding aqueous solution, gases, and other weathering factors. The reaction of oxygen addition and the formation of oxides (acidic, basic, amphoteric, salt-forming) is called oxidation. Oxidative processes are widespread during the weathering of minerals containing metal salts, especially iron. As a result of chemical weathering, the physical state of minerals changes, their crystal lattice is destroyed. The rock is enriched with new (secondary) minerals and acquires such properties as connectivity, moisture capacity, absorption capacity, etc.

23. Organic weathering of rocks:

Weathering of rocks is a complex process in which several forms of its manifestation are distinguished. The 1st form - mechanical crushing of rocks and minerals without a significant change in their chemical properties - is called mechanical or physical weathering. The 2nd form - a chemical change in matter, leading to the transformation of the original minerals into new ones - is called chemical weathering. 3rd form - organic (biological-chemical) weathering: minerals and rocks physically and mainly chemically change under the influence of the vital activity of organisms and organic matter formed during their decomposition.

Organic weathering:

The destruction of rocks by organisms is carried out by physical or chemical means. The simplest plants - lichens - are able to settle on any rock and extract nutrients from it with the help of organic acids secreted by them; this is confirmed by experiments on planting lichens on smooth glass. After some time, cloudiness appeared on the glass, indicating its partial dissolution. The simplest plants prepare the ground for life on the surface of rocks of more highly organized plants.

Woody vegetation sometimes also appears on the surface of rocks that do not have a loose soil cover. The roots of plants use the cracks in the rock, gradually expanding them. They are able to break even a very dense rock, since the turgor, or pressure developed in the cells of the root tissue, reaches 60-100 atm. A significant role in the destruction of the earth's crust in its upper part is played by earthworms, ants and termites, making numerous underground passages, contributing to the penetration of air containing moisture and CO2 into the soil - powerful factors of chemical weathering.

24. Minerals formed during the weathering of rocks:

WEATHERING DEPOSITS - deposits of minerals that have arisen in the weathering crust during the decomposition of rocks near the Earth's surface under the influence of water, carbon dioxide, oxygen, as well as organic and inorganic acids. Among the weathering of deposits, infiltration deposits and residual deposits are distinguished. Weathering deposits include some deposits of ores Fe, Mn, S, Ni, bauxite, kaolin, apatite, barite.

K infiltration B. m. include deposits of ores of uranium, copper, native sulfur. Their example is the widespread deposits of uranium ores in sandstone strata (eg, the Colorado Plateau). The deposits of ores of silicate nickel, iron, manganese, bauxite, magnesite, and kaolin belong to the residual mineral deposits. Among them, the deposits of nickel ores of the CCCP (Southern Urals), Kuba, and H. Caledonia are the most characteristic.

25. Geological wind activity:

The activity of the wind is one of the most important factors forming the relief. The processes associated with the activity of the wind are called aeolian (Eol is the god of the winds in Greek mythology).

The influence of wind on the relief occurs in two directions:

Weathering - the destruction and transformation of rocks.

Movement of material - giant accumulations of sand or clay particles.

The destructive activity of the wind consists of two processes - deflation and corrosion.

Deflation is the process of blowing and wind blowing particles of loose rocks.

Corrosion (scraping, scraping) is the process of mechanical abrasion of rocks by detrital material carried by the wind. It consists in turning, grinding, and drilling rocks.

26. Geological activity of the sea:

The seas and oceans occupy about 361 million km2. (70.8% of the entire earth's surface). The total volume of water is 10 times the volume of land above the water level, which is 1370 million km2. This huge mass of water is in constant motion and therefore performs a great destructive and creative work. Over the long history of the development of the earth's crust, the seas and oceans have changed their boundaries more than once. Almost the entire surface of modern land was repeatedly flooded with their waters. Thick layers of sediments accumulated at the bottom of the seas and oceans. Various sedimentary rocks were formed from these sediments.

The geological activity of the sea is mainly reduced to the destruction of rocks on the coast and bottom, the transfer of fragments of material and the deposition of sediments, from which sedimentary rocks of marine origin are subsequently formed.

