Cape Verde is a volcanic archipelago situated above an oceanic rise that puts the base of the islands above the rest of the

seafloor The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth an ...

. Cape Verde has been identified as a hotspot and the majority of geoscientists have argued that the archipelago is underlain by a

mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hot ...

and that this plume is responsible for the volcanic activity and associated geothermal anomalies. Evidence for a plume origin includes substantial uplift, low-velocity

seismic Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...

anomalies in the upper mantle extending to depths of around 500 km, low-velocity anomalies in the lower mantle which appear to pond beneath the transition zone with branches extending to the

Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...

Canary Canary originally referred to the island of Gran Canaria on the west coast of Africa, and the group of surrounding islands (the Canary Islands). It may also refer to: Animals Birds * Canaries, birds in the genera ''Serinus'' and ''Crithagra'' i ...

and Cape Verde hotspots, and

petrological Petrology () is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together ...

, geochemical, and isotopic evidence which are thought to indicate a deep-mantle source. Some observations, such as a lack of age-progressive volcanism and the geochemical signatures of lavas which indicate a shallow source materials, are inconsistent with the plume model, and some scientists have argued that the Cape Verde Archipelago is a product rather of sub-

lithospheric A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years or ...

small-scale

convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the conve ...

and instabilities arising from heterogeneities in the asthenosphere and variations in lithospheric thickness, with the geochemistry of the lavas attributed to remnants of subcontinental lithospheric mantle left in the oceanic lithosphere when the Atlantic Ocean opened. The lack of age progression has been accounted for in the hotspot model by the suggestion it is virtually stationary relative to the lithosphere due to being situated close to the rotational pole of the slowly moving

African Plate The African Plate is a major tectonic plate that includes much of the continent of Africa (except for its easternmost part) and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plate ...

. The unusual geochemical signatures have been ascribed to recycled oceanic crust and lithosphere in the source material. Though Cape Verde's islands are all volcanic in origin, they vary widely in terrain. A still-active volcano on the island of Fogo is the highest point on the archipelago (elevation ).''The Peace Corps Welcomes You to Cape Verde''

Peace Corps The Peace Corps is an independent agency and program of the United States government that trains and deploys volunteers to provide international development assistance. It was established in March 1961 by an executive order of President John F ...

(April 2006). ''This article incorporates text from this source, which is in the

public domain The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired, ...

.'' Extensive

salt flats Salt flats, Salt flat, Salt Flats, or Salt Flat may refer to: Geology *Salt pan (geology), a flat expanse of ground covered with salt and other minerals *Dry lake, an ephemeral lakebed that consists of fine-grained sediments infused with alkali salt ...

are found on Sal and Maio. On Santiago, Santo Antão, and São Nicolau, arid slopes give way in places to sugarcane fields or banana plantations spread along the base of towering mountains. The islands are geologically principally composed of

igneous Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or ...

rocks, with basic volcanics and pyroclastics comprising the majority of the total volume. The

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

and plutonic rocks are distinctly basic in character. The archipelago is an example of a soda-alkaline petrographic province, with a petrologic succession which is similar to that found in other Mid

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

islands.

Mount Fogo Pico do Fogo is the highest peak of Cape Verde and West Africa, rising to above sea level. It is an active stratovolcano lying on the island of Fogo. The main cone last erupted in 1680, causing mass emigration from the island. A subsidiary ven ...

is an active

volcano A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...

which most recently erupted in 2014. Fogo's

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

is in diameter, the rim is at an elevation of with an interior cone rising to from the crater's floor level. Calderas probably result from the subsidence, following the partial evacuation of the

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

chamber, of a cylindrical block into the supplying magma chamber, in this case lying at a depth of some . The archipelago has been dated at approximately 180 million years old.Mitchell-Thomé, Raoul C. "Outline of the geology of the Cape Verde Archipelago" Geologische Rundschau, Volume 61, Issue 3, pp. 1087–1109

References

{{Africa topic, Geology of

See also

References