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Taukina Seamounts
Taukina seamounts are a series of seamounts on the Pacific Plate. The Macdonald hotspot and the Ngatemato seamounts are located nearby. The Taukina and Ngatemato seamounts were discovered in 1996 by the RV Maurice Ewing and both are named after families in Rapa Iti. The Taukina seamounts are formed by small volcanoes, with heights of and widths of . They often feature a caldera on their summit. Tholeiitic rocks make up the seamounts. The shape of the Taukina seamounts resembles that of the seamounts that form on the East Pacific Rise. An alternate theory of origin is that the Ngatemato seamounts deformed the Pacific plate enough with their weight to trigger the eruption of magma. References {{Reflist, refs= {{Cite book, title=Oceanic Hotspots, last=Jordahl, first=K., last2=Caress, first2=D., last3=McNutt, first3=M., last4=Bonneville, first4=A., date=2004, publisher=Springer, Berlin, Heidelberg, isbn=9783642622908, location=, pages=22, language=en, doi=10.1007/978-3-642-18782-7 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 abruptly and are usually found rising from the seafloor to in height. They are defined by oceanographers as independent features that rise to at least above the seafloor, characteristically of conical form.IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 Izanagi Plates. The Pacific Plate subsequently grew to where it underlies most of the Pacific Ocean basin. This reduced the Farallon Plate to a few remnants along the west coast of North America and the Phoenix Plate to a small remnant near the Drake Passage, and destroyed the Izanagi Plate by subduction under Asia. The Pacific Plate contains an interior hot spot forming the Hawaiian Islands. Boundaries The north-eastern side is a divergent boundary with the Explorer Plate, the Juan de Fuca Plate and the Gorda Plate forming respectively the Explorer Ridge, the Juan de Fuca Ridge and the Gorda Ridge. In the middle of the eastern side is a transform boundary with the North American Plate along the San Andreas Fault, and a boundary with the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macdonald Hotspot
The Macdonald hotspot (also known as "Tubuai" or "Old Rurutu") is a volcanic hotspot in the southern Pacific Ocean. The hotspot was responsible for the formation of the Macdonald Seamount, and possibly the Austral-Cook Islands chain. It probably did not generate all of the volcanism in the Austral and Cook Islands as age data imply that several additional hotspots were needed to generate some volcanoes. In addition to the volcanoes in the Austral Islands and Cook Islands, Tokelau, the Gilbert Islands, the Phoenix Islands and several of the Marshall Islands as well as several seamounts in the Marshall Islands may have been formed by the Macdonald hotspot. Geology Regional geology Hotspots have been explained either by mantle plumes producing magma in the crust, reactivation of old lithospheric structures such as fractures or spreading of the crust through tectonic tension. Aside from Macdonald seamount, active volcanoes which are considered hotspots in the Pacific Ocean inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ngatemato Seamounts
Ngatemato seamounts (Name derived from a ruling family in Rapa) are a series of seamounts in the southern Pacific Ocean. These seamounts have the shape of ridges and display calderas. The Aureka () and Make () seamounts are part of the Ngatemato track. Dredged rocks are weakly tholeiitic basalts of Oligocene age. They are about high and wide at their base. Despite being smaller in size than the Macdonald seamounts however the Ngatemato seamounts have larger volumes which is masked by stronger plate deformation; the magma output that created the Ngatemato and Taukina chains when summed up is about . The seamounts were discovered in 1996 by the RV Maurice Ewing in the Austral Islands. Potassium-argon dating yields ages of about 30 million years; the seamounts developed close to the East Pacific Rise. Away from the Austral Islands the Ngatemato seamounts merge with the Foundation seamounts, with which they may share an origin. Macdonald seamount and associated seamounts as well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RV Maurice Ewing
RV ''Maurice Ewing'' was a research vessel operated by the Lamont–Doherty Earth Observatory of Columbia University. It was retired in 2005 and replaced by RV ''Marcus Langseth'' in 2008. Although a multipurpose vessel, ''Maurice Ewing''s notable capability was to collect multichannel seismic data. ''Maurice Ewing'' was named for William Maurice "Doc" Ewing, geophysicist Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' som ... and first director of Lamont Geological Observatory (now known as Lamont–Doherty Earth Observatory). The vessel was later renamed several times: - Scan Resolution, Bergan Resolution, the Reflect Resolution, and the NORDIC BAHARI. Still to this day the vessel operates as a multi-streamer seismic research vessel. External links * * * {{DEFAULTSORT:Ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rapa Iti
