Tuesday, 19 January 2016

CAMEROON LINE

The Cameroon line is a chain of volcanoes about 1,600 km (990 mi). It consolidates islands in the Gulf of Guinea and mountains that extend along the edge region of eastern Nigeria and western Cameroon, from Mount Cameroon on the Gulf of Guinea north and east towards Lake Chad. The islands, which compass the equator, have tropical environments and are home to various novel plant and youngster species. The domain mountain areas are much cooler than the including swamps, besides contain novel and ecologically basic environments.The Cameroon volcanic line is topographically unusual in connecting through both the ocean and the territory structure. Distinctive speculations have been advanced by different geologists to clear up the line.

In the Gulf of Guinea, the Cameroon line includes six offshore volcanic swells that have molded islands or seamounts. From the southwest toward the upper east the island social events are Pagalu (or Annobón), São Tomé, Príncipe and Bioko. Two gigantic seamounts lie between São Tomé and Príncipe, and amidst Principe and Bioko. On the landscape, the line starts with Mount Cameroon and intensifies upper east in a span known as the Western High Plateau, home to the Cameroonian Highlands woodlands. Volcanic swells help inland are Manengouba, Bamboutu and the Oku Massif. East side of Oku there are various volcanic mountains in the Ngaoundere Plateau, some of which appear to have near beginnings.

The southernmost island in the chain is Annobón, generally called Pagalu, with a scope of around 17.5 km2 (6.8 sq mi). It is a wiped out spring of spouting magma that risings from significant water to 598 m (1,962 ft) above sea level. The ordinary temperature is 26.1 °C (79.0 °F), with insignificant intermittent assortment. Most rain tumbles from November to May, with yearly precipitation averaging 1,196 mm (47.1 in) - not precisely on the landscape. Annobón has luxurious valleys and steep mountains, secured with rich woods and lavish vegetation. The pagalu island has a spot with Equatorial Guinea. The little masses lives in one gathering, sharpening some agribusiness however on a very basic level angling so as to live.

São Tomé Island is 854 km2 (330 sq mi) in area, lying for all intents and purposes on the equator. The entire island is a colossal shield wellspring of fluid magma which rises from the floor of the Atlantic Ocean, more than 3,000 m (10,000 ft) underneath sea level, and comes to 2,024 m (6,640 ft) above sea level in the Pico de São Tomé. The most prepared rock on Sao Tome is 13 million years old. Most of the magma radiated on São Tomé all through the latest million years has been basalt. The most energetic dated rock on the island is around 100,000 years old, yet different later cinder cones are found on the southeast side of the island.

Príncipe is the smaller of the two foremost islands of São Tomé and Príncipe, with a zone of 136 km2 (53 sq mi). Volcanic development stopped around 15.7 million years earlier, and the island has been significantly broken down isolated from wonderful towers of phonolite. The island is enveloped by more diminutive islands including Ilheu Bom, Ilhéu Caroço, Tinhosa Grande and Tinhosa Pequena, and lies in ocean 3,000 m (9,800 ft) significant. It rises in the south to 946 m (3,104 ft) at Pico de Príncipe, in a thickly forested reach within the Obo National Park. The north and center of the island were in the past farms yet have, as it were, came back to forest. Additionally as with São Tomé, the island has constantly been disconnected from the region and in this way has various exceptional sorts of plants and animals, including six endemic winged creatures. Príncipe has a masses of around 5,000 people. Other than Portuguese, some speak Principense or Lunguyê with a couple Forro speakers.

Bioko is just 32 km (20 mi) off the shore of Cameroon, on the terrain rack. The island used to be the end of a landmass joined to the region, yet was cut off when sea levels rose 10,000 years back toward the end of the last ice age. With a region of 2,017 km2 (779 sq mi) it is the greatest island in the Cameroon line.

Bioko has three basaltic shield volcanoes, joining at the lower levels. San Carlos is 2,260 m (7,410 ft) high with a far reaching summit caldera, lying at the astounding SW of the island. The spring of spouting magma dates from the Holocene age and has been changing within the latest 2000 years. Santa Isabel is the greatest spring of spouting magma at 3,007 m (9,865 ft) in stature, and contains various satellite slag cones. Three emanations have been represented from vents on the southeast flank in the midst of the late-nineteenth and mid twentieth many years. San Joaquin, generally called Pico Biao or Pico do Moka, is 2,009 m (6,591 ft) high, on the southeast of the island. The summit is cut by a little lake-filled caldera, and there is a gap lake on the NE flank. San Joaquin has in like manner been alterable in the midst of the latest 2000 years.

