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Geologic provinces of the world (USGS)      Shield      Platform      Orogen      Basin      Large igneous province      Extended crust Oceanic crust:      0–20 Ma      20–65 Ma      >65 Ma
Geologic provinces of the world (USGS)
     Shield      Platform      Orogen      Basin      Large igneous province      Extended crust Oceanic crust:      0–20 Ma      20–65 Ma      >65 Ma

Orogeny (Greek for "mountain generating") is the process of natural mountain building, and may be studied as a tectonic structural event, as a geographical event and a chronological event, in that orogenic events cause distinctive structural phenomena and related tectonic activity, affect certain regions of rocks and crust and happen within a time frame. A geologic or geomorphic province is a spatial entity with common geologic / geomorphic attributes The United States Geological Survey ( USGS) is a scientific agency of the United States government. A shield is generally a large area of exposed Precambrian Crystalline igneous and high-grade metamorphic rocks that form tectonically In geology a platform is a continental area covered by relatively flat or gently tilted mainly Sedimentary strata, which overlie a basement of consolidated A structural basin is a large-scale structural formation of rock strata formed by tectonic warping of previously flat lying strata. Large Igneous provinces (LIPS were originally defined by Coffin and Eldholm (1992 as areas of Earth's surface that contain very large volumes of magmatic rocks (typically In Geology, a crust is the outermost solid shell of a planet or moon Oceanic crust is the part of Earth's Lithosphere that surfaces in the Ocean basins Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular A mountain is a Landform that extends above the surrounding Terrain in a limited area with a peak

Orogenic events occur solely as a result of the processes of plate tectonics; the problems which were investigated and resolved by the study of orogenesis contributed greatly to the theory of plate tectonics, coupled with study of flora and fauna, geography and mid ocean ridges in the 1950s and 1960s. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere Geography (from Greek γεωγραφία - geografia) is the study of the Earth and its lands features inhabitants and phenomena A mid-ocean ridge or mid-oceanic ridge is an underwater Mountain range typically having a valley known as a Rift running along its axis formed by

The physical manifestations of orogenesis (the process of orogeny) are orogenic belts or orogens. An orogen is different from a mountain range in that an orogen may be completely eroded away, and only recognizable by studying (old) rocks that bear the traces of the orogeny. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Orogens are usually long, thin, arcuate tracts of rocks which have a pronounced linear structure resulting in terranes or blocks of deformed rocks, separated generally by dipping thrust faults. A terrane in Geology is a fragment of crustal material formed on or broken off from one Tectonic plate and accreted — " sutured " Strike and dip refer to the orientation or attitude of a Geologic feature A thrust fault is a type of fault, or break in the Earth's crust with resulting movement of each side against the other in which a lower stratigraphic position is pushed up These thrust faults carry relatively thin plates (which are called nappes, and differ from tectonic plates) of rock in from the margins of the compressing orogen to the core, and are intimately associated with folds and the development of metamorphism. In Geology, a nappe is a large sheetlike body of rock that has been moved more than 2 km (1 Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere See also Folding The term fold is used in Geology when one or a stack of originally flat and planar surfaces such as Sedimentary Metamorphism can be defined as the solid state recrystallisation of pre-existing rocks due to changes in heat and/or pressure and/or introduction of fluids i

The topographic height of orogenic mountains is related to the principle of isostasy, where the gravitational force of the upthrust mountain range of light, continental crust material is balanced against its buoyancy relative to the dense mantle. Isostasy (Greek isos = "equal" stásis = "standstill" is a term used in Geology to refer to the state of gravitational equilibrium between the Newton 's law of universal Gravitation is a physical law describing the gravitational attraction between bodies with mass The continental crust is the layer of granitic, Sedimentary, and Metamorphic rocks which form the Continents and the areas of shallow seabed The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided

Erosion inevitably takes its course, removing much of the mountains and exposing the core or mountain roots (metamorphic rocks brought from tens of km depth to the surface). Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change Such exhumation may be helped by isostatic movements balancing out the buoyancy of the evolving orogen. Isostasy (Greek isos = "equal" stásis = "standstill" is a term used in Geology to refer to the state of gravitational equilibrium between the It is a question of debate to what extent can erosion modify the patterns of tectonic deformacion (see erosion and tectonics). The interplay between erosion and tectonics has been a matter of debate since the early 1990s This is the final form of the majority of old orogenic belts, being a long arcuate strip of crystalline metamorphic rocks sequentially below younger sediments which are thrust atop them and dip away from the orogenic core.

