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La Negra Formation
La Negra Formation ( es, Formación La Negra) is a geologic formation of Jurassic age, composed chiefly of volcanic and volcaniclastic rocks, located in the Coast Range of northern Chile. The formation originated in marine and continental (terrestrial) conditions, and bears evidence of submarine volcanism as well as large explosive eruptions. The volcanism of La Negra Formation is thought to have lasted for about five million years. The formation has a thickness of about with the type section being a thick exposure in Quebrada La Negra next to Antofagasta. La Negra Formation deposited diachronously along a series of intra-arc basins and overlies conformably the formations of Pan de Azúcar and Posada de los Hidalgo. The formation is intruded by plutons of varied composition including gabbro and granite. La Negra Arc Together with the Arica Group and the Camaraca, Los Tarros and Oficina Viz formations, it constitutes the remains of the La Negra Arc, an ancient volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
La Portada
La Portada (Spanish: "The Gateway") is a natural arch on the coast of Chile, north of Antofagasta. It is one of fifteen natural monuments included among the protected areas of Chile. There is another similar but smaller structure in the spa town of Pucatrihue, Osorno Province. Description The La Portada Natural Monument covers an area of 31.27 hectares (77.27 acres), and its geomorphological features and remaining fossils stand out in the form of an arch. The arch of La Portada is 43 m (140 ft) high, 23 m (75 ft) wide, and 70 m (230 ft) long. It has a base of black andesite stone, around which are arranged marine sedimentary rocks, a stratum of yellowing sandstone, and layers of the remaining fossils of shells dating back 35 to 2 million years ago. All this was formed during a long process of marine erosion. The arch is surrounded by coastal cliffs that were also formed by marine erosion. They reach a maximum height of 52 m above sea level. On ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Way Group
Way Group ( es, Grupo Way) is a geologic group of Lower Cretaceous age located in northern Chile. The sediments of the group deposited in Coloso Basin, a small intra-arc basin made up by a half graben. The now inactive Coloso Basin is elongated along a NNW-SSE oriented axis and has its southwestern border made up by faults. The Way Group is made up of the following arrangement from top to bottom the Tablado Formation made up chiefly of limestone, the conglomerate-gravel-sandstone Lombriz Formation and the conglomerate and breccia dominated Caleta Coloso Formation. Tabledo Formation Tableado Formation is the uppermost member of Way Group. It is made up of limestone and shale deposited in the shallow marine conditions of the continental shelf. The limestones contains fossils. It rests conformably on top of Lombriz Formation. Lombriz Formation Clasts of epidotized lava are common in the conglomerates of Lombriz Formation. The clasts of Lombriz Formation are made up of andesite a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andean Geology
''Andean Geology'' (formerly ''Revista Geológica de Chile'') is a peer-reviewed scientific journal published three times per year by the National Geology and Mining Service, Chile's geology and mining agency. The journal covers the field of geology and related earth sciences, primarily on issues that are relevant to South America, Central America, and Antarctica with a particular focus on the Andes. The journal was established in 1974 and articles are published in English and Spanish. The editor-in-chief An editor-in-chief (EIC), also known as lead editor or chief editor, is a publication's editorial leader who has final responsibility for its operations and policies. The highest-ranking editor of a publication may also be titled editor, managing ... is Waldo Vivallo (National Geology and Mining Service). References External links * Geology journals Geology of South America Geology of Antarctica Publications established in 1974 Andes Multilingual journals Open ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posada De Los Hidalgo Formation
Posada may refer to: * Battle of Posada, a 1330 battle, part of the Hungarian-Wallachian Wars Places In Poland * Posada, Lower Silesian Voivodeship, south-west Poland *Posada, Łódź Voivodeship, central Poland *Posada, Masovian Voivodeship, east-central Poland *Posada, Gmina Kazimierz Biskupi in Greater Poland Voivodeship, west-central Poland *Posada, Gmina Stare Miasto in Greater Poland Voivodeship, west-central Poland *Posada, Gmina Wierzbinek in Greater Poland Voivodeship, west-central Poland *Posada, Słupca County in Greater Poland Voivodeship, west-central Poland In other countries * Posada, Sardinia, Italy *Posada, a village administered by Comarnic town, Prahova County, Romania * Posada, Asturias, a parish in Llanes, Asturias, Spain People with the surname Posada *José Guadalupe Posada (1852–1913), Mexican engraver and illustrator * Luis Posada Carriles (1928–2018), Cuban-born Venezuelan anti-communist militant * José Posada (1940–2013), Spanish member of the E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intra-arc Basin
In geology an intra-arc basin is a sedimentary basin that exists amidst a volcanic arc. Being located next to volcanoes intra-arc basins tend to host Volcano-sedimentary sequences. Cura-Mallín at the border of Chile and Argentina is an example of an intra-arc basin. Some Neoproterozoic The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is prec ... clastic metasedimentary rocks in the Central Eastern Desert of Egypt (CED) derived from bimodal volcanic sources appear to have been deposited in arc-related basins, including interarc or back-arc basins, intra-arc basins, and retro-arc basin of active continental margin.El Bahariya, G,. (2018). Geology, geochemistry, and source characteristics of Neoproterozoic arc-related clastic metasediments, Central Eastern Desert, Egypt. '' Arabian Journal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diachronous
