Indian Ocean description, interesting facts. Position and area of ​​the Indian Ocean

Indian Ocean has the fewest seas compared to other oceans. In the northern part are located the most large seas: Mediterranean - the Red Sea and the Persian Gulf, the semi-enclosed Andaman Sea and the marginal Arabian Sea; in the eastern part - the Arafura and Timor seas.

There are relatively few islands. The largest of them mainland origin and are located near the coast: Madagascar, Sri Lanka, Socotra. In the open part of the ocean, there are volcanic islands - Mascarene, Crozet, Prince Edward, etc. In tropical latitudes, coral islands rise on volcanic cones - Maldives, Laccadive, Chagos, Cocos, most of the Andaman, etc.

Shores in the N.-W. and the East are indigenous, in the S.-V. and the West are dominated by alluvial. The coastline is slightly indented, with the exception of the northern part of the Indian Ocean. Almost all the seas and large bays (Aden, Oman, Bengal) are located here. In the southern part there are the Gulf of Carpentaria, the Great Australian Gulf and the gulfs of Spencer, St. Vincent, etc.

A narrow (up to 100 km) continental shelf (shelf) stretches along the coast, the outer edge of which has a depth of 50-200 m (only near Antarctica and northwestern Australia up to 300-500 m). The continental slope is a steep (up to 10-30°) ledge, locally dissected by the underwater valleys of the Indus, Ganges, and other rivers. m). The bed of the Indian Ocean is divided by ridges, mountains and ramparts into a number of basins, the most significant of which are the Arabian Basin, the West Australian Basin, and the African-Antarctic Basin. The bottom of these basins is formed by accumulative and hilly plains; the first are located near the continents in areas with an abundant supply of sedimentary material, the second - in the central part of the ocean. Among the numerous ridges of the bed, the straightness and length (about 5,000 km) distinguish the meridional East Indian Ridge, which connects in the south with the latitudinal West Australian Ridge; large meridional ridges stretch to the south from the Hindustan peninsula and about. Madagascar. Volcanoes are widely represented on the ocean floor (the city of Bardina, the city of Shcherbakov, the city of Lena, etc.), which in places form large arrays(to the north of Madagascar) and chains (to the east of the Cocos Islands). The mid-ocean ridges are a mountain system consisting of three branches that radiate from the central part of the ocean to the north (Arabian-Indian ridge), southwest. (West Indian and African-Antarctic ridges) and Yu.-V. (Central Indian Ridge and Australo-Antarctic Rise). This system has a width of 400–800 km, a height of 2–3 km, and is most dissected by an axial (rift) zone with deep valleys and rift mountains bordering them; transverse faults are characteristic, along which horizontal displacements of the bottom up to 400 km are noted. The Australo-Antarctic Rise, in contrast to the median ridges, is a gentler swell 1 km high and up to 1500 km wide.

Bottom sediments the Indian Ocean have the greatest thickness (up to 3-4 km) at the foot of the continental slopes; in the middle of the ocean - small (about 100 m) thickness and in places where the dissected relief is distributed - discontinuous distribution. The most widely represented are foraminiferal (on continental slopes, ridges, and at the bottom of most basins at depths up to 4700 m), diatoms (south of 50° S), radiolarian (near the equator), and coral sediments. Polygenic sediments - red deep-sea clays - are distributed south of the equator at a depth of 4.5-6 km or more. Terrigenous sediments - off the coast of the continents. Chemogenic sediments are mainly represented by iron-manganese nodules, while riftogenic sediments are represented by destruction products of deep rocks. Outcrops of bedrocks are most often found on continental slopes (sedimentary and metamorphic rocks), mountains (basalts) and mid-ocean ridges, where, in addition to basalts, serpentinites and peridotites have been found, representing a slightly altered substance of the Earth's upper mantle.

The Indian Ocean is characterized by the predominance of stable tectonic structures both on the bed (thalassocratons) and along the periphery (continental platforms); active developing structures - modern geosynclines (Sonda arc) and georiftogenals (mid-ocean ridge) - occupy smaller areas and continue in the corresponding structures of Indochina and rifts of East Africa. These main macrostructures, which differ sharply in morphology, the structure of the earth's crust, seismic activity, and volcanism, are subdivided into smaller structures: plates, usually corresponding to the bottom of oceanic basins, blocky ridges, volcanic ridges, sometimes topped with coral islands and banks (Chagos, Maldives, etc.). .), trench-faults (Chagos, Ob, etc.), often confined to the foot of blocky ridges (East Indian, West Australian, Maldives, etc.), fault zones, tectonic ledges. Among the structures of the bed of the Indian Ocean special place(according to the presence of continental rocks - granites of the Seychelles and the continental type of the earth's crust) occupies the northern part of the Mascarene Range - a structure that, apparently, is part of the ancient mainland of Gondwana.

Minerals: on the shelves - oil and gas (especially the Persian Gulf), monazite sands (the coastal region of Southwestern India), etc.; in rift zones - ores of chromium, iron, manganese, copper, etc.; on the bed - huge accumulations of iron-manganese nodules.

The climate of the northern part of the Indian Ocean is monsoonal; in summer, when an area of ​​low pressure develops over Asia, southwestern flows of equatorial air dominate here, in winter - northeastern flows of tropical air. South of 8-10 ° S sh. atmospheric circulation is much more constant; here, in tropical (summer and subtropical) latitudes, stable southeasterly trade winds dominate, and in temperate latitudes, extratropical cyclones moving from West to East. In tropical latitudes in the western part, hurricanes occur in summer and autumn. average temperature air in the northern part of the ocean in summer is 25-27 ° C, off the coast of Africa - up to 23 ° C. In the southern part, it decreases in summer to 20-25 ° C at 30 ° S. sh., up to 5-6 ° С at 50 ° S. sh. and below 0 ° С south of 60 ° S. sh. In winter, the air temperature varies from 27.5 °C near the equator to 20 °C in the northern part, to 15 °C at 30 ° S. sh., up to 0-5 ° С at 50 ° S. sh. and below 0 ° С south of 55-60 ° S. sh. At the same time, in the southern subtropical latitudes, the temperature in the West all year round under the influence of the warm Madagascar current is 3-6 °C higher than in the East, where the cold West Australian current exists. Cloudiness in the monsoon northern part of the Indian Ocean in winter is 10-30%, in summer up to 60-70%. In the summer there is also the largest number precipitation. The average annual precipitation in the east of the Arabian Sea and the Bay of Bengal is more than 3000 mm, near the equator 2000-3000 mm, in the west of the Arabian Sea up to 100 mm. In the southern part of the ocean, the average annual cloudiness is 40-50%, south of 40 ° S. sh. - up to 80%. The average annual precipitation in the subtropics is 500 mm to the east and 1,000 mm to the west; in temperate latitudes, more than 1,000 mm; near Antarctica, it drops to 250 mm.