Contents

History

Before the development of geologic concepts during the 19th century, the presence of mountains was explained in Christian contexts as a result of the Biblical Deluge, for Neoplatonic thought, which influenced early Christian writers, assumed that a perfect Creation would have to have been in the form of a perfect sphere. Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit Neoplatonism (also Neo-Platonism) is the modern term for a school of religious and mystical Philosophy that took shape in the 3rd century AD founded by Such thinking persisted into the eighteenth century.

Orogeny was used by Amanz Gressly (1840) and Jules Thurmann (1854) as orogenic in terms of the creation of mountain elevations, as the term mountain building was still used to describe the processes. ( July 17, 1814 - April 13, 1865) was a was a Swiss geologist and paleontologist.

Elie de Beaumont (1852) used the evocative "Jaws of a Vise" theory to explain orogeny, but was more concerned with the height rather than the implicit structures orogenic belts created and contained. Jean-Baptiste Armand Louis Léonce Élie de Beaumont ( September 25, 1798 &ndash September 21, 1874) was a French Geologist His theory essentially held that mountains were created by the squeezing of certain rocks.

Eduard Suess (1875) recognised the importance of horizontal movement of rocks. Eduard Suess ( August 20, 1831 London &ndash April 26, 1914 Vienna) was a Geologist who was an expert on the The concept of a precursor geosyncline or initial downward warping of the solid earth (Hall, 1859) prompted James Dwight Dana (1873) to include the concept of compression in the theories surrounding mountain-building. Geosyncline theory is an obsolete concept involving vertical crustal movement that has been replaced by Plate tectonics to explain crustal movement and geologic features James Dwight Dana (February 12 1813 &ndash April 14 1895 was an American Geologist, Mineralogist and Zoologist. With hindsight, we can discount Dana's conjecture that this contraction was due to the cooling of the Earth (aka the cooling earth theory).

The cooling Earth theory was the chief paradigm for most geologists until the 1960s. It was, in the context of orogeny, contested hotly by proponents of vertical movements in the crust (similar to tephrotectonics), or convection within the asthenosphere or mantle. The asthenosphere (from an invented Greek a + ' sthenos "without strength" and Greek word σφαίρα (sphera meaning globe is the The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided

Gustav Steinmann (1906) recognised different classes of orogenic belts, including the Alpine type orogenic belt, typified by a flysch and molasse geometry to the sediments; ophiolite sequences, tholeiitic basalts, and a nappe style fold structure. Flysch is a sequence of Sedimentary rocks that is deposited in a deep Marine facies in the Foreland basin of a developing Orogen. Molasse refers to the Sandstones, Shales and conglomerates formed as terrestrial or shallow marine deposits in front of rising mountain chains An Ophiolite is a section of the Earth's Oceanic crust and the underlying upper mantle that has been uplifted or emplaced to be exposed within Continental Tholeiitic basalt is an Igneous rock, a type of Basalt. Like all basalt the rock type is dominated by Clinopyroxene plus Plagioclase, with minor In Geology, a nappe is a large sheetlike body of rock that has been moved more than 2 km (1

In terms of recognising orogeny as an event, Leopold von Buch (1855) recognised that orogenies could be placed in time by bracketing between the youngest deformed rock and the oldest undeformed rock, a principle which is still in use today, though commonly investigated by geochronology using radiometric dating. Christian Leopold Freiherr von Buch ( April 26, 1774 - March 4, 1853) was a German Geologist and Paleontologist In the Natural sciences under the umbrella of Natural history, Geochronology is the Science of determining the absolute age of rocks, Fossils

H. J. Zwart (1967) drew attention to the metamorphic differences in orogenic belts, proposing three types, modified by W. S. Pitcher (1979);