The destructive activity of the sea consists in the destruction of the shores and the bottom and is called abrasion, which is most pronounced on steep coasts at great coastal depths. This is due to the high height of the waves and their high pressure. It enhances the destructive activity of the clastic material contained in sea water and air bubbles, which burst and a pressure drop occurs ten times greater than abrasion. Under the influence of sea surf, the coast gradually moves away and in its place (at a depth of 0–20 m) a flat area is formed - a wave-cut or abrasion terrace, the width of which can be > 9 km, the slope is ~ 1°.

If the sea level remains constant for a long time, then the steep coast gradually recedes and a boulder-pebble beach appears between it and the abrasion terrace. The coast from abrasion becomes accumulative.

The shores are intensively destroyed during the transgression (advance) of the sea and turn, leaving from under the water level, into a sea terrace during the regression of the sea. Examples: coasts of Norway and Novaya Zemlya. Abrasion does not occur during rapid continuous uplifts and on gently sloping banks.

The destruction of the coast is also facilitated by the tides, sea currents (Gulf Stream).

Sea water carries substances in a colloidal, dissolved state and in the form of mechanical suspensions. She drags the coarser material along the bottom.

27. Precipitation of the shelf zone of the sea:

Seas and oceans occupy about 71% of the Earth's surface. Water is in constant motion, which leads to the destruction of the banks (abrasion), the movement of a huge amount of clastic material and dissolved substances carried by the rivers, and, finally, their deposition with the formation of a variety of sediments.

Shelf (from English) - a continental shelf, is an underwater slightly sloping plain. The shelf is a leveled part of the underwater margin of the continent, adjacent to the land and characterized by a common geological structure with it. From the ocean side, the shelf is limited by a clearly defined ridge, located to depths of 100–200 m.

The main factors determining the type of marine deposits are the nature of the relief and the depth of the seabed, the degree of remoteness from the coast, and climatic conditions.

The littoral zone is called the coastal shallow part of the sea, periodically flooded during high tides and drained at low tides. This zone has a lot of air, light and nutrients. The sediments of the littoral zone are characterized primarily by strong variability, which is a consequence of the periodically changing hydrodynamic regime of water.

A beach is formed in the littoral zone. The beach is an accumulation of detrital material in the zone of action of the surf. The beaches are composed of a wide variety of materials - from large boulders to fine sand. Waves crashing onto the beach sort the material they carry. As a result, areas enriched with heavy minerals may appear in the beach zone, which leads to the formation of coastal-marine placers.

In areas of the littoral, where there are no strong disturbances, the nature of the deposits is significantly different. The sediments here are predominantly fine-grained: silty and clayey. Sometimes the entire intertidal zone is occupied by sandy-argillaceous silts.

The neritic zone is an area of shallow water, stretching from a depth where waves cease to appear to the outer edge of the shelf. Terrigenous, organogenic and chemogenic sediments accumulate in this zone.

Terrigenous sediments are most widespread, due to the proximity of land. Among them, coarse clastic sediments are distinguished: blocks, boulders, pebbles and gravel, as well as sandy, silty and clayey sediments. On the whole, the following distribution of sediments is observed in the shelf zone: coarse clastic material and sands accumulate near the shore, followed by silty sediments, and even further clayey sediments (silts). Sediment sorting deteriorates as the impact from the coast due to the weakening of the sorting work of the waves.

28. Sediments of the continental slope, continental foot and ocean floor:

The main elements of the topography of the bottom of ocean basins are:

1) Continental shelf, 2) Continental slope with submarine canyons, 3) Continental foot, 4) Mid-ocean ridge system, 5) island arcs, 6) Ocean bed with abyssal plains, positive landforms (mainly volcanoes, guillots and atolls) ) and deep sea trenches.

Continental slope - represents the margins of the continents, submerged up to 200 - 300 m below sea level at their outer edge, from where the steeper subsidence of the seabed begins. The total area of the shelf is about 7 million km2, or about 2% of the area of the bottom of the World Ocean.