The circulation of surface waters in the northern part of the Indian Ocean has a monsoonal character: in summer - northeast and east current, in winter - southwestern and western current. During the winter months between 3° and 8° S. sh. an inter-trade (equatorial) countercurrent develops. In the southern part of the Indian Ocean, water circulation forms an anticyclonic circulation, which is formed from warm currents - the South Trade Winds in the north, Madagascar and Needles in the West, and cold currents - the West Winds in the South and the West Australian in the East South of 55 ° S. sh. several weak cyclonic water cycles develop, closing off the coast of Antarctica with an easterly current.

The heat balance is dominated by a positive component: between 10° and 20° N. sh. 3.7-6.5 GJ/(m2×year); between 0° and 10°S sh. 1.0-1.8 GJ/(m2×year); between 30° and 40°S sh. - 0.67-0.38 GJ/(m2×year) [from - 16 to 9 kcal/(cm2×year)]; between 40° and 50°S sh. 2.34-3.3 GJ/(m2×year); south of 50°S sh. -1.0 to -3.6 GJ/(m2×yr) [-24 to -86 kcal/(cm2×yr)]. In the expenditure part of the heat balance north of 50 ° S. sh. the main role belongs to the cost of heat for evaporation, and south of 50 ° S. sh. - heat exchange between the ocean and the atmosphere.

The surface water temperature reaches its maximum (over 29 °C) in May in the northern part of the ocean. In the summer of the Northern Hemisphere, it is 27-28 ° C here, and only off the coast of Africa decreases to 22-23 ° C under the influence of cold waters coming to the surface from the depths. At the equator, the temperature is 26-28 ° C and decreases to 16-20 ° C at 30 ° S. sh., up to 3-5 ° С at 50 ° S. sh. and below -1 ° С south of 55 ° S. sh. In the winter of the Northern Hemisphere, the temperature in the north is 23–25°C, at the equator 28°C, and at 30°S. sh. 21-25 ° С, at 50 ° S sh. from 5 to 9 ° С, south of 60 ° S sh. temperatures are negative. In subtropical latitudes all year round in the West, the water temperature is 3-5 °C higher than in the East.

The salinity of water depends on the water balance, which is formed on average for the surface of the Indian Ocean from evaporation (-1380 mm/year), precipitation (1000 mm/year) and continental runoff (70 cm/year). Main stock fresh water give the rivers of South Asia (Ganges, Brahmaputra, etc.) and Africa (Zambezi, Limpopo). The highest salinity is observed in the Persian Gulf (37-39‰), in the Red Sea (41‰) and in the Arabian Sea (more than 36.5‰). In the Bay of Bengal and the Andaman Sea, it decreases to 32.0-33.0‰, in the southern tropics - to 34.0-34.5‰. In the southern subtropical latitudes, salinity exceeds 35.5‰ (maximum 36.5‰ in summer, 36.0‰ in winter), and south of 40°S. sh. drops to 33.0-34.3‰. The highest water density (1027) is observed in the Antarctic latitudes, the lowest (1018, 1022) - in the northeastern part of the ocean and in the Bay of Bengal. In the northwestern part of the Indian Ocean, the density of water is 1024-1024.5. The oxygen content in the surface water layer increases from 4.5 ml/l in the northern part of the Indian Ocean to 7-8 ml/l south of 50°S. sh. At depths of 200-400 m, the oxygen content is much lower in absolute value and varies from 0.21-0.76 in the north to 2-4 ml / l in the south, at greater depths it gradually increases again and in the bottom layer is 4.03 -4.68 ml/l. The color of the water is predominantly blue, in the Antarctic latitudes it is blue, in some places with greenish hues.

The tides in the Indian Ocean are usually low (off the coast open ocean and on the islands from 0.5 to 1.6 m), only in the tops of some bays they reach 5-7 m; in the Gulf of Cambay 11.9 m. The tides are predominantly semi-diurnal.

Ice forms at high latitudes and is carried by winds and currents along with icebergs in a northerly direction (up to 55°S in August and up to 65-68°S in February).

The deep circulation and vertical structure of the Indian Ocean are shaped by waters plunging into the subtropical (under surface water) and Antarctic (intermediate waters) zones of convergence and along the continental slope of Antarctica (bottom waters), as well as coming from the Red Sea and the Atlantic Ocean (deep waters). Subsurface waters have a temperature of 10-18°C at a depth of 100-150 m to 400-500 m, salinity of 35.0-35.7‰, intermediate waters occupy a depth of 400-500 m to 1000-1500 m, have a temperature of 4 to 10°C, salinity 34.2-34.6‰; deep waters at a depth of 1000-1500 m to 3500 m have a temperature of 1.6 to 2.8 ° C, salinity of 34.68-34.78‰; bottom waters below 3500 m in the south have a temperature of -0.07 to -0.24 ° C, salinity 34.67-34.69 ‰, in the north - about 0.5 ° C and 34.69-34.77 ‰ respectively.

Flora and fauna

The entire water area of ​​the Indian Ocean lies within the tropical and southern temperate. The shallow waters of the tropical zone are characterized by numerous 6- and 8-ray corals, hydrocorals, capable of creating islands and atolls together with calcareous red algae. The richest fauna of various invertebrates (sponges, worms, crabs, mollusks, sea ​​urchins, ophiurs and sea ​​stars), small but brightly colored coral fish. Most of the coasts are occupied by mangroves, in which the mudskipper stands out - a fish capable of long time exist in the air. The fauna and flora of the beaches and rocks that dry out at low tide are quantitatively depleted as a result of the depressing effect of the sun's rays. In the temperate zone, life on such stretches of coasts is much richer; dense thickets of red and brown algae (kelp, fucus, reaching the enormous size of macrocystis) develop here, various invertebrates are abundant. For open spaces The Indian Ocean, especially for the surface layer of the water column (up to 100m), is also characterized by rich flora. Of the unicellular planktonic algae, several species of peredinium and diatom algae predominate, and in the Arabian Sea - blue-green algae, which often cause the so-called water bloom during mass development.

