| Tchabal Nganha | |
|---|---|
  Tchabal Nganha Location in Cameroon | |
| Highest point | |
| Elevation | 1,927 m (6,322 ft) |
| Prominence | 1,000 metres (3,300 ft) |
| Coordinates | 7°21′13″N14°00′53″E / 7.353687°N 14.014683°E Coordinates: 7°21′13″N14°00′53″E / 7.353687°N 14.014683°E |
| Geology | |
| Mountain type | Stratovolcano |
| Volcanic arc | Cameroon line |
Tchabal Nganha is a stratovolcano on the Ngaoundere Plateau, a highland area in the Adamawa Region of Cameroon.
Tchabal Nganha is a large composite volcano located within the Ngaoundere volcanic field in the east of the Adamawa Plateau. [1] It is the only stratovolcano in the field. [2] Nganha rises about 1,000 metres (3,300 ft) above the surrounding plateau to a height of 1,927 metres (6,322 ft) at Doïtaïa Mounts. [3]
The Adamawa plateau is an asymmetrical horst bounded by N70°E faults and tilted to the south. [4] The plateau has a Precambrian metamorphic basement that is intruded by granite and syenite plutons from the Paleozoic. It is partly covered by volcanic formations from the Cenozoic to Recent ages. The crust is 33 kilometres (21 mi) thick below the plateau. [3] Although considered by many geologists to be part of the Cameroon line, the silicic volcanism of the Ngaoundere Plateau is younger (11 to 9 million years old) than silicic volcanism in the Western Highlands, with much more alkaline basalts than in the western part of the line. [5]
Basalt and trachyte rock samples from Nganha have K–Ar ages of 7.2, 7.9 and 9.8 Ma (million years). The volcano was formed in four overlapping phases. First, many basaltic lava flows erupted throughout the region, creating the generally smooth relief. Next, voluminous breccias were deposited. Most of these have been deeply eroded except where covered by later lava flows. Thick, radially distributed trachyte and phonolite flows then erupted. They have steep margins and are separated by deep and narrow valleys. Later there was basaltic activity at the summit. [3]
Rhyolite is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent to granite.
A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid lava, which travels farther and forms thinner flows than the more viscous lava erupted from a stratovolcano. Repeated eruptions result in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form.
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A flood basalt is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reaching the surface of the earth via a mantle plume. Flood basalt provinces such as the Deccan Traps of India are often called traps, after the Swedish word trappa, due to the characteristic stairstep geomorphology of many associated landscapes.
Mount Taylor is a dormant stratovolcano in northwest New Mexico, northeast of the town of Grants. It is the high point of the San Mateo Mountains and the highest point in the Cibola National Forest.
The Cameroon line is a 1,600 km (990 mi) chain of volcanoes. It includes islands in the Gulf of Guinea and mountains that extend along the border region of eastern Nigeria and the West Region of Cameroon, from Mount Cameroon on the Gulf of Guinea north and east towards Lake Chad. The islands, which span the equator, have tropical climates and are home to many unique plant and bird species. The mainland mountain regions are much cooler than the surrounding lowlands, and also contain unique and ecologically important environments.
The Itcha Range, also known as the Itchas, is a small isolated mountain range in the West-Central Interior of British Columbia, Canada. It is located 40 km (25 mi) northeast of the community of Anahim Lake. With a maximum elevation of 2,375 m (7,792 ft), it is the lowest of three mountain ranges on the Chilcotin Plateau extending east from the Coast Mountains. Two mountains are named in the Itcha Range; Mount Downton and Itcha Mountain. A large provincial park surrounds the Itcha Range and other features in its vicinity. More than 15 animal species are known to exist in the Itcha Range area, as well as a grassland community that is limited only to this location of British Columbia. The Itcha Range is within territory which has been occupied by aboriginal peoples for millennia. This area has a relatively dry environment compared to the Coast Mountains in the west.
Namarunu is a shield volcano located in the Great Rift Valley, Kenya.
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The volcanism of New Zealand has been responsible for many of the country's geographical features, especially in the North Island and the country's outlying islands.
The Barrier is an active shield volcano located in the north of Kenya. It is last known to have erupted in 1921.