Continental slope with canyons. From the edge of the shelf, the bottom descends steeper, forming a continental slope. Its width is from 15 to 30 km and it plunges to a depth of 2000 - 3000 m. It is cut by deep valleys - canyons up to 1200 m deep and having a V - shaped transverse profile. In the lower part of the canyons reach a depth of 2000 - 3000 and below sea level. The walls of the canyons are rocky, and the bottom sediments unloaded at their mouths on the continental foot indicate that the canyons play the role of flumes, along which fine and coarse sedimentary material from the shelf is carried to great depths.

The continental foot is a sedimentary rim with a gently sloping surface at the base of the continental slope. It is an analogue of foothill alluvial plains formed by river sediments at the foot of mountain ranges.

The ocean floor, in addition to the deep-water plains, also includes other large and small landforms.

29. Minerals and landforms of marine origin:

A significant percentage of minerals are found in the ocean.

Shell rock and shell sand are mined for the cement industry. The sea also supplies significant masses of material for alluvial shores, islands, and dams.

However, iron-manganese nodules and phosphorites are of the greatest interest. Rounded or disk-shaped concretions and their aggregates are found on large areas of the ocean floor and gravitate towards the zones of development of volcanoes and metal-bearing hydrotherms.

Pyrite nodules are typical for the geologically calm Arctic Ocean, and disks of iron-manganese nodules have been found at the bottom of the Black Sea rift valley.

A significant amount of phosphorus is dissolved in ocean water. The concentration of phosphates at a depth of 100 meters varies from 0.5 to 2 or more micrograms per liter. Phosphate concentrations are especially significant on the shelf. Probably, these concentrations are secondary. The original source of phosphorus is volcanic eruptions that occurred in the distant past. Then phosphorus was relay-race transferred from minerals to living matter and vice versa. Large burials of phosphorus-rich sediments form deposits of phosphorites, usually enriched in uranium and other heavy metals.

Seabed relief:

The relief of the ocean floor in its complexity is not much different from the relief of the land, and often the intensity of the vertical dissection of the bottom is greater than the surface of the continents.

Most of the ocean floor is occupied by oceanic platforms, which are sections of the crust that have lost significant mobility and ability to deform.

There are four main forms of relief of the ocean floor: the underwater margin of the continents, the transition zone, the ocean floor and mid-ocean ridges.

The underwater margin consists of the shelf, the continental slope and the continental foot.

*The shelf is a shallow water zone around the continents, extending from the coastline to a sharp inflection of the bottom surface at an average depth of 140 m (in specific cases, the depth of the shelf can vary from several tens to several hundreds of meters). The average shelf width is 70-80 km, and the largest is in the area of the Canadian Arctic Archipelago (up to 1400 km)

*The next form of the continental margin, the continental slope, is a relatively steep (slope 3-6°) part of the bottom, located at the outer edge of the shelf. Off the coast of volcanic and coral islands, slopes can reach 40-50°. The width of the slope is 20-100 km.

* The mainland foot is an inclined, often slightly undulating plain, bordering the base of the mainland slope at depths of 2-4 km. The mainland foot can be both narrow and wide (up to 600-1000 km wide) and have a stepped surface. It is characterized by a significant thickness of sedimentary rocks (up to 3 km or more).

* The area of the ocean floor exceeds 200 million km2, i.e. makes up approximately 60% of the area of the oceans. The characteristic features of the bed are the wide development of the flat relief, the presence of large mountain systems and uplands not associated with the median ridges, as well as the oceanic type of the earth's crust.

The most extensive forms of the ocean floor are oceanic basins, submerged to a depth of 4-6 km and representing flat and hilly abyssal plains.

*Mid-ocean ridges are characterized by high seismic activity, expressed by modern volcanism and earthquake sources.

30. Geological activity of lakes:

It is characterized by both destructive work and creative work, i.e. accumulation of sedimentary material.

