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Lo-En
Lo-En or Hess is an Albian–Campanian guyot in the Marshall Islands. One among a number of seamounts in the Pacific Ocean, it was probably formed by a hotspot in what is present-day French Polynesia. Lo-En lies southeast of Eniwetok which rises above sea level, and Lo-En is almost connected to it through a ridge. The seamount is formed by basaltic rocks that probably formed a shield volcano first. It is believed that a number of hotspots such as the Macdonald hotspot, the Rarotonga hotspot and the Rurutu hotspot may have been involved in the formation of Lo-En. After volcanic activity, by the Turonian the seamount was submerged although it is possible that a carbonate platform formed during the Albian. After a hiatus, sedimentation commenced on the seamount in Oligocene time and led to the deposition of manganese crusts and pelagic sediments including limestone, some of which were later modified by phosphate. Name and research history The name "Lo-En" is a reference ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rurutu Hotspot
Arago hotspot is a hotspot in the Pacific Ocean, presently located below the Arago seamount close to the island of Rurutu, French Polynesia. Arago is part of a family of hotspots in the southern Pacific, which include the Society hotspot and the Macdonald hotspot among others. These are structures beneath Earth's crust which generate volcanoes and which are in part formed by mantle plumes, although Arago itself might have a shallower origin. As the Pacific plate moves over the hotspots, new volcanoes form and old volcanoes are carried away; sometimes an older volcano is carried over the hotspot and is then uplifted as happened with Rurutu. The Arago hotspot is responsible for the formation of Arago seamount and uplift on Rurutu; however reconstructions of the past positions of tectonic plates and geochemistry suggest that other islands and seamounts were constructed by the Arago hotspot during the past 120 million years. These potentially include Tuvalu, Gilbert Islands, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rarotonga Hotspot
The Rarotonga hotspot is a volcanic hotspot in the southern Pacific Ocean. The hotspot was responsible for the formation of Rarotonga and some volcanics of Aitutaki. In addition to these volcanoes in the Cook Islands, the composition of volcanic rocks in Samoa and in the Lau Basin may have been influenced by the Rarotonga hotspot, and some atolls and seamounts in the Marshall Islands may have formed on the hotspot as well. Geology Oceanic plateaus and linear volcanic chains dot the floor of the Pacific Ocean. Their formation has been explained with mantle plumes which rise from the core-mantle boundary and spread out when they rise, forming a large "head" that causes intense volcanic activity once it hits the crust. This volcanism is responsible for the formation of the oceanic plateaus. Later, the remnant "tail" of the plume is still rising and induces the formation of volcano chains as the crust moves over the plume tail, thus forming the linear chains. A number of hotsp ... [...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] |
Guyot
In marine geology, a guyot (pronounced ), also known as a tablemount, is an isolated underwater volcanic mountain ( seamount) with a flat top more than below the surface of the sea. The diameters of these flat summits can exceed .Guyot ''Encyclopædia Britannica Online'', 2010. Retrieved January 14, 2010. Guyots are most commonly found in the , but they have been identified in all the oceans except the . History Guyots were first recognized in 1945 by H ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drill Core
A modern core drill is a drill specifically designed to remove a cylinder of material, much like a hole saw. The material left inside the drill bit is referred to as the ''core''. Core drills used in metal are called annular cutters. Core drills used for concrete and hard rock generally use industrial diamond grit as the abrasive material and may be electrical, pneumatic or hydraulic powered. Core drills are commonly water cooled, and the water also carries away the fine waste as a slurry. For drilling masonry, carbide core drills can be used, but diamond is more successful when cutting through rebar. The earliest core drills were those used by the ancient Egyptians, invented in 3000 BC. Core drills are used for many applications, either where the core needs to be preserved (the drilling apparatus used in obtaining a core sample is often referred to as a corer), or where drilling can be done more rapidly since much less material needs to be removed than with a standard bit. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphate
