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Late Ruker Orogeny
The Late Ruker orogeny, also known as the Nimrod orogeny, was a mountain building event around 1 billion years ago in the Proterozoic. Large portions of West Antarctica were added to the continent during this event. The orogeny was marked by subsidence, sedimentation and underwater volcanic eruptions along the proto-Pacific Ocean margin of proto-Antarctica. This melted some older igneous plutonic rocks and metamorphic rocks and caused some new metamorphism. Red beds were deposited and are now preserved in the Ritscher Upland of Queen Maud Land. Stromatolite carbonate beds and quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ... arenite in the Shackleton Range serves as evidence for a stable platform and epicratonic sea during the period. See also * List of orogenies * Geol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orogeny
Orogeny () is a mountain-mountain formation, building process that takes place at a convergent boundary, convergent plate margin when plate motion compresses the margin. An or develops as the compressed plate crumples and is tectonic uplift, uplifted to form one or more mountain ranges. This involves a series of geological processes collectively called orogenesis. These include both structural deformation (physics), deformation of existing continental crust and the creation of new continental crust through volcanism. Magma rising in the orogen carries less dense material upwards while leaving more dense material behind, resulting in compositional differentiation of Earth's lithosphere (crust (geology), crust and uppermost mantle (geology), mantle). A synorogenic (or synkinematic) process or event is one that occurs during an orogeny. The word ''orogeny'' comes . Although it was used before him, the American geologist Grove Karl Gilbert, G. K. Gilbert used the term in 1890 to me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proterozoic
The Proterozoic ( ) is the third of the four geologic eons of Earth's history, spanning the time interval from 2500 to 538.8 Mya, and is the longest eon of Earth's geologic time scale. It is preceded by the Archean and followed by the Phanerozoic, and is the most recent part of the Precambrian "supereon". The Proterozoic is subdivided into three geologic eras (from oldest to youngest): the Paleoproterozoic, Mesoproterozoic and Neoproterozoic. It covers the time from the appearance of free oxygen in Earth's atmosphere to just before the proliferation of complex life on the Earth during the Cambrian Explosion. The name ''Proterozoic'' combines two words of Greek origin: meaning "former, earlier", and , meaning "of life". Well-identified events of this eon were the transition to an oxygenated atmosphere during the Paleoproterozoic; the evolution of eukaryotes via symbiogenesis; several global glaciations, which produced the 300 million years-long Huronian glaciation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
West Antarctica
West Antarctica, or Lesser Antarctica, one of the two major regions of Antarctica, is the part of that continent that lies within the Western Hemisphere, and includes the Antarctic Peninsula. It is separated from East Antarctica by the Transantarctic Mountains and is covered by the West Antarctic Ice Sheet. It lies between the Ross Sea (partly covered by the Ross Ice Shelf), and the Weddell Sea (largely covered by the Filchner-Ronne Ice Shelf). It may be considered a giant peninsula, stretching from the South Pole towards the tip of South America. West Antarctica is largely covered by the Antarctic ice sheet, but there have been signs that climate change is having some effect and that this ice sheet may have started to shrink slightly. Over the past 50 years, the west coast of the Antarctic Peninsula has been – and still is – one of the most rapidly warming parts of the planet, and the coasts of the Peninsula are the only parts of West Antarctica that become (in summer) i ... [...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) and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamorphic Rock
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causing profound physical or chemical changes. During this process, the rock remains mostly in the solid state, but gradually recrystallizes to a new texture or mineral composition. The protolith may be an igneous, sedimentary, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by their protolith, their chemical and mineral makeup, and their texture. They may be formed simply by being deeply buried beneath the Earth's surface, where they are subject to high temperatures and the great pressure of the rock layers above. They can also form from tectonic processes such as continental collisions, which cause horizontal pressure, friction, and dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamorphism
Metamorphism is the transformation of existing Rock (geology), rock (the protolith) to rock with a different mineral composition or Texture (geology), texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chemically active fluids, but the rock remains mostly solid during the transformation. Metamorphism is distinct from weathering or diagenesis, which are changes that take place at or just beneath Earth's surface. Various forms of metamorphism exist, including Regional metamorphism, regional, Contact metamorphism, contact, Hydrothermal metamorphism, hydrothermal, Shock metamorphism, shock, and Dynamic metamorphism, dynamic metamorphism. These differ in the characteristic temperatures, pressures, and rate at which they take place and in the extent to which reactive fluids are involved. Metamorphism occurring at increasing pressure and temperature conditions is known as ''prograde metamorphism'', while decreasin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Beds