Copepods (more than 100 species) make up the bulk of the ocean's animals, followed by pteropods, jellyfish, siphonophores, and other invertebrates. Of the unicellular, radiolarians are characteristic; numerous squids. Of the fish, the most abundant are several species of flying fish, luminous anchovies - myctophids, dolphins, large and small tuna, sailfish and various sharks, poisonous sea snakes. common sea ​​turtles and major marine mammals(dugongs, toothed and toothless whales, pinnipeds). Among the birds, the most characteristic are albatrosses and frigates, as well as several species of penguins that inhabit the coasts of South Africa, Antarctica and the islands that lie in the temperate zone of the ocean.

Introduction

1.History of the formation and exploration of the Indian Ocean

2.General information about the Indian Ocean

Bottom relief.

.Characteristics of the waters of the Indian Ocean.

.Bottom sediments of the Indian Ocean and its structure

.Minerals

.Climate of the Indian Ocean

.Flora and fauna

.Fishing and marine industry

Introduction

Indian Ocean- the youngest and warmest among the world's oceans. Most of it is in the southern hemisphere, and in the north it goes far into the mainland, which is why ancient people considered it just a big sea. It was here, in the Indian Ocean, that man began his first sea voyages.

belong to the Indian Ocean basin major rivers Asia: Salween, Irrawaddy and Ganges with Brahmaputra flowing into the Bay of Bengal; the Indus, which flows into the Arabian Sea; Tigris and Euphrates, merging a little above the confluence with the Persian Gulf. Of the major rivers of Africa, which also flow into the Indian Ocean, the Zambezi and Limpopo should be mentioned. Because of them, the water off the coast of the ocean is muddy, with a high content of sedimentary rocks - sand, silt and clay. But the open waters of the ocean are amazingly clear. The tropical islands of the Indian Ocean are famous for their cleanliness. A variety of animals have found their place on coral reefs. The Indian Ocean is home to the famous sea devils, rare whale sharks, bigmouths, sea cows, sea snakes, etc.

1. History of formation and research

Indian Oceanformed at the junction of the Jurassic and Cretaceous periods as a result of the collapse of Gondwana (130-150 million years ago). Then there was a separation of Africa and the Deccan from Australia with Antarctica, and later - Australia from Antarctica (in the Paleogene, about 50 million years ago).

The Indian Ocean and its shores remain poorly explored. The name of the Indian Ocean is found already at the beginning of the 16th century. Schöner under the name Oceanus orientalis indicus, in contrast to the Atlantic Ocean, then known as Oceanus occidentalis. Subsequent geographers called the Indian Ocean mostly the Sea of ​​India, some (Varenius) the Australian Ocean, and Fleurie recommended (in the 18th century) to call it even the Great Indian Gulf, considering it as part of the Pacific Ocean.

In ancient times (3000-1000 BC), sailors from India, Egypt and Phoenicia traveled across the northern part of the Indian Ocean. The first navigation charts were compiled by the ancient Arabs. At the end of the 15th century, the first European, the famous Portuguese Vasco da Gama, circled Africa from the south and entered the waters of the Indian Ocean. By the 16th-17th centuries, Europeans (the Portuguese, and later the Dutch, French and British) increasingly appeared in the Indian Ocean basin, and by the middle of the 19th century, most of its coasts and islands were already the property of Great Britain.

Discovery historycan be divided into 3 periods: from ancient voyages to 1772; from 1772 to 1873 and from 1873 to the present. The first period is characterized by the study of the distribution of ocean and land waters in this part of the globe. It began with the first voyages of the Indian, Egyptian and Phoenician sailors, which for 3000-1000 years BC. traveled through the northern part of the Indian Ocean, and ended with the voyage of J. Cook, who in 1772-75 penetrated south to 71 ° S. sh.

The second period was marked by the beginning of deep-sea research, first conducted by Cook in 1772 and continued by Russian and foreign expeditions. The main Russian expeditions were - O. Kotzebue on the "Rurik" (1818) and Pallen on the "Cyclone" (1858-59).

The third period is characterized by complex oceanographic research. Until 1960 they were carried out on separate ships. The largest work was carried out by expeditions on the ships Challenger (English) in 1873-74, Vityaz (Russian) in 1886, Valdivia (German) in 1898-99 and Gauss (German) in 1901-03, "Discovery II" (English) in 1930-51, the Soviet expedition to the "Ob" in 1956-58, etc. In 1960-65, the Intergovernmental Oceanographic Expedition under UNESCO conducted an international Indian Ocean Expedition, which collected new valuable data on hydrology, hydrochemistry, meteorology , geology, geophysics and biology of the Indian Ocean.

. General information

Indian Ocean- the third largest ocean of the Earth (after the Pacific and Atlantic), covering about 20% of its water surface. Almost all of it is in the southern hemisphere. Its area is 74917 thousand km ² ; average volume of water - 291945 thousand km ³. In the north it is bounded by Asia, in the west by the Arabian Peninsula and Africa, in the east by Indochina, the Sunda Islands and Australia, in the south by Southern Ocean. border between Indian and Atlantic Ocean runs along the 20° meridian east longitude (meridian Cape Agulhas), between Indian and Pacific Ocean passes along the 147 ° meridian of east longitude (meridian of the southern cape of the island of Tasmania). The most north point The Indian Ocean is located at approximately 30° north latitude in the Persian Gulf. The width of the Indian Ocean is approximately 10,000 km between the southern points of Australia and Africa.

The greatest depth of the Indian Ocean is the Sunda, or Java Trench (7729 m), the average depth is 3700 m.

The Indian Ocean washes three continents at once: Africa from the east, Asia from the south, Australia from the north and northwest.

The Indian Ocean has the fewest seas compared to other oceans. The largest seas are located in the northern part: the Mediterranean - the Red Sea and the Persian Gulf, the semi-enclosed Andaman Sea and the marginal Arabian Sea; in the eastern part - the Arafura and Timor seas.

