Indian Ocean: geographical location, bottom topography. Africa. Geographical position, discoveries and exploration of the mainland. Geological structure, relief, minerals
"PROFESSIONAL"
Abstract by discipline:
« physical geography continents and oceans and teaching methods with ICT”
On this topic:
"Physical and geographical characteristics of the Indian Ocean"
Executor:
Saprykina Ludmila Nikolaevna
Moscow 2017
Introduction
1. Physical and geographical position
2. Geological structure and bottom topography
2.1 Underwater continental margins
2.2 Transition zone
2.3 Mid-Atlantic Ridge
2.4 Ocean floor
Conclusion
List of sources used
Knowledge.
The third largest ocean on Earth, covering about 20% of its water surface. Its area is 76.17 million square meters. km, volume - 282.65 million cubic meters. km. The most deep point ocean is located in the Sunda Trench (7729 m).
In the north it washes Asia, in the west - Africa, in the east - Australia; in the south it borders on Antarctica. border with passes along the 20 ° meridian of east longitude; from the Pacific - along the 146 ° 55 'meridian of eastern longitude. The northernmost point of the Indian Ocean is approximately 30° northern latitude in the Persian Gulf. The width of the Indian Ocean is approximately 10,000 km between southern points Australia and Africa.
The ancient Greeks known to them western part ocean with adjacent seas and bays was called the Eritrean Sea (ancient Greek - Red, and in old Russian sources the Red Sea). Gradually, this name began to be attributed only to the nearest sea, and the ocean gets its name from India, the country most famous at that time for its wealth on the shores of the ocean. So Alexander the Great in the IV century BC. e. calls it Indicon Pelagos (ancient Greek - "Indian Sea"). Among the Arabs, it is known as Bar-el-Hind - "Indian Ocean". Since the 16th century, the name Oceanus Indicus (lat. Oceanus Indicus) introduced by the Roman scientist Pliny the Elder back in the 1st century was established - the Indian Ocean.
The purpose of the abstract: to describe the Indian Ocean using modern data.
1. Physical and geographical characteristics.
The 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 are of continental 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 and others.
IN tropical latitudes rising on volcanic cones coral islands- Maldivian, Laccadive, Chagos, Coconut, most Andaman and others.
The shores in the North-West and East are indigenous, in the North-East and West, alluvial ones predominate. Coastline 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 and others.
2. Relief and geological structure of the bottom.
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, in some places dissected by underwater valleys of the Indus, Ganges and other rivers. In the northeastern part of the ocean, there is the Sunda Island Arc and the Sunda Trench associated with it, to which the maximum depths (up to 7130 m) are confined. 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 5000 km) distinguishes the meridional East Indian Ridge, which connects in the South with the latitudinal West Australian Ridge; large meridional ridges stretch south of the Hindustan peninsula and the island of Madagascar. Volcanoes are widely represented on the ocean floor (the city of Bardina, the city of Shcherbakov, the city of Lena and others), which in places form large massifs (to the north of Madagascar) and chains (to the east of the Cocos Islands).
Mid-ocean ridges - mountain system, consisting of three branches diverging from the central part of the ocean in the North (Arabian-Indian Ridge), South-West (West Indian and African-Antarctic Ridges) and South-East (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 more gentle swell 1 km high and up to 1500 km wide.
The bottom sediments of the Indian Ocean are thickest (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 the continental slopes, ridges and at the bottom of most basins at a depth of up to 4700 m), diatoms (south of 50 ° south latitude), 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 little-altered matter 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 (Zonda arc) and georiftogenals (mid-ocean ridge) - occupy smaller areas and continue in the corresponding structures of Indochina and rifts 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, in places topped with coral islands and banks (Chagos, Maldives and others), trench-faults (Chagos, Ob and others), often confined to the foot of blocky ridges (East Indian, West Australian, Maldives and others), fault zones, tectonic ledges. Among the structures of the bed of the Indian Ocean, a special place (according to the presence of continental rocks - granites Seychelles and the continental type of the earth's crust) occupies Northern part Mascarene Ridge - a structure that is apparently part of ancient mainland 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 and others; on the bed - huge accumulations of ferromanganese nodules.
