Daikakuji Guyot

Daikakuji Seamount is a seamount (underwater volcano) and the southwesternmost volcanic feature in the Hawaiian Emperor chain bend area.

Daikakuji Seamount
EmperorSeamounts
Elevation of the Pacific seafloor, showing the Hawaiian-Emperor seamount chain, including Daikakuji Seamount near the prominent "V"-shaped bend, which separates the Hawaiian Ridge from the older Emperor Seamount portion of the chain. Daikakuji is the southeastern of the two moderately-sized seamounts just after the bottom of the V-bend, and the most recent of the large volcanoes for a long time.
Summit depth1,000 m (3,281 ft)
Height4,000 m (157,480 in)
Summit area30 km (19 mi) diameter
Location
LocationCentral Pacific Ocean
GroupEmperor seamounts
Coordinates32°5.00′N 172°18′E / 32.08333°N 172.300°ECoordinates: 32°5.00′N 172°18′E / 32.08333°N 172.300°E
Geology
TypeGuyot
Volcanic arc/chainHawaiian-Emperor seamount chain
Age of rock43 million years
History
First visitGLORIA program, USGS[1] [2]

Geology

The seamount is very close to the "V"-shaped bend in the Hawaiian-Emperor seamount chain, and thus would be useful in understanding the exact age of the bend. Although few dredge samples are available, they have all been reliably dated at 43 million years, during the Eocene epoch of the Paleogene period.

During the cruise SO112 of the R/V SONNE, high resolution bathymetric mapping was conducted, showing that Daikakuji is nearly 30 km (19 mi) in diameter and nearly 4,000 m (13,123 ft) in height, with a summit lying 1,000 m (3,281 ft) underwater.

Because of its flat capped top, Daikakuji is considered a guyot. A smaller, younger, secondary guyot just east of the main mass overlaps its slope. The western site suffered a large collapse sometime in its history, evident by a large slump, that likely carried away a significant part of the volcano's caldera.

Daikakuji Seamount has some well developed rift zones oriented towards the Emperor portion of the chain, whereas the younger, secondary cone has rift flanks in the direction of the Hawaiian ridge.

See also

References

  1. ^ B. C. Kerr; D. W. Scholl & S. L. Klemperer (12 July 2005). "Seismic stratigraphy of Detroit Seamount, Hawaiian-Emperor Seamount chain" (PDF). Scientific Publication. Stanford University. Archived from the original (PDF) on 2011-07-16. Retrieved 2009-04-03.
  2. ^ "DRILLING STRATEGY". OCean Drilling Program. Retrieved 2009-04-04.
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 Hawaiian–Emperor seamount chain, a 5,800-kilometre (3,600 mi) mostly undersea volcanic mountain range. Four of these volcanoes are active, two are dormant; more than 123 are extinct, most now preserved as atolls or seamounts. The chain extends from south of the island of Hawaiʻi to the edge of the Aleutian Trench, near the eastern coast of Russia.

While most volcanoes are created by geological activity at tectonic plate boundaries, the Hawaii hotspot is located far from plate boundaries. The classic hotspot theory, first proposed in 1963 by John Tuzo Wilson, proposes that a single, fixed mantle plume builds volcanoes that then, cut off from their source by the movement of the Pacific Plate, become increasingly inactive and eventually erode below sea level over millions of years. According to this theory, the nearly 60° bend where the Emperor and Hawaiian segments of the chain meet was caused by a sudden shift in the movement of the Pacific Plate. In 2003, fresh investigations of this irregularity led to the proposal of a mobile hotspot theory, suggesting that hotspots are mobile, not fixed, and that the 47-million-year-old bend was caused by a shift in the hotspot's motion rather than the plate's.

Ancient Hawaiians were the first to recognize the increasing age and weathered state of the volcanoes to the north as they progressed on fishing expeditions along the islands. The volatile state of the Hawaiian volcanoes and their constant battle with the sea was a major element in Hawaiian mythology, embodied in Pele, the deity of volcanoes. After the arrival of Europeans on the island, in 1880–1881 James Dwight Dana directed the first formal geological study of the hotspot's volcanics, confirming the relationship long observed by the natives. The Hawaiian Volcano Observatory was founded in 1912 by volcanologist Thomas Jaggar, initiating continuous scientific observation of the islands. In the 1970s, a mapping project was initiated to gain more information about the complex geology of Hawaii's seafloor.