The advent of plate tectonics has explained the vast majority of orogenic belts and their features. Back-arc basins (or retro-arc basins are geologic features submarine basins associated with Island arcs and Subduction zones. Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. Migmatite is a rock at the frontier between igneous and Metamorphic rocks They can also be known as diatexite. An Ophiolite is a section of the Earth's Oceanic crust and the underlying upper mantle that has been uplifted or emplaced to be exposed within Continental Ultramafic (also referred to as ultrabasic) rocks are igneous and meta -igneous rocks with very low Silica content (less than 45% generally In Geology, a nappe is a large sheetlike body of rock that has been moved more than 2 km (1 Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock For the extinct cephalopod genus see Andesites. Andesite (ˈændəsaɪt is an igneous, Volcanic rock, of intermediate Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. A batholith (from Greek bathos, depth + lithos, rock is a large emplacement of Igneous intrusive (also called plutonic rock that forms Migmatite is a rock at the frontier between igneous and Metamorphic rocks They can also be known as diatexite. The geothermal gradient is the rate of increase in temperature per unit depth in the Earth. An Ophiolite is a section of the Earth's Oceanic crust and the underlying upper mantle that has been uplifted or emplaced to be exposed within Continental Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) Shale (also called mudstone) is a fine-grained Sedimentary rock whose original constituents were Clay minerals or Muds It is characterized by Chert (ˈtʃɝt is a fine-grained Silica -rich Microcrystalline, Cryptocrystalline or Microfibrous Sedimentary rock that may contain In Geology, a nappe is a large sheetlike body of rock that has been moved more than 2 km (1 The cooling earth theory (principally advanced by Descartes) is dispensed with, and tephrotectonic style vertical movements have been explained primarily by the process of isostasy. Isostasy (Greek isos = "equal" stásis = "standstill" is a term used in Geology to refer to the state of gravitational equilibrium between the

Some oddities exist, where simple collisional tectonics are modified in a transform plate boundary, such as in New Zealand, or where island arc orogenies, for instance in New Guinea occur away from a continental backstop. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island New Guinea, located just north of Australia, is the world's second largest island, having become separated from the Australian mainland when the area now known Further complications such as Proterozoic continent-continent collisional orogens, explicitly the Musgrave Block in Australia, previously inexplicable (see Dennis, 1982) are being brought to light with the advent of seismic imaging techniques which can resolve the deep crust structure of orogenic belts. The Musgrave Block is an east-west trending belt of Proterozoic Granulite - Gneiss basement rocks approximately 500km long

Physiography

The process of orogeny can take tens of millions of years and build mountains from plains or even the ocean floor. "Ocean Floor" redirects here For the 2001 song by Audio Adrenaline, see Lift (Audio Adrenaline album. Orogeny can occur due to continental collision or volcanic activity. Continental collision is a phenomenon of the Plate tectonics of Earth. Plate tectonics and hotspots Divergent plate boundaries At the Frequently, rock formations that undergo orogeny are severely deformed and undergo metamorphism. This is a List of rock formations meaning isolated scenic or spectacular surface rock outcrops Metamorphism can be defined as the solid state recrystallisation of pre-existing rocks due to changes in heat and/or pressure and/or introduction of fluids i During orogeny, deeply buried rocks may be pushed to the surface. Sea bottom and near shore material may cover some or all of the orogenic area. If the orogeny is due to two continents colliding, the resulting mountains can be very high (see Himalaya).

Orogeny usually produces long linear structures, known as orogenic belts. Generally, orogenic belts consist of long parallel strips of rock exhibiting similar characteristics along the length of the belt. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere Orogenic belts are associated with subduction zones, which consume crust, produce volcanoes, and build island arcs. In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other In Geology, a crust is the outermost solid shell of a planet or moon A volcanic arc is a chain of volcanic islands or Mountains formed by Plate tectonics as an oceanic Tectonic plate subducts under These island arcs may be added to a continent during an orogenic event. A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions

List of orogenies

North American orogenies

Taconic orogeny
Taconic orogeny

European orogenies

Asian orogenies

South American orogenies

African orogenies

Australian orogenies

Antarctic orogenies

New Zealand orogenies

See also

References

External links

Dictionary

orogeny

-noun

  1. (geology) the process of mountain building by the upward folding of the Earth's crust
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