3. Climate.
The climate of the northern Indian Ocean is monsoonal; in summer, when an area develops over Asia reduced pressure, southwestern flows of equatorial air dominate here, in winter - northeastern flows of tropical air. South of 8-10 ° south latitude, atmospheric circulation is very stable; 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 °С at 30 ° south latitude, to 5-6 °С at 50 ° south latitude and below 0 °С south of 60 ° south latitude. In winter, the air temperature varies from 27.5 ° C near the equator to 20 ° C in the northern part, up to 15 ° C at 30 ° C. ksh., up to 0-5 ° С at 50 ° south latitude and below 0 ° С south of 55-60 ° south latitude At the same time, in the southern subtropical latitudes all year round the temperature in the West, 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 amount of 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 ° south latitude - up to 80%. The average annual rainfall in the subtropics is 500 mm in the East,
1000 mm in the West, in temperate latitudes more than 1000 mm, near Antarctica it drops to 250 mm.
4. Hydrological regime.
Circulation surface water in the northern part of the ocean it has a monsoonal character: in summer - northeast and east currents, in winter - southwest and west currents. In the winter months, between 3° and 8° south latitude, the Intertrade (equatorial) countercurrent develops. In the southern part of the Indian Ocean, water circulation forms an anticyclonic circulation, which is formed from warm currents- South Tradewind to the North, Madagascar and Needle to the West and cold - currents West Winds to the South and Western Australian to the East. South of 55° south latitude, 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° north latitude 3.7-6.5 GJ/(m2×year); between 0° and 10° south latitude 1.0-1.8 GJ/(m2×year); between 30° and 40° south latitude - 0.67-0.38 GJ/(m2×year) [from - 16 to 9 kcal/(cm2×year)]; between 40° and 50° south latitude 2.34-3.3 GJ/(m2×year); south of 50° south latitude -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° south latitude, the main role is played by heat consumption for evaporation, and south of 50° south latitude, 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 ° south latitude, to 3-5 ° C at 50 ° south latitude and below -1 ° C south of 55 ° south latitude. N. is equal to 23-25 ° С, at the equator 28 ° С, at 30 ° south latitude 21-25 ° С, at 50 ° south latitude from 5 to 9 ° С, south of 60 ° south latitude 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° south latitude it 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° south latitude. 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 ° south latitude in August and up to 65-68 ° south latitude in February).
The deep circulation and vertical structure of the Indian Ocean is shaped by waters sinking into the subtropical (subsurface waters) and Antarctic (intermediate waters) convergence zones and along the continental slope of Antarctica (bottom waters), as well as 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, a 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 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.
4. Flora and fauna.
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, molluscs, 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 mudskipper- 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 oppressive effect sun rays. IN temperate zone life on such sections of the coast is much richer; dense thickets of red and brown algae develop here (kelp, fucus, reaching huge size macrocystis), a variety of 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.
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 tunas, 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 islands lying in the temperate zone of the ocean.
Conclusion
The history of Indian Ocean exploration can 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 Indian, Egyptian and Phoenician navigators, who traveled in the northern part of the Indian Ocean in 3000-1000 BC, and ended with the voyage of James Cook, who in 1772-75 penetrated south to 71 ° south latitude. The second period was marked by the beginning of deep-sea research, first carried out by Cook in 1772 and continued by Russian and foreign expeditions. The main Russian expeditions were - O. Kotzebue on the "Rurik" (1818) and Pallena on the "Cyclone" (1858-59). The third period is characterized by complex oceanographic research. Economic-geographical and political-geographical essay. The penetration of Europeans (Portuguese, then the Dutch, French and British) into the Indian Ocean basin dates back to the 16th-17th centuries, and by the middle of the 19th century, Great Britain secured most of its coasts and islands, which exported from here the most important raw materials and food products for its economy. . Naval (and later air) bases were established at all entrances to the Indian Ocean: in the Atlantic Ocean - Simonstown, in the Pacific Ocean - Singapore, in the Red Sea - Aden, on the approaches to India - Trincomalee. In the northeastern part of the Indian Ocean there were colonies of France, the Netherlands (Netherlands India), Portugal.
