The Ngaoundéré Plateau is a highland area in the

Adamawa Region The Adamawa Region (french: Région de l'Adamaoua) is a constituent region of the Republic of Cameroon. It borders the Centre and East regions to the south, the Northwest and West regions to the southwest, Nigeria to the west, the Central Afr ...

Cameroon Cameroon (; french: Cameroun, ff, Kamerun), officially the Republic of Cameroon (french: République du Cameroun, links=no), is a country in west-central Africa. It is bordered by Nigeria to the west and north; Chad to the northeast; the C ...

. It contains Tchabal Nganha, a large volcano, and many other recent volcanic structures.

Location

The plateau is between the forested south and savannah north of Cameroon.

Ngaoundéré Ngaoundéré, or N'Gaoundéré (Fula: N'gamdere 𞤲'𞤺𞤢𞤥𞤣𞤫𞥅𞤪𞤫𞥅) is the capital of the Adamawa Region of Cameroon. It had a population of 152,700 at the 2005 census. According to the film ''Les Mairuuwas – Maitre de l' ...

, the capital of the Adamawa region, is located on the plateau. It lies over the Ngaoundere fault zone, which was reactivated in the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

. The Ngaoundere fault belongs the Central African Fault Zone. In this region the asthenosphere upwells from a depth of about 190 km to about 120 km in a relatively narrow belt.

Formation

The plateau was formed by flows of

basaltic Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% of a ...

lavas that filled two broad valleys eroded into the Precambrian basement, followed by further flows that built up the plateau. There are many

trachyte Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava enriched with silica and al ...

and phonolite plugs across the plateau, and lines of cinder cones from the most recent eruptions. The plateau contains Tchabal Nganha, a large stratovolcano of basanitic to

trachytic Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava enriched with silica and ...

composition. Nganha is about 1,000 m high. It developed in four main events: eruption of numerous basaltic flows which form the bulk of the mountain; deposit of voluminous breccias, most of which were deeply eroded; eruption of trachytes and phonolites as thick flows; and finally basaltic activity in the summit area. Rocks date from 9.8 to 7 million years ago.

Related volcanic zones

Although considered by many geologists to be part of the Cameroon Volcanic Line, the

silicic Silicic is an adjective to describe magma or igneous rock rich in silica. The amount of silica that constitutes a silicic rock is usually defined as at least 63 percent. Granite and rhyolite are the most common silicic rocks. Silicic is the grou ...

volcanism of the Ngaoundere plateau is younger (11-9 million years old) than silicic volcanism in the Western Highlands, with much more alkaline

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

s than in the western part of the line. This has been cited as evidence that the line is not caused by movement of the plate over a hotspot. To the east of Ngaoundere and Wakwa there is Quaternary volcanic activity consisting of scoria cones and lava flows, maars, and tuff cones. One lava flow in this area has been dated to 0.9 million years ago. Some of the volcanoes may be from the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

period.

References

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