Tectonic lakes: examples, list. The largest glacial-tectonic lakes. Lakes of tectonic origin

Definition 1

In the aspect of planetology, a lake is an object stably existing in space and time, which is filled with a substance in liquid form.

In a geographical sense, it can be represented as a closed depression of land, into which water is systematically. For a sufficiently long period of time, the chemical composition of lakes does not change. The liquid filling it is renewed, but much less frequently than in a river. At the same time, the currents present in it do not act as the main factor by which it is possible to determine the general regime.

Remark 1

Lakes mainly provide a balancing of river flow, as complex chemical reactions take place in their waters.

In the process of interactions, some elements pass into the liquid, while others settle in bottom sediments. In some water bodies that do not have such a runoff, the salt content increases significantly due to evaporation. As a result, there is a fundamental change in the mineral and salt composition lakes. Large objects soften climatic conditions territories close to them through large-scale thermal inertia, thereby reducing seasonal and annual weather fluctuations.

Tectonic lakes: characteristics, examples

Definition 2

tectonic lakes- reservoirs that were formed at the sites of faults and shifts of the earth's crust.

Basically, these objects are narrow and deep, and also distinguished by rectilinear steep banks. Such lakes are located mainly in deep through gorges. The tectonic lakes of Russia (examples: Far and Kuril in the territory of Kamchatka) are characterized by a low-lying bottom. Thus, the Kuril reservoir flows in the southern part of Kamchatka, in a colorful deep basin. This area is completely surrounded by mountains. The maximum depth of the lake is about 360 m, and a huge amount of mountain streams constantly flows from the steep banks. The Ozernaya River flows out of this reservoir, along the banks of which quite hot springs come to the surface. In the center of the reservoir there is an island in the form of a small dome-shaped elevation, popularly referred to as the "heart-stone". Not far from the lake there are unique pumice deposits called Kutkhiny Baty. Today, Lake Kurilskoye is considered a reserve and declared a natural zoological monument.

Interestingly, tectonic lakes are located only in the pipes of the explosion and extinct craters. Such reservoirs are often found in European countries. For example, volcanic lakes are observed in the Eifel region (in Germany), near which a weak manifestation is recorded volcanic activity in the form of hot springs. A water-filled crater is the most common type of such reservoirs.

Example 1

For example, Lake Crater of Mazama Volcano in Oregon formed about 6.5 thousand years ago.

Its diameter reaches 10 km, and its depth is more than 589 m. Part of the reservoir was formed by volcanic valleys in the process of blocking by continuous lava flows, in which water accumulates over time and a lake is formed. This is how the Kivu reservoir appeared, which is a depression of the East African rift structure, which is located on the border of Zaire and Rwanda. Flowing more than 7 thousand years ago from Tanganyika, the Ruzizi River flowed through the Kivu valley to northern regions towards the Nile. But since that period, the channel has been "sealed" in with the eruption of a nearby volcano.

Profile of the bottom of tectonic lakes

Tectonic reservoirs of the world have a clearly defined bottom relief, represented as a broken curve.

Accumulative processes and glacial deposits in the sediments did not have a significant effect on the relief of the lines of the basins, but in a number of special cases the effect can be quite noticeable.

Glacial-tectonic lakes can have a bottom covered with "scars" and "ram's foreheads", which can be observed on rocky shores and islands. The latter are formed mainly from hard rocks, which are practically not amenable to erosion. As a result of this process, a small rate of accumulation of precipitation occurs. Similar tectonic reservoirs of Russia are classified by geographers as: a = 2-4 and a = 4-10. The deep-water surface (over 10 m) of the total volume reaches approximately 60-70%, shallow-water (up to 5 m) - 15-20%. Such lakes are characterized by diverse waters in terms of thermal parameters. Low temperature bottom waters is preserved during the period of maximum surface heating. This is due to thermally stable stratifications. Vegetation in these areas is extremely rare, as it can only be found along the coast in closed bays.

Features of the formation of reservoirs

Lakes arise for a variety of reasons. Their natural creators are:

• water;
• wind;
• tectonic forces.