Coastal erosion is carried out only by waves and rarely by currents. Naturally, in large lakes with a large water surface, the destructive effect of waves is stronger. But if the lake is ancient, then the coastlines have already been determined, the balance profile has been reached, and the waves, rolling onto narrow beaches, only carry sand and pebbles over short distances. If the lake is young, then abrasion tends to cut off the shores and reach an equilibrium profile. Therefore, the lake, as it were, expands its borders. A similar phenomenon is observed in recently created large reservoirs, in which waves cut the banks at a speed of 5-7 m per year. As a rule, lake shores are covered with vegetation, which reduces wave action. Sedimentation in lakes is carried out both due to the supply of clastic material by rivers, and biogenic, as well as chemogenic ways. Rivers flowing into lakes, as well as temporary water flows, carry with them material of various sizes, which is deposited near the shore, or carried along the lake, where the suspension precipitates.

Organogenic sedimentation is due to abundant vegetation in shallow waters, well warmed by the Sun. The shores are covered with weeds. And algae grow under water. In winter, after the death of vegetation, it accumulates at the bottom, forming a layer rich in organic matter. Phytoplankton develops in the surface layer of water and blooms in summer. In autumn, when algae, grass and phytoplankton. They sink to the bottom, where a muddy layer is formed, saturated with organic matter. Because there is almost no oxygen at the bottom in stagnant lakes, then anaerobic bacteria turn sludge into a fatty, jelly-like mass - sapropel containing up to 60-65% carbon, which is used as fertilizer or therapeutic mud. The sapropelic layers are 5-6 meters thick, although sometimes they reach 30 or even 40 meters, as, for example, in Pereyaslavsky Lake on the Russian Plain. The reserves of valuable sapropel are huge and only in Belarus they amount to 3.75 billion m3, where they are intensively mined.

In some lakes, unseasoned limestone layers are formed - shell rocks or diatomites, formed from diatoms with a siliceous skeleton. Many lakes today are subjected to a large anthropogenic load, which changes their hydrological regime, reduces water transparency, and the content of nitrogen and phosphorus increases sharply. The technogenic impact on the lakes consists in the reduction of catchment areas, the redistribution of groundwater flows, the use of lake waters as coolants for power plants, including nuclear power plants.

Chemogenic sediments are especially typical for lakes in arid zones, where water evaporates intensively and therefore table and potassium salts (NaCl), (KCl, MgCl2), boron compounds, sulfur and others precipitate out. Depending on the most characteristic chemogenic sediments, lakes are divided into sulfate, chloride, and borate lakes. The latter are characteristic of the Caspian lowland (Baskunchak, Elton, Aral).

31. Geological activity of flowing water:

Rivers move soil, stones and other rocks. Running water has no small force, in a fast chaotic flow, large stones crumble into small pieces. The geological activity of rivers, like other flowing waters, is expressed mainly by: 1) Erosion, destruction of rocks, 2) transfer of eroded material either in dissolved form or in mechanical suspension, 3) deposition of the transferred material in places more or less remote from that area . The erosion is most pronounced in the upper reaches where the slopes are steeper. Groundwater refers to all natural waters that are under the surface of the Earth in a mobile state, which wash out the soil layer. River sediments fertilize the soil, level the earth's surface.

32. Concepts of balance profile, bottom and side erosion:

Equilibrium profile (watercourse) - longitudinal profile of the channel of the watercourse in the form of a smooth curve, steeper in the upper reaches and almost horizontal in the lower reaches; such a flow should not produce bottom erosion throughout its entire length. The shape of the equilibrium profile depends on the change in the course of the river of a number of factors (water discharge, the nature of sediments, features of rocks, the shape of the channel, etc.) that affect erosion-accumulation processes. However, the determining factor is the nature of the relief along the river valley. Thus, the exit of the river from the mountainous area to the plain causes a rapid decrease in the slopes of the channel.

The equilibrium profile of a river is the limiting shape of the profile towards which a stream tends with a stable basis of erosion.

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.

Linear erosion occurs in small areas of the surface and leads to the dissection of the earth's surface and the formation of various erosional forms (gullies, ravines, gullies, valleys).

