The Shona or Meteor hotspot is a

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 ...

hotspot located in the southern

Atlantic Ocean 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 ...

. Its zig-zag-shaped hotspot track, a chain of

seamount A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abru ...

s and ridges, stretches from its current location at or near the southern end of the

Mid-Atlantic Ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North Ame ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

Location

The present location of the hotspot is disputed. proposed a location below a small seamount, the "Shona Seamount" (), just west of the Mid-Atlantic Ridge. This location was used by . however proposed , the eastern end of the Shona Rise/ Shona Ridge. simply located the hotspot at where its volcanic trail begin.

Discovery

The hotspot was first proposed by . They noted that the Meteor Rise and Cape Rise seamount chain (west of South Africa) could not be associated with the Bouvet hotspot and therefore predicted the existence of another hotspot near the southern end of the Mid-Atlantic Ridge. Hartnady and le Roex explained the peculiar zig-zag pattern of this seamount chain as the result of the hotspot crossing the

Agulhas Falkland Fracture Zone Agulhas (''needles'' in the Portuguese language — or ) may refer to: * Cape Agulhas, the southernmost point of Africa * L'Agulhas, a town near the Cape * Cape Agulhas Lighthouse, located at the Cape * Cape Agulhas Local Municipality, the municipa ...

(AFFZ, a system of ridges stretching across the South Atlantic; the Mid-Atlantic Ridge makes a 'jump' just south of the AFFZ). The tracks of the Bouvet and Shona hotspots probably passed under the

Agulhas Ridge Agulhas (''needles'' in the Portuguese language — or ) may refer to: * Cape Agulhas, the southernmost point of Africa * L'Agulhas, a town near the Cape * Cape Agulhas Lighthouse, located at the Cape * Cape Agulhas Local Municipality, the municipa ...

(eastern part of the AFFZ) during the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

and supplied the ridge with excess material.

Plume–Mid-ocean ridge interaction

Between 51°S and 52°S the

mid-ocean ridge A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a diverge ...

basalt Basalt (; ) is an aphanite, 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 planetary surface, surface of a terrestrial ...

s (MORBs) of the Mid-Atlantic Ridge have a composition that is associated with hotspots. Based on anomalously high Nb/ Zr ratios in the southern end of the ridge, le Roex in 1987 suggested that the plume interacts with the ridge. Furthermore, inflated bathymetry and gravity coupled with increase in ( La/ Sm)_n ratios (ratio of light

rare-earth element The rare-earth elements (REE), also called the rare-earth metals or (in context) rare-earth oxides or sometimes the lanthanides (yttrium and scandium are usually included as rare earths), are a set of 17 nearly-indistinguishable lustrous silve ...

s in MORBs) are indications that the plume is interacting with the ridge. analysed lavas dredged from the Shona Ridge System, the hotspot track formed by the Shona Rise, Meteor Rise, Agulhas Ridge, and Cape Rise, and concluded that those lavas are geochemically enriched compared to the MORBs, an indication that the Mid-Atlantic Ridge is interacting with a plume.

References

Notes

Sources

* * * * * * * {{Coord, 51.6, S, 1.0, E, type:mountain_region:SH, display=title Hotspots of the Atlantic Ocean Mid-Atlantic Ridge