The Louisville hotspot is a volcanic

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 hotspot

Hotspot (geology)

The places known as hotspots or hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be on, near to, or far from tectonic plate boundaries. There are two hypotheses to explain them...

 responsible for the volcanic activity that has formed the Louisville seamount chain

Louisville seamount chain

The Louisville seamount chain is an underwater chain of over 70 seamounts in the Southwest Pacific Ocean. One of the longest seamount chains on Earth, it stretches some 4,300 kilometres from the Pacific-Antarctic Ridge ENE to the Tonga-Kermadec Trench, where it subducts under the...

 in the southern Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

.

Location

The Louisville hotspot is believed to lie close to the Pacific-Antarctic Ridge

Pacific-Antarctic Ridge

The Pacific–Antarctic Ridge is a divergent tectonic plate boundary located on the seafloor of the South Pacific Ocean, separating the Pacific Plate from the Antarctic Plate...

, although its exact location is, however, uncertain.

Geological history

The Louisville hotspot has produced the Louisville seamount chain

Louisville seamount chain

The Louisville seamount chain is an underwater chain of over 70 seamounts in the Southwest Pacific Ocean. One of the longest seamount chains on Earth, it stretches some 4,300 kilometres from the Pacific-Antarctic Ridge ENE to the Tonga-Kermadec Trench, where it subducts under the...

, which is one of the longest seamount

Seamount

A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...

 chains on Earth, stretching some 4300 km (2,672 mi) from the Pacific-Antarctic Ridge where it subducts under the Indo-Australian Plate

Indo-Australian Plate

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

 as part of the Pacific Plate

Pacific Plate

The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....

.

The Louisville hotspot is believed to have been active for at least 80 million years based on age of the Louisville seamount chain, which is comparable to that of the Hawaiian-Emperor seamount chain

Hawaiian-Emperor seamount chain

The Hawaiian–Emperor seamount chain is composed of the Hawaiian ridge, consisting of the islands of the Hawaiian chain northwest to Kure Atoll, and the Emperor Seamounts, a vast underwater mountain region of islands and intervening seamounts, atolls, shallows, banks and reefs along a line trending...

, although the rate of volcanism at the two chains are relatively different and the Louisville chain has a relatively small bend unlike the Hawaiian-Emperior chain. During the Early Oligocene

Oligocene

The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...

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

Hawaii hotspot

The Hawaii hotspot is the volcanic hotspot that created the Hawaiian Islands in the central Pacific Ocean, and is one of Earth's best-known and most heavily-studied hotspots....

 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-Emperior seamount chain such that none of the volcanoes emerged above sea level in the past 11 million years. The Louisville seamount chain 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

Ontong Java Plateau

The Ontong Java Plateau is a huge oceanic plateau located in the Pacific Ocean, lying north of the Solomon Islands. The plateau covers an area of approximately , or roughly the size of Alaska, and reaches a thickness of up to . The plateau is of volcanic origin, composed mostly of flood basalts...

, the world's largest oceanic plateau

Oceanic plateau

An oceanic plateau is a large, relatively flat submarine region that rises well above the level of the ambient seabed. While many oceanic plateaus are composed of continental crust, and often form a step interrupting the continental slope, some plateaus are undersea remnants of large igneous...

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

Plate reconstruction

Plate reconstruction is the process of reconstructing the positions of tectonic plates relative to each other or to other reference frames, such as the earth's magnetic field or groups of hotspots, in the geological past...

, arguing against this, although other factors mean their linkage may still be possible.