The hotspot has since been tomographically imaged, showing it to be 500 to 600 km (310 to 370 mi) wide and up to 2,000 km (1,200 mi) deep, and olivine and garnet-based studies have shown its magma chamber is approximately 1,500 °C (2,730 °F). In its at least 85 million years of activity the hotspot has produced an estimated 750,000 km3 (180,000 cu mi) of rock. The chain's rate of drift has slowly increased over time, causing the amount of time each individual volcano is active to decrease, from 18 million years for the 76-million-year-old Detroit Seamount, to just under 900,000 for the one-million-year-old Kohala; on the other hand, eruptive volume has increased from 0.01 km3 (0.002 cu mi) per year to about 0.21 km3 (0.050 cu mi). Overall, this has caused a trend towards more active but quickly-silenced, closely spaced volcanoes—whereas volcanoes on the near side of the hotspot overlap each other (forming such superstructures as Hawaiʻi island and the ancient Maui Nui), the oldest of the Emperor seamounts are spaced as far as 200 km (120 mi) apart.

List of volcanoes in the Hawaiian – Emperor seamount chain

The Hawaiian–Emperor seamount chain is a series of volcanoes and seamounts extending about 6,200 km across the Pacific Ocean. The chain has been produced by the movement of the ocean crust over the Hawaiʻi hotspot, an upwelling of hot rock from the Earth's mantle. As the oceanic crust moves the volcanoes farther away from their source of magma, their eruptions become less frequent and less powerful until they eventually cease to erupt altogether. At that point, erosion of the volcano and subsidence of the seafloor cause the volcano to gradually diminish. As the volcano sinks and erodes, it first becomes an atoll island and then an atoll. Further subsidence causes the volcano to sink below the sea surface, becoming a seamount and/or a guyot. This list documents the most significant volcanoes in the chain, ordered by distance from the hotspot; however, there are many others that have yet to be properly studied.

The chain can be divided into three subsections. The first, the Hawaiian archipelago (also known as the Windward isles), consists of the islands comprising the U.S. state of Hawaiʻi (not to be confused with the island of Hawaiʻi). As it is the closest to the hotspot, this volcanically active region is the youngest part of the chain, with ages ranging from 400,000 years to 5.1 million years. The island of Hawaiʻi is comprised by five volcanoes, of which two (Kilauea and Mauna Loa) are still active. Lōʻihi Seamount continues to grow offshore, and is the only known volcano in the chain in the submarine pre-shield stage.The second part of the chain is composed of the Northwestern Hawaiian Islands, collectively referred to as the Leeward isles, the constituents of which are between 7.2 and 27.7 million years in age. Erosion has long since overtaken volcanic activity at these islands, and most of them are atolls, atoll islands, and extinct islands. They contain many of the most northerly atolls in the world; one of them, Kure Atoll, is the northern-most atoll in the world.The oldest and most heavily eroded part of the chain are the Emperor seamounts, which are 39 to 85 million years in age. The Emperor and Hawaiian chains are separated by a large L-shaped bend that causes the orientations of the chains to differ by about 60°. This bend was long attributed to a relatively sudden change in the direction of plate motion, but research conducted in 2003 suggests that it was the movement of the hotspot itself that caused the bend. The issue is still currently under debate. All of the volcanoes in this part of the chain have long since subsided below sea level, becoming seamounts and guyots (see also the seamount and guyot stages of Hawaiian volcanism). Many of the volcanoes are named after former emperors of Japan. The seamount chain extends to the West Pacific, and terminates at the Kuril–Kamchatka Trench, a subduction zone at the border of Russia.

Outline of oceanography

The following outline is provided as an overview of and introduction to Oceanography.

Windward
Isles
Leeward
Isles
Emperor
Seamounts
Notable eruptions
and vents
Topics

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