After the end of World War II (1939-1945), the collapse of the colonial system of imperialism introduced fundamental amendments to political map basin of the Indian Ocean.
In the pool Persian Gulf rich oil fields. Production is carried out both at land and underwater fields within the shelf. The countries of the Indian Ocean also have significant resources of other valuable types of minerals (tin, iron and manganese ore, natural gas, diamonds, phosphorites and others).
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. In Sri Lanka, on the Bahrain Islands and on the northwestern coast of Australia, pearls and mother-of-pearl are mined.
Economic activity human activity in the Indian Ocean has led to pollution of its waters and a reduction in biodiversity. At the beginning of the 20th century, some species of whales were almost completely exterminated, others - sperm whales and sei whales - still survived, but their number was greatly reduced. Since the 1985-1986 season, the International Whaling Commission has introduced a complete moratorium on commercial whaling of any kind. In June 2010, at the 62nd meeting of the International Whaling Commission, under pressure from Japan, Iceland and Denmark, the moratorium was suspended. The Mauritius dodo, destroyed by 1651 on the island of Mauritius, became a symbol of extinction and extinction of species. After it became extinct, people first formed the opinion that they could cause the extinction of other animals.
A great danger in the ocean is the pollution of waters with oil and oil products (the main pollutants), some heavy metals and waste from the nuclear industry. The routes of oil tankers transporting oil from the countries of the Persian Gulf run across the ocean. Any major accident can lead to an ecological disaster and the death of many animals, birds and plants.
The main recreational areas of the Indian Ocean: the Red Sea, the western coast of Thailand, the islands of Malaysia and Indonesia, the island of Sri Lanka, the area of coastal urban agglomerations of India, the eastern coast of Madagascar, the Seychelles and Maldives. Among the countries of the Indian Ocean with the largest flow of tourists (according to 2010 data from the World Tourism Organization) stand out: Malaysia, Thailand, Egypt, Saudi Arabia, South Africa, Arabic, Indonesia, Australia, India, Qatar, Oman.
Bibliography
Pospelov E.M. Geographical names of the world: toponymic dictionary/ EAT. Pospelov - Moscow - Russian Dictionaries, Astrel, AST, 2001. - P. 24.
Atlas of the oceans. Terms, concepts, reference tables. - Moscow: GUNK MO USSR, 1980. S. 84-85
Ryabchikov A.M. Physical Geography of Continents and Oceans: textbook / A.M. Ryabchikov - Moscow - GEOGRAFGIZ, 2005. - S. 535-540.
Great Russian Encyclopedia. T.11. - M.: Great Russian Encyclopedia, 2008. - S. 228.
Great Russian Encyclopedia. T. 2. - M.: Great Russian Encyclopedia, 2005. - S. 445.
South ocean. Russian universal encyclopedias Brockhaus-Efron and Bolshaya Soviet Encyclopedia combined vocabulary. Retrieved July 24, 2012. Archived from the original on August 4, 2012.
For the preparation of this work, materials from the site http://www.bolshe.ru/
Despite the relatively small size indian ocean, relief his bottom quite varied. In the north, the underwater margin of the mainland is clearly expressed. Here, near Eurasia, it is constantly increasing due to the large amount of sedimentary material carried by powerful rivers.
IN Bay of Bengal the continental slope descends to the bed at an angle of more than 45°. Such a steep continental slope is nowhere else in the oceans. Only in the area sunda islands the continental slope is separated from the ocean floor by a transition zone. It has many underwater ridges rising to the surface in the form of island arcs of volcanic origin. There are more than 300 volcanoes, of which over 100 are active. Deep sea trenches extend along the island arc. For example, sunda trench is the deepest part of the bottom of the Indian Ocean (7729 m).
