The Louisville 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 responsible for the volcanic activity that has formed the

Louisville Ridge The Louisville Ridge, also known as the Louisville Seamount Chain, is an underwater chain of over 70 seamounts located in the Southwest portion of the Pacific Ocean. As one of the longest seamount chains on Earth it stretches some Vanderkluysen, ...

in the southern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

Location

The Louisville hotspot is believed to lie close to the

Pacific-Antarctic Ridge The Pacific-Antarctic Ridge (PAR) is a Divergent boundary, divergent tectonic plate boundary located on the seafloor of the South Pacific Ocean, separating the Pacific Plate from the Antarctic Plate. It is regarded as the southern section of the ...

, although its exact location is uncertain.

Geological history

The Louisville hotspot has produced the

, which is one of the longest

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 ...

chains on Earth, stretching some Vanderkluysen, L.; Mahoney, J. J.; Koppers, A. A.; and Lonsdale, P. F. (2007)
Geochemical Evolution of the Louisville Seamount Chain
American Geophysical Union, Fall Meeting 2007, abstract #V42B-06. from the Pacific-Antarctic Ridge to the Tonga Trench where it subducts under the

Indo-Australian Plate The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and the surrounding ocean and extends northwest to include the Indian subcontinent and the adjacent waters. It was formed by the fusion of the Indian an ...

as part of the

Pacific Plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...

. The Louisville hotspot is believed to have been active since at least 78.8 ± 1.3 Ma based on age of the oldest seamount (Osbourn ). This duration is comparable to that of the Hawaiian-Emperor seamount chain, although the rate of volcanism at the two chains are relatively different and the Louisville Ridge has a relatively small bend compared to that in the Hawaiian-Emperior chain. During the Early

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

period, the Louisville hotspot's magma source rate was much steadier than the

Hawaii hotspot The Hawaii hotspot is a volcanic hotspot located near the namesake Hawaiian Islands, in the northern Pacific Ocean. One of the best known and intensively studied hotspots in the world, the Hawaii plume is responsible for the creation of the ...

rate, and had a lower total volume in eruption. During the Late Oligocene, the magma source decreased to a small fraction of that in the Hawaiian-Emperor seamount chain, such that none of the volcanoes has emerged above sea level in the past 11 million years. The Louisville Ridge is only half as wide as the Hawaiian-Emperior seamount chain. Therefore, unlike the Hawaii hotspot, the Louisville hotspot is believed to have decreased in activity with time. The Louisville hotspot may have created the

Ontong Java Plateau The Ontong Java Plateau (OJP) is a massive oceanic plateau located in the southwestern Pacific Ocean, north of the Solomon Islands. The OJP was formed around (Ma) with a much smaller volcanic event around 90 Ma. Two other southwestern Pacific ...

, the world's largest

oceanic plateau An oceanic or submarine plateau is a large, relatively flat elevation that is higher than the surrounding relief with one or more relatively steep sides. There are 184 oceanic plateaus in the world, covering an area of or about 5.11% of the ...

, around 120 million years ago. The modelled locations of the plateau and hotspot at the time do not coincide under one recent

plate reconstruction :''This article describes techniques; for a history of the movement of tectonic plates, see Geological history of Earth.'' Plate reconstruction is the process of reconstructing the positions of tectonic plates relative to each other (relative motio ...

, arguing against this, although other factors mean their linkage may still be possible.Antretter, M.; Riisager, P.; Hall, S.; Zhao, X.; and Steinberger, B. (2004)
Modelled palaeolatitudes for the Louisville hot spot and the Ontong Java Plateau
in ''Origin and Evolution of the Ontong Java Plateau'' Geological Society, London, Special Publications, v. 229, p. 21-30. .

References

{{Hotspots Hotspots of the Pacific Ocean

Location

Geological history

See also

References