Rapa, also called Rapa Iti, or "Little Rapa", to distinguish it from Easter Island, whose Polynesian name is Rapa Nui, is the largest and only inhabited island of the Bass Islands in French Polynesia. An older name for the island is Oparo. The total land area including offshore islets is . As of the 2017 census, Rapa had a population of 507.Répartition de la population en Polynésie française en 2017 Institut de la statistique de la Polynésie française The island's highest point is at elevation at Mont Perahu. Its main town is Ahuréi. The inhabitants of Rapa Iti speak their own Polynesian language called the |
Volcano
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 are diverging or converging, and most are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, deep in the Earth. This results in hotspot volcanism, of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is gone. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a Volcanic crater, crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur each century, the formation of a caldera is a rare event, occurring only a few times per century. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018. Etymology The term ''caldera'' comes from Spanish language, S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tholeiitic
The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma into a more evolved, silica rich end member. Rock types of the tholeiitic magma series include tholeiitic basalt, ferro-basalt, tholeiitic basaltic andesite, tholeiitic andesite, dacite and rhyolite. The variety of basalt in the series was originally called ''tholeiite'' but the International Union of Geological Sciences recommends that ''tholeiitic basalt'' be used in preference to that term.Le Maitre ''et al.'' 2002 Tholeiitic rock types tend to be more enriched in iron and less enriched in aluminium than calc-alkaline rock types. They are thought to form in a less oxidized environment than calc-alkaline rocks. Tholeiitic basalt is formed at mid-ocean ridges and makes up much of the oceanic crust. Almost all the basalt found on the Moon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Pacific Rise
The East Pacific Rise is a mid-ocean rise (termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from (north to south) the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate. It runs south from the Gulf of California in the Salton Sea basin in Southern California to a point near 55° S, 130° W, where it joins the Pacific-Antarctic Ridge trending west-southwest towards Antarctica, near New Zealand (though in some uses the PAR is regarded as the southern section of the EPR). Much of the rise lies about 3200 km (2000 mi) off the South American coast and rises about 1,800–2,700 m (6,000–9,000 ft) above the surrounding seafloor. Overview The oceanic crust is moving away from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1996 In Science
The year 1996 in science and technology involved many significant events, listed below. Astronomy and space exploration * January 30 – Comet Hyakutake is discovered. * February 17 – NEAR Shoemaker spacecraft launched. The craft landed on asteroid 433 Eros in 2001. * May – First naked-eye observation of Comet Hale-Bopp. * June 4 – The European Space Agency's Cluster is lost when the maiden flight of the Ariane 5 rocket fails, self-destructing 37 seconds after launch from the Guiana Space Centre because of a software bug in the computer control system. * October 3 – Reinhard Genzel and Andrea Ghez demonstrate the existence of a supermassive compact object at the centre of our galaxy, later identified as a black hole. * November 7 – NASA launches the ''Mars Global Surveyor''. * The second 9.8 m reflecting telescope opens at Keck Observatory, Mauna Kea, Hawaii. Biology * July 5 – Dolly the sheep, the first mammal to be successfully cloned from an adult cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of The Pacific Ocean
The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth. The East Pacific Rise near Easter Island is the fastest spreading mid-ocean ridge, with a spreading rate of over 15 cm/yr. The Pacific Plate moves generally towards the northwest at between 7 and 11 cm/yr while the Juan De Fuca Plate has an east-northeasterly movement of some 4 cm/yr. Most subduction zones around the rim of the Pacific are directed away from a large area in the southern Pacific. At the core–mantle boundary below this area there is a large low-shear velocity province (LLSVP). Most of Pacific hotspots are located above the LLSVP while the longest Pacific hotspot tracks are located at or near its boundaries pointing at the positi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