Types of linear erosion

Deep (bottom) - destruction of the bottom of the watercourse. Bottom erosion is directed from the mouth upstream and occurs before the bottom reaches the level of the erosion basis.

Lateral - destruction of the coast.

In each permanent and temporary watercourse (river, ravine), both forms of erosion can always be found, but at the first stages of development, the deep one prevails, and in the subsequent stages, the lateral one.

33. Landforms and minerals of river origin:

River landforms are erosive and accumulative landforms that have arisen as a result of the work of flowing waters, both temporary and permanent. These include different types of valleys, erosion ledges and slopes (which are also formed by gravitational processes), terraces, floodplains complicated by oxbow lakes, riverbeds, riverbed dunes, waterfalls, rapids, alluvial fans, dry deltas, deltas (together with the sea). Carbonate rocks cf. Carboniferous, limestones, clays, carbonaceous shales.

34. Geological activity of swamps:

A swamp is a piece of land (or landscape) characterized by excessive moisture, sewage or running water, but without a permanent layer of water on the surface. The swamp is characterized by the deposition of incompletely decomposed organic matter on the soil surface, which later turns into peat. The layer of peat in swamps is at least 30 cm, if less, then these are just wetlands.

The main result of the geological work of the swamps is the accumulation of peat. In addition to peat, other precipitations are often formed, including mineral ones. The color of the peat is usually dark. In fresh (not compacted) peat, moisture is 85-95%, mineral impurities from - 2 to 20% of the dry mass of peat. Peat bogs differ in the amount of ash residue. Most of the ash gives lowland peat (8-20%), less - transitional (4-6%) and least of all - high-moor peat (2-4%). Depending on the predominance of vegetation, wood, grass and moss peat are distinguished.

35. Geological work of glaciers:

The moving masses of ice do an enormous amount of geological work. Ice carries frozen stone blocks (Fig. 3, scratching the bed of the ice flow, tearing off pieces of rocks and grinding them, shifts rock layers. Ice plows soft rocks, forming grooves and hollows in them. Stones frozen into ice smooth and cover rocks with strokes, forming ram foreheads, curly rocks and hatched boulders.

Descending to the sea, the glacier breaks off, and mountains of floating ice are formed - icebergs that melt for years. Icebergs can carry boulders, blocks and other torn rock material on and in themselves.

As it moves from the mountains below the snow line and across the mainland, the ice melts, as the continental ice of ice ages melted in the relatively recent geological past. The melted ice leaves coarse, inhomogeneous, unsorted, unstratified clastic material. Most often, these are boulder sandy red-brown loams and clays or gray inequigranular clayey sands with boulders. Boulders of various sizes (from centimeters to several meters in diameter) consist of granite, gabbro, quartzite, limestone and, in general, rocks of various petrographic compositions. This is due to the fact that the glacier brings material from afar and at the same time captures fragments and blocks of local rocks.

37. Genetic classification of sedimentary rocks:

By origin and geological features, all rocks are divided into 3 classes:

Sedimentary

Igneous

Metamorphic.

According to the way they form, sedimentary rocks are divided into three main genetic groups:

Clastic rocks (breccias, conglomerates, sands, silts) are coarse products of predominantly mechanical destruction of parent rocks, usually inheriting the most stable mineral associations of the latter;

Clay rocks are dispersed products of deep chemical transformation of silicate and aluminosilicate minerals of parent rocks, which have passed into new mineral species;

Chemogenic, biochemogenic and organogenic rocks - products of direct precipitation from solutions (for example, salts), with the participation of organisms (for example, siliceous rocks), accumulation of organic matter (for example, coals) or waste products of organisms (for example, organogenic limestones).

A characteristic feature of sedimentary rocks associated with the conditions of formation is their layering and occurrence in the form of more or less regular geological bodies (layers).

38. Structures and textures of sedimentary rocks:

Sedimentary rocks are formed only on the surface of the earth's crust during the destruction of any pre-existing rocks, as a result of the vital activity and death of organisms and precipitation from supersaturated solutions.

The structure is understood as the internal structure of the rock, a set of features determined by the degree of crystallinity, absolute and relative sizes, shape, mutual arrangement and ways of combining mineral components.

