On this day, May 21, 1937 - 79 years ago, the expedition of I. Papanin, E. Krenkel, P. Shirshov, E. Fedorov landed on the ice of the Arctic Ocean near the North Pole and deployed the first polar station "North Pole-1".
For decades, thousands of desperate travelers and explorers of the North have sought to get to the North Pole, tried at all costs to hoist the flag of their country there, marking the victory of their people over the harsh and powerful forces of nature.
With the advent of aviation, new opportunities arose to reach the North Pole. Such as the flights of R. Amundsen and R. Byrd on airplanes and the flights of the airships "Norway" and "Italy". But for serious scientific research in the Arctic, these expeditions were short-lived and not very significant. The real breakthrough was the successful completion of the first high-latitude Soviet air expedition and the landing on drifting ice in 1937 of the heroic "four" under the leadership of I. D. Papanin.
So, O.Yu. Schmidt headed the air part of the transfer to the Pole, and I. D. Papanin was responsible for its sea part and wintering at the drifting station "SP-1". The expedition planned to land in the area of the North Pole for a year, during which it was supposed to collect a huge amount of various scientific data on meteorology, geophysics, and hydrobiology. Five planes took off from Moscow on 22 March. The flight ended on May 21, 1937.
At 11:35 a.m., the flagship aircraft under the control of the commander of the flight detachment, Hero of the Soviet Union M.V. Vodopyanov landed on the ice, flying 20 km beyond the North Pole. And the last of the planes landed only on June 5, the flight and landing conditions were so difficult. On June 6, the flag of the USSR was raised over the North Pole, and the planes set off on their return journey.
Four brave researchers remained on the ice floe with a tent for living and working, two radio stations connected by an antenna, a workshop, a meteorological booth, a theodolite for measuring the height of the sun and warehouses built of ice. The expedition included: P.P. Shirshov - hydrobiologist, glaciologist; E.K. Fedorov - meteorologist-geophysicist; THIS. Krenkel - radio operator and I.D. Papanin is the head of the station. There were months of exhausting work, hard life. But it was a time of mass heroism, high spirituality and impatient striving forward.
Every day of stay at the North Pole brought new discoveries to the researchers, and the first of them was the depth of water under the ice at 4290 meters. Soil samples were taken daily at certain times of observation, the depths and drift speed were measured, coordinates were determined, magnetic measurements, hydrological and meteorological observations were made.
Soon the drift of the ice floe, on which the researchers' camp was located, was discovered. Her wanderings began in the region of the North Pole, then the ice floe rushed south at a speed of 20 km per day.
A month after the landing of the Papaninites on the ice floe (as the brave four were dubbed all over the world), when the Kremlin hosted a solemn meeting of the participants of the World's First Air Expedition to the North Pole, a decree was read out awarding O.Yu. Schmidt and I.D. Papanin with the titles of Hero of the Soviet Union, the rest of the drift participants were awarded the Orders of Lenin. The ice floe, on which the Papanin camp was located, after 274 days turned into a fragment no more than 30 meters wide with several cracks.
A decision was made to evacuate the expedition. Behind was a path of 2,500 km across the Arctic Ocean and the Greenland Sea. On February 19, 1938, the polar explorers were removed from the ice floe by the icebreakers Taimyr and Murman. On March 15, the polar explorers were delivered to Leningrad.
The scientific results obtained in a unique drift were presented to the General Meeting of the USSR Academy of Sciences on March 6, 1938 and were highly appreciated by specialists. The scientific staff of the expedition were awarded degrees. Ivan Dmitrievich Papanin received the title of Doctor of Geographical Sciences.
With the heroic drift of the Papanins, the systematic development of the entire Arctic basin began, which made navigation along the Northern Sea Route regular. Despite all the gigantic obstacles and hardships of fate, the people of Papanin, with their personal courage, wrote one of the brightest pages in the history of the development of the Arctic.
The movement of the vessel occurs simultaneously in two environments - in water and air, which are rarely in a calm state. The air environment exerts its effect on a moving ship primarily by the speed (force) and direction of the wind. Wind speed is measured by anemometers and is expressed in meters per second, and strength is in points from 0 to 12 on a special scale (see Table 49 MT-63).The heading angle of the wind is called the course of the ship relative to the wind. Depending on the value of this angle, the ship's courses relative to the wind received various names (Fig. 47).
If the wind blows to the starboard side, then the ship's course relative to the wind is also called "starboard tack", and when it blows to the port side - "port tack".
When, due to a change in the direction of the wind, its heading angle decreases, the wind is said to be setting or becoming steeper; if it increases, then the wind moves away, or becomes fuller. When the change in angle is caused by a change in the course of the ship, then in the first case it is said that the ship is brought to the wind, or lay down more steeply, and in the second, that it went down, or lay down more completely.
Rice. 48
Under the influence of the wind and the waves and currents it causes, a moving ship deviates from the intended course and changes its speed. Consider the effect of wind on a moving ship in the following example (Fig. 48). Let us assume that the ship is moving along some course IR with a speed along the log vl and it is affected by the observed (apparent) wind Kw with a speed w at an angle q. The resultant of the wind pressure on the ship, equal to the vector A, is applied to the center of the ship's sail area and makes an angle y with its diametrical plane.
Let us decompose the wind pressure resultant A into two components X and Z. The force X is directed along the center plane and is equal to X = A cozy, it affects the speed of the vessel relative to the water (in this case it reduces the speed) vl.
The force Z is directed perpendicular to the diametrical plane, Z = A.siny and causes lateral displacement - the drift of the vessel from the course line at a speed V etc.