The largest form bottom topography Indian Ocean is mid-ocean ridge. It consists of three branches extending in different directions from the center. In the south of the ocean, parts of the ridge connect with the same ridges of the Atlantic and Pacific oceans.
In the northern part of the mid-ocean ridge there is rift dissected by deep transverse faults. Near the Red Sea, the fault zone forks. One branch runs through eastern Africa as a complex fault system ( Great African Rift), the second lies along the bottom of the Red Sea and across the territory of Eurasia (along the bottom Dead Sea and further north).
The fault zone of the mid-ocean ridge of the Indian Ocean is a "living" section of the earth's crust. This is evidenced by the presence of hot springs and frequent earthquakes. material from the site
Trouble in the Indian Ocean. In December 2004, a catastrophic earthquake occurred, the epicenter of which was in the Indian Ocean, 250 km from the northern outskirts of Sumatra. People were affected in Indonesia, Sri Lanka, India, Thailand, Malaysia, Burma, Bangladesh and Maldives. The disaster also affected some African countries - the Seychelles, Somalia, Tanzania, Kenya.
The relief of the ocean is characterized by the swiftness of the continental slope, one transitional zone and a branched mid-ocean ridge.
On this page, material on the topics:
Landforms of the Indian Ocean
Indian Ocean Report Grade 5 Briefly
Tsikavinka about the relief of the bottom of the Indian Ocean
Relief of the bottom of the Indian Ocean summary
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The Indian Ocean is the third largest. The area of the Indian Ocean is 76.17 million km2, average depth- 3711 m. The name of the ocean is associated with the name of the Indus River - "sprinkler", "river".
A characteristic feature of the geographical position of the Indian Ocean is its location almost entirely in southern hemisphere and entirely in the East. Its waters wash the shores of Africa, Eurasia, Australia and Antarctica. The Indian Ocean includes 8 seas, the largest is the Arabian. One of the warmest (up to +32 °C) and salty (38-42 ‰) seas in the world is the Red Sea. It got its name from the significant accumulation of algae, which gives the water its red color.
Bottom relief The Indian Ocean is diverse. The shelf zone occupies a narrow strip and makes up only 4% of the total bottom area. The continental slope is very gentle. The ocean bed is crossed by mid-ocean ridges with an average height of about 1500 m. They are characterized by rifts and transverse faults, areas of seismic activity. There are separate volcanic mountains, several large basins (Central, Western Australian, etc.). The greatest depth is 7729 m (Zonda Trench).
Climate determined by the location of the main part of the Indian Ocean in the equatorial, subequatorial and tropical climatic zones. On the climate of the northern part of the ocean big influence renders dry. Seasonal monsoon winds in summer from the ocean carry a huge amount of moisture to land (in the Bay of Bengal area up to 3000 mm per year), in winter they blow from land to the ocean. From the area high pressure the southeast trade wind blows towards the equator. dominated in temperate latitudes westerly winds great strength, accompanied by cyclones. The proximity of Antarctica has a cooling effect on the southern margins of the ocean.
The Indian Ocean is called the "ocean of heated waters" for the high temperature of the water on the surface. The average temperature is +17 °C. (Refer to climate maps for surface water temperatures and precipitation.) The Persian Gulf region has the highest temperature (+34°C in August). The least amount of precipitation (100 mm) falls off the coast of Arabia. Average salinity waters of the Indian Ocean - 34.7 ‰, maximum - 42 ‰ (in the north of the Red Sea).
Due to high evaporation from the water surface, a small amount precipitation and the absence of river runoff in the Red Sea, the highest salinity in the oceans is observed.