In the Indian Ocean, there are the island states of Madagascar (the fourth largest island in the world), Sri Lanka, the Maldives, Mauritius, the Comoros, and the Seychelles. The ocean washes in the east such states: Australia, Indonesia; in the northeast: Malaysia, Thailand, Myanmar; in the north: Bangladesh, India, Pakistan; in the west: Oman, Somalia, Kenya, Tanzania, Mozambique, South Africa. In the south it borders on Antarctica. There are relatively few islands. In the open part of the ocean, there are volcanic islands - Mascarene, Crozet, Prince Edward, etc. In tropical latitudes, coral islands rise on volcanic cones - Maldives, Laccadive, Chagos, Cocos, most of the Andaman, etc.

. Bottom relief

The ocean floor is a system of mid-ocean ridges and basins. In the region of Rodrigues Island (Mascarene Archipelago) there is a so-called triple junction, where the Central Indian and West Indian ridges converge, as well as the Australo-Antarctic Rise. The ridges consist of steep mountain ranges, cut by normal or oblique faults with respect to the axes of the chains, and divide the basalt ocean floor into 3 segments, and their tops are, as a rule, extinct volcanoes. The bottom of the Indian Ocean is covered with deposits of the Cretaceous and later periods, the thickness of which varies from several hundred meters to 2-3 km. The deepest of the numerous trenches of the ocean is the Yavan (4,500 km long and 29 km wide). The rivers flowing into the Indian Ocean carry with them huge amounts of sedimentary material, especially from the territory of India, creating high alluvial rapids.

The coast of the Indian Ocean is replete with cliffs, deltas, atolls, coastal coral reefs and salt marshes overgrown with mangroves. Some islands - for example, Madagascar, Socotra, Maldives - are fragments of ancient continents. Numerous islands and archipelagos of volcanic origin are scattered in the open part of the Indian Ocean. In the northern part of the ocean, many of them are crowned with coral structures. Andaman, Nicobar or Christmas Island - are of volcanic origin. Volcanic origin also has the Kerguelen Plateau located in the southern part of the ocean.

An underwater earthquake in the Indian Ocean on December 26, 2004 triggered a tsunami, which was recognized as the deadliest natural disaster in modern history. The magnitude of the earthquake was, according to various estimates, from 9.1 to 9.3. This is the second or third strongest earthquake on record.

The epicenter of the earthquake was located in the Indian Ocean, north of the island of Simeulue, located near the northwestern coast of the island of Sumatra (Indonesia). The tsunami reached the shores of Indonesia, Sri Lanka, southern India, Thailand and other countries. The height of the waves exceeded 15 meters. The tsunami caused massive destruction and a huge number of dead people, even in Port Elizabeth, in South Africa, 6900 km from the epicenter. Died, according to various estimates, from 225 thousand to 300 thousand people. The true death toll is unlikely to ever be known, as many people were swept into the sea by the water.

With regard to the properties of the bottom soil, then, like in other oceans, sediments on the bottom of the Indian Ocean can be divided into three classes: coastal sediments, organic silt (globigerine, radiolar or diatom) and special clay of great depths, the so-called red clay. Coastal sediments are sand, located mostly on coastal shallows to a depth of 200 meters, green or blue silt near rocky coasts, brown in volcanic areas, but lighter and sometimes pinkish or yellowish near coral coasts due to the lime prevailing here. Globigerin silt, consisting of microscopic foraminifers, covers the deeper parts of the ocean floor almost to a depth of 4500 m; south of parallel 50°S sh. calcareous foraminiferal deposits disappear and are replaced by microscopic siliceous, from the group of algae, diatoms. Concerning the accumulation of diatom remains on the bottom South part The Indian Ocean is especially different from other oceans, where diatoms are found only in places. Red clay occurs at depths greater than 4500 m; it has the color red, or brown, or chocolate.

indian ocean climate fossil fishery

4. Characteristics of waters

Surface water circulationin the northern part of the Indian Ocean it has a monsoonal character: in summer - northeast and east currents, in winter - southwest and west currents. During the winter months between 3° and 8° S. sh. an inter-trade (equatorial) countercurrent develops. In the southern part of the Indian Ocean, water circulation forms an anticyclonic circulation, which is formed from warm currents - the South Trade Wind in the North, Madagascar and Needle in the West and cold ones - the West Winds in the South and West Australian in the East South of 55 ° S. sh. several weak cyclonic water cycles develop, closing off the coast of Antarctica with an easterly current.

Belt of the Indian Oceanbetween 10 ° With. sh. and 10 ° Yu. sh. called the thermal equator, where the surface water temperature is 28-29°C. To the south of this zone, the temperature drops, reaching ?1°C off the coast of Antarctica. In January and February, the ice along the coast of this mainland melts, huge ice blocks break off from the ice sheet of Antarctica and drift towards the open ocean. North temperature characteristics waters are determined by monsoon air circulation. In summer, temperature anomalies are observed here, when the Somali current cools surface waters to a temperature of 21-23°C. In the eastern part of the ocean at the same geographical latitude, the water temperature is 28 ° C, and the highest temperature mark - about 30 ° C - was recorded in the Persian Gulf and the Red Sea. The average salinity of ocean waters is 34.8‰. The most salty waters are the Persian Gulf, the Red and Arabian Seas: this is due to intensive evaporation with a small amount of fresh water brought into the seas by rivers.

The tides in the Indian Ocean, as a rule, are small (off the coast of the open ocean and on the islands from 0.5 to 1.6 m), only at the tops of some bays they reach 5-7 m; in the Gulf of Cambay 11.9 m. The tides are predominantly semi-diurnal.

Ice forms at high latitudes and is carried by winds and currents along with icebergs in a northerly direction (up to 55 ° S in August and up to 65-68 S in February).

. Bottom sediments of the Indian Ocean and its structure

Bottom sedimentsthe Indian Ocean have the greatest thickness (up to 3-4 km) at the foot of the continental slopes; in the middle of the ocean - small (about 100 m) thickness and in places where the dissected relief is distributed - discontinuous distribution. The most widely represented are foraminiferal (on continental slopes, ridges, and at the bottom of most basins at depths up to 4700 m), diatoms (south of 50° S), radiolarian (near the equator), and coral sediments. Polygenic sediments - red deep-sea clays - are distributed south of the equator at a depth of 4.5-6 km or more. Terrigenous sediments - off the coast of the continents. Chemogenic sediments are mainly represented by ferromanganese nodules, while riftogenic sediments are represented by destruction products of deep rocks. Outcrops of bedrocks are most often found on continental slopes (sedimentary and metamorphic rocks), mountains (basalts) and mid-ocean ridges, where, in addition to basalts, serpentinites and peridotites have been found, representing a slightly altered substance of the Earth's upper mantle.