Having geometrically added the speed of the ship along the lag vl AND the drift of blows, we obtain the vector of the actual speed of the ship relative to the water v0, in the direction of which the actual movement of the ship occurs under the action of this wind.
The line of the actual movement of the vessel under the action of the wind is called the track line during the drift of the launcher, and the angle between the nordic part of the true meridian and this line is called the track angle. The angle a between the true course line and the drift track is called the drift angle. When solving problems, the drift angle is assigned a sign: with the wind on the right tack - minus, and on the left tack - plus.
With the same strength of the apparent wind, but at different heading angles, its influence on a moving ship is not the same. At heading wind angles equal to 0 or 180°, the drift angle is equal to zero, and at heading angles K w close to 50-60°, it reaches its maximum value due to the fact that the direction Kw is the resultant of the speed and direction of the true wind and the speed of the wind itself. ship. At angles K w ~ 50 / 60°, the angle between the direction of the true wind and the center plane of the vessel will be approximately 90°.
Rice. 49
The drift angle increases with a decrease in the ship's speed and with an increase in its sail area (in the case of a decrease in the ship's draft). Practice shows that ships with straight stems have less drift than inclined ones, and that ships with sharp lines have less drift than ships with full formations. The wind, creating excitement, causes the ship to roll, worsens the controllability, and the ship becomes less stable on the course (the ship becomes yawed).
With prolonged action of wind in one direction, a surface current is created, which also causes the ship to drift off the true course line.
Thus, the cumulative effect of the wind and the waves and currents caused by it during navigation must be taken into account by introducing a drift correction equal to the drift angle.
True heading, drifting track and drift angle are in the following algebraic relationship (Fig. 49):
At the same time, it should be remembered that the ship, moving along the track with the drift of launcher a, maintains the direction of its diametrical plane parallel to the IR line and the latter always lies closer to the wind, and launcher a - further from the wind (see Fig. 49).
Drift Angle Determination
Currently, there are no instruments for determining the drift angle that are convenient for use on a ship, and only experience and practice enable the navigator to correctly assess the effect of the wind on the ship and its probable drift by wind waves and currents.In the practice of navigation, the drift angle is determined from direct observations using one of the following methods.
Rice. fifty
When sailing in the visibility of the shores according to coastal landmarks. Following the same course KK1 (Fig. 50), several times (at least three) determine the position of the vessel according to coastal landmarks. Then, by connecting the obtained points A1 A2 and A3, the protractor is used to measure the angle between the nordic part of the true meridian and the line of the actual movement of the ship-track line PP1. The drift angle a is obtained as the difference between PU and IR, i.e. a = PU - IR. This value of the drift angle is taken into account in the future. However, it should be borne in mind that such a determination can be made when there is no constant current in the area.
Direction finding of the wake jet (used as an approximate method). The wake stream is a trace of a moving vessel due to the perturbation of the water mass by the rotation of the propellers. With wind, the direction of the wake stream almost does not shift. Therefore, to obtain the drift angle, it is possible to measure the angle between the directions of the center plane of the vessel and the wake jet. Bearings are taken according to the compass closest to the stern, setting the sighting plane of the direction finder parallel to the wake stream. If the reading is noticed on the azimuth circle of the compass, then
A \u003d KU - 180 °,
And if they remove the OKP, then a \u003d OKP - KK.
The value of the drift angle, determined by all available methods, and the conditions under which it was determined (vessel's heading relative to the wind, ship's speed, wind strength, ship's state of loading, draft, etc.), must be recorded in a special notebook in order to it was possible under similar conditions to take into account the drift in advance, i.e., when laying, take into account the correction for the wind.
Dead reckoning of the ship's course when drifting
When maintaining a graphical reckoning, taking into account the drift angle, in addition to the true course line, a track line is laid when the PU a drifts along a given or calculated drift angle a and above it, in addition to the compass heading and compass correction, indicate the value of the drift angle with the corresponding sign. The distance traveled by the ship (taking into account the correction or the lag coefficient) is always taken into account along the path of the launcher.The distance traveled along the log (except for the outboard) at drift angles of more than 8 ° is calculated with the introduction of a correction for the drift angle according to the formula
If the distance traveled is determined by the revolutions of the propellers (according to the table of correspondence of the speed to the revolutions of the propellers), then no corrections are introduced.
When maintaining a graphical dead reckoning, taking into account the drift, the position of the vessel at the moment of the traverse of the landmark should be plotted on the map; calculate the moment of arrival of the vessel on the traverse of the landmark; determine the shortest distance to the landmark when following a given course and the moment of opening or hiding the landmark.
To plot the ship's position on the map at the time of the traverse of the landmark, the reverse true bearing is calculated using the following formulas. When observing a landmark: right
left
The IIP is laid from the landmark to the PUa, and point A (the intersection of the IIP with PU a) will be the position of the vessel on the map at the moment of traverse (Fig. 51). In order to determine when the ship will actually come to the traverse of the landmark, it is necessary shortly before that to put the compass direction finder on the pre-calculated GST = KK ± 90 ° (+90 ° - landmark on the left, -90 ° - on the right) and observe. As soon as the direction to the landmark coincides with the sighting plane of the direction finder, this moment will be the moment of traverse.
Such a problem often has to be solved when determining the turning point on a new course.
Rice. 51
In order to pre-calculate the moment of arrival of the vessel on the traverse of the landmark, measure on the map along the path line the distance S from the last observed point B to point A (see Fig. 51), obtained by crossing the IIP line with the PUa line, and, dividing it by the ship's speed according to lag, get a time interval corresponding to the duration of the ship's transition from point B to point A.
By adding T to the time T1 (observation at point B), we get the moment T2 of the ship's arrival on the traverse, i.e. T2 \u003d T1 + T. To speed up the calculation of the value of T, use Table. 27-b "Time by distance and speed" (MT-63).