In geology, a diachronism (Greek language, Greek ''dia'', "through" + ''chronos'', "time" + ''-ism''), or diachronous deposit, is a sedimentary rock formation in which the material, although of a similar nature, varies in age with the place where it was deposited.Whitten F.G.A & Brooks J.R.V., (1972),''A Dictionary of Geology'', Penguin, Typically this occurs as a result of a Transgression (geology), marine transgression or regression, or the progressive development of a River delta, delta. As the shoreline advances or retreats, a succession of continuous deposits representing different environments (for example beach, shallow water, deeper water) may be left behind. Although each type of deposit (facies) may be continuous over a wide area, its age varies according to the position of the shoreline through time. An example is the sandy beds near the end of the lower Carboniferous of the west of England (the ''Drybrook sandstone'' of the Forest of Dean). Deposition of this began muc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antofagasta
Antofagasta () is a port city in northern Chile, about north of Santiago. It is the capital of Antofagasta Province and Antofagasta Region. According to the 2015 census, the city has a population of 402,669. After the Spanish American wars of independence, Bolivia claimed Antofagasta as part of its territory. Despite having an overwhelmingly ethnic Chilean population, Chile recognised Bolivian sovereignty of Antofagasta in 1866, but in 1879 Chile recanted its recognition of Bolivian sovereignty citing a Bolivian breach of the latest boundary treaty. Antofagasta was captured by Chile in February 14 1879 triggering the War of the Pacific (1879–83). Chilean sovereignty was officially recognised by Bolivia under the terms of the 1904 Treaty of Peace and Friendship. The city of Antofagasta is closely linked to mining activity, being a port and the chief service hub for one of Chile's major mining areas. While silver and saltpeter mining have been historically important for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratotype
A stratotype or type section in geology is the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary. If the stratigraphic unit is layered, it is called a stratotype, whereas the standard of reference for unlayered rocks is the type locality. Also it can be defined as "The particular sequence of strata chosen as standard of reference of a layered stratigraphic unit." When a stratigraphic unit is nowhere fully exposed, the original type section may be supplemented with reference sections covering the full thickness of the unit. A reference section may also be defined when the original type section is poorly exposed, or for historical units which were designated without specifying a type section according to more modern standards. See also * Global Boundary Stratotype Section and Point A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explosive Eruption
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent. Sometimes a lava plug will block the conduit to the summit, and when this occurs, eruptions are more violent. Explosive eruptions can expel as much as per second of rocks, dust, gas and pyroclastic material, averaged over the duration of eruption, that travels at several hundred meters per second as high as into the atmosphere. This cloud may subsequently collapse, creating a fast-moving pyroclastic flow of hot volcanic matter. Stages of an explosive eruption An explosive eruption begins with some form of blockage in the crater of a volcano that prevents the release of gases trapped in highly viscous andesitic or rhyolitic magma. The pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine Eruption
Submarine eruptions are those volcano eruptions which take place beneath the surface of water. These occur at constructive margins, subduction zones and within tectonic plates due to hotspots. This eruption style is far more prevalent than subaerial activity. For example, it is believed that 70 to 80% of the Earth's magma output takes place at mid-ocean ridges.Parfitt, L. and Wilson, L. (2008) ''Fundamentals of Physical Volcanology'', Blackwell Publishing. Detection Submarine eruptions are less studied than subaerial volcanoes due to their inaccessibility. Developments in technology mean that submarine volcanoes can now be studied in greater detail. Despite this progress, understanding is still limited. Mid ocean ridges for example are the most active volcanic systems on Earth but roughly only 5% of their length has been studied in detail.Fagents, S.A., Gregg, T.K.P. and Lopes, R.M.C. (2013) ''Modelling Volcanic processes: the Physics and Mathematics of Volcanism'', Cambridge U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chilean Coast Range
The Chilean Coastal Range ( es, Cordillera de la Costa) is a mountain range that runs from north to south along the Pacific coast of South America parallel to the Andean Mountains, extending from Morro de Arica in the north to Taitao Peninsula, where it ends at the Chile Triple Junction, in the south. The range has a strong influence on the climate of Chile since it produces a rain shadow to the east. Because of this the vegetation growing on the seaward slopes is much more exuberant than in the interior. Compared to the coastal lowlands and the Intermediate Depression, it is sparsely populated with land use varying from protected areas to grazing and silviculture. The range is present in all Chilean regions, except for Coquimbo Region and Magallanes Region. Geography Like the Andes, the coastal range becomes progressively lower with increasing latitude. The range begins at Morro de Arica in the north and reaches its highest point, of 3114 m, in Sierra Vicuña Mackenna in the An ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geologic Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
