the World Ocean, the area with the seas is 91.6 million km 2; average depth 3926 m; the volume of water is 337 million m 3 . Includes: Mediterranean seas (Baltic, North, Mediterranean, Black, Azov, Caribbean with the Gulf of Mexico), little isolated seas (in the North - Baffin, Labrador; near Antarctica - Scotia, Weddell, Lazareva, Riiser-Larsen), large bays (Guinean , Biscay, Hudson, Over Lawrence). Islands of the Atlantic Ocean: Greenland (2176 thousand km 2), Iceland (103 thousand km 2), (230 thousand km 2), Greater and Lesser Antilles (220 thousand km 2), Ireland (84 thousand km 2), Cape Verde (4 thousand km 2), Faroe (1.4 thousand km 2), Shetland (1.4 thousand km 2), Azores (2.3 thousand km 2), Madeira (797 km 2), Bermuda (53.3 km 2) and others (See map).
Historical outline. The Atlantic Ocean became an object of navigation from the 2nd millennium BC. In the 6th century BC. Phoenician ships sailed around Africa. Ancient Greek navigator Pytheas in the 4th century BC sailed to the North Atlantic. In the 10th century AD. Norman navigator Eric the Red explored the coast of Greenland. During the Age of Discovery (15th-16th centuries), the Portuguese mastered the way to the Indian Ocean along the coast of Africa (Vasco da Gama, 1497-98). The Genoese H. Columbus (1492, 1493-96, 1498-1500, 1502-1504) discovered the islands of the Caribbean and. In these and subsequent travels, the outlines and nature of the coasts were established for the first time, coastal depths, directions and speeds of currents, and climatic characteristics of the Atlantic Ocean were determined. The first soil samples were taken by the English scientist J. Ross in the Baffin Sea (1817-1818 and others). Determination of temperature, transparency and other measurements were carried out by expeditions of Russian navigators Yu. F. Lisyansky and I. F. Kruzenshtern (1803-06), O. E. Kotsebu (1817-18). In 1820, the Russian expedition of F. F. Bellingshausen and M. P. Lazarev discovered Antarctica. Interest in the study of the relief and soils of the Atlantic Ocean increased in the middle of the 19th century due to the need to lay transoceanic telegraph cables. Dozens of ships measured depths and took soil samples (American vessels "Arktik", "Cyclops"; English - "Lighting", "Porcupine"; German - "Gazelle", "Valdivia", "Gauss"; French - "Travier", " Talisman, etc.).
An important role in the study of the Atlantic Ocean was played by the British expedition aboard the Challenger (1872-76), based on which, using other data, the first relief and soils of the World Ocean were compiled. The most important expeditions of the 1st half of the 20th century: German on the Meteor (1925-38), American on the Atlantis (30s), Swedish on the Albatross (1947-48). In the early 50s, a number of countries, primarily and, launched extensive research into the geological structure of the bottom of the Atlantic Ocean using accurate echo sounders, the latest geophysical methods, automatic and controlled underwater vehicles. Great work has been carried out by modern expeditions on the ships Mikhail Lomonosov, Vityaz, Zarya, Sedov, Equator, Ob, Akademik Kurchatov, Akademik Vernadsky, Dmitry Mendeleev, and others. 1968 Deep-sea drilling started on board the American vessel Glomar Challenger.
Hydrological regime. There are 4 large-scale gyres in the upper layer of the Atlantic Ocean: the Northern cyclonic gyre (to the north of 45° north latitude), the anticyclonic gyre of the Northern Hemisphere (45° north latitude - 5° south latitude), the anticyclonic gyre of the Southern Hemisphere (5° south latitude - 45° south latitude), Antarctic circumpolar current of cyclonic rotation (45 ° south latitude - Antarctica). On the western periphery of the gyres, there are narrow but powerful currents (2-6 km/h): Labrador - Northern cyclonic gyre; the Gulf Stream (the most powerful current in the Atlantic Ocean.), the Guiana Current - the Northern Anticyclonic Gyre; Brazilian-Southern Anticyclonic Gyre. In the central and eastern regions of the ocean, the currents are relatively weak, with the exception of the equatorial zone.
Bottom waters are formed when surface waters sink in polar latitudes (their average temperature is 1.6°C). In some places, they move at high speeds (up to 1.6 km/h) and are able to erode sediments, carry suspended material, creating underwater valleys and large bottom accumulative landforms. Cold and slightly saline near-bottom Antarctic waters penetrate through the bottoms of basins in the western regions of the Atlantic Ocean up to 42° north latitude. The average temperature of the Atlantic Ocean at the surface is 16.53°C (the South Atlantic is 6°C colder than the North). The warmest waters with an average temperature of 26.7°C are observed at 5-10° north latitude (thermal equator). To Greenland and Antarctica, the water temperature drops to 0 ° C. The salinity of the waters of the Atlantic Ocean is 34.0-37.3 0/00, the highest density of water is over 1027 kg / m 3 in the northeast and south, towards the equator it decreases to 1022.5 kg / m 3. Tides are predominantly semi-diurnal (highest 18 m in the Bay of Fundy); in some areas, mixed and daily tides of 0.5-2.2 m are observed.
Ice. In the northern part of the Atlantic Ocean, ice forms only in the inland seas of temperate latitudes (the Baltic, North and Azov Seas, the Gulf of St. Lawrence); a large amount of ice and icebergs is carried out of the Arctic Ocean (Greenland and Baffin Seas). In the South Atlantic Ocean, ice and icebergs form off the coast of Antarctica and in the Weddell Sea.
Relief and geological structure. Within the Atlantic Ocean, a powerful mountain system extending from north to south is distinguished - the Mid-Atlantic Ridge, which is an element of the global system of Mid-ocean ridges, as well as deep-water basins and (map). The Mid-Atlantic Ridge extends for 17,000 km at a latitude of up to 1,000 km. Its crest is dissected in many areas by longitudinal gorges - rift valleys, as well as transverse depressions - transform faults, which break it into separate blocks with a latitudinal displacement relative to the axis of the ridge. The relief of the ridge, strongly dissected in the axial zone, flattens out towards the periphery due to the burial of sediments. The epicenters of shallow-focus are localized in the axial zone along the crest of the ridge and in areas. Deep-sea basins are located along the outskirts of the ridge: in the west - Labrador, Newfoundland, North American, Brazilian, Argentinean; in the east - European (including Icelandic, Iberian and Irish Trench), North African (including Canary and Cape Verde), Sierra Leone, Guinean, Angolan and Cape. Within the ocean floor, abyssal plains, hill zones, uplifts, and seamounts are distinguished (map). Abyssal plains stretch in two discontinuous bands in the coastal parts of deep-sea basins. These are the flattest areas of the earth's surface, the primary relief of which is leveled by precipitation 3-3.5 km thick. Closer to the axis of the Mid-Atlantic Ridge, at a depth of 5.5-6 km, there are zones of abyssal hills. Oceanic rises are located between the continents and the mid-ocean ridge and separate the basins. The largest uplifts: Bermuda, Rio Grande, Rockall, Sierra Leone, Whale Ridge, Canary, Madeira, Cape Verde, etc.