To calculate in advance the indication of the lag at the moment the vessel arrives at the beam (at point A), using the distance S, determine the roll according to Table. 28-a or 28-6 (MT-63) depending on the sign Al or according to the formula roll = S/Cl. Then, to the lag reading, during the determination along the landmark (at point B), the found roll is added and ol2 = ol1 + roll is obtained.
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According to modern theories of lithospheric plates the entire lithosphere is divided by narrow and active zones - deep faults - into separate blocks moving in the plastic layer upper mantle relative to each other at a rate of 2-3 cm per year. These blocks are called lithospheric plates.
Alfred Wegener first suggested horizontal movement of crustal blocks in the 1920s as part of the “continental drift” hypothesis, but this hypothesis did not receive support at that time.
Only in the 1960s, studies of the ocean floor provided indisputable evidence of the horizontal movement of plates and the processes of expansion of the oceans due to the formation (spreading) of the oceanic crust. The revival of ideas about the predominant role of horizontal movements occurred within the framework of the "mobilistic" direction, the development of which led to the development of the modern theory of plate tectonics. The main provisions of plate tectonics were formulated in 1967-68 by a group of American geophysicists - W. J. Morgan, C. Le Pichon, J. Oliver, J. Isaacs, L. Sykes in the development of earlier (1961-62) ideas of American scientists G. Hess and R. Digts on the expansion (spreading) of the ocean floor.
It is argued that scientists are not entirely sure what causes these very shifts and how the boundaries of tectonic plates were designated. There are countless different theories, but none of them fully explains all aspects of tectonic activity.
Let's at least find out how they imagine it now.
Wegener wrote: "In 1910, the idea of moving the continents first occurred to me ... when I was struck by the similarity of the outlines of the coasts on both sides of the Atlantic Ocean." He suggested that in the early Paleozoic there were two large continents on Earth - Laurasia and Gondwana.
Laurasia - it was the northern mainland, which included the territories of modern Europe, Asia without India and North America. southern mainland- Gondwana united the modern territories of South America, Africa, Antarctica, Australia and Hindustan.
Between Gondwana and Laurasia was the first sea - Tethys, like a huge bay. The rest of the Earth's space was occupied by the Panthalassa ocean.
About 200 million years ago, Gondwana and Laurasia were united into a single continent - Pangea (Pan - universal, Ge - earth)
Approximately 180 million years ago, the mainland of Pangea again began to be divided into constituent parts, which mixed up on the surface of our planet. The division took place as follows: first, Laurasia and Gondwana reappeared, then Laurasia divided, and then Gondwana also split. Due to the split and divergence of parts of Pangea, oceans were formed. The young oceans can be considered the Atlantic and Indian; old - Quiet. The Arctic Ocean became isolated with the increase in land mass in the Northern Hemisphere.
A. Wegener found a lot of evidence for the existence of a single continent of the Earth. The existence in Africa and in South America remains of ancient animals - listosaurs. These were reptiles, similar to small hippos, that lived only in freshwater reservoirs. So, to swim huge distances on the salty sea water they couldn't. He found similar evidence in the plant world.
Interest in the hypothesis of the movement of the continents in the 30s of the XX century. decreased slightly, but in the 60s it revived again, when, as a result of studies of the relief and geology of the ocean floor, data were obtained indicating the processes of expansion (spreading) of the oceanic crust and the “diving” of some parts of the crust under others (subduction).
The structure of the continental rift
The upper stone part of the planet is divided into two shells, which differ significantly in rheological properties: a rigid and brittle lithosphere and an underlying plastic and mobile asthenosphere.
The base of the lithosphere is an isotherm approximately equal to 1300°C, which corresponds to the melting temperature (solidus) of mantle material at lithostatic pressure existing at depths of a few hundreds of kilometers. The rocks lying in the Earth above this isotherm are quite cold and behave like a rigid material, while the underlying rocks of the same composition are quite heated and deform relatively easily.
The lithosphere is divided into plates, constantly moving along the surface of the plastic asthenosphere. The lithosphere is divided into 8 large plates, dozens of medium plates and many small ones. Between the large and medium slabs there are belts composed of a mosaic of small crustal slabs.
Plate boundaries are areas of seismic, tectonic, and magmatic activity; the inner areas of the plates are weakly seismic and are characterized by a weak manifestation of endogenous processes.
More than 90% of the Earth's surface falls on 8 large lithospheric plates:
Some lithospheric plates are composed exclusively of oceanic crust (for example, the Pacific Plate), others include fragments of both oceanic and continental crust.
Diagram of rift formation
There are three types of relative plate movements: divergence (divergence), convergence (convergence) and shear movements.
Divergent boundaries are boundaries along which plates move apart. The geodynamic setting in which the process of horizontal stretching occurs earth's crust, accompanied by the appearance of extended linearly elongated slot or rov-like depressions, is called rifting. These boundaries are confined to continental rifts and mid-ocean ridges in ocean basins. The term "rift" (from the English rift - gap, crack, gap) is applied to large linear structures of deep origin, formed during the stretching of the earth's crust. In terms of structure, they are graben-like structures. Rifts can be laid both on the continental and oceanic crust, forming a single global system oriented relative to the geoid axis. In this case, the evolution of continental rifts can lead to a break in the continuity of the continental crust and the transformation of this rift into an oceanic rift (if the expansion of the rift stops before the stage of break of the continental crust, it is filled with sediments, turning into an aulacogen).
The process of plate expansion in the zones of oceanic rifts (mid-ocean ridges) is accompanied by the formation of a new oceanic crust due to magmatic basalt melts coming from the asthenosphere. Such a process of formation of a new oceanic crust due to the influx of mantle matter is called spreading (from the English spread - to spread, unfold).