The structure is the most important characteristic of the rock, expressing its granularity.

Under the texture understand the features of the external structure of the rock, characterizing the degree of its uniformity and continuity.

Internal textures are divided into non-layered and layered.

39. Forms of geological bodies composed of sedimentary rocks:

Sedimentary rocks form layers, layers, lenses and other geological bodies of various shapes and sizes, occurring in the earth's crust normally horizontally, obliquely or in the form of complex folds. The internal structure of these bodies, determined by the orientation and mutual arrangement of grains (or particles) and the way space is filled, is called the texture of sedimentary rocks. Most of these rocks are characterized by a layered texture: the types of texture depend on the conditions of their formation (mainly on the dynamics of the environment).

The formation of sedimentary rocks occurs according to the following scheme: the emergence of initial products by the destruction of parent rocks, the transfer of matter by water, wind, glacier and its deposition on the land surface and in water basins. As a result, a loose and porous, saturated with water, completely or partially, sediment, composed of heterogeneous components, is formed.

40. Origin and forms of groundwater:

By origin, groundwater can be divided into infiltration and sedimentation.

Infiltration waters are formed during seepage, penetration of atmospheric precipitation and surface waters into porous and fractured rocks. Ground waters, as well as part of artesian waters, are of infiltration origin.

Sedimentary waters are waters formed during the process of sedimentation. Sediments deposited in the aquatic environment are saturated with the water of the basin in which sedimentation occurs.

Forms of groundwater location:

Water, filling the pores, cracks and voids of rocks, can be present in them in three phases: liquid, vapor and solid. The last phase is most typical for permafrost zones, as well as for regions of the globe with negative winter temperatures.

Gravitational water, i.e., water that obeys the forces of gravity, can fill the pores and voids of rock layers (in sands, sandstones, etc.) - these are formation waters or be in rock cracks (in granites, basalts, etc.) .) are fissure waters. Formation-fissure waters are also known, contained in cracks in porous rocks (some sandstones and other sedimentary deposits). Finally, waters can fill voids, channels, pipes of karst rocks - these are karst waters (in limestones, dolomites, salts, etc.).

41. Water properties of rocks:

The main water properties of soils include moisture, moisture capacity, water loss, water permeability, capillarity.

Moisture capacity is the property of a rock to contain one or another amount of water in its pores.

Total moisture capacity - the amount of water that fills all the voids of the rock.

The actual water capacity is determined by the amount of water actually contained in the rock.

Capillary moisture capacity is the amount of water held by the rock in the capillaries with free flow. The capillary moisture capacity is the lower, the greater the permeability of the rock.

Water yield refers to the amount of gravitational water that can be contained in the rock and which it can give up when pumped out. Water yield can be expressed as a percentage of the volume of water flowing freely from the rock to the volume of the rock.

The water saturation of rocks represents the amount of water that is given off by the rock. According to the degree of water abundance, the rocks are divided into highly water-bearing wells with a flow rate of more than 10 l / s, water-abundant wells with a flow rate of 1 - 10 l / s, low water-abundant - 0.1 - 1 l / s.

Water-pumping rocks, as well as layers, lenses, etc., are those in which pores, cracks and other voids are filled with gravitational waters - gravitational aquifers, capillary waters and film aquifers.

Water permeability - the property of rocks to pass water due to the presence of pores, cracks and other voids in them. The value of water permeability is determined by the coefficient of water permeability. According to the degree of permeability, rocks can be divided into permeable, semi-permeable and impervious.

Water resistance - the property of rocks not to let water through. These include, for example, non-fractured limestones, crystalline schists, etc.

Questions

1.Endogenous and exogenous processes

Earthquake

.Physical properties of minerals

.Epeirogenic movements

.Bibliography

1. EXOGENOUS AND ENDOGENOUS PROCESSES

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.

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 generated 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 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.

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 were destroyed.

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.