There are thousands of seamounts known in the Atlantic Ocean; almost all of them are probably volcanic edifices. The Atlantic Ocean is characterized by a discontinuous cutting of the geological structures of the continents by the coastline. The depth of the edge is 100-200 m, in the polar regions 200-350 m, the width is from several kilometers to several hundred kilometers. The most extensive shelf areas are near the island of Newfoundland, in the North Sea, the Gulf of Mexico and off the coast of Argentina. The relief of the shelf is characterized by longitudinal grooves, along the outer edge -. The continental slope of the Atlantic Ocean has a slope of several degrees, a height of 2-4 km, terrace-like ledges and transverse canyons are characteristic. Within the sloping plain (the foot of the mainland), the "granite" layer of the continental crust is wedged out. The transitional zone with a special structure of the crust includes the marginal deep-water trenches: Puerto Rico (maximum depth 8742 m), South Sandwich (8325 m), Cayman (7090 m), Oriente (up to 6795 m), within which are observed as shallow, and deep-focus earthquakes (map).
The similarity of the contours and geological structure of the continents surrounding the Atlantic Ocean, as well as the increase in the age of the basalt bed, the thickness and age of sediments with distance from the axis of the mid-ocean ridge served as the basis for explaining the origin of the ocean within the concept of Mobilism. It is assumed that the North Atlantic was formed in the Triassic (200 million years ago) during the separation of North America from Northwest Africa, the South - 120-105 million years ago during the separation of Africa and South America. The connection of the basins occurred about 90 million years ago (the youngest age of the bottom - about 60 million years - was found in the northeast of the southern tip of Greenland). Subsequently, the Atlantic Ocean expanded with constant new formation of the crust due to effusions and intrusions of basalts in the axial zone of the mid-ocean ridge and its partial subsidence into the mantle in marginal trenches.
Mineral resources. Among the mineral resources of the Atlantic Ocean, gas is also of the greatest importance (map to World Ocean station). North America has oil and gas bearing Labrador Sea, bays: St. Lawrence, Nova Scotia, Georges Bank. Oil reserves on the eastern shelf of Canada are estimated at 2.5 billion tons, gas 3.3 trillion. m 3 , on the eastern shelf and continental slope of the United States - up to 0.54 billion tons of oil and 0.39 trillion. m 3 gas. More than 280 fields have been discovered on the southern shelf of the United States, and more than 20 fields offshore (see). More than 60% of Venezuela's oil is produced in the Maracaibo lagoon (see). The deposits of the Gulf of Paria (Trinidad Island) are actively exploited. The total reserves of the Caribbean Sea shelves are up to 13 billion tons of oil and 8.5 trillion. m 3 gas. Oil and gas bearing areas have been identified on the shelves (Toduz-yc-Santos Bay) and (San Xopxe Bay). Oil fields have been discovered in the North (114 fields) and the Irish Seas, the Gulf of Guinea (50 offshore Nigeria, 37 off Gabon, 3 off the Congo, etc.).
The predicted oil reserves on the Mediterranean shelf are estimated at 110-120 billion tons. Deposits are known in the Aegean, Adriatic, Ionian seas, off the coast of Tunisia, Egypt, Spain, etc. Sulfur is mined in the salt-dome structures of the Gulf of Mexico. With the help of horizontal underground workings, coal is mined from coastal mines in offshore extensions of continental basins - in Great Britain (up to 10% of national production) and Canada. Off the east coast of Newfoundland is the largest iron ore deposit, Waban (total reserves of about 2 billion tons). Tin deposits are being developed off the coast of Great Britain (Cornwall Peninsula). Heavy minerals ( , ) are mined off the coast of Florida, in the Gulf of Mexico. off the coast of Brazil, Uruguay, Argentina, the Scandinavian and Iberian Peninsulas, Senegal, South Africa. The shelf of South West Africa is an area of industrial diamond mining (reserves 12 million). Gold-bearing placers have been discovered off the Nova Scotia Peninsula. found on the shelves of the United States, on the Agulhas Bank. The largest fields of ferromanganese nodules in the Atlantic Ocean are found in the North American Basin and on the Blake Plateau near Florida; their extraction is still unprofitable. The main sea routes in the Atlantic Ocean, along which minerals are transported, were mainly formed in the 18-19 centuries. In the 1960s, the Atlantic Ocean accounted for 69% of all maritime traffic, except for floating craft; pipelines are used to transport oil and gas from offshore fields to shore. The Atlantic Ocean is increasingly polluted with oil products, industrial wastewater from enterprises containing pesticides, radioactive and other substances that harm marine flora and fauna, are concentrated in marine food, posing a great danger to humanity, which requires the adoption of effective measures to prevent further pollution of the ocean environment.
The Atlantic Ocean provides 2/5 of the world catch and its share decreases over the years. In subantarctic and antarctic waters, notothenia, blue whiting and others are of commercial importance, in the tropical zone - mackerel, tuna, sardine, in areas of cold currents - anchovies, in temperate latitudes of the northern hemisphere - herring, cod, haddock, halibut, sea bass. In the 1970s, due to overfishing of some fish species, the volume of fishing fell sharply, but after the introduction of strict limits, fish stocks are gradually recovering. Several international fisheries conventions operate in the Atlantic Ocean basin, which aim at the efficient and rational use of biological resources, based on the application of scientifically based measures to regulate fishing. The shelves of the Atlantic Ocean are rich in deposits of oil and other minerals. Thousands of wells have been drilled offshore in the Gulf of Mexico and in the North Sea. Phosphorite deposits have been discovered in the area of deep water rise off the coast of North Africa in tropical latitudes. Placer deposits of tin off the coast of Great Britain and Florida, as well as diamond deposits off the coast of South-West Africa, have been found on the shelf in the sediments of ancient and modern rivers. Ferromanganese nodules have been found in bottom basins off the coasts of Florida and Newfoundland.
In connection with the growth of cities, the development of navigation in many seas and in the ocean itself, a deterioration in natural conditions has recently been observed. Water and air are polluted, conditions for recreation on the shores of the ocean and its seas have deteriorated. For example, the North Sea is covered with many kilometers of oil slicks. Off the coast of North America, the oil film is hundreds of kilometers wide. The Mediterranean Sea is one of the most polluted on Earth. The Atlantic is no longer able to clean up waste on its own.