On the earth's surface, basins are often washed out with water. Due to the action of the wind, a depression is created, after which the glacier polishes the depression, and the mountain collapse gradually dams the river valley. This is how the bed for the future reservoir is formed.

By origin, the lakes are divided into:

• river reservoirs;
• seaside lakes;
• mountain reservoirs;
• glacial lakes;
• dam reservoirs;
• tectonic lakes;
• failed lakes.

Tectonic lakes appear as a result of filling small cracks in the crust with water. Thus, the shifts formed the Caspian Sea - the largest body of water in Russia and the entire planet. Before lifting Caucasian ridge The Caspian Sea was directly connected with the Black Sea. Another a prime example large-scale fault in the earth's crust is the East African structure, which extends from the southwestern region of the continent north to southeast Asia. Here is a chain of tectonic reservoirs. The most famous are Tanganyika, Albert Edward, Nyasa. To the same system, experts include the Dead Sea - the lowest tectonic lake in the world.

Seaside lakes are estuaries and lagoons, which are mainly located in the northern regions Adriatic Sea. One of the specifics of failed reservoirs is their systematic disappearance and emergence. This a natural phenomenon depends directly on the unique dynamics underground water. An ideal example of this object is Lake Ertsov, located in South Ossetia. Mountain reservoirs are located in ridge basins, and glacial lakes are formed during the displacement of the layer of multi-year ice.

Not having direct connection with the sea. Lakes occupy about 1.8% of the land surface, but are extremely unevenly distributed.

The area of ​​the lake is very diverse. Especially large ones are even called seas ().

According to the origin of lake depressions, there are:

• tectonic. These are usually the most deep lakes formed on the spot (Baikal - depth 1620 m; - 1470 m). Depth of most lakes tectonic origin usually less than 1000 m. Doña is the most deep lakes lie below the ocean level (the bottom of Baikal is 1165 m below the ocean level);
• volcanic. These are lakes formed in craters or in calderas, as well as in depressions on the surface of lava flows: lakes, Kronotsky lake on, lakes and Java;
• glacial. These are lakes formed in areas that have undergone continental glaciation. They are created either as a result or as a result of a glacial. To erosion glacial type include lakes located in, in (), (Russia), in the northeast. The shape of these lakes is long, narrow, and they are elongated in the direction of the movement of the glacier. Lakes that have arisen as a result of lacustrine accumulation are confined to areas of hilly-morainic relief (see Glaciation). Some lakes occupy lowlands between hills and usually have a lobed shape and shallow depths (). Others arose among the moraine relief. They are wide, oval and small: , White;
• karst. They are located in or in karst sinkholes and arise in areas composed of soluble rocks. In the regions, thermokarst basins are formed, which are due to the melting of fossil ice and frozen, as well as subsidence of the soil. Many tundra lakes are thermokarst;
• coastal lakes. They were formed as a result of the separation of part of the sea from the rest by sediments of sand or silt. There are many estuaries and lagoons on the coast and;
• dammed lakes occur when a watercourse is dammed by landslides, landslides, lava flows and. So in 1911 Sarez Lake was formed with a depth of 505 m. It was dammed by a colossal mountain collapse. Dammed lakes are frequent and in. Many lakes of the Sikhote-Alin (Russia), Lake Sevan, Lake Tana () were formed as a result of the damming of the river by lava flows;
• - ponds and;
• oxbow lakes formed during the meandering of riverbeds.

The water mass of lakes is predominantly of origin and enters the lake by condensation on the water surface, when water enters from rivers and streams and due to ground feeding. The consumption of lake water is carried out through evaporation, and runoff in. In some lakes, the modern water mass has replaced the marine one, which occupied the basin in the recent geological past. On the site of modern, Ladoga and, as well as in ice age, there was the Yoldian Sea. After its collapse, lakes were formed, first with salty sea, and then with fresh water. Such lakes are called relict or residual. Animals that live there adapt to lake habitat conditions.