The Indian Ocean is characterized by the predominance of stable tectonic structures both on the bed (thalassocratons) and along the periphery (continental platforms); active developing structures - modern geosynclines (Sonda arc) and georiftogenals (mid-ocean ridge) - occupy smaller areas and continue in the corresponding structures of Indochina and rifts of East Africa. These main macrostructures, which differ sharply in morphology, the structure of the earth's crust, seismic activity, and volcanism, are subdivided into smaller structures: plates, usually corresponding to the bottom of oceanic basins, blocky ridges, volcanic ridges, sometimes topped with coral islands and banks (Chagos, Maldives, etc.). .), trench-faults (Chagos, Ob, etc.), often confined to the foot of blocky ridges (East Indian, West Australian, Maldives, etc.), fault zones, tectonic ledges. Among the structures of the Indian Ocean bed, a special place (according to the presence of continental rocks - granites of the Seychelles and the continental type of the earth's crust) is occupied by the northern part of the Mascarene Range - a structure that is apparently part of the ancient Gondwana mainland.

. Minerals

The most important minerals of the Indian Ocean are oil and natural gas. Their deposits are found on the shelves of the Persian and Suez Gulfs, in the Bass Strait, on the shelf of the Hindustan Peninsula. In terms of reserves and production of these minerals, the Indian Ocean ranks first in the world. On the coasts of Mozambique, the islands of Madagascar and Ceylon, ilmenite, monazite, rutile, titanite and zirconium are exploited. Off the coast of India and Australia there are deposits of barite and phosphorite, and in the shelf zones of Indonesia, Thailand and Malaysia, deposits of cassiterite and ilmenite are exploited on an industrial scale. On the shelves - oil and gas (especially the Persian Gulf), monazite sands (the coastal region of Southwestern India), etc.; in reef zones - ores of chromium, iron, manganese, copper, etc.; on the bed - huge accumulations of ferromanganese nodules.

. Climateindian ocean

Most of the Indian Ocean is located in warm climatic zones - equatorial, subequatorial and tropical. Only its southern regions, located at high latitudes, are strongly influenced by Antarctica. The equatorial climate zone of the Indian Ocean is characterized by a constant predominance of humid warm equatorial air. Average monthly temperatures range here from 27° to 29°. The water temperature is slightly higher than the air temperature, which creates favorable conditions for convection and precipitation. Their annual amount is large - up to 3000 mm and more.

. Flora and fauna

The most dangerous mollusks in the world live in the Indian Ocean - cone snails. Inside the snail there is a rod-like container with poison, which it injects into its prey (fish, worms), its poison is also dangerous for humans.

The entire water area of ​​the Indian Ocean lies within the tropical and southern temperate zones. The shallow waters of the tropical zone are characterized by numerous 6- and 8-ray corals, hydrocorals, capable of creating islands and atolls together with calcareous red algae. The richest fauna of various invertebrates (sponges, worms, crabs, mollusks, sea urchins, brittle stars and starfish), small but brightly colored coral fish live among the powerful coral structures. Most of the coasts are occupied by mangroves, in which the mud jumper stands out - a fish that can exist in the air for a long time. The fauna and flora of the beaches and rocks that dry out at low tide are quantitatively depleted as a result of the depressing effect of the sun's rays. In the temperate zone, life on such stretches of coasts is much richer; dense thickets of red and brown algae (kelp, fucus, reaching the huge size of microcystis) develop here, various invertebrates are abundant. For the open spaces of the Indian Ocean, especially for the surface layer of the water column (up to 100 m), rich flora is also characteristic. Of the unicellular planktonic algae, several species of peredinium and diatom algae predominate, and in the Arabian Sea - blue-green algae, which often cause the so-called water bloom during mass development.

The bulk of the ocean's animals are copepods (more than 100 species), followed by pteropods, jellyfish, siphonophores, and other invertebrates. Of the unicellular, radiolarians are characteristic; numerous squids. Of the fish, the most abundant are several species of flying fish, luminous anchovies - myctophids, dolphins, large and small tuna, sailfish and various sharks, poisonous sea snakes. Sea turtles and large marine mammals (dugongs, toothed and toothless whales, pinnipeds) are common. Among the birds, the most characteristic are albatrosses and frigates, as well as several species of penguins that inhabit the coasts of South Africa, Antarctica and the islands that lie in the temperate zone of the ocean.

At night, the surface of the Indian Ocean shimmers with lights. Light is produced by small marine plants called dinoflagellates. Luminous areas sometimes have the shape of a wheel with a diameter of 1.5 m.

. Fishing and marine industry

Fishing is underdeveloped (the catch does not exceed 5% of the world catch) and is limited to the local coastal zone. Near the equator (Japan) is fishing for tuna, and in Antarctic waters - whale fishing. Sri Lanka, the Bahrain Islands and northwest coast Australia produces pearls and mother-of-pearl.

The countries of the Indian Ocean also have significant resources of other valuable types of mineral raw materials (tin, iron and manganese ores, natural gas, diamonds, phosphorites, etc.).

Bibliography:

1.Encyclopedia "Science" Dorling Kindersley.

.“I know the world. Geography” V.A. Markin

3.slovari.yandex.ru ~ TSB books / Indian Ocean /

4.Big Encyclopedic Dictionary of Brockhaus F.A., Efron I.A.

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The Indian Ocean ranks third in terms of area. At the same time, compared with others, the greatest depth of the Indian Ocean is very modest - only 7.45 kilometers.

Location

It is not difficult to find it on the map - the Asian part of Eurasia is located in the north of the ocean, on southern shores Antarctica is spread out, Australia lies in the path of the currents from the east. Africa is in the western part of it.

Most of the ocean area is located in the southern hemisphere. A very conditional line separates the Indian and - from Africa, down the twentieth meridian to Antarctica itself. It is separated from the Pacific by the Indochinese peninsulas of Malacca, the border goes to the north then along a line that on the map connects the islands of Sumatra, Java, Sumba and New Guinea. With the fourth - the Arctic - the Indian Ocean has no common borders.