The structure of the mid-ocean ridge. 1 - asthenosphere, 2 - ultrabasic rocks, 3 - basic rocks (gabbroids), 4 - complex of parallel dikes, 5 - ocean floor basalts, 6 - oceanic crust segments formed at different times (I-V as they age), 7 - near-surface igneous chamber (with ultrabasic magma in the lower part and basic in the upper part), 8 – sediments of the ocean floor (1-3 as they accumulate)
In the course of spreading, each stretching pulse is accompanied by the inflow of a new portion of mantle melts, which, while solidifying, build up the edges of the plates diverging from the MOR axis. It is in these zones that the formation of young oceanic crust occurs.
Collision of continental and oceanic lithospheric plates
Subduction is the process of subduction of an oceanic plate under a continental or other oceanic one. The subduction zones are confined to the axial parts of deep-sea trenches conjugated with island arcs (which are elements of active margins). Subduction boundaries account for about 80% of the length of all convergent boundaries.
When continental and oceanic plates collide, a natural phenomenon is the subduction of the oceanic (heavier) plate under the edge of the continental one; when two oceanic ones collide, the older one (that is, the cooler and denser) of them sinks.
The subduction zones have a characteristic structure: their typical elements are a deep-water trough - a volcanic island arc - a back-arc basin. A deep-water trench is formed in the zone of bending and underthrust of the subducting plate. As this plate sinks, it begins to lose water (which is found in abundance in sediments and minerals), the latter, as is known, significantly reduces the melting temperature of rocks, which leads to the formation of melting centers that feed island arc volcanoes. In the rear of the volcanic arc, some extension usually occurs, which determines the formation of a back-arc basin. In the zone of the back-arc basin, the extension can be so significant that it leads to the rupture of the plate crust and the opening of the basin with oceanic crust (the so-called back-arc spreading process).
The volume absorbed in subduction zones oceanic crust equal to the volume of the crust that appears in the spreading zones. This provision emphasizes the opinion about the constancy of the volume of the Earth. But such an opinion is not the only and definitively proven. It is possible that the volume of the plans changes pulsatingly, or there is a decrease in its decrease due to cooling.
The subduction of the subducting plate into the mantle is traced by earthquake foci that occur at the contact of the plates and inside the subducting plate (which is colder and therefore more fragile than the surrounding mantle rocks). This seismic focal zone is called the Benioff-Zavaritsky zone. In subduction zones, the process of formation of a new continental crust begins. A much rarer process of interaction between the continental and oceanic plates is the process of obduction - thrusting of a part of the oceanic lithosphere onto the edge of the continental plate. It should be emphasized that in the course of this process, the oceanic plate is stratified, and only its upper part is advancing - the crust and several kilometers of the upper mantle.
Collision of continental lithospheric plates
When continental plates collide, the crust of which is lighter than the substance of the mantle and, as a result, is not able to sink into it, a collision process occurs. In the course of collision, the edges of colliding continental plates are crushed, crushed, and systems of large thrusts are formed, which leads to the growth of mountain structures with a complex fold-thrust structure. A classic example of such a process is the collision of the Hindustan plate with the Eurasian one, accompanied by the growth of the grandiose mountain systems of the Himalayas and Tibet. The collision process replaces the subduction process, completing the closure of the ocean basin. At the same time, at the beginning of the collision process, when the edges of the continents have already approached, the collision is combined with the subduction process (the remains of the oceanic crust continue to sink under the edge of the continent). Collision processes are characterized by large-scale regional metamorphism and intrusive granitoid magmatism. These processes lead to the creation of a new continental crust (with its typical granite-gneiss layer).
The main cause of plate movement is mantle convection, caused by mantle heat and gravity currents.
The source of energy for these currents is the temperature difference between the central regions of the Earth and the temperature of its near-surface parts. At the same time, the main part of the endogenous heat is released at the boundary of the core and mantle during the process of deep differentiation, which determines the decay of the primary chondrite substance, during which the metal part rushes to the center, increasing the core of the planet, and the silicate part is concentrated in the mantle, where it further undergoes differentiation.
The rocks heated in the central zones of the Earth expand, their density decreases, and they float, giving way to descending colder and therefore heavier masses, which have already given up part of the heat in near-surface zones. This process of heat transfer goes on continuously, resulting in the formation of ordered closed convective cells. At the same time, in the upper part of the cell, the flow of matter occurs in an almost horizontal plane, and it is this part of the flow that determines the horizontal movement of the matter of the asthenosphere and the plates located on it. In general, the ascending branches of convective cells are located under the zones of divergent boundaries (MOR and continental rifts), while the descending branches are located under the zones of convergent boundaries. Thus, the main reason for the movement of lithospheric plates is "drag" by convective currents. In addition, a number of other factors act on the plates. In particular, the surface of the asthenosphere turns out to be somewhat elevated above the zones of ascending branches and more lowered in the zones of subsidence, which determines the gravitational "slip" of the lithospheric plate located on an inclined plastic surface. Additionally, there are processes of pulling the heavy cold oceanic lithosphere in the subduction zones into the hot, and, as a result, less dense, asthenosphere, as well as hydraulic wedging by basalts in the MOR zones.
