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Benmoreite
Benmoreite is a volcanic rock of intermediate composition. It is a silica-undersaturated sodium-rich variety of trachyandesite (the other kind is latite) and belongs to the alkaline suite of igneous rocks. It was named after Ben More, a mountain on the Isle of Mull, Scotland. Benmoreite has been found, for example, on Ascension Island and Easter Island, at Mount Berlin in Antarctica, and in Atakor volcanic field, Algeria. Benmoreite lava was erupted during the 2010 eruptions of Eyjafjallajökull. An origin by fractionation from basanite through nepheline hawaiite to nepheline benmoreite has been demonstrated for a volcanic suite in the McMurdo Volcanic Group of late Cenozoic age in McMurdo Sound area of Antarctica. Nepheline benmoreite magmas derived from mantle sources, containing lherzolite xenoliths, display similarities to some plutonic nepheline syenite Nepheline syenite is a holocrystalline Intrusion, plutonic rock that consists largely of nepheline and alkal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Trachyandesite
Trachyandesite is an extrusive igneous rock with a composition between trachyte and andesite. It has little or no free quartz, but is dominated by sodic plagioclase and alkali feldspar. It is formed from the cooling of lava enriched in alkali metals and with an intermediate content of silica. The term ''trachyandesite'' had begun to fall into disfavor by 1985 but was revived to describe extrusive igneous rocks falling into the S3 field of the TAS classification. These are divided into sodium-rich benmoreite and potassium-rich latite. Trachyandesitic magma can produce explosive Plinian eruptions, such as happened at Tambora in 1815. The Eyjafjallajökull 2010 eruption (VEI-4), which disrupted European and transatlantic air travel from 15-20 April 2010, for some time was dominated by trachyandesite. Petrology Trachyandesite is characterized by a silica content near 58% and a total alkali oxide content near 9%. This places trachyandesite in the S3 field of the TAS diagr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Alkaline Magma Series
The alkaline magma series is a chemically distinct range of magma compositions that describes the evolution of an Alkaline volcanic rock, alkaline mafic magma into a more evolved, silica-rich end member. Geochemical characterization Rocks in the alkaline magma series are distinguished from rocks in the subalkaline tholeiitic and calc-alkaline magma series by their high content of alkali metal oxides (K2O plus Na2O) relative to silica (SiO2). They are distinct from the rare peralkaline volcanic rock, peralkaline magmas, which have excess alkali oxides relative to alumina (Na2O + K2O > Al2O3). Alkaline magmas tend to show high titanium oxide (TiO2) content, typically in excess of 3% by weight. Other incompatible elements, such as phosphorus and LREE, light rare earth elements, are also elevated. This is attributed to a very low degree of partial melting of the source rock, with only 5% or less of the source rock going into the magma melt. Petrography All alkaline series magmas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Atakor Volcanic Field
Atakor volcanic field ("Atakor" in Tuareg means "swollen part, knot at the end of something") is a volcanic field in Algeria. It lies in the Hoggar Mountains, Hoggar mountains and consists of a variety of volcanic features such as lava flows and about 450 individual vents. Atakor is one of several large volcanic fields in this mountain range, which sits atop of a Geologic uplift, domal uplift and has erupted basalt, trachyte and phonolite. Volcanism in Atakor took place in several different phases, beginning 20 million years ago and continuing into the Holocene. Presently there is Fumarole, fumarolic activity. Geography and geomorphology The field lies in the Hoggar and the terrain approaches elevations of although the volcanics form an only superficial cover. The ground has a desert-like appearance. The scenery of the volcanic field is considered to be spectacular, with the lava domes and volcanic necks rising above the surrounding terrain. The field consists of lava domes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Mount Berlin
Mount Berlin is a glacier-covered volcano in Marie Byrd Land, Antarctica, from the Amundsen Sea. It is a roughly mountain with parasitic vents that consists of two coalesced volcanoes: Berlin proper with the Berlin Crater and Merrem Peak with a crater, away from Berlin. The summit of the volcano is above sea level. It has a volume of and rises from the West Antarctic Ice Sheet. It is part of the Marie Byrd Land Volcanic Province. Trachyte is the dominant volcanic rock and occurs in the form of lava flows and pyroclastic rocks. The volcano began erupting during the Pliocene and was active into the late Pleistocene and the Holocene. Several tephra layers encountered in ice cores all over Antarctica – but in particular at Mount Moulton – have been linked to Mount Berlin, which is the most important source of such tephras in the region. The tephra layers were formed by explosive eruptions that generated high eruption columns. Presently, fumarolic activity occurs at Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Igneous Rock
Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses. Igneous rocks occur in a wide range of geological settings: shields, platforms, orogens, basins, large igneous provinces, extended crust and oceanic crust. Geological significance Igneous and metamorphic rocks make up 90–95% of the top of the Earth's crust by volume. Igneous rock ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Easter Island
Easter Island (, ; , ) is an island and special territory of Chile in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian Triangle in Oceania. The island is renowned for its nearly 1,000 extant monumental statues, called ''moai'', which were created by the early Rapa Nui people. In 1995, UNESCO named Easter Island a World Heritage Site, with much of the island protected within Rapa Nui National Park. Experts differ on when the island's Polynesian inhabitants first reached the island. While many in the research community cited evidence that they arrived around the year 800, a 2007 study provided compelling evidence suggesting their arrival was closer to 1200. The inhabitants created a thriving and industrious culture, as evidenced by the island's numerous enormous stone ''moai'' and other artifacts. Land clearing for cultivation and the introduction of the Polynesian rat led to gradual deforestation. By the time of European arrival in 1722, the i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Dragon's Teeth (15516917296)
