|
Casma Group
The Casma Group () is a stratigraphic group of Cretaceous (Albian to Cenomanian) sedimentary formations exposed along the coast and within the Cordillera Occidental near Casma, Peru. Description The sediments of the Casma Group reflect deposition in two distinct environments of the West Peruvian Basin. Some sediments were deposited near the Casma Volcanic Arc in an intra-cratonic sedimentary basin that was occasionally connected to the ocean. Other sediments were deposited in what was once a continental platform bounded by reefs and with anoxic pockets.Compare et al, 1983 Together with the Morro Solar and Imperial Groups, the Casma Group contains clastic volcanosedimentary material derivative of the Mesozoic Casma Volcanic Arc.Pfiffner & González, 2013 The folding of the Casma Group sediments is the result of the Cretaceous Mochica Phase of the Andean orogeny. The group is intruded by plutons of the Coastal Batholith of Peru. The Casma Group include the following ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group (stratigraphy)
In geology, a group is a lithostratigraphy, lithostratigraphic Stratigraphic unit, unit consisting of a series of related Geological formation, formations that have been classified together to form a group. Formations are the fundamental unit of stratigraphy. Groups may sometimes be combined into Supergroup (geology), supergroups. Groups are useful for showing relationships between formations, and they are also useful for small-scale mapping or for studying the stratigraphy of large regions. Geologists exploring a new area have sometimes defined groups when they believe the strata within the groups can be divided into formations during subsequent investigations of the area. It is possible for only some of the strata making up a group to be divided into formations. An example of a group is the Glen Canyon Group, which includes (in ascending order) the Wingate Sandstone, the Moenave Formation, the Kayenta Formation, and the Navajo Sandstone. Each of the formations can be distingui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Casma Volcanic Arc
Casma is a city in the coastal desert of Peru, located northwest of Lima. It is the capital of the province of Casma and the third most populous city in the Ancash Region with an estimated population of 29,343 (2015). It is located in the lower Casma Valley, covering an area of 1,205 km2. The name of the city may derive from the extinct ''Quingman'' language. Santa Maria Magdalena Mary Magdalene (sometimes called Mary of Magdala, or simply the Magdalene or the Madeleine) was a woman who, according to the four canonical gospels, traveled with Jesus as one of his followers and was a witness to crucifixion of Jesus, his cr ... is the city's patron saint, whose day is celebrated on July 22. Some of the largest prehistoric monuments around the world are situated around the city, in the Casma and Sechin valleys. These include Sechin, Chanquillo, Mojeque and Las Aldas. The nearby Pacific coastline boasts beaches such as La Gramita, El Litro, Punta el Huaro and Tortug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pluton
In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and compositions, illustrated by examples like the Palisades Sill of New York and New Jersey; the Henry Mountains of Utah; the Bushveld Igneous Complex of South Africa; Shiprock in New Mexico; the Ardnamurchan intrusion in Scotland; and the Sierra Nevada Batholith of California. Because the solid country rock into which magma intrudes is an excellent insulator, cooling of the magma is extremely slow, and intrusive igneous rock is coarse-grained ( phaneritic). Intrusive igneous rocks are classified separately from extrusive igneous rocks, generally on the basis of their mineral content. The relative amounts of quartz, alkali feldspar, plagioclase, and feldspathoid is particularly important in classifying intrusive igneous rocks. Intru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andean Orogeny
The Andean orogeny () is an ongoing process of orogeny that began in the Early Jurassic and is responsible for the rise of the Andes mountains. The orogeny is driven by a reactivation of a long-lived subduction system along the western margin of South America. On a continental scale the Cretaceous (90 Ma) and Oligocene (30 Ma) were periods of re-arrangements in the orogeny. The details of the orogeny vary depending on the segment and the geological period considered. Overview Subduction orogeny has been occurring in what is now western South America since the break-up of the supercontinent Rodinia in the Neoproterozoic. The Paleozoic Pampean, Famatinian and Gondwanan orogenies are the immediate precursors to the later Andean orogeny.Charrier ''et al''. 2006, pp. 113–114. The first phases of Andean orogeny in the Jurassic and Early Cretaceous were characterized by extensional tectonics, rifting, the development of back-arc basins and the emplacement of large batholiths. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fold (geology)
In structural geology, a fold is a stack of originally planar surfaces, such as sedimentary rock, sedimentary stratum, strata, that are bent or curved (''"folded"'') during permanent deformation (engineering), deformation. Folds in rocks vary in size from microscopic crinkles to mountain-sized folds. They occur as single isolated folds or in periodic sets (known as ''fold trains''). wikt:synsedimentary, Synsedimentary folds are those formed during sedimentary deposition. Folds form under varied conditions of stress (physics), stress, pore pressure, and temperature gradient, as evidenced by their presence in soft sedimentary rock, sediments, the full spectrum of metamorphic rocks, and even as primary flow structures in some igneous rocks. A set of folds distributed on a regional scale constitutes a fold belt, a common feature of orogeny, orogenic zones. Folds are commonly formed by shortening of existing layers, but may also be formed as a result of displacement on a non-planar f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcano-sedimentary Sequence