The main driving forces of plate tectonics are applied to the bottom of the intraplate parts of the lithosphere: the mantle drag forces FDO under the oceans and FDC under the continents, the magnitude of which depends primarily on the velocity of the asthenospheric current, and the latter is determined by the viscosity and thickness of the asthenospheric layer. Since the thickness of the asthenosphere under the continents is much less and the viscosity is much higher than under the oceans, the magnitude of the FDC force is almost an order of magnitude inferior to that of the FDO. Under the continents, especially their ancient parts (continental shields), the asthenosphere almost wedges out, so the continents seem to be “sitting aground”. Since most of the lithospheric plates modern earth include both oceanic and continental parts, it should be expected that the presence of a continent in the composition of the plate in the general case should “slow down” the movement of the entire plate. This is how it actually happens (the fastest moving are the almost purely oceanic plates Pacific, Cocos and Nasca; the slowest are the Eurasian, North American, South American, Antarctic and African, a significant part of whose area is occupied by continents). Finally, at convergent plate boundaries, where the heavy and cold edges of lithospheric plates (slabs) sink into the mantle, their negative buoyancy creates the FNB force (negative buoyance). The action of the latter leads to the fact that the subducting part of the plate sinks in the asthenosphere and pulls the entire plate along with it, thereby increasing the speed of its movement. Obviously, the FNB force acts episodically and only in certain geodynamic settings, for example, in the cases of the collapse of slabs through the 670 km section described above.
Thus, the mechanisms that set the lithospheric plates in motion can be conventionally assigned to the following two groups: 1) associated with the forces of the mantle “dragging” (mantle drag mechanism) applied to any points of the bottom of the plates, in the figure - the forces of FDO and FDC; 2) associated with the forces applied to the edges of the plates (edge-force mechanism), in the figure - the forces FRP and FNB. The role of this or that driving mechanism, as well as these or those forces, is evaluated individually for each lithospheric plate.
The totality of these processes reflects the general geodynamic process, covering areas from the surface to deep zones of the Earth. At present, two-cell closed-cell mantle convection is developing in the Earth's mantle (according to the through-mantle convection model) or separate convection in the upper and lower mantle with the accumulation of slabs under subduction zones (according to the two-tier model). The probable poles of the rise of the mantle matter are located in northeast Africa (approximately under the junction zone of the African, Somali and Arabian plates) and in the area of Easter Island (under the middle ridge of the Pacific Ocean - the East Pacific Rise). The equator of mantle subsidence runs along an approximately continuous chain of convergent plate boundaries along the periphery of the Pacific and eastern Indian Oceans. convection) or (according to an alternative model) convection will become through the mantle due to the collapse of slabs through the 670 km section. This may lead to the collision of the continents and the formation of a new supercontinent, the fifth in the history of the Earth.
Plate movements obey the laws of spherical geometry and can be described on the basis of Euler's theorem. Euler's rotation theorem states that any rotation of three-dimensional space has an axis. Thus, rotation can be described by three parameters: the coordinates of the rotation axis (for example, its latitude and longitude) and the angle of rotation. Based on this position, the position of the continents in past geological epochs can be reconstructed. An analysis of the movements of the continents led to the conclusion that every 400-600 million years they unite into a single supercontinent, which is further disintegrated. As a result of the split of such a supercontinent Pangea, which occurred 200-150 million years ago, modern continents were formed.
Plate tectonics is the first general geological concept that could be tested. Such a check has been made. In the 70s. deep-sea drilling program was organized. As part of this program, several hundred wells were drilled by the Glomar Challenger drillship, which showed good agreement of ages estimated from magnetic anomalies with ages determined from basalts or from sedimentary horizons. The distribution scheme of uneven-aged sections of the oceanic crust is shown in Fig.:
The age of the oceanic crust according to magnetic anomalies (Kenneth, 1987): 1 - areas of lack of data and dry land; 2–8 - age: 2 - Holocene, Pleistocene, Pliocene (0–5 Ma); 3 - Miocene (5–23 Ma); 4 - Oligocene (23–38 Ma); 5 - Eocene (38–53 Ma); 6 - Paleocene (53–65 Ma) 7 - Cretaceous (65–135 Ma) 8 - Jurassic (135–190 Ma)
At the end of the 80s. completed another experiment to test the movement of lithospheric plates. It was based on baseline measurements relative to distant quasars. Points were selected on two plates, at which, using modern radio telescopes, the distance to quasars and their declination angle were determined, and, accordingly, the distances between points on two plates were calculated, i.e., the baseline was determined. The accuracy of the determination was a few centimeters. Several years later, the measurements were repeated. Very good convergence of results calculated from magnetic anomalies with data determined from baselines was obtained.
Scheme illustrating the results of measurements of the mutual displacement of lithospheric plates, obtained by the method of interferometry with an extra long baseline - ISDB (Carter, Robertson, 1987). The movement of the plates changes the length of the baseline between radio telescopes located on different plates. The map of the Northern Hemisphere shows the baselines from which the ISDB measured enough data to make a reliable estimate of the rate of change in their length (in centimeters per year). The numbers in parentheses indicate the amount of plate displacement calculated from the theoretical model. In almost all cases, the calculated and measured values are very close.
Thus, lithospheric plate tectonics has been tested over the years by a number of independent methods. It is recognized by the world scientific community as the paradigm of geology at the present time.
Knowing the position of the poles and the speed of the current movement of lithospheric plates, the speed of expansion and absorption of the ocean floor, it is possible to outline the path of movement of the continents in the future and imagine their position for a certain period of time.