In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosphoric acid by the removal of three protons . Removal of one or two protons gives the dihydrogen phosphate ion and the hydrogen phosphate ion ion, respectively. These names are also used for salts of those anions, such as ammonium dihydrogen phosphate and trisodium phosphate. File:3-phosphoric-acid-3D-balls.png, Phosphoricacid File:2-dihydrogenphosphate-3D-balls.png, Dihydrogenphosphate File:1-hydrogenphosphate-3D-balls.png, Hydrogenphosphate File:0-phosphate-3D-balls.png, Phosphate In organic chemistry, phosphate or orthophosphate is an organophosphate, an ester of orthophosphoric acid of the form where one or more hydrogen atoms are replaced by organic groups. An example is trimethyl phosphate, . The term also refers to the triv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hibiscus
''Hibiscus'' is a genus of flowering plants in the mallow family, Malvaceae. The genus is quite large, comprising several hundred species that are native to warm temperate, subtropical and tropical regions throughout the world. Member species are renowned for their large, showy flowers and those species are commonly known simply as "hibiscus", or less widely known as rose mallow. Other names include hardy hibiscus, rose of sharon, and tropical hibiscus. The genus includes both annual and perennial herbaceous plants, as well as woody shrubs and small trees. The generic name is derived from the Greek name ἰβίσκος (''ibískos'') which Pedanius Dioscorides gave to ''Althaea officinalis'' ( 40–90 AD). Several species are widely cultivated as ornamental plants, notably ''Hibiscus syriacus'' and ''Hibiscus rosa-sinensis''. A tea made from hibiscus flowers is known by many names around the world and is served both hot and cold. The beverage is known for its red colour, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ocean Drilling Program
The Ocean Drilling Program (ODP) was a multinational effort to explore and study the composition and structure of the Earth's oceanic basins. ODP, which began in 1985, was the successor to the Deep Sea Drilling Project initiated in 1968 by the United States. ODP was an international effort with contributions of Australia, Germany, France, Japan, the United Kingdom and the ESF Consortium for Ocean Drilling (ECOD) including 12 further countries. The program used the drillship ''JOIDES Resolution'' on 110 expeditions (legs) to collect about 2,000 deep sea cores from major geological features located in the ocean basins of the world. Drilling discoveries led to further questions and hypotheses, as well as to new disciplines in earth sciences such as the field of paleoceanography. In 2004 ODP transformed into the Integrated Ocean Drilling Program (IODP). See also * Project Mohole * Deep Sea Drilling Program * Integrated Ocean Drilling Program * Allison Guyot Allison Guyot (fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from the Ancient Greek (''olígos'', "few") and (''kainós'', "new"), and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period. The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major changes during the Oligocene included a global expansion o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ralik Chain
The Ralik Chain ( Marshallese: , ) is a chain of islands within the island nation of the Marshall Islands. Ralik means "sunset". It is west of the Ratak Chain. In 1999 the total population of the Ralik islands was 19,915. Christopher Loeak, who became President of the Marshall Islands in 2012, was formerly Minister for the Ralik Chain. List of atolls and isolated islands in the chain: * Ailinginae Atoll * Ailinglaplap Atoll * Bikini Atoll * Ebon Atoll * Enewetak Atoll * Jabat Island * Jaluit Atoll * Kili Island * Kwajalein Atoll * Lae Atoll * Lib Island * Namdrik Atoll * Namu Atoll * Rongdrik Atoll * Rongelap Atoll * Ujae Atoll * Ujelang Atoll * Wotho Atoll Language The Rālik Chain is home to the Rālik dialect (or western dialect) of the Marshallese language. It is mutually intelligible with the Ratak dialect (or eastern dialect) located on the Ratak Chain The Ratak Chain ( Marshallese: , ) is a chain of islands within the island nation of the Marshall Islands. Ratak mea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ratak Chain
The Ratak Chain ( Marshallese: , ) is a chain of islands within the island nation of the Marshall Islands. Ratak means "sunrise". It lies to the east of the country's other island chain, the Ralik Chain. In 1999 the total population of the Ratak islands was 30,925. The atolls and isolated islands in the chain are: * Ailuk Atoll * Arno Atoll * Aur Atoll * Bikar Atoll * Bokak Atoll * Erikub Atoll * Jemo Island * Knox Atoll * Likiep Atoll * Majuro Atoll * Maloelap Atoll * Mejit Island * Mili Atoll * Taka Atoll * Utirik Atoll * Wotje Atoll The Ratak Chain forms a continuous chain of seamounts with the Gilbert Islands to the south, which are part of Kiribati. Language The Ratak Chain is home to the Ratak dialect (or eastern dialect) of the Marshallese language. It is mutually intelligible with the Rālik dialect (or western dialect) located on the Rālik Chain The Ralik Chain ( Marshallese: , ) is a chain of islands within the island nation of the Marshall Islands. Ralik mea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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