124.Physical-geographical zoning of the Atlantic Ocean. At the level of physical and geographical zones, the following divisions are distinguished: 1. Northern subpolar belt (north-western part of the ocean adjacent to Labrador and Greenland). Despite the low temperatures of water and air, these areas are distinguished by high productivity and have always been of great commercial importance.2. Northern temperate belt (spreads far beyond the Arctic Circle into the waters of the Arctic Ocean). The coastal regions of this belt have a particularly rich organic world and have long been famous for the productivity of the fishing regions.3. Northern subtropical belt (narrow). It is distinguished, first of all, by high salinity and high water temperature. Life here is much poorer than in higher latitudes. Commercial value is small, except for the Mediterranean (the pearl of the entire belt =)4. Northern tropical belt. It is characterized by a rich organic world within the neritic zone of the Caribbean Sea and very sparse within the open water area.5. equatorial belt. It is distinguished by the constancy of temperature conditions, the abundance of precipitation and the general richness of the organic world.6. The southern tropical, subtropical and temperate belts, in general, are similar to those of the same name in the northern hemisphere, only the boundaries of the southern tropical and southern subtropical pass in the western part of approx. to the south (influence of the Brazilian current), and in the east - to the north (influence of the cold Benguela current) .7. Southern subpolar - important commercial value.8. South polar! (it is absent in the north), they are distinguished by the greatest severity of natural conditions, ice cover and much less populated.
125. Geographical position, size, boundaries, configuration of the Pacific Ocean. Pacific Ocean - greatest ocean of the earth. It accounts for about half (49%) of the area and more than half (53%) of the volume of the waters of the World Ocean, and the surface area is equal to almost a third of the entire surface of the Earth as a whole. In terms of the number (about 10 thousand) and the total area (more than 3.5 million km 2) of islands, it ranks first among the rest of the oceans of the Earth. Pacific Ocean to the northwest and west limited coasts of Eurasia and Australia, in the northeast and east - the coasts of North and South America. The border with the Arctic Ocean is drawn through the Bering Strait along the Arctic Circle. The southern border of the Pacific Ocean (as well as the Atlantic and Indian) is considered the northern coast of Antarctica. When identifying the Southern (Antarctic) Ocean, its northern boundary is drawn along the waters of the World Ocean, depending on the change in the regime of surface waters from temperate latitudes to Antarctic ones. Square The Pacific Ocean from the Bering Strait to the coast of Antarctica is 178 million km 2, the volume of water is 710 million km 3. Borders with other oceans south of Australia and South America are also conditionally drawn along the water surface: with the Indian Ocean - from Cape South East Point at about 147 ° E, with the Atlantic Ocean - from Cape Horn to the Antarctic Peninsula. In addition to a wide connection with other oceans in the south, there is communication between the Pacific and the northern part of the Indian Ocean through the interisland seas and the straits of the Sunda archipelago. Northern and western (Eurasian) coasts of the Pacific Ocean dismembered seas (there are more than 20 of them), bays and straits that separate large peninsulas, islands and entire archipelagos of continental and volcanic origin. The coasts of Eastern Australia, the southern part of North America and especially South America are usually straight and difficult to access from the ocean. With a huge surface area and linear dimensions (more than 19 thousand km from west to east and about 16 thousand km from north to south), the Pacific Ocean is characterized by a weak development of the continental margin (only 10% of the bottom area) and a relatively small number of shelf seas. Within the intertropical space, the Pacific Ocean is characterized by accumulations of volcanic and coral islands.
The Atlantic Ocean, or the Atlantic, is the second largest (after the Pacific) and the most developed among other water areas. From the east it is limited by the coast of South and North America, from the west - by Africa and Europe, in the north - by Greenland, in the south it merges with the Southern Ocean.
Distinctive features of the Atlantic: a small number of islands, a complex bottom topography and a heavily indented coastline.
Ocean characteristics
Area: 91.66 million sq. km, with 16% of the territory falling on the seas and bays.
Volume: 329.66 million sq. km
Salinity: 35‰.
Depth: average - 3736 m, maximum - 8742 m (Puerto Rico Trench).
Temperature: in the very south and north - about 0 ° C, at the equator - 26-28 ° C.
Currents: conventionally, 2 circulations are distinguished - the Northern (currents move clockwise) and the Southern (counterclockwise). The gyres are separated by the Equatorial inter-trade countercurrent.
Main currents of the Atlantic Ocean
Warm:
Northern trade wind - begins off the western coast of Africa, crosses the ocean from east to west and meets the Gulf Stream near Cuba.
Gulfstream- the most powerful current in the world, which carries 140 million cubic meters of water per second (for comparison: all the rivers of the world carry only 1 million cubic meters of water per second). It originates near the coast of the Bahamas, where the Florida and Antilles currents meet. Together, they give rise to the Gulf Stream, which, through the strait between Cuba and the Florida Peninsula, enters the Atlantic Ocean with a powerful stream. The current then moves north along the US coast. Approximately off the coast of North Carolina, the Gulf Stream turns east and out into the open ocean. After about 1500 km, it meets the cold Labrador Current, which slightly changes the course of the Gulf Stream and carries it to the northeast. Closer to Europe, the current is divided into two branches: Azores and North Atlantic.
It has only recently become known that a reverse current flows 2 km below the Gulf Stream, heading from Greenland to the Sargasso Sea. This stream of icy water was called the Antigulf Stream.
north atlantic- a continuation of the Gulf Stream, which washes the western coast of Europe and brings the warmth of the southern latitudes, providing a mild and warm climate.
Antillean- begins east of the island of Puerto Rico, flows north and joins the Gulf Stream near the Bahamas. Speed — 1-1.9 km/h, water temperature 25-28°C.
Intertrade countercurrent - current around the globe at the equator. In the Atlantic, it separates the North Equatorial and South Equatorial currents.
South trade wind (or South Equatorial) - passes through the southern tropics. The average water temperature is 30°C. When the South Equatorial Current reaches the shores of South America, it divides into two branches: caribbean, or Guiana (flows north to the coast of Mexico) and brazilian- moves south along the coast of Brazil.
Guinean located in the Gulf of Guinea. It flows from west to east and then turns south. Together with the Angolan and South Equatorial forms a cyclic course of the Gulf of Guinea.
Cold:
Lomonosov countercurrent - discovered by a Soviet expedition in 1959. It originates off the coast of Brazil and moves north. A stream 200 km wide crosses the equator and flows into the Gulf of Guinea.
Canarian- flows from north to south, towards the equator along the coast of Africa. This wide stream (up to 1 thousand km) near Madeira and the Canary Islands meets the Azores and Portuguese currents. Approximately in the region of 15°N. joins with the Equatorial Countercurrent.
Labrador - begins in the strait between Canada and Greenland. It flows south to the Newfoundland bank, where it meets the Gulf Stream. The waters of the current carry cold from the Arctic Ocean, and along with the stream, huge icebergs are carried south. In particular, the iceberg that destroyed the famous Titanic was brought by the Labrador Current.