Square

Average depth The Indian Ocean is 3897 meters. At the same time, it occupies an area of ​​74,917 thousand kilometers, which allows it to be in third place in size among its "brothers". The shores of this huge reservoir are very weakly indented - this is the reason why there are few seas in its composition.

Relatively few islands lie in this ocean. The most significant of them once broke away from the mainland, so they are located close to the coastline - Socotra, Madagascar, Sri Lanka. Far from the coast, in the open part, you can find islands that originated from volcanoes. These are Crozet, Mascarensky and others. In the tropics, on the cones of volcanoes, there are islands of coral origin, such as the Maldives, Cocos, Adaman and others.

The shores in the east and northwest are indigenous, while in the west and northeast they are mostly alluvial. The edge of the coast is indented very weakly, except for its northern part. It is here that most of the large bays are concentrated.

Depth

Of course, on such large area the depth of the Indian Ocean cannot be the same - the maximum is 7130 meters. This point is located in the Sunda Trench. The average depth of the Indian Ocean is 3897 meters.

Sailors and water explorers cannot rely on the average figure. Therefore, scientists have long drawn up a map of the depths of the Indian Ocean. It accurately indicates the height of the bottom at various points, all the shoals, gutters, depressions, volcanoes and other features of the relief are visible.

Relief

Along the coast lies a narrow strip of continental shallows, about 100 kilometers wide. The edge of the shelf, located in the ocean, has a shallow depth - from 50 to 200 meters. Only in the northwest of Australia and along the Antarctic coast does it increase to 300-500 meters. The slope of the mainland is quite steep, in some places separated by underwater valleys of large rivers, such as the Ganges, Indus and others. In the northeast, the rather monotonous relief of the bottom of the Indian Ocean is enlivened by the Sunda Island Arc. It is here that the most significant depth of the Indian Ocean is found. Maximum point This trough is located 7130 meters below sea level.

Ridges, ramparts and mountains broke the bed into several basins. The most famous are the Arabian Basin, African-Antarctic and Western Australian. These depressions have formed hilly, located in the center of the ocean, and accumulative plains, located not far from the continents, in those areas where sedimentary material is supplied in sufficient quantities.

Among the large number of ridges, the East Indian is especially noticeable - its length is about 5 thousand kilometers. However, the relief of the bottom of the Indian Ocean has other significant ridges - the Western Australian, meridional and others. The bed is also rich in various volcanoes, in places forming chains and even rather large massifs.

Mid-ocean ridges - three branches mountain system dividing the ocean from the center to the north, southeast and southwest. The width of the ranges ranges from 400 to 800 kilometers, the height is 2-3 kilometers. The relief of the bottom of the Indian Ocean in this part is characterized by faults across the ridges. Along them, the bottom is most often horizontally displaced by 400 kilometers.

Unlike the ridges, the Australo-Antarctic Rise is a rampart with gentle slopes, the height of which reaches a kilometer, while the width extends up to one and a half thousand kilometers.

The predominantly tectonic structures of the bottom of this particular ocean are quite stable. Active developing structures occupy a much smaller area and flow into similar structures in Indochina and East Africa. These main macrostructures are divided into smaller ones: plates, blocky and volcanic ridges, banks and coral islands, trenches, tectonic ledges, depressions of the Indian Ocean and others.

Among the various irregularities, a special place is occupied by the north of the Mascarene Range. Presumably, this part previously belonged to the long-lost ancient mainland Gondwana.

Climate

The area and depth of the Indian Ocean make it possible to assume that the climate in its different parts will be completely different. And indeed it is. The northern part of this huge body of water has a monsoonal climate. IN summer time, during a period of low pressure over mainland Asia, south-western flows of equatorial air prevail over the water. IN winter time tropical air masses from the northwest dominate here.

A little south of 10 degrees south latitude, the climate over the ocean becomes much more constant. In tropical (and subtropical in summer) latitudes, southeast trade winds rule here. In temperate - extratropical cyclones that move from west to east. Hurricanes are often found in the west of tropical latitudes. Most often they sweep in the summer and autumn.

The air in the north of the ocean warms up to 27 degrees in summer. African coasts are blown with air with a temperature of about 23 degrees. In winter, the temperature drops depending on latitude: in the south it can be below zero, while in northern Africa the thermometer does not fall below 20 degrees.

The water temperature depends on the currents. The shores of Africa are washed by the Somali current, which has quite low temperatures. This leads to the fact that the water temperature in this region is kept at about 22-23 degrees. In the north of the ocean, the upper layers of water can reach temperatures of 29 degrees, while in southern regions, off the coast of Antarctica, it drops to -1. Of course, we are talking only about the upper layers, since the greater the depth of the Indian Ocean, the more difficult it is to draw conclusions about the water temperature.

Water

The depth of the Indian Ocean does not affect the number of seas at all. And there are fewer of them than in any other ocean. mediterranean seas there are only two: Red and Persian Gulf. In addition, there is also the marginal Arabian Sea, the Andaman Sea, which is only partially enclosed. To the east of the vast waters are Timor and

The largest rivers in Asia belong to the basin of this ocean: the Ganges, Salween, Brahmaputra, Irwaddy, Indus, Euphrates and Tigris. Among the African rivers, it is worth highlighting the Limpopo and Zambezi.

The average depth of the Indian Ocean is 3897 meters. And in this water column is happening unique phenomenon- change in the direction of currents. The currents of all other oceans are unchanged from year to year, while in the Indian one the currents are subject to winds: in winter they are monsoon, in summer they prevail.

Since the deep waters originate in the Red Sea and the Persian Gulf, almost the entire body of water has an increased salinity with a low percentage of oxygen.

coast

In the west and northeast, there are mainly alluvial shores, while in the northwest and east they are bedrock. As already said, coastline almost even, very weakly indented almost along the entire length of this water body. The exception is the northern part - it is here that most of the seas belonging to the Indian Ocean basin are concentrated.

inhabitants

The rather small average depth of the Indian Ocean boasts a wide variety of representatives of the animal and plant worlds. The Indian Ocean is located in the tropical and temperate zones. The shallow waters are full of corals and hydrocorals, among which a huge number of invertebrate species live. These are worms, and crabs, and sea urchins, stars and other animals. An equal number of brightly colored tropical fish find shelter in these areas. The coasts are rich in mangroves, in which the mudskipper has settled - this fish can live for a very long time without water.