Such a forecast was made by American geologists R. Dietz and J. Holden. After 50 million years, according to their assumptions, the Atlantic and Indian oceans will grow at the expense of the Pacific, Africa will shift to the north and due to this, the Mediterranean Sea will gradually be liquidated. The Strait of Gibraltar will disappear, and the “turned” Spain will close the Bay of Biscay. Africa will be split by the great African faults and the eastern part of it will shift to the northeast. The Red Sea will expand so much that it will separate the Sinai Peninsula from Africa, Arabia will move to the northeast and close the Persian Gulf. India will increasingly move towards Asia, which means that the Himalayan mountains will grow. California will separate from North America along the San Andreas Fault, and a new ocean basin will begin to form in this place. Significant changes will occur in the southern hemisphere. Australia will cross the equator and come into contact with Eurasia. This forecast requires significant refinement. Much here is still debatable and unclear.
sources
http://www.pegmatite.ru/My_Collection/mineralogy/6tr.htm
http://www.grandars.ru/shkola/geografiya/dvizhenie-litosfernyh-plit.html
http://kafgeo.igpu.ru/web-text-books/geology/platehistory.htm
http://stepnoy-sledopyt.narod.ru/geologia/dvizh/dvizh.htm
And let me remind you, but here are some interesting ones and this one. Look at and The original article is on the website InfoGlaz.rf Link to the article from which this copy is made -The drift of the first research expedition led by Ivan Papanin began in May 1937. 9 months of work, observations and research of the North Pole station ended when an ice floe collapsed in the Greenland Sea and scientists had to curtail their activities. The entire Soviet Union watched the epic rescue of the four Papanins.
Ivan Dmitrievich Papanin
The ideologist of this expedition was Otto Yulievich Schmidt. After Stalin's approval, he quickly found people for this project - all of them were not new to the Arctic campaigns. The efficient team consisted of four people: Ivan Papanin, Ernst Krenkel, Evgeny Fedorov and Pyotr Shirshov. The head of the expedition was Ivan Dmitrievich Papanin.
Although he was born on the Black Sea coast in Sevastopol in the family of a sailor, he connected his life with the seas of the Arctic Ocean. Papanin was first sent to the Far North in 1925 to build a radio station in Yakutia. In 1931, he participated in the voyage of the Malygin icebreaker to the Franz Josef Land archipelago, a year later he returned to the archipelago as the head of a field radio station, and then created a scientific observatory and a radio center at Cape Chelyuskin.
P.P. Shirshov
Hydrobiologist and hydrologist Pyotr Petrovich Shirshov was also not new to Arctic expeditions. He graduated from the Odessa Institute of Public Education, was an employee of the Botanical Garden of the Academy of Sciences, but he was attracted by travel, and in 1932 he was hired on an expedition to the icebreaker A. Sibiryakov", and a year later became a member of the tragic flight on the Chelyuskin.
E.K. Fedorov
The youngest member of the expedition was Evgeny Konstantinovich Fedorov. He graduated from Leningrad University in 1934 and devoted his life to geophysics and hydrometeorology. Fedorov was familiar with Ivan Papanin even before this expedition "North Pole - 1". He worked as a magnetologist at the polar station in Tikhaya Bay at the FJL, and then at the observatory at Cape Chelyuskin, where Ivan Papanin was his boss. After these winterings, Fedorov was included in the team for drifting on an ice floe.
THIS. Krenkel
The virtuoso radio operator Ernst Teodorovich Krenkel in 1921 graduated from the courses of radiotelegraph operators. At the final exams, he showed such a high speed in Morse code that he was immediately sent to the Lyubertsy radio station. Since 1924, Krenkel worked in the Arctic - first at Matochkin Shar, then at several more polar stations of Novaya and Severnaya Zemlya. In addition, he participated in expeditions on the "Georgy Sedov" and "Sibiryakov" and in 1930 managed to set a world record by contacting the American Antarctic station from the Arctic.
Dog Cheerful
Another full member of the expedition is the dog Vesely. It was presented by the winterers of the island of Rudolf, from which the planes made a throw to the pole. He brightened up the monotonous life on the ice floe and was the soul of the expedition. The thieving dog never denied himself the pleasure, on occasion, of sneaking into a warehouse with food and stealing something edible. In addition to enlivening the atmosphere, Vesely's main duty was to warn of the approach of polar bears, which he did very well.
There was no doctor on the expedition. His duties were assigned to Shirshov.
When preparing the expedition, we tried to take into account everything possible - from the operating conditions of the equipment to household trifles. The Papaninites were provided with a solid supply of provisions, a field laboratory, a windmill that generated energy, and a radio station for communication with the earth. However, the main feature of this expedition was that it was prepared on the basis of theoretical ideas about the conditions of stay on the ice floe. But without practice, it was difficult to imagine how the expedition could end and, most importantly, how to remove scientists from the ice floe at all.
A tent served as a dwelling and camping laboratory for the duration of the drift. The structure was small - 4 by 2.5 meters. It was insulated according to the principle of a down jacket: the frame was covered with three covers: the inner one was made of canvas, the middle one was made of silk stuffed with eiderdown, the outer one was made of thin black tarpaulin soaked in a waterproof composition. Deer skins lay on the canvas floor of the tent as insulation.
The Papaninites recalled that it was very crowded inside and they were afraid to hurt something - laboratory samples were also stored in the tent, raised from the depths of the Arctic Ocean and alcoholized in flasks.
Papanin is preparing dinner
The requirements for the nutrition of polar explorers were quite strict - each day the diet of each had to consist of food with a calorie content of up to 7000 kcal. At the same time, the food had to be not only nutritious, but also contain a significant amount of vitamins - mainly vitamin C. Concentrated soup mixtures were specially developed to feed the expedition - a kind of current bouillon cubes, only more healthy and rich. One pack of such a mixture was enough to cook a good soup for four members of the expedition. In addition to soups, porridge and compotes could be prepared from such mixtures. Even cutlets were prepared dry for the expedition - in total, about 40 types of instant concentrates were developed - this required only boiling water, and all the food was ready in 2-5 minutes.