Benguela- is born near the Cape of Good Hope and moves along the coast of Africa to the north.
Falkland (or Malvinas) branches off from the West Wind Current and flows north along the east coast of South America to La Plata Bay. Temperature: 4-15°C.
The course of the westerly winds encircles the globe in the region of 40-50 °S. The stream moves from west to east. In the Atlantic it branches off South Atlantic flow.
Underwater world of the Atlantic Ocean
The underwater world of the Atlantic is poorer in diversity than in the Pacific Ocean. This is due to the fact that the Atlantic Ocean was more frozen during the ice age. But the Atlantic is richer in the number of individuals of each species.
The flora and fauna of the underwater world is clearly distributed across climatic zones.
The flora is represented mainly by algae and flowering plants (Zostera, Posidonia, Fucus). In the northern latitudes, kelp predominates, in temperate latitudes - red algae. Phytoplankton flourishes throughout the ocean at depths of up to 100 m.
The fauna is rich in species. Almost all species and classes of marine animals live in the Atlantic. Of the commercial fish, herring, sardine, and flounder are especially valued. There is an active catch of crustaceans and mollusks, whaling is limited.
The tropical belt of the Atlantic is striking in its abundance. There are many corals and many amazing species of animals: turtles, flying fish, several dozen species of sharks.
For the first time the name of the ocean is found in the writings of Herodotus (5th century BC), who calls it the sea of Atlantis. And in the 1st century AD. Roman scientist Pliny the Elder writes about the vast expanse of water, which he calls Oceanus Atlantikus. But the official name "Atlantic Ocean" was fixed only by the 17th century.
There are 4 stages in the history of Atlantic exploration:
1. From antiquity to the 15th century. The first documents that talk about the ocean date back to the 1st millennium BC. The ancient Phoenicians, Egyptians, Cretans and Greeks knew the coastal zones of the water area well. Preserved maps of those times with detailed measurements of depths, indications of currents.
2. Time of the Great geographical discoveries (XV-XVII centuries). The development of the Atlantic continues, the ocean becomes one of the main trade routes. In 1498, Vasco de Gama, rounding Africa, paved the way to India. 1493-1501 Three voyages of Columbus to America. The Bermuda anomaly has been identified, many currents have been discovered, detailed maps of depths, coastal zones, temperatures, and bottom topography have been compiled.
Expeditions of Franklin in 1770, I. Kruzenshtern and Yu. Lisyansky in 1804-06.
3. XIX-first half of the XX century - the beginning of scientific oceanographic research. Chemistry, physics, biology, geology of the ocean are being studied. A map of currents has been drawn up, and research is being carried out to lay a submarine cable between Europe and America.
4. 1950s - our days. A comprehensive study of all components of oceanography is being carried out. In priority: studying the climate of different zones, identifying global atmospheric problems, ecology, mining, ensuring the movement of ships, seafood.
In the center of the Belize Barrier Reef is a unique underwater cave - the Great Blue Hole. Its depth is 120 meters, and at the very bottom there is a whole gallery of smaller caves connected by tunnels.
The only sea in the world without shores, the Sargasso, is located in the Atlantic. Its borders are formed by ocean currents.
One of the most mysterious places on the planet is located here: the Bermuda Triangle. The Atlantic Ocean is also the birthplace of another myth (or reality?) - the mainland of Atlantis.
TABLE OF CONTENTS
INTRODUCTION
The scientific direction of ocean geography, which was formed as an independent branch of geographical science in the second half of the 20th century, was officially approved in the decisions of the V and VI Congresses of the Geographical Society of the USSR (1970, 1975) and the I All-Union Conference on Ocean Geography (1983). The main tasks of ocean geography were the study of general geographic patterns within the oceanosphere, the establishment of specific relationships between natural conditions and ocean ecosystems, between natural resources and the economy of the ocean, and the determination of anomalous regimes of rational nature management.The physical geography of the ocean deals with the study of the spatial structure and basic physical properties of the ocean as a single natural system, on the one hand, and as part of a more general planetary system - the biosphere - on the other hand. Its tasks include revealing the relationship between the nature of the ocean and continents, large-scale connections between the oceanosphere and the rest of the elements of the geographic envelope of the Earth, the processes of energy and mass transfer between them, and other phenomena.
The twentieth century, especially its last quarter, was marked by a very intensive growth of anthropogenic impact on the environment, which caused an ecological crisis on Earth, which continues in our time. This process covered not only the land, but also the World Ocean, especially the inland and marginal seas adjacent to economically developed countries. Most of the anthropogenic load is experienced by the Atlantic Ocean.
The above circumstances determine the relevance of the chosen topic. Object of study at work is the Atlantic Ocean, subject its natural wealth.
Objective– to analyze the natural resources of the Atlantic. To achieve this goal, we have set the following tasks:
- give a general description of the Atlantic Ocean;
- analyze the properties of waters, the composition of flora and fauna, as well as pay attention to the minerals of the ocean;
- to reveal the features and problems of ocean development.
This work will be useful to everyone who is interested in oceanology, as well as nature management.
CHAPTER 1. CHARACTERISTICS OF THE ATLANTIC OCEAN
1.1 Geographic location, climatic and hydrological conditions
The Atlantic Ocean is the most studied and mastered by people. It got its name from the name of the titan Atlanta (according to Greek mythology, holding the vault of heaven on his shoulders). At different times it was called differently: "The Sea behind the Pillars of Hercules", "Atlantic", "Western Ocean", "Sea of Darkness", etc. The name "Atlantic Ocean" first appeared in 1507 on Wald-Semüller's map, and the name has since established itself in geography.The boundaries of the Atlantic Ocean along the coasts of the continents (Eurasia, Africa, the Americas and Antarctica) are natural, with other oceans (the Arctic, Pacific and Indian) are largely conditional.
The Atlantic Ocean borders the Arctic Ocean at 70°N. sh. (Baffin Island - Disko Island), then from Cape Brewster (Greenland) along the Iceland-Farrer threshold to 6 ° N. sh. (Scandinavian Peninsula); with the Pacific Ocean - from about. Ost (Tierra del Fuego) to Cape Sternek (Antarctic Peninsula); with the Indian Ocean - at 20 ° E. from Cape Agulhas to Antarctica. The rest of the ocean is limited by the coastline of Eurasia, Africa, North and South America, Antarctica (Fig. 1.). The above boundaries are officially accepted in our country and are indicated in the Atlas of the Oceans (published by the Ministry of Defense of the USSR and the Navy, 1980). Within the indicated limits, the ocean area is 93.4 million km 2, the volume of water is 322.7 million km 3. The exchange of water takes 46 years, which is 2 times faster than in the Pacific Ocean.