The flora and fauna of the beaches subject to low tide is very poor, as the hot sun rays destroy all living things here. in this sense, it is much more diverse: there is a rich selection of algae and invertebrates.

The open ocean is even richer in living beings - representatives of both the animal and plant worlds.

The main animals are copepods. More than a hundred species of them live in the waters of the Indian Ocean. Pteropods, siphonophores, jellyfish and other invertebrates are almost as numerous as species. Several species of flying fish, sharks, glowing anchovies, tuna, and sea snakes frolic in the waters of the ocean. Whales, pinnipeds, sea turtles, dugongs are no less common in these waters.

Feathered inhabitants are represented by albatrosses, frigates and several species of penguins.

Minerals

Oil deposits are being developed in the waters of the Indian Ocean. In addition, the ocean is also rich in phosphates, potash raw materials necessary for fertilizing agricultural land.

We bring to your attention short review countries located in the Indian Ocean that will take part in the Eighth Indian Ocean Olympic Games. Games will be played on Seychelles from 5 to 14 August 2011.

Mayotte
Mayotte (fr. Mayotte) is an overseas community of France located in the Mozambique Channel, in the western Indian Ocean, between northern Mozambique and northern Madagascar. It consists of the main island, Grande-Terre (or Maore), the smaller island of Petit-Terre (or Pamanzi), and several other tiny islets. Geographically, it belongs to the Comoros. Area - 374 km², population - 223.8 thousand (July 2009 estimate). Religions - Muslims 97%, Christians (mostly Catholics) 3%. Mayotte is a separate member of the Indian Ocean Commission (COI), separate from the Comoros. On March 29, 2009, the inhabitants of the island of Mayotte voted by a majority in a referendum to make the island a department of France. 95.2% of voters out of 61.2% of Mayotte residents who took part in the voting were in favor. Mayotte will finally receive the status of a department in 2011 and will thus become the 101st department in France.

Economy of Mayotte The main economic activity is in agriculture and fisheries. Mayotte does not provide itself with food and imports it, as well as manufactured goods, fuel, etc. Export is very insignificant - mainly flavors (vanilla and ylang-ylang), copra, coconuts. The development of the tourism business is difficult due to the remoteness of the island. Mayotte's budget is supported by substantial financial subsidies from France. Monetary unit - euro.

Maldives

The Republic of Maldives is located in equatorial waters Indian Ocean about 700 km southwest of Sri Lanka. A chain of 20 atolls, consisting of 1192 coral islands. The population is a little over 309 thousand people. Religion - Sunni Islam. total area- about 300 km². The capital of Male, the only city and port of the archipelago, is located on the atoll of the same name. On July 26, 1965, Britain granted independence to the Maldives. On November 11, 1968, according to the results of a referendum, the Maldives was proclaimed a republic. Since 1978, the Maldives has been ruled by President Maumoon Abdul Gayoom (6 consecutive five-year terms). In October 2008, Mohamed Nasheed became the first President of the Republic of Maldives elected by popular vote.

Economy of the Maldives The main sectors of the economy are tourist services (28% of GDP) and fishing. The industrial sector is the production of clothing, souvenirs and boats. Agriculture is poorly developed. A significant part of food is imported. The main crop is coconut palm, bananas, vegetables, fruits, sweet potatoes, breadfruit are also grown. Livestock is practically not bred. Export commodities are fish and postage stamps. Main vehicles- sailing and motor boats.

Mauritius

Mauritius - Island state in the southwestern Indian Ocean, about 900 km east of Madagascar. The republic includes the islands of Mauritius (the largest, 1,865 km²) and Rodrigues (104 km²), which are part of the archipelago Mascarene Islands, as well as the Cargados Carajos archipelago, the Agalega Islands and many small islands. The total area of ​​the country is 2,045 km². Population - 1.284 million (July 2009 estimate). The capital of Mauritius is the city of Port Louis, located on the island of Mauritius. On March 12, 1968, Mauritius was declared an independent state within the British Commonwealth. Mauritius became a republic on March 12, 1992.

Economy of Mauritius It is based on sugar production (sugar cane is grown on about 90% of cultivated farmland), on tourism and on the textile industry. Recently, offshore and banking business, as well as the extraction and processing of fish. 9% of employees are employed in agriculture, 30% in industry, and 61% in the service sector. Export commodities ($2.4 billion in 2008): sugar, clothing and textiles, flowers, shellfish, fish. The main buyers are Great Britain 30%, France 15%, USA 8%. Imports ($4.4 billion in 2008): manufactured goods, foodstuffs, petroleum products, chemicals. The main suppliers are India 21%, France 11%, China 9%. Despite the remoteness, Mauritius is very popular among European tourists. In Mauritius, mainly beach holidays are common, but excursions to the ocean are also popular, less often inland. Mauritius is one of the three most beautiful and popular tourist resorts along with the Maldives and Seychelles.

Comoros

Union of the Comoros, Comoros, until 2002 Islamic Federal Republic of the Comoros - a state in the Indian Ocean, located in the northern part of the Mozambique Channel between northern Madagascar and northern Mozambique. Area - 2170 km². Population - about 798,000 people (2005), mainly the Antaloatran people. The capital is the city of Moroni. official languages- Comorian, French and Arabic. The state religion is Islam. On July 6, 1975, the Chamber of Deputies unilaterally proclaimed the independent Republic of the Comoros (RKO) as part of the islands of Anjouan, Grand Comore and Moheli. Ahmed Abdallah, chairman of the Government Council, became president. This council was abolished, a parliament was formed, a constitution was adopted and the Arabic names islands. In November 1975, the Comoros were admitted to the UN as part of four islands as a single state. France, recognizing the independence of the RKO, assigned to Fr. Mayotte the status of its "territorial unit". Following a referendum in April 2002, a new constitution was approved, granting the islands more autonomous rights. The country became known as the Union of the Comoros (UKO).