Monsoons have a great influence on the formation of currents. The Indian Ocean has a complex system of currents. In the equatorial part of the ocean, the current system is directed clockwise, in the Southern Hemisphere - against. (Point currents on a map. Look for cold currents.)
Natural Resources and Environmental Issues of the Indian Ocean
The largest oil and gas fields are located in the Persian Gulf. The main areas of modern oil production are the countries of the Persian Gulf: Iran, Iraq, Kuwait, Saudi Arabia, etc. At the bottom of the ocean basins, a large number of ferromanganese nodules, but their quality is lower than in pacific ocean, and they occur at great depths (4000 m).
The fauna of the warm waters of the Indian Ocean is diverse, especially in the northern tropical part: there are many sharks, sea snakes, coral polyps. Giant sea turtles are at the stage of extinction. Oysters, shrimps, crabs are found in the mangroves of tropical coasts. In open waters tropical belts widespread fishing for tuna. The Indian Ocean is famous for pearling. In temperate latitudes, toothless and blue whales, seals, sea Elephant. The species composition of fish is rich: sardinella, mackerel, anchovy, etc.
Dozens of countries with a total population of about 2 billion people are located on the coast of the Indian Ocean. Mainly developing countries. Therefore, development natural resources ocean is slower than in other oceans. In the development of shipping, the Indian Ocean is inferior to the Atlantic and Pacific. (Explain why.) The Indian Ocean is of great transport importance for the countries of South and Southeast Asia and Australia. Intensive transportation of oil and oil products from the Persian Gulf has led to a deterioration in water quality, a decrease in reserves commercial fish and seafood.
Whaling has practically ceased. Warm waters, coral islands, the beauty of the Indian Ocean attract many tourists here.
In the shelf of the northwestern part of the Indian Ocean, intensive oil production is underway. Important transport routes pass through the Indian Ocean. The ocean holds the third place in the world in maritime transportation, the largest oil flow comes from the Persian Gulf.
Common features of the topography of the ocean floor are the presence of the main morphostructural zones: the underwater margin of the continents, the transition zone, the ocean floor, ocean ridges and uplifts, mid-ocean ridges. But these structures within each of the oceans have a number of features.
Indian Ocean. In the bottom topography of the western part, there are many common features with the Atlantic Ocean, and the eastern with the Pacific. Thus, for example, the Middle Range of the Indian Ocean, with the exception of the Australo-Antarctic one, is clearly expressed in relief, broken up by transverse and longitudinal faults. average speed extensions in the rift reach 2.5-3.0 cm/year, maximum up to 16 cm/year.The basins are well expressed in the relief and are outlined by the ridges and hills separating them. In the western part of the ocean, as in the Atlantic, there are many plateaus and banks (Agulyas, banks of the Ob and Lena, Prince Edward).
In the Indian Ocean, there are ridges of microcontinents (Mozambique, Madagascar, Mascarene), which have a continental type of the earth's crust, according to many studies, these are the fragments of Gondwana, which split at the beginning of the Mesozoic into southern continents. The shelf in the ocean is poorly developed, only in the north of Australia. The trenches of the Indian Ocean are not deep, such as, for example, Timorsky 3310 m and Kai - 3680 m. The maximum depth is in the Yavan trench (7209 m).
Relief of the bed of the Indian Ocean.
The orography of the bottom of the Indian Ocean is determined primarily by the mid-ocean ridges, which divide the Indian Ocean into the African, Asian-Australian and Antarctic segments.
The African segment of the bed, bounded on the east and southeast by the West Indian and Arabian-Indian mid-ranges, has a particularly complex relief. Of the large ranges of the segment, we note the Mascarene, Amirantsky, Cheyne, as well as the Medingley Upland, which lies to the northeast of the Mascarean Range. In addition to linearly oriented uplifts, there are many separate mountains in this area. Some of them protrude above the ocean level and form islands.