The significant role of the Atlantic in people's lives is largely due to purely geographical circumstances:
a large extent (from the Arctic to the Antarctic) between four continents, and it separates mostly flat areas on the continents, convenient for human settlement and mastered by them for a long time;
the fact that large and medium-sized rivers flow into the ocean (Amazon, Congo, Niger, Mississippi, St. Lawrence, etc.), which served and continue to serve as natural means of communication;
the large indentation of the coastline of Europe, the presence of the Mediterranean Sea, the Gulf of Mexico, which contributed to the development of navigation and ocean exploration.
The Atlantic Ocean has several seas: the Baltic, Mediterranean, Black, Marmara, Azov, Caribbean and 3 large bays: Mexican, Biscay and Guinea. The largest islands - Great Britain, Ireland are located off the coast of Europe. Particularly large clusters of islands are located off the coast of Central America: the Greater and Lesser Antilles, the Bahamas; off the coast of South America - Falkland, in the southern part of the ocean - South Orkney and South Sandwich; off the coast of Africa - Canaries, Cape Verde, Azores, Madeira, Principe, Sao Tome, etc. In the axial zone of the ocean are the islands of Iceland, Ascension, St. Helena, Tristan da Cunha, on the border with the Arctic Ocean - the largest island on Earth is Greenland.
The climates of the Atlantic are largely determined by its large meridional extent, the features of the formation of the baric field, and the peculiarity of the configuration (water areas are larger in temperate latitudes than in equatorial-tropical ones). On the northern and southern outskirts there are huge regions of cooling and the formation of centers of high atmospheric pressure. Over the ocean area, constant areas of low pressure are also formed in equatorial and temperate latitudes and high pressure in subtropical latitudes.
These are the Equatorial and Antarctic depressions, the Icelandic low, the North Atlantic (Azores) and South Atlantic highs 1 .
In the southern hemisphere, where the surface of the ocean is interrupted by land only in relatively small spaces, all the main baric systems are extended along the equator in the form of sublatitudinal belts separated by frontal zones, and during the year they only slightly shift following the sun towards the summer hemisphere.
In the winter of the southern hemisphere, the southeast trade wind penetrates to the equator and somewhat to the north, towards the Gulf of Guinea and the northern part of South America. The main precipitation at this time falls in the northern hemisphere, and dry weather prevails on both sides of the Southern Tropic. South of 40° S western transport is active, winds blow, often reaching storm strength, dense clouds and fogs are observed, and heavy precipitation in the form of rain and snow falls. These are the "roaring forties" latitudes. Southeasterly and easterly winds blow from Antarctica in high latitudes, with which icebergs and sea ice are carried northward.
In the warm half of the year, the main directions of movement of air flows remain, but the equatorial trough expands to the south, the southeast trade wind intensifies, rushing into the area of low pressure over South America, and precipitation falls along its eastern coast. Western winds in temperate and high latitudes remain the dominant atmospheric process.
Natural conditions in the subtropical and temperate latitudes of the North Atlantic differ significantly from those that are characteristic of the southern part of the ocean. This is due both to the characteristics of the water area itself and to the size of the land that limits it, the temperature and air pressure over which change dramatically during the year. The most significant contrasts in pressure and temperature are created in winter, when high pressure centers form over ice-covered Greenland, North America and the interior of Eurasia due to cooling, and the temperature not only over land, but also over ice-filled interisland waters of the Canadian Arctic Archipelago is very low. . The ocean itself, with the exception of the coastal northwestern part, even in February maintains a surface water temperature of 5 to 10 °C. This is due to the influx of warm water from the south into the northeastern part of the Atlantic and the absence of cold water from the Arctic Ocean.
In the north of the Atlantic Ocean, a closed area of low pressure forms in winter - the Icelandic, or North Atlantic, minimum. Its interaction with the Azores (North Atlantic) maximum located at the 30th parallel creates a predominant westerly wind flow over the North Atlantic, which carries humid, unstable relatively warm air from the ocean to the Eurasian continent. This atmospheric process is accompanied by precipitation in the form of rain and snow at positive temperatures. A similar situation applies to the ocean area south of 40°N. and in the Mediterranean, where it rains at this time.
In the summer season of the northern hemisphere, the high pressure area persists only above the Greenland ice sheet, low pressure centers are established over the continents, and the Icelandic low is weakening. The western transport remains the main circulation process in temperate and high latitudes, but it is not as intense as in winter. The Azores High is intensifying and expanding, and most of the North Atlantic, including the Mediterranean Sea, is under the influence of tropical air masses and does not receive precipitation. Only off the coast of North America, where moist-unstable air enters along the periphery of the Azores High, monsoon-type precipitation falls, although this process is not at all as pronounced as on the Pacific coast of Eurasia.
In summer and especially in autumn, tropical hurricanes arise over the Atlantic Ocean between the northern tropic and the equator (as in the Pacific and Indian oceans at these latitudes), which sweep over the Caribbean Sea, the Gulf of Mexico, Florida with great destructive force, and sometimes penetrate far to the north, up to 40°N
In connection with the high solar activity observed in recent years off the coast of the Atlantic Ocean, the frequency of tropical hurricanes has increased significantly. In 2005, three hurricanes - Katrina, Rita and Emily - hit the south coast of the United States, the first of which caused great damage to the city of New Orleans.
1.2. Bottom relief
The Mid-Atlantic Ridge runs through the entire ocean (approximately at an equal distance from the coasts of the continents) (Fig. 2).The outlines of the shores of the Atlantic Ocean are extremely remarkable. If Africa and South America, Europe and North America are moved close to each other on the map so that their coastlines coincide, then the contours of the continents will converge like two halves of a torn ruble. This coincidence in the outlines of the shores led some scientists to a rather simple and original conclusion that the listed continents used to form a single supercontinent, in which a giant crack appeared under the influence of the Earth's rotation. America separated from Europe and Africa and drifted along the viscous deep rocks to the west, and the depression formed between them filled with water and turned into the Atlantic Ocean.
Later, when it was established that a huge mountain system stretched from north to south in the Atlantic Ocean - the Mid-Atlantic Ridge, it turned out to be not so easy to explain the origin of the Atlantic Ocean depression by the drift of America. The question arose: if America sailed away from Africa, then where did the 300-1500 kilometers wide range between them come from, the peaks of which rise 1500-4500 meters above the ocean floor? Maybe there was no continental drift? Maybe the waves of the Atlantic walk over the flooded continents? This is the opinion of most geologists.
But the more information was accumulated about the structure of the mysterious ridge, about the details of the bottom topography and the rocks that make it up, the clearer the complexity and seriousness of the problem became for scientists. This was aggravated by the fact that the obtained scientific data often gave rise to conflicting judgments.