Dragon's teeth or dragon's tooth may refer to: * Dragon's teeth (mythology), in Greek mythology; once planted, each tooth grew into an armed warrior. Books * '' Dragon's Teeth: A Novel'', an 1878 realist novel by José Maria de Eça de Queiroz * "The Dragon's Teeth; or, Army-Seed," a chapter in the 1901 children's book '' The Wouldbegoods'' by E. Nesbit. * '' The Dragon's Teeth'', a 1939 mystery novel by Ellery Queen * ''Dragon's Teeth'' (novel), a 1942 Pulitzer Prize-winning historical novel by Upton Sinclair * ''Dragon's teeth: the background, contents and consequences of the North Atlantic Pact'', 1949 non-fiction book by Konni Zilliacus * "Dragons' Teeth" (short story), a 1977 fantasy short story by David Drake * '' The Dragon's Teeth?'', a 1982 American book by Benjamin S. Kelsey * ''The Dragon's Tooth'', a 2011 fantasy novel by N.D. Wilson * Dragon's Teeth Mountains, a fictional mountain range in the ''Shannara'' series of books * ''Dragon Teeth'', a posthumous novel by l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
McMurdo Sound
The McMurdo Sound is a sound in Antarctica, known as the southernmost passable body of water in the world, located approximately from the South Pole. Captain James Clark Ross discovered the sound in February 1841 and named it after Lieutenant Archibald McMurdo of HMS ''Terror''. The sound serves as a resupply route for cargo ships and airplanes that land on floating ice airstrips near McMurdo Station. The McMurdo seasonal Ice Runway was operated from October to December from the 1950s to the 2010s, then in December the ice breaks up and McMurdo port is opened by an Icebreaker ship and ships can resupply the Antarctic bases. Physical characteristics Boundary and extents The sound extends approximately 55 kilometers (34 mi) in length and width, and opens into the larger Ross Sea to the north. To the south, the sound is bounded by the Ross Ice Shelf cavity, to the west lies the Royal Society Range, and to the east is Ross Island. McMurdo Sound is separated from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cenozoic
The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three geological eras of the Phanerozoic Eon, preceded by the Mesozoic and Paleozoic. The Cenozoic started with the Cretaceous–Paleogene extinction event, when many species, including the non-avian dinosaurs, became extinct in an event attributed by most experts to the impact of a large asteroid or other celestial body, the Chicxulub impactor. The Cenozoic is also known as the Age of Mammals because the terrestrial animals that dominated both hemispheres were mammalsthe eutherians ( placentals) in the Northern Hemisphere and the metatherians (marsupials, now mainly restricted to Australia and to some extent South America) in the Southern Hemisphere. The extinction of many groups allowed mammals and birds to greatly diversify so that large m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Xenolith
A xenolith ("foreign rock") is a rock (geology), rock fragment (Country rock (geology), country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term ''xenolith'' is almost exclusively used to describe inclusion (mineral), inclusions in igneous rock entrained during magma ascent, emplacement and eruption. Xenoliths may be engulfed along the margins of a magma chamber, torn loose from the walls of an erupting lava conduit or explosive diatreme or picked up along the base of a flowing body of lava on the Earth's surface. A xenocryst is an individual foreign crystal included within an igneous body. Examples of xenocrysts are quartz crystals in a silica-deficient lava and diamonds within kimberlite diatremes. Xenoliths can be non-uniform within individual locations, even in areas which are spatially limited, e.g. rhyolite-dominated lava of Nii-jima, Niijima volcano (Japan) contains two types of gabbroic xenoliths which a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Mantle (geology)
A mantle is a layer inside a planetary body bounded below by a Planetary core, core and above by a Crust (geology), crust. Mantles are made of Rock (geology), rock or Volatile (astrogeology), ices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone planetary differentiation, differentiation by density. All Terrestrial planet, terrestrial planets (including Earth), half of the giant planets, specifically ice giants, a number of Asteroid, asteroids, and some planetary Natural satellite, moons have mantles. Examples Earth The Earth's mantle is a layer of Silicate minerals, silicate rock between the Crust (geology), crust and the Earth's outer core, outer core. Its mass of 4.01 × 1024 kg is 67% the mass of the Earth. It has a thickness of making up about 84% of Earth's volume. It is predominantly solid, but in Geologic time scale, geological time it behaves as a Viscosity, visc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Lherzolite
Lherzolite is a type of ultramafic igneous rock. It is a coarse-grained rock consisting of 40 to 90% olivine along with significant orthopyroxene and lesser amounts of calcic chromium-rich clinopyroxene. Minor minerals include chromium and aluminium spinels and garnets. Plagioclase can occur in lherzolites and other peridotites that crystallize at relatively shallow depths (20 – 30 km). At greater depth plagioclase is unstable and is replaced by spinel. At approximately 90 km depth, pyrope garnet becomes the stable aluminous phase. Garnet lherzolite is a major constituent of the Earth's upper mantle (Earth), upper mantle (extending to ~300 km depth). Lherzolite is known from the lower Ultramafic rock, ultramafic part of ophiolite complexes (although harzburgite is more common in this setting), from alpine-type peridotite massifs, from fracture zones adjacent to mid-oceanic ridges, and as xenoliths in kimberlite pipes and alkali basalts. Partial melting of spinel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