The Mount Edziza volcanic complex is a large and potentially active north-south trending complex volcano in Stikine Country, northwestern British Columbia, Canada, located 38 kilometres (24 mi) southeast of the small community of Telegraph Creek. It occupies the southeastern portion of the Tahltan Highland, an upland area of plateau and lower mountain ranges, lying east of the Boundary Ranges and south of the Inklin River, which is the east fork of the Taku River. As a volcanic complex, it consists of many types of volcanoes, including shield volcanoes, calderas, lava domes, stratovolcanoes, and cinder cones.
Lava is magma once it has been expelled from the interior of a terrestrial planet or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or undersea, usually at temperatures from 800 to 1,200 °C. The volcanic rock resulting from subsequent cooling is also often called lava.
Nganha is a commune in Cameroon. It has a population between 3,000 and 5,000. It is about 10 kilometres (6.2 mi) northwest of the summit of Tchabal Nganha, a large stratovolcano on the Ngaoundere Plateau, a highland area in the Adamawa Region of Cameroon.
The volcanic history of the Northern Cordilleran Volcanic Province presents a record of volcanic activity in northwestern British Columbia, central Yukon and the U.S. state of easternmost Alaska. The volcanic activity lies in the northern part of the Western Cordillera of the Pacific Northwest region of North America. Extensional cracking of the North American Plate in this part of North America has existed for millions of years. Continuation of this continental rifting has fed scores of volcanoes throughout the Northern Cordilleran Volcanic Province over at least the past 20 million years and occasionally continued into geologically recent times.
The Canadian Cascade Arc, also called the Canadian Cascades, is the Canadian segment of the North American Cascade Volcanic Arc. Located entirely within the Canadian province of British Columbia, it extends from the Cascade Mountains in the south to the Coast Mountains in the north. Specifically, the southern end of the Canadian Cascades begin at the Canada–United States border. However, the specific boundaries of the northern end are not precisely known and the geology in this part of the volcanic arc is poorly understood. It is widely accepted by geologists that the Canadian Cascade Arc extends through the Pacific Ranges of the Coast Mountains. However, others have expressed concern that the volcanic arc possibly extends further north into the Kitimat Ranges, another subdivision of the Coast Mountains, and even as far north as Haida Gwaii.
The Ngaoundéré Plateau is a highland area in the Adamawa Region of Cameroon. It contains Tchabal Nganha, a large volcano, and many other recent volcanic structures.
The Tengchong Volcanic Field (TVF) is a Cenozoic volcanic field located in the Southeastern margin of the Tibetan Plateau around 40 km from the Chinese border with Myanmar. The TVF is uniquely the only region affected by Quaternary volcanism that is part of the Himalayan Geothermal Belt caused by the Indo-Asian continent-continent collision. The TVF is characterized by hydrothermal activity and large-scale eruptions last recorded in 1609CE. Although the volcanoes themselves are considered extinct, several geothermal fields geographically linked to the TVF are still highly active. Evidence for geothermal activity can be linked to several prevalent active hot-springs located predominantly within the vicinity of the volcanoes in the TVF. Holocene eruptions occurred predominantly in the three largest volcanoes in the TVF named the Dayingshan, Maa'nshan and Heikongshan, the highest of which (Dayingshan) reaches 2865 meters above sea level. The volcanoes are distributed in a string-like pattern clustered from North to South in the middle on the Tengchong basin and are characterized by post-collisional high-Potassium (K) calc-alkaline series eruptions. The TVF provides unique geographical and geological knowledge as understanding the geological processes of creation provides insight into aspects such as the history of volcanism during the Quaternary Era in the region and as well as compositional information of its source and crustal assimilants. The TVF can be visited in the Tengchong Volcanic Geothermal National Geological Park.`
The Udokan Plateau is a volcanic field in Transbaikalia, Russia. It covers a surface area of 3,000 square kilometres (1,200 sq mi) northeast of Lake Baikal in North Asia. Volcanism in the Udokan Plateau included both basaltic lava flows and later individual volcanic cones. Volcanism commenced in the Miocene and continued on into the Holocene.