In the process of studying the ocean, it turned out that a deep valley runs along the axis of the Mid-Atlantic Ridge - a crack that cuts the ridge along almost its entire length. Such valleys usually arise under the action of tectonic tensile forces and are called rift valleys. They are zones of active manifestation of tectonics, seismicity and volcanism in the geological history of the Earth. The discovery of a rift valley at the bottom of the ocean was reminiscent of a giant crack in a hypothetical supercontinent and continental drift. However, these new data and, above all, the features of the relief of the ridge demanded a different explanation of the mechanism of continental drift.
Schematically, the Mid-Atlantic Ridge is now presented as a symmetrical mountain structure, where the rift valley serves as the axis of symmetry. Interestingly, the earthquakes that occur in the Atlantic Ocean are mostly associated with the Mid-Atlantic Ridge, and most of them are confined to the rift valley. Examining the topography of the ridge and pieces of rocks raised from the bottom, scientists noticed a regularity that surprised them in the geological structure of this mountain structure, namely: the farther - whether to the west or east - from the rift valley, the older the bottom topography and the older the mountains become. rocks that make up the mysterious underwater mountainous country. Thus, basalt rocks lifted by geologists from the crest of the ridge and from the rift valley, as a rule, are several hundred thousand years old, some samples of basalt are several million years old, but not more than five million. In the geological sense, these rocks are young. On the flanks of the ridge, the basalts are much older than on the crest; their age reaches 30 million years or more. Even farther from the axis of symmetry, closer to the continents, the age of rocks raised from the ocean floor has been determined at 70 million years. It is important to note that no rocks older than 100 million years have been found in the Atlantic Ocean, while on land the age of the oldest rocks has been determined to be more than three billion years.
The given information about the age of oceanic rocks allows us to consider the Mid-Atlantic Ridge as a fairly young rock formation, which continues to develop and change at the present time.
The Atlantic Ocean is second in size only to the Pacific. It is distinguished from other oceans by the strong indentation of the coastline, which forms numerous seas and bays, especially in the northern part. In addition, the total area of river basins flowing into this ocean or its marginal seas is much larger than that of rivers flowing into any other ocean. Another difference of the Atlantic Ocean is a relatively small number of islands and a complex bottom topography, which, thanks to underwater ridges and uplifts, forms many separate basins.
The Atlantic Ocean is located in all climatic zones of the Earth. The main part of the ocean area is between 40°N. and 42° S - is located in subtropical, tropical, subequatorial and equatorial climatic zones. There are high positive air temperatures all year round. The most severe climate is in the subantarctic and antarctic latitudes, and to a lesser extent in the subpolar, northern latitudes.
CHAPTER 2. NATURAL RICHES OF THE ATLANTIC OCEAN
2.1. Waters and their properties
The zonality of water masses in the ocean is complicated by the influence of land and sea currents. This is manifested primarily in the temperature distribution of surface waters. In many areas of the ocean, the isotherms near the coast deviate sharply from the latitudinal direction.The northern half of the ocean is warmer than the southern one, the temperature difference reaches 6°С. The average surface water temperature (16.5°C) is slightly lower than in the Pacific Ocean. The cooling effect is exerted by the waters and ices of the Arctic and Antarctic.
In equatorial latitudes, there are two trade wind currents - the North Trade Wind and the South Trade Wind, moving from east to west. Between them, the trade wind countercurrent moves to the east. The Northern Equatorial Current passes near 20°N. and off the coast of North America gradually deviates to the north. The South Trade Wind Current, passing south of the equator from the coast of Africa to the west, reaches the eastern ledge of the South American mainland and at Cape Cabo Branco is divided into two branches running along the coast of South America. Its northern branch (the Guiana Current) reaches the Gulf of Mexico and, together with the North Trade Wind Current, takes part in the formation of the system of warm currents in the North Atlantic. The southern branch (Brazilian Current) reaches 40°S, where it meets with a branch of the circumpolar West Winds Current, the cold Falkland Current. Another branch of the West Winds current, carrying relatively cold water northward, enters the Atlantic Ocean off the southwestern coast of Africa. This is the Benguela Current - an analogue of the Peru Current of the Pacific Ocean. Its influence can be traced almost to the equator, where it flows into the South Equatorial Current, closing the southern Atlantic gyre and significantly reducing the temperature of surface waters off the coast of Africa.
The overall picture of surface currents in the North Atlantic is much more complex than in the southern part of the ocean.
A branch of the North Tradewind Current, reinforced by the Guiana Current, penetrates through the Caribbean Sea and the Yucatan Strait into the Gulf of Mexico, causing a significant increase in the water level there compared to the ocean. As a result, a powerful sewage current arises, which, bending around Cuba, through the Florida Strait, enters the ocean called the Gulf Stream (“stream from the bay”). Thus, off the southeastern coast of North America, the greatest system of warm surface currents of the World Ocean is born.
Gulf Stream at 30°N and 79°W merges with the warm Antilles Current, which is a continuation of the North Trade Wind Current. Further, the Gulf Stream runs along the edge of the continental shelf to about 36°N. At Cape Hatteras, deviating under the influence of the rotation of the Earth, it turns east, skirting the edge of the Great Newfoundland bank, and leaves for the shores of Europe called the North Atlantic Current, or "Gulf Stream Drift".
At the outlet of the Florida Strait, the width of the Gulf Stream reaches 75 km, the depth is 700 m, and the current speed is from 6 to 30 km/h. The average water temperature on the surface is 26 °C. After the confluence with the Antilles current, the width of the Gulf Stream increases 3 times, and the water flow is 82 million m 3 / s, i.e., 60 times the flow of all the rivers of the globe.
North Atlantic Current at 50°N and 20°W splits into three branches. The northern one (the Irminger Current) goes to the southern and western shores of Iceland, and then goes around the southern coast of Greenland. The main middle branch continues to move northeast, towards the British Isles and the Scandinavian Peninsula, and goes into the Arctic Ocean called the Norwegian Current. The width of its flow to the north of the British Isles reaches 185 km, the depth is 500 m, the flow rate is from 9 to 12 km per day. The water temperature on the surface is 7 ... 8 °C in winter and 11 ... 13 °C in summer, which is on average 10 °C higher than at the same latitude in the western part of the ocean. The third, southern, branch penetrates the Bay of Biscay and continues south along the Iberian Peninsula and the northeastern coast of Africa in the form of the cold Canary Current. Pouring into the Northern Equatorial Current, it closes the subtropical circulation of the North Atlantic.
The northwestern part of the Atlantic Ocean is mainly under the influence of cold waters coming from the Arctic, and other hydrological conditions develop there. In the area of Newfoundland Island, the cold waters of the Labrador Current move towards the Gulf Stream, pushing the warm waters of the Gulf Stream from the northeastern coast of North America. In winter, the waters of the Labrador Current are 5 ... 8 ° C colder than the Gulf Stream; all year round their temperature does not exceed 10 ° C, they form the so-called "cold wall". The convergence of warm and cold waters contributes to the development of microorganisms in the upper layer of water and, consequently, to the abundance of fish. Especially famous in this regard is the Great Newfoundland Bank, where cod, herring, and salmon are caught.
