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17-626: The formation is together with the Reyhuau basalts part of the Pilcaniyeu Belt , a volcanic belt active in Paleocene to middle Eocene times. The Huitrera Formation was first defined by Ravazzoli and Sesana in 1977. The name has been used to identify various volcaniclastic sequences, among others in the Ñirihuau fold-and-thrust belt . The up to 1,300 metres (4,300 ft) thick formation comprises mudstones and sandstones deposited in

34-555: A crater lake environment . Part of the formation comprises andesites , dacitic and rhyolitic ignimbrites , volcanic breccias , tuffs and trachybasalts . The formation was initially described as Late Eocene to Early Oligocene , but was later dated to 54.24 ± 0.45 Ma, meaning the Huitrera Formation is Ypresian , or in the SALMA classification , Casamayoran in age. The following macrofossils were reported from

51-449: A viscous fluid . Partial melting of the mantle at mid-ocean ridges produces oceanic crust , and partial melting of the mantle at subduction zones produces continental crust . Mercury has a silicate mantle approximately 490 kilometers (300 miles) thick, constituting only 28% of its mass. Venus 's silicate mantle is approximately 2,800 kilometers (1,700 miles) thick, constituting around 70% of its mass. Mars 's silicate mantle

68-421: A narrow stream of hot mantle convecting up from the mantle-core boundary called a mantle plume . But more recently some geologists, such as Gillian Foulger view upper-mantle convection as a cause. This in turn has re-raised the antipodal pair impact hypothesis, the idea that pairs of opposite hot spots may result from the impact of a large meteor. Geologists have identified some 40-50 such hotspots around

85-476: A result, they are less explosive than subduction zone volcanoes, which have high water contents. Where hotspots occur under continental crust, basaltic magma is trapped in the less dense continental crust, which is heated and melts to form rhyolites. These rhyolites can be quite hot and form violent eruptions, despite their low water content. For example, the Yellowstone Caldera was formed by some of

102-491: A subduction-zone related volcanic belt is the Okhotsk-Chukotka Volcanic Belt in northeastern Eurasia , which is one of the largest subduction-zone related volcanic provinces in the world, stretching some 3,200 kilometres (2,000 mi) and comprising about 2 × 10 cubic kilometres (4.8 × 10  cu mi) of volcanic and plutonic material. Volcanic belts may also be formed by hotspots , which

119-529: Is a location on the Earth's surface that has experienced active volcanism for a long period of time. These volcanic belts are called volcanic chains. Canadian geologist John Tuzo Wilson came up with the idea in 1963 that volcanic chains like the Hawaiian Islands result from the slow movement of a tectonic plate across a "fixed" hot spot deep beneath the surface of the planet, thought to be caused by

136-463: Is approximately 1,600 kilometers (990 miles) thick, constituting ~74–88% of its mass, and may be represented by chassignite meteorites. Uranus and Neptune 's ice mantles are approximately 30,000 km thick, composing 80% of both masses. Jupiter 's moons Io , Europa , and Ganymede have silicate mantles; Io's ~1,100 kilometers (680 miles) silicate mantle is overlain by a volcanic crust, Ganymede's ~1,315 kilometers (817 miles) thick silicate mantle

153-565: Is created by partial melting of solid material in the Earth's crust and upper mantle . These areas usually form along tectonic plate boundaries at depths of 10 to 50 kilometres (6.2 to 31.1 mi). For example, volcanoes in Mexico and western North America are mostly in volcanic belts, such as the Trans-Mexican Volcanic Belt that extends 900 kilometres (560 mi) from west to east across central-southern Mexico and

170-479: Is one of the world's largest greenstone belts. Volcanic belts are similar to a mountain range , but the mountains within the mountain range are volcanoes, not mountains that are formed by faulting and folding by the collision of tectonic plates . Volcanic belts may be formed by multiple tectonic settings. They may be formed by subduction zones , which is an area on Earth where two tectonic plates meet and move towards one another, with one sliding underneath

187-597: Is overlain by ~835 kilometers (519 miles) of ice, and Europa's ~1,165 kilometers (724 miles) km silicate mantle is overlain by ~85 kilometers (53 miles) of ice and possibly liquid water. The silicate mantle of the Earth's moon is approximately 1300–1400 km thick, and is the source of mare basalts . The lunar mantle might be exposed in the South Pole-Aitken basin or the Crisium basin . The lunar mantle contains

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204-1106: The Northern Cordilleran Volcanic Province in western Canada . In the case of Iceland, the geologist G.G. Bárdarson in 1929 identified clusters of volcanic belts while studying the Reykjanes Peninsula . The deeply deformed and eroded remnants of ancient volcanic belts are found in volcanically inactive regions such as the Canadian Shield . It contains over 150 volcanic belts (now deformed and eroded down to nearly flat plains ) that range from 600 to 1,200 million years old. These are zones of variably metamorphosed mafic to ultramafic volcanic sequences with associated sedimentary rocks that form what are known as greenstone belts . They are thought to have formed at ancient oceanic spreading centers and island arc terranes . The Abitibi greenstone belt in Ontario and Quebec , Canada

221-436: The giant planets , specifically ice giants , a number of asteroids , and some planetary moons have mantles. The Earth's mantle is a layer of silicate rock between the crust and the outer core . Its mass of 4.01 × 10 kg is 67% the mass of the Earth. It has a thickness of 2,900 kilometres (1,800 mi) making up about 84% of Earth's volume. It is predominantly solid, but in geological time it behaves as

238-410: The formation: The formation has also provided many pollen , analyzed in 2003 by Melendi et al. Volcanic belt A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields or volcanic systems. Volcanic belts are found above zones of unusually high temperature (700 to 1,400 °C (1,292 to 2,552 °F)) where magma

255-696: The globe, with Hawaii , Réunion , Yellowstone , Galápagos , and Iceland overlying the most currently active. An example of a hotspot volcanic belt is the Anahim Volcanic Belt in British Columbia , Canada , which was formed as a result of the North American Plate sliding westward over the Anahim hotspot . Most hotspot volcanoes are basaltic because they erupt through oceanic lithosphere (e.g., Hawaii, Tahiti). As

272-454: The most powerful volcanic explosions in geologic history. Mantle (geology) A mantle is a layer inside a planetary body bounded below by a core and above by a crust . Mantles are made of rock or ices , and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density . All terrestrial planets (including Earth ), half of

289-405: The other and moving down into the mantle , at rates typically measured in centimeters per year. An oceanic plate ordinarily slides underneath a continental plate; this often creates an orogenic zone with many volcanoes and earthquakes . In a sense, subduction zones are the opposite of divergent boundaries , areas where material rises up from the mantle and plates are moving apart. An example of

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