The Western High Plateau, also called the Western Highlands or the Bamenda Grassfields, continues with the Cameroon line into the territory of Cameroon. The level climbs in endeavors from the west. At the east, it closes in mountains that range in reach from 1,000 m (3,300 ft) to 2,500 meters (8,200 ft). The level offers way to the Adamawa Plateau toward the upper east, a greater yet less intense region.The Western High Plateau highlights a couple of slow volcanoes, including the Bamboutos Mountains, Mount Oku, and Mount Kupe. Cavity lakes detect the level, the result of dead volcanoes stacking with water. This joins Lake Barombi Mbo and Lake Bermin, which have the most bewildering number of endemic fish species per range recorded wherever on the planet.

The 4,095 m (13,435 ft) Mount Cameroon on the coastline, which may have been seen by the Carthaginian Hanno the Navigator in the fifth century BC, catapulted in 2000. Help inland, the stratovolcano Mount Oku at 3,011 meters (9,879 ft) is the second most shocking mountain in sub-Saharan domain West Africa. In 1986, Lake Nyos, a hole lake in the Oku volcanic plain, released a surge of carbon dioxide gas that butchered no under 1,200 people.

Disregarding the way that geographers may control the Cameroon line to the volcanoes in the island chain and the Western High Plateau, various geologists similarly fuse the Ngaoundere Plateau which develops the line toward the east in the Adamawa level, and some would moreover consolidate the Biu level and the Jos Plateau in Nigeria.

Geologists contrast over which volcanic zones should be fused into the Cameroon Volcanic Line. All fuse the island line and the territory line up to Oku. Considering comparable qualities in age and piece, some furthermore join the Ngaoundere Plateau, the Biu level of Nigeria toward the north of the Yola arm of the Benue Trough, and the Jos Plateau toward the west of the Benue Trough. There are changing theories for the comparable qualities between the sea and territory volcanoes.

The Cameroon line cuts up the point where the shoreline of Africa makes a 90° turn from the southern coast along the west of the Congo craton and the western coast along the south of the West African craton. The coastline by and large identifies with the bank of the Borborema land district of northeastern Brazil, which began to free from this part Africa around 115 million years back.

The Central African Shear Zone (CASZ), a lineament that connects from the Sudan to waterfront Cameroon, continues running under the terrain fragment of the Cameroon line. It is detectable in the Foumban Shear Zone, which was progressive before and in the midst of the opening of the South Atlantic in the Cretaceous period. The western end of the shear zone is obfuscated by the volcanoes of the Cameroon line, yet considering redoing of the setup of South America before it confined from Africa, the Foumban Shear Zone can be identified with the Pernambuco defect in Brazil. An important tremor in 1986 could show that the shear zone is reactivating.

The Benue Trough cheats the west of the Cameroon line. The Benue Trough was molded by splitting of the central West African storm basement, heading toward the start of the Cretaceous period. An average elucidation of the trough's improvement is that it is an aulacogen, a left arm of a three-outfitted extended break structure. The other two arms continued spreading in the midst of the detachment of Gondwana, as South America separated from Africa. In the midst of the Santonian age, around 84 million years back, the Benue Trough experienced genuine weight and giving way. Starting now and into the foreseeable future it has been tectonically serene.

The basaltic rocks in the oceanic and terrain ranges of the Cameroon line are similar in sythesis, in spite of the way that the more propelled rocks are extremely unmistakable. The closeness in basaltic rocks may demonstrate they have the same source. Ensuing to the lithosphere mantle underneath Africa must be various in substance and isotopic piece from the more energetic lithosphere underneath the Atlantic, one illumination is that the source is in the asthenosphere instead of in metasomatized lithosphere. A substitute viewpoint is that the likenesses are brought on by shallow contamination of the sea section, which could be made by sediment from the landmass or by rafted crustal impedes that were gotten in the oceanic lithosphere in the midst of the separation between South America and Africa.

By geologists, there is certification that a mantle tuft has existed in the area for around 140 million years, first staying in generally the same position while the African plate turned above it, and a brief timeframe later staying stationary under the Oku space following around 66 million years back. The strange warmth ascending in a mantle tuft would impel consolidating of the upper mantle, which raises, diminishes and debilitates the structure and underpins breaking. This might have been emphasized a few times in the Benue Trough between 140 Ma and 49 Ma. One speculation for the later change of the Cameroon Line around 30 Ma is that it concurs with movement of a shallow mantle convection framework focused on the mantle tuft, and is identified with diminishing and advancement of the structure along the Cameroon line as weights free in the now stationary plate. The mantle tuft speculation is examined by others, who say the area is to a great degree not precisely the same as what is normal by that theory, and that a source in lithospheric break will doubtlessly be the explanation.

The line might be an immediate consequence of a more identity boggling correspondence between a hotspot and Precambrian inadequacies. A gravity examination of the southern part of the Adamawa level has demonstrated a belt of thick shakes at a standard criticalness of 8 km running parallel to the Foumban shear zone. The material emanates an impression of being a volcanic obstruction that might have been engaged by reactivation of the shear zone, and might be joined with the Cameroon line.