Collapses and cracks formed in the mountains, through which flows of underground water came to the surface in some places. 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. ATplan 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, with many objects shifting vertically (bouncing), 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 are described with even more aftershocks. 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 entire 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 made of raw brick crumbled, and the roofs were covered with these piles of bricks, household utensils, etc. In more solidly built houses, individual walls flew out, pipes and stoves collapsed. 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 occurred 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 swells strongly, short-term currents form 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 are highly reflective 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).

Colour- 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. The hardness depends on the crystal structure: the more strongly the atoms in the structure of the mineral are bound together, the more difficult 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 the 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. - Kyiv: 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.

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, the force of gravity and the vital activity of organisms.

Erosion (from Latin erosio - corrosive) is 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. The accelerated one goes 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.

Weathering-- a set of complex processes of qualitative and quantitative transformation of rocks and their constituent minerals, leading to the formation of soil. Occurs due to the action on the lithosphere of the hydrosphere, atmosphere and biosphere. If rocks are on the surface for a long time, then as a result of their transformations, a weathering crust is formed. There are three types of weathering: physical (mechanical), chemical and biological.

physical weathering- this is the mechanical grinding of rocks without changing their chemical structure and composition. Physical weathering begins on the surface of rocks, in places of contact with the external environment. As a result of temperature fluctuations during the day, microcracks form on the surface of the rocks, which, over time, penetrate deeper and deeper. The greater the temperature difference during the day, the faster the weathering process. The next step in mechanical weathering is the entry of water into the cracks, which, when frozen, increases in volume by 1/10 of its volume, which contributes to even greater weathering of the rock. If blocks of rocks fall, for example, into a river, then there they are slowly worn down and crushed under the influence of the current. Mudflows, wind, gravity, earthquakes, volcanic eruptions also contribute to the physical weathering of rocks. Mechanical grinding of rocks leads to the passage and retention of water and air by the rock, as well as a significant increase in surface area, which creates favorable conditions for chemical weathering.

chemical weathering-- this is a combination of various chemical processes, as a result of which there is a further destruction of rocks and a qualitative change in their chemical composition with the formation of new minerals and compounds. The most important chemical weathering factors are water, carbon dioxide and oxygen. Water is an energetic solvent of rocks and minerals. The main chemical reaction of water with minerals of igneous rocks is hydrolysis, which leads to the replacement of cations of alkaline and alkaline earth elements of the crystal lattice with hydrogen ions of dissociated water molecules.

biological weathering produce living organisms (bacteria, fungi, viruses, burrowing animals, lower and higher plants, etc.).

Endogenous processes- geological processes associated with the energy arising in the bowels 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 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
- superficial

According to the composition of magma:

- ultrabasic
- basic
- sour
- alkaline

Metamorphism (Greek metamorphoumai - undergoing transformation, transforming) is the process of solid-phase mineral and structural changes in rocks under the influence of temperature and pressure in the presence of fluid.

According to the size of the distribution areas of metamorphic rocks, their structural position and the causes of metamorphism, the following are distinguished:

Regional metamorphism that affects large volumes of the earth's crust and is distributed over large areas

Ultra-high pressure metamorphism

Contact metamorphism is confined to igneous intrusions, and occurs from the heat of cooling magma.

Dynamo metamorphism occurs in fault zones, it is associated with significant deformation of rocks

Impact metamorphism, which occurs when a meteorite hits the surface of a planet

The main factors of metamorphism are temperature, pressure and fluid.

Fluids are the volatile components of metamorphic systems. This is primarily water and carbon dioxide. Less often, oxygen, hydrogen, hydrocarbons, halogen compounds, and some others can play a role. In the presence of fluid, the stability region of many phases (especially those containing these volatile components) changes. In their presence, the melting of rocks begins at much lower temperatures.