In addition to the usual dishes, completely new products with an interesting taste appeared in the diet of polar explorers: in particular, crackers, 23 percent meat, and “salty chocolate with an admixture of meat and chicken powder.” In addition to concentrates, the Papanin people had butter, cheese, and even sausage in their diet. The expedition members were also provided with vitamin tablets and sweets.
All dishes were made according to the principle that one item fits into another to save space. This subsequently began to be used by manufacturers of dishes not only expeditionary, but also ordinary, household.
Almost immediately after landing on the ice floe, work began. Petr Shirshov carried out depth measurements, took soil samples, water samples at different depths, determined its temperature, salinity, and oxygen content in it. All samples were immediately processed in the field laboratory. Evgeny Fedorov was responsible for meteorological observations. Atmospheric pressure, temperature, relative humidity, wind direction and speed were measured. All information was transmitted by radio to Rudolf Island. These communication sessions were carried out 4 times a day.
For communication with the earth, the central radio laboratory in Leningrad manufactured two radio stations on special order - a powerful 80 watt and a 20-watt emergency one. The main power source for them was a windmill (besides it there was a hand-operated engine). All this equipment (its total weight was about 0.5 tons) was made under the personal supervision of Krenkel and the guidance of radio engineer N.N. Stromilova.
Difficulties began in January 1938. The ice floe drifted south and fell into bad weather. A crack appeared on it, and its size rapidly decreased. However, the polar explorers tried to maintain peace of mind and observed the usual daily routine.
“In the tent, our nice old living tent, the kettle was boiling, supper was being prepared. Suddenly, in the midst of pleasant preparations, there was a sharp push and a creaking rustle. It seemed that silk or linen was being torn somewhere nearby, ”Krenkel recalled how the ice cracked.
“Dmitrich (Ivan Papanin) could not sleep. He smoked (the first sign of excitement) and busied himself with household chores. Sometimes he looked longingly at the loudspeaker suspended from the ceiling. When pushed, the loudspeaker swayed slightly and rattled. In the morning Papanin offered to play chess. They played thoughtfully, calmly, with full awareness of the importance of the work being done. And suddenly, through the roar of the wind, an unusual noise broke through again. The ice floe shook convulsively. We still decided not to stop the game,” he wrote about the moment when the ice floe cracked right under the tent.
Krenkel then quite casually transmitted Papanin's message on the radio: “As a result of a six-day storm at 8 o'clock in the morning on February 1, in the area of \u200b\u200bthe station, the field was torn apart by cracks from half a kilometer to five. We are on a fragment of a field 300 meters long and 200 meters wide (the initial size of the ice floe was approximately 2 by 5 kilometers). Cut off two bases, also a technical warehouse with secondary property. Everything of value was saved from the fuel and utility depots. There was a crack under the living tent. We will move to the snow house. Coordinates will inform additionally today; If the connection is interrupted, please do not worry.
The ships "Taimyr" and "Murman" have already moved to the polar explorers, but it was not easy to get to the station due to the difficult ice conditions. The planes also could not take the polar explorers from the ice floe - the platform for their landing on the ice collapsed, and one plane sent from the ship itself got lost, and a rescue expedition was created to search for it. The ships were able to break through to the station only when a polynya formed, they received significant damage in the ice along the way.
February 19 at 13:40 "Murman" and "Taimyr" moored to the ice field 1.5 kilometers from the polar station. They took on board all the members of the expedition and their equipment. The last message of the expedition was as follows: “... At this hour we are leaving the ice floe at the coordinates of 70 degrees 54 minutes north, 19 degrees 48 minutes wind and passing over 2500 km in 274 days of drift. Our radio station was the first to announce the news of the conquest of the North Pole, ensured reliable communication with the Motherland, and this telegram ends its work.” On February 21, the Papaninites switched to the Yermak icebreaker, which delivered them to Leningrad on March 16.
The scientific results obtained in a unique drift were presented to the General Meeting of the USSR Academy of Sciences on March 6, 1938 and were highly appreciated by specialists. All members of the expedition were awarded academic degrees and titles of Heroes of the Soviet Union. This title was also awarded to pilots - A.D. Alekseev, P.G. Golovin, I.P. Mazuruk and M.I. Shevelev.
Thanks to this first expedition, the following ones became possible - in the 1950s, the North Pole - 2 expedition followed, and soon such winterings became permanent. In 2015, the last expedition "North Pole" took place.
The average value of irregularities in the lower surface of the pack ice is approximately 3 m, which significantly affects the nature of the propagation of sound energy emitted by hydroacoustic instruments, making it difficult to detect polynyas. However, for correct orientation in an ice situation, it is necessary to know not only the nature of the ice surface, but also its shape, size and concentration.
In terms of shapes and sizes, ice fields and broken ice are distinguished. Ice fields are divided into vast (more than 10 km across), large (2-10 km, small (0.5-2 km) and fragments (100-500 m). m), small-sized (2-20 m), pieces (0.5-2.0 m) and ice porridge. Broken ice in polynyas and leads makes it very difficult to ascend. Therefore, the equipment designed to provide this maneuver must have a high resolution , which makes it possible to distinguish between finely broken ice and even pieces, since they can damage the wheelhouse fence, retractable devices, rudders and propellers, which, for example, happened to the American submarine Karp.
The possibility of ascent also depends on the concentration (density) of the drifting ice. Cohesion is the ratio of the total area of ice, which is illuminated by the sound beam of a hydroacoustic device, to the area of clear water gaps between individual ice floes. It should be remembered that drifting ice, as a rule, covers the sea unevenly (especially in summer) and its density varies in different sectors.