Most of the Mozambique Channel, also located in the described segment, belongs to the underwater margin of the African continent; its southern part, bounded by the Madagascar and Mozambique protrusions of the submarine continental margin, forms a rather isolated oceanic basin with a maximum depth of 6046 m. A small flat abyssal plain is located on the border with the submarine margin of the continent, the rest of the bottom of the basin has a hilly relief. To the north and east of Madagascar, which has a typical continental structure, are the Somali basins. Mascarene and Madagascar. Somali - the largest basin (maximum depth - 5477 m is confined to the Amirant Trench). In its northern part, there is a narrow blocky Cheyne Ridge, connected with the Owen Fault Zone, which crosses the Middle Ridge to the north. A significant part of the bottom of the basin is a flat abyssal plain.
The Mascarene basin (maximum depth 5342 m) is separated from the Somali one by the Amirant and Mascarene ranges. In the western part of the basin, the relief is leveled; in the eastern part, hills, seamounts, and ridges abound, genetically associated with numerous faults obliquely cutting the Arabian-Indian ridge. The uplifted Gromlen Atoll and sharp fluctuations in depths indicate a significant differentiation of the vertical movements of the bed.
The relief and geological structure of the Mascarene Range are very interesting. In essence, this is a heterogeneous morphostructure consisting of several flat-topped shallow water massifs. Its northernmost part is formed by the Seychelles Bank with the islands of the same name, a real microcontinent composed of granites, whose age is 600 million years. To the south is the bank of Saia de Malla with minimum depths above it of 7–20 m.
Relief of the bed of the Indian Ocean
The orography of the Indian Ocean floor is determined primarily by the mid-ocean ridges that divide the Indian Ocean into African, Asian-Australian And Antarctic segments.
African segment lodge bounded on the east and southeast West Indian And Arabian-Indian median ridges, has a particularly complex relief. Of the major ridges of the segment, we note Mascarene, Amirantsky, Chain, as well as medingley upland, lying to the northeast of the Mascarei Range. In addition to linearly oriented uplifts, there are many separate mountains in this area. Some of them protrude above the ocean level and form islands.
Most of Mozambique Channel, also located in the described segment, refers to the underwater margin of the African continent; its southern part, limited Madagascar And Mozambican ledges the underwater continental margin, forms a rather isolated oceanic basin with a maximum depth of 6046 m. A small flat abyssal plain is located on the border with the underwater continental margin, the rest of the bottom of the basin has a hilly relief. To the north and east of Madagascar, which has a typical continental structure, there are basins Somali. Mascarene And Madagascar. Somali - the largest basin (maximum depth - 5477 m is confined to the Amirant Trench). In its northern part there is a narrow blocky Cheyne Ridge, connected with owen fault zone, crossing the median ridge to the north. A significant part of the bottom of the basin is a flat abyssal plain.
Mascarene basin(maximum depth 5342 m) is separated from the Somali by the Amirant and Mascarene ridges. In the western part of the basin, the relief is leveled; in the eastern part, hills, seamounts, and ridges abound, genetically associated with numerous faults obliquely cutting the Arabian-Indian ridge. lifted Gromlen atoll and sharp fluctuations in depths indicate a significant differentiation of the vertical movements of the bed.
Very interesting relief and geological structure Mascarene Ridge. In essence, this is a heterogeneous morphostructure consisting of several flat-topped shallow water massifs. Its northernmost part is seychelles bank with the islands of the same name, a real microcontinent composed of granites, whose age is 600 million years. South is located Bank of Saia de Malla with minimum depths above it of 7 - 20 m. Examination of the bank (Fedorov, Danilov, 1980) showed that it is composed of sedimentary carbonate rocks (the base of the Paleogene stratum) with a thickness of more than 1600 m, lying on basalts. Has a similar structure Bank of Nazareth. Mauritius island with an underwater base is a mountain volcanic massif.
Mysterious education - Amirant Range, in outline very similar to an island arc, moreover, accompanied by Amirantsky "gutter". The tops of the seamounts that form the ridge are crowned with coral structures.