Red beds (or redbeds) are sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain thin beds of Conglomerate (geology), conglomerate, marl, limestone, or some combination of these sedimentary rocks. The ferric oxides, which are responsible for the red color of red beds, typically occur as a coating on the grains of sediments comprising red beds. Classic examples of red beds are the Permian and Triassic strata of the western United States and the Devonian Old Red Sandstone facies of Europe. Primary red beds Primary red beds may be formed by the erosion and redeposition of red soils or older red beds, but a fundamental problem with this hypothesis is the relative scarcity of red-colored source sediments of suitable age close to an area of red-bed sediments in Geology of Cheshire, Cheshire, England. Primary red beds may al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Queen Maud Land
Queen Maud Land () is a roughly region of Antarctica Territorial claims in Antarctica, claimed by Norway as a dependent territory. It borders the claimed British Antarctic Territory 20th meridian west, 20° west, specifically the Caird Coast, Coats Land on the West, and the Australian Antarctic Territory 45th meridian east, 45° east, specifically Enderby Land on the East. In addition, a small unclaimed area from 1939 was annexed in June 2015. Positioned in East Antarctica, it makes out about one-fifth of the continent, and is named after the Norwegian Maud of Wales, Queen Maud (1869–1938). In 1930, the Norwegian Hjalmar Riiser-Larsen was the first person known to have set foot in the territory. On 14 January 1939, the territory was claimed by Norway. On 23 June 1961, Queen Maud Land became part of the Antarctic Treaty System, making it a demilitarised zone. It is one of dependencies of Norway, two Antarctic claims made by Norway, the other being Peter I Island. They are adm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stromatolite
Stromatolites ( ) or stromatoliths () are layered Sedimentary rock, sedimentary formation of rocks, formations (microbialite) that are created mainly by Photosynthesis, photosynthetic microorganisms such as cyanobacteria, sulfate-reducing microorganism, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). These microorganisms produce adhesive compounds that cementation (geology), cement sand and other rocky materials to form mineral "microbial mats". In turn, these mats build up layer by layer, growing gradually over time. This process generates the characteristic Lamination (geology), lamination of stromatolites, a feature that is hard to interpret, in terms of its temporal and environmental significance. Different styles of stromatolite lamination have been described, which can be studied through microscopic and mathematical methods. A stromatolite may grow to a meter or more. Fossilized stromatolites provide important records of some of the most ancient ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonate
A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group . The term is also used as a verb, to describe carbonation: the process of raising the concentrations of carbonate and bicarbonate ions in water to produce carbonated water and other carbonated beverageseither by the addition of carbon dioxide gas under pressure or by dissolving carbonate or bicarbonate salts into the water. In geology and mineralogy, the term "carbonate" can refer both to carbonate minerals and carbonate rock (which is made of chiefly carbonate minerals), and both are dominated by the carbonate ion, . Carbonate minerals are extremely varied and ubiquitous in chemically precipitated sedimentary rock. The most common are calcite or calcium carbonate, , the chief constituent of limestone (as well as the main component of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of Silicon dioxide, SiO2. Quartz is, therefore, classified structurally as a Silicate mineral#Tectosilicates, framework silicate mineral and compositionally as an oxide mineral. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation from α-quartz to β-quartz takes place abruptly at . Since the transformation is accompanied by a significant change in volume, it can easily induce microfracturing of ceramics or rocks passing through this temperature threshold. There are many different varieties of quartz, several of which are classifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arenite
Arenite (from the Latin ''arena'', "sand") is a sedimentary clastic rock with sand grain size between 0.0625 mm (0.00245 in) and 2 mm (0.08 in) and containing less than 15% matrix. The related adjective is ''arenaceous''. The equivalent Greek-derived term is psammite, though this is more commonly used for metamorphosed sediments. Since it refers to grain size rather than chemical composition, the term is used for example in the classification of clastic carbonatic limestones, as the granulometrically equivalent term sandstone is not appropriate for limestone. Other arenites include sandstones, arkoses, greensands, and greywackes. Arenites mainly form by erosion of other rocks or turbiditic re-deposition of sands. Some arenites contain a varying amount of carbonatic components and thus belong to the rock-category of carbonatic sandstones or silicatic limestones. Arenites often appear as massive or bedded medium-grained rocks with a middling- to wide-space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