Icebergs and ice islands pose a great danger during under-ice navigation. Icebergs are found in many areas of the Arctic Ocean. The height of their above-water part reaches 50 m, while the draft is several times higher than this value. There are icebergs 2-2.5 km long and up to 1.5 km wide. It is clear that an unexpected encounter with such an underwater obstacle threatens the submarine with major troubles. In this case, hydroacoustic equipment comes to the rescue of submariners - sonars and iceberg meters, but the difficulties of under-ice navigation still remain quite significant.
Icebergs enter the CAB mainly from the area of Franz Josef Land, Severnaya Zemlya; here are the most of them. Ice mountains, which are born in the regions of Greenland and Svalbard, almost do not fall into high latitudes. Polar explorers note that the number of icebergs can change dramatically from year to year.”
At the end of the 1940s, Soviet polar pilots discovered drifting ice islands in the TsAB and the adjacent Arctic seas. Now there are about two dozen known. The largest of them (discovered in April 1948 by pilot I.P. Mazuruk has dimensions of 17x18 miles. The thickness of drifting ice islands varies from 50 to 70 m, the specific gravity of ice is from 0.87 to 0.92 g / cm 3 , the draft reaches 50 m.
Despite the numerous and obvious difficulties of under-ice voyages to high latitudes, except for nuclear submarines of the Soviet Union under the polar ice cap, last years submarines of the USA, England and France visited. He also floated to the surface in areas of clear water or in young thin ice. The correct assessment of the possibility of ascent largely depends on the determination of the size and nature of such spaces. In this regard, we will consider in more detail the characteristics of such forms as a polynya, a lead, a channel, a crack, a window.
A polynya is a fairly stable expanse of clear water among ice fields. The sizes of polynyas are very different: from several tens of square meters to tens of square kilometers. Most often they have the shape of a rectangle, square or circle. However, there are giant polynyas, elongated in length. Their size and location certainly represent great interest, especially since they are detected in advance and fixed by aerial reconnaissance. So, from the Soviet aircraft H-169 on March 2-3, 1941, in the area of the "pole of relative inaccessibility", polynyas up to 500 m wide and up to 18 km long were observed; occasionally came across vast expanses of clear water up to 10 km wide and up to 45 km long. In addition, two large open spaces of clear water constantly exist in the Central Arctic Basin: the "Siberian Polynya" north of the New Siberian Islands and Severnaya Zemlya and the "Great Polynya" northeast of Ellesmere Island. Aerial reconnaissance also revealed that the formation of large polynyas occurring at the border of drifting ice and fast ice is mainly associated with the wind regime.
A brook is a less stable expanse of clear water several tens of meters wide, subject to the action of winds and tides. The most characteristic form of dilutions is elongated, up to several kilometers long. Leads are often curved, making it difficult to choose a site for ascent.
A channel is a narrow long strip of water (the length is more than 10 times the width between large ice floes, which usually appears as a result of the expansion of cracks. As the researchers note, channels, as well as polynyas and leads, are found in the central Arctic not only in summer, but also in Due to their small width, it is difficult to detect channels with the help of echometers, which was noted in his book "Sea Dragon" by the commander of the American nuclear submarine D. Steele during a special flight over the Arctic ice.
A fissure is a gap in the ice up to 10 m wide. When swimming under ice, it is useful to mark the location of long cracks on the map, since it is known that in a short time a narrow crack can turn into a fairly wide channel. Cracks can be used for radio communication by releasing special buoy radio antennas into them.
Window is an unsettled term adopted to refer to areas of young ice covering the surface of polynyas, leads and channels. The window is clearly visible through the periscope. It stands out as a bright spot against a darker background of the rest of the surface, covered with thick pack ice.
The formation of young ice in polynyas, leads and channels begins in the first half of September, and sometimes even in the second half of August. Its growth rate depends primarily on the air temperature. At minus 40 °C, one can expect an increase in ice thickness by an average of 2.5 cm in a few hours, in a week - by 30 cm, in a month - up to 1 m. other devices that provide swimming in the winter.
For a successful ascent, it is also important to take into account the course, nature, direction and speed of ice drift in general and individual ice formations in particular. In confirmation, we can cite an example when the submarine "Skate" in a lead about 100 m wide, due to disregard for ice drift, could not surface the first time. The maneuver succeeded only after careful consideration of the ice drift and the submarine's ascent rate.
Project 613 submarine in Arctic ice.
What does ice drift depend on and what are its elements? Professor N.N. Zubov gives three most characteristic cases:
– wind drift of close-packed ice, causing even an independent drift under-ice current;
- drift of an individual ice floe under the action of wind on its upper part and wind current to the bottom;
- wind drift of rarefied ice, when it turns out that each ice floe (due to differences in shape and size) drifts in its own way, which is especially dangerous when ascending, since the ice situation in such cases changes very quickly.
The drift direction of ice in steady winds differs from the wind direction by about 30° to the right, and the dependence of the drift velocity on the wind velocity is determined in the general case by a wind coefficient equal to 0.32. The direction of the wind current (when there is no ice on the sea surface) deviates from the direction of the wind by 45° to the right.
The reasons causing the general movement of large masses of ice in the CAB are mainly constant currents and prevailing winds associated with the distribution of atmospheric pressure. Under the influence of these factors, a significant part of the ice is carried out into the passage between Greenland and Svalbard. In the sector adjacent to America, the ice drifts clockwise in a vicious circle. These general directions become noticeable only at great distances. When drifting, ice floes usually describe bizarre loops and zigzags and often return to their original points. With regard to annual fluctuations in the removal of ice, the famous Soviet polar explorers N.A. Volkov and Z.M. Gudkovich note: “The average speed of the surface outflow current also changes noticeably during the year. The maximum speed is in July-September, and the minimum is in October-December.