A volcano-sedimentary sequence is a stratigraphic sequence derived from the alternation and combination of volcanic and sedimentary events. The volcanic material of these sequences may include lava flows and tephra or reworked volcanic material, for example basaltic sand or pebbles. Areas surrounding volcanic arc A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc ...s are common settings for volcano-sedimentary sequences. Volcanic rocks Stratigraphy Sedimentary rocks {{Stratigraphy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clastic Rock
Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus,Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-3 chunks, and smaller grains of rock broken off other rocks by physical weathering.Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-5 Geologists use the term clastic to refer to sedimentary rocks and particles in sediment transport, whether in suspension or as bed load, and in sediment deposits. Sedimentary clastic rocks Clastic sedimentary rocks are rocks composed predominantly of broken pieces or ''clasts'' of older weathered and eroded rocks. Clastic sediments or sedimentary rocks are classified based on grain size, clast and cementing material (matrix) composition, and texture. The classification factors are often useful in determining a sample's environment of deposition. An example of clastic environment would be a river system in which the full range of grains being transported b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imperial Group (geology)
Imperial Brands plc (originally the Imperial Tobacco Company of Great Britain & Ireland, and subsequently Imperial Tobacco Group plc) is a British multinational tobacco company headquartered in Bristol, England. It is the world's fourth-largest international cigarette company measured by market share after Philip Morris International, British American Tobacco and Japan Tobacco and the world's largest producer of fine-cut tobacco and tobacco papers. Imperial Brands is listed on the London Stock Exchange and is a constituent of the FTSE 100 Index. Imperial Brands has 30 factories worldwide and its products are sold in around 120 countries. Its tobacco brands include Davidoff, West, Golden Virginia, Drum and Rizla. Imperial Brands's alternative nicotine products include the blu brand of electronic cigarettes, the Pulze and iD brands of heated tobacco systems, and the Zone X and Skruf brands of nicotine pouches. Imperial Tobacco Canada is the Canadian subsidiary of British ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morro Solar Group
The Morro Solar Group () is a stratigraphic group of Mesozoic-aged sedimentary formations exposed near Lima, Peru. The groups formations more specifically of Berriasian and Valanginian age (Early Cretaceous) and overlies the Jurassic Puente Piedra Group and underlies the Cretaceous Pamplona Formation. The Morro Solar Group is intruded by sills of andesitic composition. Together with the Casma and Imperial Groups, the Morro Solar Group contains clastic volcanosedimentary material derivative of the Mesozoic Casma Volcanic Arc. The formations of the group hosts mostly local fossils which do not have counterparts for biochronological correlation in other regions. Stratigraphy The formations of the Morro Solar Group are: La Herradura Formation (), whose sediments reflect a marine near-shore deposition environment, the Valanginian Salto del Fraile Formation (), and the Marcavilca Formation (). The Salto del Fraile Formation is equivalent to the basal part of the Huancané F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anoxic Waters
Anoxic waters are areas of sea water, fresh water, or groundwater that are depleted of dissolved oxygen. The US Geological Survey defines anoxic groundwater as those with dissolved oxygen concentration of less than 0.5 milligrams per litre. Anoxic waters can be contrasted with hypoxic waters, which are low (but not lacking) in dissolved oxygen. Often, hypoxia is defined as waters that have less than 2 milligrams per litre of dissolved oxygen. This condition is generally found in areas that have restricted water exchange. In most cases, oxygen is prevented from reaching the deeper levels by a physical barrier, as well as by a pronounced density stratification, in which, for instance, denser, colder or hypersaline waters rest at the bottom of a basin. Anoxic conditions will occur if the rate of oxidation of organic matter by bacteria is greater than the supply of dissolved oxygen. Anoxic waters are a natural phenomenon, and have occurred throughout geological history. The Permia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reef
A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geology), deposition of sand or wave erosion planning down rock outcrops. However, reefs such as the coral reefs of tropical waters are formed by biotic component, biotic (living) processes, dominated by corals and coralline algae. Artificial reefs, such as shipwrecks and other man-made underwater structures, may occur intentionally or as the result of an accident. These are sometimes designed to increase the physical complexity of featureless sand bottoms to attract a more diverse range of organisms. They provide shelter to various aquatic animals which help prevent extinction. Another reason reefs are put in place is for aquaculture, and fish farmers who are looking to improve their businesses sometimes invest in them. Reefs are often quite n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