Facies of metamorphism

Subsequently, an intensive experimental study of mineral reactions began, and through the efforts of many researchers, a metamorphism facies scheme was compiled - a P-T diagram, which shows the semi-stability of individual minerals and mineral associations. The facies scheme has become one of the main tools for the analysis of metamorphic sets. Geologists, having determined the mineral composition of the rock, correlated it with any facies, and according to the appearance and disappearance of minerals, they compiled maps of isograds - lines of equal temperatures. Examples of the manifestation of global processes on the Earth's surface are mountain building processes lasting tens of millions of years, slow movements of huge blocks of the earth's crust, having a speed from fractions of a millimeter to a few centimeters per year. Rapid processes - manifestations of the differentiation of global processes of the planet's development - are represented here by volcanic eruptions, earthquakes, which are the result of the impact of deep processes on the near-surface zones of the planet. These processes, generated by the internal energy of the Earth, are called endogenous, or internal.

The processes of transformation of the deep matter of the Earth already at the initial stages of its development led to the release of gases and the formation of the atmosphere. Condensation of water vapor from the latter and direct dehydration of deep matter led to the formation of the hydrosphere. Along with the energy of solar radiation, the action of the gravitational fields of the Sun. The moon and the Earth itself, other cosmic factors, the impact of the atmosphere and hydrosphere on the earth's surface leads to the manifestation here of a whole complex of processes of transformation and movement of matter.

These processes, manifested against the background of endogenous ones, are subject to other cycles due to long-term climate changes, seasonal and daily variations in physical conditions on the earth's surface. Examples of such processes are the destruction of rocks - weathering, the movement of rock destruction products down slopes - landslides, talus, landslides, the destruction of rocks and the transfer of material by water flows - erosion, the dissolution of rocks by groundwater - karst, as well as a large number of secondary processes movement, sorting and redeposition of rocks and products of their destruction. These processes, the main factors of which are forces external to the solid body of the planet, are called exogenous.

Thus, under natural conditions, the lithosphere, which is part of the "Biosphere" ecosystem, is under the influence of endogenous (internal) factors (movement of blocks, mountain building, earthquakes, volcanic eruptions, etc.) and exogenous (external) factors (weathering, erosion, suffusion, karst, movement of destruction products, etc.).

The former seek to dissect the relief, increase the gradient of the gravitational potential of the surface; the second - to smooth (peneplanize) the relief, destroy the hills, fill the depressions with destruction products.

The former lead to an acceleration of the surface runoff of atmospheric precipitation, as a result - to erosion and drying of the aeration zone; the second - to slow down the surface runoff of atmospheric precipitation, as a result - to the accumulation of washout materials, waterlogging of the aeration zone and swamping of the territory. It should be taken into account that the lithosphere is composed of rocky, semi-rocky and loose rocks, which differ in the amplitudes of influence and the rates of processes.

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 of the 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: 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 (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), are not widely used, 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 is 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 constituent part 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). In the form of 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 the 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 the chemical industry, mineral fertilizers, etc., combustible minerals - coal, oil, combustible gases, combustible 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

Element	% mass
Oxygen	49.5
Silicon	25.3
Aluminum	7.5
Iron	5.08
Calcium	3.39
Sodium	2.63
Potassium	2.4
Magnesium	1.93
Hydrogen	0.97
Titanium	0.62
Carbon	0.1
Manganese	0.09
Phosphorus	0.08
Fluorine	0.065
Sulfur	0.05
Barium	0.05
Chlorine	0.045
Strontium	0.04
Rubidium	0.031
Zirconium	0.02
Chromium	0.02
Vanadium	0.015
Nitrogen	0.01
Copper	0.01
Nickel	0.008
Zinc	0.005
Tin	0.004
Cobalt	0.003
Lead	0.0016
Arsenic	0.0005
Bor	0.0003
Uranus	0.0003
Bromine	0.00016
Iodine	0.00003
Silver	0.00001
Mercury	0.000007
Gold	0.0000005
Platinum	0.0000005
Radium	0.0000000001

9- General information about minerals

Mineral(from late Latin "minera" - ore) - a natural solid body with a certain chemical composition, physical properties and crystal structure, formed as a result of natural physical and chemical processes and which is an integral part of the Earth's Crust, rocks, ores, meteorites and other planets of the Solar systems. 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 Earth
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Endogenous processes
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Exogenous processes
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Material from Wikipedia - the free encyclopedia

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