Madagascar Basin(maximum depth 5815 m) has a predominantly ridge-hilly relief. The earth's crust and within the basin is broken by numerous faults. The most significant of them fault mauritius, with which modern volcanism is associated (Reunion Island).
The main orographic elements of the western part Asian-Australian segment bed of the Indian Ocean - ranges Maldivian And East Indian. To the west of the Maldives range is located Arabian Basin. In the western part of the basin, a small blocky Murray Ridge, genetically and spatially associated with the Owen Fault Zone. To the north, this zone can be traced in the structures of the shelf and the continent in the form seismic zone of Quetta. Most of the Arabian Basin is filled with an underwater fan of the Indus, along the southern periphery of which a narrow abyssal flat plain with seamounts rising above it stretches.
central basin in the north it is occupied by an even more grandiose fan of turbidity flows associated with the underwater canyon of the Ganges. A flat abyssal plain extends along the periphery of the cone. The southern part of the basin is dominated by undulating and hilly relief, there are large seamounts and a small blocky ridge Lanka.
maldives ridge, dividing the basins, has a wide flattened vault. The depths above it are not great, a lot of coral buildings are planted on the vault - very large atolls, often consisting of small atolls - "pharos". The southern part of the ridge is Chagos bank with the coral islands of the same name.
East Indian Range, which limits the Central Basin from the east, is unique both in its straightness and in its length. It is almost exactly elongated along the 90th meridian, so on English and American maps it is called Ninety East Ridge. Its length is more than 4 thousand km. He's clearly sleazy. This is a system of narrow horsts stretched along a thick fault zone and accompanied on the eastern side by a deep graben-type depression. From the southern end of the ridge to the east departs Broken Range or Western Australian - typical oblique horst, inclined to the north and abruptly breaking off to the south, where it runs parallel to Diamantina fault system. It is represented by several short and narrow horsts and deep narrow grabens-troughs of the Ob and Diamantina (maximum depth 7102 m). The fault zone extends to the east almost parallel to the northern boundary of the median ridge (Australian-Antarctic Rise) and fades south of the Great Australian Bight.
East Indian Range And Australo-Antarctic Rise form the boundaries of the eastern part of the Australo-Asian segment of the Indian Ocean bed. Here, a little south of 10 ° S. sh. from west to east, a shaft of the vodovoe uplift type with implanted underwater volcanoes stretches, broken by transverse faults into separate blocks and known as Coconut lift. One of the Cocos Islands Keeling Atoll - was first described by C. Darwin. christmas island, also located in this area, is a raised (up to a height of 350 m) coral reef.
North of the Cocos Rise is coconut basin, the northern part of which is occupied by a vast fan of turbidity flows penetrating here from the Bay of Bengal. The bottom of the southern part of the basin is characterized by a hilly relief. There are several large seamounts. South of the Cocos Rise lies Western Australian Basin(maximum depth 6218 m) with exceptionally hilly terrain. In the south, it is bounded by the West Australian Rise, as well as by a threshold adjacent to the ledge of the underwater margin of Australia - Cuvier plateau. The threshold separates the south naturalist's basin with the abyssal plain of the same name and a maximum depth of 6035 m.
A series of basins in the Australo-Asian sector ends south australian basin, most of the bottom of which is occupied by a large flat abyssal plain.
Antarctic segment the bed of the Indian Ocean includes three basins - Azeri-Antarctic, Crozet And Australo-Antarctic. The first of them has a maximum depth of 6972 m; most of its bottom is occupied by a vast flat abyssal plain composed of diatom sediments from the surface. In the north, the basin is bounded by volcanic Crozet Plateau, and in the east - far out into the ocean Kerguelen ledge underwater margin of Antarctica. North of the Crozet plateau is located Crozet Basin with a maximum depth of 5625 m and predominantly large-hilly vertical dissection. In the Australo-Antarctic Basin (maximum depth 6089 m), the southern part of the bottom is leveled, while the northern part is dominated by a large hilly relief.