Up to about 43°N The Labrador Current carries icebergs and sea ice, which, combined with the fogs characteristic of this part of the ocean, poses a great danger to navigation. A tragic illustration is the disaster of the Titanic liner, which crashed in 1912 800 km southeast of Newfoundland.
The temperature of the water on the surface of the Atlantic Ocean, as in the Pacific, is generally lower in the southern hemisphere than in the northern. Even at 60°N (with the exception of the northwestern regions), the temperature of surface waters fluctuates during the year from 6 to 10 °C. In the southern hemisphere at the same latitude it is close to 0°C and lower in the eastern part than in the western.
The warmest surface waters of the Atlantic (26 ... 28 ° C) are confined to the zone between the equator and the Northern Tropic. But even these maximum values do not reach the values noted at the same latitudes in the Pacific and Indian Oceans.
Salinity indicators of the surface waters of the Atlantic Ocean are much more diverse than in other oceans. The highest values (36-37% o - the maximum value for the open part of the World Ocean) are typical for tropical regions with low annual precipitation and strong evaporation. High salinity is also associated with the inflow of salt water from the Mediterranean Sea through the shallow Strait of Gibraltar. On the other hand, large areas of the water surface have an average oceanic and even low salinity. This is due to large amounts of atmospheric precipitation (in equatorial regions) and the desalination effect of large rivers (Amazon, La Plata, Orinoco, Congo, etc.). In high latitudes, the decrease in salinity to 32-34% o, especially in summer, is explained by the melting of icebergs and floating sea ice.
The structural features of the North Atlantic Basin, the circulation of the atmosphere and surface waters in subtropical latitudes determined the existence of a unique natural formation here, called the Sargasso Sea (Fig. 2). This mysterious region of almost stagnant water lies in the southwestern part of the North Atlantic, between Bermuda and the West Indies. This sea got its name from the Portuguese word "saggaso", which means "seaweed". Almost stagnant, but clean and warm water is inhabited by Sargassum algae, which are able to live and reproduce afloat (Fig. 3). Thanks to them, the conditions here are more reminiscent of the intertidal zone, rather than the open ocean. Microscopic plankton does not live here, as the water temperature is too high.
2.2.Flora
The vegetation of the ocean is very diverse. Phytobenthos (bottom vegetation) occupies about 2% of the bottom area and is distributed on the shelf to a depth of 100 m. It is represented by green, brown, red algae and some higher plants. The tropical ocean belt is characterized by high species diversity, but a small amount of biomass compared to cold and temperate geographic zones. Brown algae are characteristic of the northern littoral zone, and kelp is characteristic of the sublittoral zone. There are red algae and some types of sea grasses. In the tropical zone, green algae are very common. The largest sizes are different types of sea lettuce. Of the red algae, porphyries, rodilinia, haidrus, anfeltia are widely represented. For many animals, free-floating Sargassum algae, typical of the Sargasso Sea, form a kind of biotope. Of the brown algae in the sublittoral zone in the northern part of the ocean, giant representatives of macrocystis are characteristic. Phytoplankton, unlike phytobenthos, develops throughout the water space. In the cold and temperate zones of the ocean, it is concentrated at a depth of up to 50 m, and in the tropical zone - up to 80 m. It is represented by 234 species. Important representatives of phytoplankton are silicon algae, which are characteristic of temperate and circumpolar regions. In these areas, silicon algae represent more than 95% of the total phytoplankton. Near the equator, the amount of algae is negligible. The mass of phytoplankton ranges from 1 to 100 mg/m 3 , and in the high latitudes of the Northern and Southern Hemispheres during the period of mass development (sea bloom) it reaches 10 g/m 3 or more.2.3 Fauna
The fauna of the Atlantic Ocean is rich and diverse. Animals inhabit the entire water column of the ocean. The diversity of fauna increases towards the tropics. In polar and temperate latitudes, they number thousands of species, in tropical - tens of thousands.Large marine mammals live in temperate and cold waters - whales and pinnipeds, from fish - herring, cod, perch and flatfish, in zooplankton there is a sharp predominance of copepods and sometimes pteropods. There is a great similarity between the faunas of the temperate zones of both hemispheres. More than 100 species of animals are bipolar, that is, they live only in the cold and temperate zones, these include seals, seals, whales, sprats, sardines, anchovies, and many invertebrates, including mussels. The tropical waters of the Atlantic Ocean are characterized by: sperm whales, sea turtles, crustaceans, sharks, flying fish, crabs, coral polyps, scyphoid jellyfish, siphonophores, radiolarians. There are also many inhabitants dangerous to humans: sharks, barracudas, moray eels. There are urchin fish and invertebrate sea urchins whose needle pricks are very painful.
The world of corals is very peculiar, but the coral structures of the Atlantic are insignificant in comparison with the Pacific Ocean. At a depth of about 4 m off the coast of Cuba, there is a “sea fan” coral that looks like burdock-shaped leaves pierced by a network of vessels - this is a soft gogonaria coral that forms whole thickets - “underwater forests”.
The deep-water regions of the Atlantic, like other oceans, are a special environment of enormous pressure, low temperatures and eternal darkness. Here you can find crustaceans, echinoderms, annelids, silicon sponges, sea lilies.
In the Atlantic, there is also an “ocean desert” (“oceanic Sahara”) - this is the Sargasso Sea, where the biomass value is no more than 25 mg / m 3, which is primarily due, apparently, to the special gas regime of the sea.
2.4 Minerals
A large number of offshore oil and gas fields have been discovered in the Atlantic Ocean and its seas, which are being intensively developed. The richest offshore oil and gas regions in the world include: the Gulf of Mexico, the Maracaibo lagoon, the North Sea, the Gulf of Guinea, which are being intensively developed. Three large oil and gas provinces have been identified in the Western Atlantic: 1) from the Davis Strait to the latitude of New York (commercial reserves near Labrador and south of Newfoundland); 2) offshore Brazil from Cape Kalkanyar to Rio de Janeiro (more than 25 fields have been discovered); 3) in the coastal waters of Argentina from the Gulf of San Jorge to the Strait of Magellan. According to estimates, promising oil and gas areas make up about 1/4 of the ocean, and the total potential recoverable oil and gas resources are estimated at more than 80 billion tons. The largest iron ore deposit, Waban (total reserves of about 2 billion tons), is located off the eastern coast of Newfoundland. Tin deposits are being developed off the coast of Great Britain and Florida. Heavy minerals (ilmenite, rutile, zircon, monazite) are mined off the coast of Florida, in the Gulf of Mexico. off the coast of Brazil, Uruguay, Argentina, the Scandinavian and Iberian Peninsulas, Senegal, South Africa. The shelf of South West Africa is an area of industrial diamond mining (reserves of 12 million carats). Gold-bearing placers have been discovered off the Nova Scotia Peninsula. Phosphorites are found on the shelves of the USA, Morocco, Liberia, on the Agulhas Bank. Diamond deposits have been discovered off the coast of South West Africa on the shelf in the sediments of ancient and modern rivers. Ferromanganese nodules have been found in bottom basins off the coasts of Florida and Newfoundland 2 . Coal, barite, sulfur, sand, pebbles and limestone are also mined from the seabed.As for the entire World Ocean, the Atlantic is characterized by an abundance of biomass with a relative poverty of the species composition of the organic world in temperate and high latitudes, and a much greater species diversity in the intertropical space and subtropics.
