The Shona or Meteor hotspot is a

volcanic A volcano is commonly defined as a vent or fissure 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 fo ...

hotspot located in the southern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

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

seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...

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 boundary, divergent or constructive Plate tectonics, plate boundary) located along the floor of the Atlantic Ocean, and part of the List of longest mountain chains on Earth, longest mountai ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

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 (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 (eastern part of the AFFZ) during the

Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...

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 undersea mountain range, 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 ...

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 rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set o ...

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