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Benmoreite
Benmoreite is a silica-undersaturated volcanic rock of intermediate composition. It is a sodium-rich variety of trachyandesite and belongs to the alkalic suite of igneous rocks. Nepheline benmoreite 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 plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varieties are al ...s. See also * References Petrology Intermediate rocks Volcanic rocks {{petrology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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'', a 1939 mystery novel by Ellery Queen * Dragon's Teeth (novel), ''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), "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 late Michael Crichton (published in May 2017) *Pull the Dragon Too ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
McMurdo Volcanic Group
The McMurdo Volcanic Group is a large group of Cenozoic volcanic rocks in the western Ross Sea and central Transantarctic Mountains areas of Antarctica. It is one of the largest provinces of alkaline volcanism in the world, having formed as a result of continental rifting along the West Antarctic Rift System. The McMurdo Volcanic Group is part of the Western Ross Supergroup, a stratigraphic unit that also includes the Meander Intrusive Group. Subdivisions Three subprovinces comprise the McMurdo Volcanic Group, namely the Hallett, Melbourne and Erebus volcanic provinces. The Balleny Volcanic Province along the Balleny Fracture Zone in the Southern Ocean was originally defined as part of the McMurdo Volcanic Group but is now excluded due to its location on oceanic crust with no obvious geographic or tectonic relationship to the other McMurdo volcanic provinces. Hallett Volcanic Province The Hallett Volcanic Province in northern Victoria Land is situated along the margin of the Tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petrology
Petrology () is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because they both contain heavy use of chemistry, chemical methods, and phase diagrams. Sedimentary petrology is, on the other hand, commonly taught together with stratigraphy because it deals with the processes that form sedimentary rock. Background Lithology was once approximately synonymous with petrography, but in current usage, lithology focuses on macroscopic hand-sample or outcrop-scale description of rocks while petrography is the speciality that deals with microscopic details. In the petroleum industry, lithology, or more specifically mud logging, is the graphic representation of geological formations being drilled through and drawn on a log called a mud log. As the cuttings are circulated out of the borehole, they are sample ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nepheline Syenite
Nepheline syenite is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varieties are also known. Phonolite is the fine-grained extrusive equivalent. Petrology Nepheline syenites are silica-undersaturated and some are peralkaline (terms discussed in igneous rock). Nepheline is a feldspathoid, a solid-solution mineral, that does not coexist with quartz; rather, nepheline would react with quartz to produce alkali feldspar. They are distinguished from ordinary basic syenites not only by the presence of nepheline but also by the occurrence of many other minerals rich in alkalis and in rare earths and other incompatible elements. Alkali feldspar dominates, commonly represented by orthoclase and the exsolved lamellar albite, form perthite. In some rocks the potash feldspar, in others the soda feldspar predominates. Fresh clear m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutonic Rock
Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March 27, 2017.Igneous intrusive rocks, accessdate: March 27, 2017.Britannica.comintrusive rock , geology , Britannica.com accessdate: March 27, 2017. Intrusion is one of the two ways igneous rock can form. The other is extrusion, such as a volcanic eruption or similar event. An intrusion is any body of intrusive igneous rock, formed from magma that cools and solidifies within the crust of the planet. In contrast, an ''extrusion'' consists of extrusive rock, formed above the surface of the crust. Some geologists use the term plutonic rock synonymously with intrusive rock, but other geologists subdivide intrusive rock, by crystal size, into coarse-grained plutonic rock (typically formed deeper in the Earth's crust in batholiths or stocks) an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenolith
A xenolith ("foreign rock") is a rock fragment (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 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 Niijima volcano (Japan) contains two types of gabbroic xenoliths which are of different origin - they were formed in different temperature and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 (extending to ~300 km depth). Lherzolite is known from the lower 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 lherzolite is one of the primary sou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 Volatiles, 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), a number of Asteroid, asteroids, and some planetary Natural satellite, moons have mantles. Earth's mantle 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, viscous fluid. Partial melting of the mantle at mid-ocean ridges produ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
McMurdo Sound
McMurdo Sound is a sound in Antarctica. It is the southernmost navigable body of water in the world, and is about from the South Pole. Captain James Clark Ross discovered the sound in February 1841, and named it after Lt. Archibald McMurdo of HMS ''Terror''. The sound today serves as a resupply route for cargo ships and for airplanes that land on the floating ice airstrips near McMurdo Station. Physical characteristics Wildlife in the sound include killer whales, seals, Adélie penguins, and emperor penguins. 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 McMurdo Ice Shelf (itself part of the Ross Ice Shelf) by the Haskell Strait. Winter Quarters Bay lies at the south end of the Sound, and is the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cenozoic
The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configuration of continents. It is the latest of three geological eras since complex life evolved, preceded by the Mesozoic and Paleozoic. It 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) in the southern hemisphere. The extinction of many groups allowed mammals and birds to greatly diversify so that l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hawaiite
Hawaiite is an olivine basalt with a composition between alkali basalt and mugearite. It was first used as a name for some lavas found on the island of Hawaii. It occurs during the later stages of volcanic activity on oceanic islands such as Hawaii, which happens to be when the alkaline metals are most present. In gemology, hawaiite is a colloquial term for Hawaii-originated peridot, which is a gem-quality form of the mineral olivine. Description Hawaiite is an aphanitic (fine-grained) volcanic rock produced by rapid cooling of lava moderately poor in silica and enriched in alkali metal oxides (potassium oxide plus sodium oxide). It is often impractical to determine the mineral composition of such a fine-grained rock, and so hawaiite is defined chemically. Under the TAS classification, hawaiite is sodic trachybasalt, with a silica content close to 49 wt%, a total alkali metal oxide content close to 6%, and wt% > wt% + 2. This places hawaiite in the S1 field of the TAS dia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Rock
Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "volcaniclastics," and these are technically sedimentary rocks. Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces. It has been estimated t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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