Economy The Comoros is one of the poorest countries in Africa. Main income items: export of ylang-ylang (the world's largest exporter), vanilla (the world's second largest exporter after Madagascar); tourism, fishing.

reunion

Reunion is an island in the Indian Ocean, east of Madagascar, an overseas region of France. The area is 2.5 thousand km². The population is 793 thousand people (2007 estimate). More than half of the population of Reunion are Creoles (of mixed origin, mainly French-African-Malagasy), "white" French make up about a quarter of the population, Indians - about 20%, the rest - Chinese and others. About 90% of the population are Catholics, there are Hindus, Muslims, Buddhists, and also Rastafarians. Creole is still widely spoken (based on French), although the school teaches only in official French. Administrative center- Saint-Denis (95 thousand people in 2004). Since 1946, Reunion has become an overseas department of France, since 1974 - an administrative region. Reunion is governed by a prefect appointed by the President of France.

Economy of Reunion The main agricultural export crop is sugarcane. Corn, potatoes, bananas, and mangoes are also cultivated. Livestock - mainly pigs and goats. Widely developed travel business. The industry is mainly the production of sugar and rum from sugar cane. In addition to sugar, rum, vanilla, geranium essence and other flavors are exported. There is a noticeable difference in the standard of living of the French living on the island and those of the Indian, Creole and other communities. The French government subsidizes the island's economy in an attempt to close this gap.

Madagascar

The Republic of Madagascar is a state in the western Indian Ocean, on the island of Madagascar and adjacent small islands off the east coast of Africa. The total area of ​​the state is 587.040 km². The length is about 1600 km, the width is over 600 km. The central part of the island is occupied by the high-altitude Anjafi plateau, gently descending to the west and abruptly breaking off to the lowlands of the eastern coast. Population - 18.4 million people. (2005 UN est.). The capital is Antananarivo. Date of independence June 26, 1960 (from France). Official languages ​​- Malagasy, French, English.

Economy of Madagascar generally regarded as developing. The main sectors of the economy of Madagascar are agriculture, fishing and the cultivation of spices and spices for export. The main exports are coffee, vanilla (Madagascar is the world's largest producer), cocoa powder, sugarcane, rice, tapioca, legumes, bananas and peanuts. There is a well-known incident when the Coca-Cola company switched from real vanilla to synthetic, which was a significant blow to the economy of the republic. The main sources of economic growth at the moment are tourism, exports of textile and light industries, exports of agricultural products and exports of minerals. Thanks to unique fauna islands, bio-tourism attracts more and more people from all over the world. Approximately 80% of the entire flora and fauna of the island are endemic, and 5% of the total species diversity of the planet live in Madagascar. The Free Trade Zones, located near Antananarivo and Antsirabe, aim to trade with the US and Europe. As natural resources, coal, ilmenite and nickel are mainly mined for export. Two large oil fields have been discovered in the south of the republic. Structural reforms in the economic sector began in the 80s of the last century, mainly under pressure from foreign financial institutions, especially the World Bank. A privatization program was carried out (1988-1993), a free trade zone (Export Processing Zone) was introduced. Madagascar and Mauritania are the last countries in the world not to use a decimal currency. Madagascar ariary is equal to five iraimbilani.

Seychelles

Economy of the Seychelles It is based on serving tourists (30% of employees and more than 70% of foreign exchange earnings) and on fishing (canned and frozen fish are the main export goods). Agriculture is poorly developed. Coconuts, cinnamon and vanilla (for export), sweet potato, cassava (tapioca), bananas are grown. Breeding poultry. In 1978, the national airline, Air Seychelles, was founded.

The area of ​​the Indian Ocean exceeds 76 million square kilometers - it is the third largest water area in the world.

From the western part of the Indian Ocean, Africa is comfortably located, from the East - the Sunda Islands and Australia, in the south sparkles Antarctica and in the north is captivating Asia. Peninsula Hindustan divides northern part The Indian Ocean is divided into two parts - the Bay of Bengal and the Arabian Sea.

Borders

The Cape Meridian coincides with the border between the Atlantic and Indian Oceans, and the line that connects the Malaaka Peninsula with the islands of Java, Sumatra and runs along the Southeast Cape meridian south of Tasmania is the border between the Indian and Pacific Oceans.

Indian Ocean islands

Here are such famous islands like Maldives, Seychelles, Madagascar, Cocos Islands, Laccadive, Nicobar, Chagos Archipelago and Christmas Island.

It is impossible not to mention the group of Mascarene Islands, which are located to the east of Madagascar: Mauritius, Reunion, Rodrigues. And on the south side of the island are Croe, Prince Edward, Kerguelen with beautiful beaches.

Brethren

The Strait of Maoakka connects the Indian Ocean and the South China Sea, and the Sunda Strait and Lombok Strait act as a connective tissue between the Indian Ocean and the Java Sea.

From the Gulf of Oman, which is located in the northwest of the Arabian Sea, you can get to the Persian Gulf by sailing through the Strait of Hormuz.
Opens the road to the Red Sea Gulf of Aden which is located slightly to the south. Madagascar separates from the African continent mozambique channel.

Basin and list of inflowing rivers

The major rivers of Asia belong to the Indian Ocean basin, such as:

• Indus, which flows into the Arabian Sea,
• Irrawaddy,
• salween,
• Ganges with Brahmaputra going to the Bay of Bengal,
• Euphrates and Tigris, which merge a little above the point of confluence with the Persian Gulf,
• The Limpopo and Zambezi, the largest rivers in Africa, also flow into it.

The greatest depth (maximum - almost 8 kilometers) of the Indian Ocean was measured in the Yavan (or Sunda) deep sea trench. The average depth of the ocean is almost 4 kilometers.

Influenced seasonal changes monsoon winds change surface currents in the north of the ocean.

In winter, monsoons blow from the northeast, and in summer from the southwest. Currents south of 10°S tend to move counterclockwise.

In the ocean south, currents move east from the west, while the South Equatorial Current (north of 20°S) moves in the opposite direction. The equatorial countercurrent, which is located immediately south of the equator itself, carries water to the east.

Etymology

The Eritrean Sea - that's what the ancient Greeks called western part Indian Ocean with the Persian and Arabian Gulfs. Over time, this name began to be identified only with the nearest sea, and the ocean itself was named after India, which was very famous for its wealth among all the countries that are located off the coast of this ocean.

In the fourth century BC, Alexander Macdonsky called the Indian Ocean Indicon Pelagos (which means "Indian Sea" in ancient Greek). The Arabs called it Bar-el-Khid.

In the 16th century, the Roman scientist Pliny the Elder introduced the name, which has stuck to this day: Oceanus Indicus, (which in Latin corresponds to the modern name).

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