According to the inflow and outflow of water mass, all lakes are divided into:

• well flowing. Rivers flow into and out of them. The water in these lakes is constantly changing. Such lakes are located in zones of excessive atmospheric moisture (Baikal, Geneva);
• low-flow. Rivers also flow into them, but much less of them flow out. These lakes are located in a zone with insufficient moisture (Balaton, Tanganyika);
• drainless. Formed in zones and . Rivers flow into such lakes, but not a single one flows out (, Dead Sea);
• deaf. They feed on rain or melt water, since rivers do not flow into them and do not flow out of them. This small lakes, and zones or craters. Outside these groups were karst lakes, since their nutrition is carried out primarily at the expense of.

According to their lakes can also be divided into:

• insipid(their salinity does not exceed 1%o);
• salty(their salinity is from 1 to 47% o);
• (their salinity exceeds 47%o). Of these, salts can precipitate (Elton, Baskunchak).

Salinity dead lake 270%©.

Ozer. In countries with a warm climate, it fluctuates slightly throughout the year. In temperate latitudes, the water temperature decreases with depth in summer. In winter, the top layer of water cools below freezing, and the lake is covered with ice, and the temperature of the water rises with depth. How saltier water the lower its freezing point. Large and deep lakes do not freeze longer than shallow ones. So, Baikal freezes only at the beginning of January, when all the water bodies around have long been covered with ice.

According to their biological properties, lakes are divided into:

• up to a depth of 1 m there are thickets of sedge, arrowhead, etc.;
• to a depth of 2-3 m - reeds, reeds;
• up to a depth of 4 m - submerged plants: pondweeds and others.
• lakes poor in nutrients. They are transparent, deep and cold;
• lakes with a rich They are usually shallow, well warmed up;
• lakes poor in life, with brown water lacking oxygen.

Most lakes are characterized by abundant vegetation, especially in the coastal zone. It is arranged in tiers:
Lakes in their development go through several stages. In a wetter climate, they overgrow and turn into. In a dry climate, lakes dry up; they become salty and with poor vegetation.

The movement of water in lakes, as well as in the seas, manifests itself in the form of currents, but very slow, as well as waves reaching large sizes only in large lakes. For example, up to 2-2.5 m are observed in and on. With differences in different parts of the lake, standing waves are also observed.

Lakes play a very important role both in nature and in human life. Like the seas, they have a warming effect on the world. Lakes also influence the relief, as they also carry out erosive and accumulative work.

The science of limonology deals with the study of lakes. By origin, scientists distinguish several types, among which there are tectonic lakes. They are formed as a result of the movement of lithospheric plates and the appearance of depressions in the earth's crust. Thus was formed the deepest lake in the world - Baikal and the largest in area - the Caspian Sea. A large fault has formed in the East African rift system, where a number of lakes are concentrated:

• Tanganyika;
• Albert;
• Nyasa;
• Edward;
• The Dead Sea (is the lowest-lying lake on the planet).

In their form, tectonic lakes are very narrow and deep reservoirs, with sheer shores. Their bottom, as a rule, is located below the level of the ocean. It has a clear outline, resembling a curved broken curved line. Traces of various landforms can be found at the bottom. coast tectonic lakes made up of solid rocks and are weakly eroded. On average, the deep-water zone of lakes of this type is up to 70%, and shallow water - no more than 20%. The water of tectonic lakes is not the same, but in general it has a low temperature.

The largest tectonic lakes in the world

There are both large and medium-sized tectonic lakes in the Suna river basin:

• Randozero;
• Palier;
• Salvilambi;
• Sandal;
• Sundozero.

Among the lakes of tectonic origin in Kyrgyzstan, Son-Kul, Chatyr-Kul and Issyk-Kul should be mentioned. On the territory of the Trans-Ural Plain there are also several lakes formed as a result of a tectonic fault of the solid shell of the earth. These are Argayash and Kaldy, Uelgi and Tishki, Shablish and Sugoyak. In Asia, there are also tectonic lakes Kukunor, Khubsugul, Urmia, Biva and Van.