The zooplankton includes copepods (krill) and pteropods; phytoplankton is dominated by diatoms. For the corresponding latitudes of the northern part of the Atlantic Ocean (the North Atlantic biogeographic region), the presence in the composition of the organic world of the same groups of living organisms as in the southern hemisphere is typical, but they are represented by other species and even genera. And compared with the same latitudes of the Pacific Ocean, the North Atlantic is distinguished by a large species diversity. This is especially true for fish and some mammals. Many areas of the North Atlantic have long been and continue to be places of intensive fishing. On the banks off the coast of North America, in the North and Baltic Seas, cod, herring, halibut, sea bass, and sprat are caught. Since ancient times, mammals have been hunted in the Atlantic Ocean, especially seals, whales and other marine animals. This led to a severe depletion of the fishing resources of the Atlantic compared to the Pacific and Indian Oceans.
etc.................
Some areas of the Atlantic shelf are rich in coal. Great Britain conducts the largest underwater mining of coal. The largest exploited Nor Tumberland Derham field with reserves of about 550 million tons is located on the northeast coast of England. Coal deposits have been explored in the shelf zone northeast of Cape Breton Island. However, in the economy, underwater coal is of less importance than offshore oil and gas fields. The main supplier of monazite to the world market is Brazil. The United States is also the leading producer of ilmenite, rutile and zircon concentrates (placers of these metals are almost ubiquitous on the shelf of North America - from California to Alaska). Of considerable interest are cassiterite placers off the coast of Australia, off the Cornwall peninsula (Great Britain), and in Brittany (France). The largest deposits of ferruginous sands are located in Canada. Ferrous sands are also mined in New Zealand. Alluvial gold in coastal marine deposits has been found on the western coasts of the United States and Canada.
The main deposits of coastal-marine diamondiferous sands are concentrated on the southwestern coast of Africa, where they are associated with deposits of terraces, beaches, and shelves down to depths of 120 m. Significant marine terrace diamond placers are located in Namibia. African coastal-marine placers are promising.
In the coastal zone of the shelf there are underwater deposits of iron ore. The most significant development of offshore deposits of iron ore is carried out in Canada, on the east coast of Newfoundland (the Wabana deposit). In addition, Canada mines iron ore in the Hudson Bay.
In small quantities, copper and nickel are mined from underwater mines (Canada - in the Hudson Bay). Tin is mined on the Cornwall peninsula (England). In Turkey, on the coast of the Aegean Sea, mercury ores are being developed. Sweden mines iron, copper, zinc, lead, gold and silver in the bowels of the Gulf of Bothnia.
Large salt sedimentary basins in the form of salt domes or stratal deposits are often found on the shelf, slope, foot of the continents and in deep-sea basins (Gulf of Mexico, shelves and slopes of West Africa, Europe). The minerals of these basins are represented by sodium, potassium and magnesite salts, gypsum. Calculation of these reserves is difficult: the volume of potassium salts alone is estimated in the range from hundreds of millions of tons to 2 billion tons. Two salt domes are being exploited in the Gulf of Mexico off the coast of Louisiana.
More than 2 million tons of sulfur are extracted from underwater deposits. Exploited the largest accumulation of sulfur Grand Isle, located 10 miles from the coast of Louisiana. Commercial reserves of phosphorites have been found near the Californian and Mexican coasts, along the coastal zones of South Africa, Argentina, off the coast of New Zealand. Phosphorites are mined in the California region from depths of 80-330 m, where the concentration averages 75 kg/m3.
A large number of offshore oil and gas fields have been discovered in the Atlantic Ocean and its seas, including those with one of the highest levels of production of these fuels in the world. They are located in different areas of the ocean shelf zone. In its western part, the bowels of the Maracaibo lagoon are distinguished by very large reserves and production volumes. Oil is extracted here from more than 4,500 wells, from which in 2006 93 million tons of "black gold" were produced. The Gulf of Mexico is considered to be one of the richest offshore oil and gas regions in the world, believing that only a small part of potential oil and gas reserves have been discovered in it at present. 14,500 wells have been drilled at the bottom of the bay. In 2011, 60 million tons of oil and 120 billion m3 of gas were produced from 270 offshore fields, and in total, 590 million tons of oil and 679 billion m3 of gas were extracted here during the development period. The most significant of them are located off the coast of the Paraguano Peninsula, in the Gulf of Paria and off the island of Trinidad. Oil reserves here amount to tens of millions of tons.
In addition to the above areas, three large oil and gas provinces can be traced in the western Atlantic. One of them stretches from the Davis Strait to the latitude of New York. Within its limits, commercial oil reserves have so far been identified near Labrador and south of Newfoundland. The second oil and gas province stretches along the coast of Brazil from Cape Calcañar in the north to Rio de Janeiro in the south. 25 deposits have already been discovered here. The third province occupies the coastal areas of Argentina from the Gulf of San Jorge to the Strait of Magellan. Only small deposits have been discovered in it, so far unprofitable for offshore development.
In the shelf zone of the eastern coast of the Atlantic, oil shows have been discovered south of Scotland and Ireland, off the coast of Portugal, in the Bay of Biscay. A large oil and gas region is located near the African continent. About 8 million tons are produced by the oil fields concentrated near Angola.
Very significant oil and gas resources are concentrated in the depths of some seas of the Atlantic Ocean. Among them, the most important place is occupied by the North Sea, which knows no equal in terms of the pace of development of underwater oil and gas fields. Significant underwater deposits of oil and gas have been explored in the Mediterranean Sea, where 10 oil and 17 offshore gas fields are currently operating. Significant volumes of oil are extracted from fields located off the coasts of Greece and Tunisia. Gas is being developed in the Gulf of Sidra (Bol. Sirte, Libya), off the Italian coast of the Adriatic Sea. In the future, the subsoil of the Mediterranean Sea should produce at least 20 million tons of oil per year.