In Europe, there are also a number of lakes of tectonic origin. These are Geneva and Weettern, Como and Constance, Balaton and Lake Maggiore. Among the American lakes of tectonic origin, the Great North American Lakes should be mentioned. The same type of Winnipeg, Athabasca and the Great Bear Lake.

Tectonic lakes are located on the plains or in the area of ​​intermountain troughs. They have considerable depth and enormous dimensions. Not only the folds of the lithosphere, but also ruptures of the earth's crust take part in the process of formation of the lake basins. The bottom of tectonic lakes is below the ocean level. Such reservoirs are found on all continents of the earth, however, the largest number of them is located precisely in the fault zone of the earth's crust.

Tectonic lakes are formed in places of faults and shifts of the earth's crust. As a rule, these are deep narrow reservoirs with straight steep banks, located in deep through gorges. The bottom of such lakes located in Kamchatka is below the ocean level. Tectonic lakes include Dalnee and Kuril. Kurile Lake is located in the south of Kamchatka in a deep picturesque basin surrounded by mountains. Greatest depth lakes 306 m. Its banks are steep. Numerous mountain streams flow from them. The lake is sewage, the Ozernaya River originates from it. Hot springs come to the surface along the shores of the lake.

Tectonic depressions arise as a result of movements of the earth's crust, and many lake basins of tectonic origin have large area And ancient age. They occupy depressions resulting from tectonic movements of the earth's crust: faults, normal faults, grabens, intermountain and flat troughs. As a rule, they are very deep, some tectonic lakes are superior to the sea. It is not by chance that the Caspian and Aral lakes are called seas. Caspian lake 4 times more than White, almost 3 times more than Adriatic and 2 times - Aegean Seas. And the deepest lakes in the world - Baikal and Tanganyika - are much deeper than ours. northern seas- Barents, Kara, East Siberian and others.

Tectonic processes manifest themselves in different ways. For example, the Caspian Sea is confined to a deflection at the bottom ancient sea Tethys. In the Neogene, an uplift occurred, as a result of which the Caspian depression became isolated. Its waters gradually desalinated under the influence of atmospheric precipitation and river runoff. The basin of the lake Victoria in East Africa formed as a result of the uplift of the surrounding land. The Great Salt Lake in Utah also arose due to the tectonic uplift of the area through which the flow from the lake was previously carried out. Tectonic activity often leads to the formation of faults (cracks in the earth's crust), which can turn into lake basins if a reverse fault occurs in the area or if a block enclosed between faults sinks. In the latter case, the lacustrine basin is said to be associated with a graben. Several lakes within the East African Rift System have this origin. Among them - lake. Tanganyika, which was formed about 17 million years ago and is very deep (1470 m). On the continuation of this system to the north are the Dead Sea and Lake Tiberias. Both are very ancient. The maximum depth of Lake Tiberias is currently only 46 m. ​​Lakes Tahoe on the border of the states of California and Nevada in the USA, Biwa (the source of freshwater pearls) in Japan and Lake Baikal are also associated with grabens. The profile of the bottom of tectonic lakes is sharply defined and has the form of a broken curve. Glacial deposits and processes of sediment accumulation have little changed the clarity of the tectonic lines of the lake basin. The influence of the glacier on the formation of the basin can be noticeable, it leaves traces of its presence in the form of scars, sheep's foreheads, which are clearly visible on the rocky shores and islands. The shores of the lakes are composed mainly of hard stone rocks that are weakly susceptible to erosion, which is one of the reasons for the weak process of sedimentation. The waters of the lakes are thermally heterogeneous: during the period of the greatest warming surface water low bottom temperatures are maintained, which is facilitated by stable thermal stratification. Aquatic vegetation is rare, only in a narrow strip along the shores of closed bays. As a result of the movement of the earth's crust, depressions form in some places over time. It is in these depressions that tectonic lakes arise. Three most large lakes Kyrgyzstan: Issyk-Kul, Son-Kul and Chatyr-Kul are formed by tectonic way.