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Magma is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and gas bubbles.
Andesite is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende.
A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it upwards. If the magma finds a path to the surface, then the result will be a volcanic eruption; consequently, many volcanoes are situated over magma chambers. These chambers are hard to detect deep within the Earth, and therefore most of those known are close to the surface, commonly between 1 km and 10 km down.
A flood basalt is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reaching the surface of the earth via a mantle plume. Flood basalt provinces such as the Deccan Traps of India are often called traps, after the Swedish word trappa, due to the characteristic stairstep geomorphology of many associated landscapes.
In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or along the direction of foliation in metamorphic rock. A sill is a concordant intrusive sheet, meaning that a sill does not cut across preexisting rock beds. Stacking of sills builds a sill complex and a large magma chamber at high magma flux. In contrast, a dike is a discordant intrusive sheet, which does cut across older rocks. Sills are fed by dikes, except in unusual locations where they form in nearly vertical beds attached directly to a magma source. The rocks must be brittle and fracture to create the planes along which the magma intrudes the parent rock bodies, whether this occurs along preexisting planes between sedimentary or volcanic beds or weakened planes related to foliation in metamorphic rock. These planes or weakened areas allow the intrusion of a thin sheet-like body of magma paralleling the existing bedding planes, concordant fracture zone, or foliations.
The rock cycle is a basic concept in geology that describes transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. Each rock type is altered when it is forced out of its equilibrium conditions. For example, an igneous rock such as basalt may break down and dissolve when exposed to the atmosphere, or melt as it is subducted under a continent. Due to the driving forces of the rock cycle, plate tectonics and the water cycle, rocks do not remain in equilibrium and change as they encounter new environments. The rock cycle explains how the three rock types are related to each other, and how processes change from one type to another over time. This cyclical aspect makes rock change a geologic cycle and, on planets containing life, a biogeochemical cycle.
In geology, igneous differentiation, or magmatic differentiation, is an umbrella term for the various processes by which magmas undergo bulk chemical change during the partial melting process, cooling, emplacement, or eruption. The sequence of magmas produced by igneous differentiation is known as a magma series.
Cerro Galán is a caldera in the Catamarca Province of Argentina. It is one of the largest exposed calderas in the world and forms part of the Central Volcanic Zone of the Andes, one of the three volcanic belts found in South America. One of several major caldera systems in the Central Volcanic Zone, the mountain is grouped into the Altiplano–Puna volcanic complex.
The Paraná-Etendeka traps (or Paraná and Etendeka Plateau; or Paraná and Etendeka Province) comprise a large igneous province that includes both the main Paraná traps (in Paraná Basin, a South American geological basin) as well as the smaller severed portions of the flood basalts at the Etendeka traps (in northwest Namibia and southwest Angola). The original basalt flows occurred 138 to 128 million years ago. The province had a post-flow surface area of 1,500,000 square kilometres (580,000 sq mi) and an original volume projected to be in excess of 2.3 x 106 km³.
Jonathan David Blundy FRS is Royal Society Research Professor at the School of Earth Sciences at the University of Oxford and honorary professor at the University of Bristol.
Igneous rock, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava.
Magmatic underplating occurs when basaltic magmas are trapped during their rise to the surface at the Mohorovičić discontinuity or within the crust. Entrapment of magmas within the crust occurs due to the difference in relative densities between the rising magma and the surrounding rock. Magmatic underplating can be responsible for thickening of the crust when the magma cools. Geophysical seismic studies utilize the differences in densities to identify underplating that occurs at depth.
The Altiplano–Puna volcanic complex, also known as APVC, is a complex of volcanic systems in the Puna of the Andes. It is located in the Altiplano area, a highland bounded by the Bolivian Cordillera Real in the east and by the main chain of the Andes, the Western Cordillera, in the west. It results from the subduction of the Nazca Plate beneath the South American Plate. Melts caused by subduction have generated the volcanoes of the Andean Volcanic Belt including the APVC. The volcanic province is located between 21° S–24° S latitude. The APVC spans the countries of Argentina, Bolivia and Chile.
The Deep Crustal Hot Zone (DCHZ), or just deep hot zone, is a zone in the lower crust where hot mantle material intrudes. In a volcanic arc setting, hot, molten material from the mantle may intrude the lower crust. This hot material generates a new, more evolved melt in this area of the crust, which may collect and migrate upwards towards the upper crust. Here, it would collect in a magma chamber and later erupt.
A crystal mush is magma that contains a significant amount of crystals suspended in the liquid phase (melt). As the crystal fraction makes up less than half of the volume, there is no rigid large-scale three-dimensional network as in solids. As such, their rheological behavior mirrors that of absolute liquids.
Uturuncu is a dormant volcano in the Sur Lípez Province of Bolivia. It is 6,008 metres (19,711 ft) high, has two summit peaks, and consists of a complex of lava domes and lava flows with a total volume estimated to be 50–85 km3. It bears traces of a former glaciation, even though it does not currently carry glaciers. Volcanic activity took place during the Pleistocene epoch and the last eruption was 250,000 years ago; since then Uturuncu has not erupted but active fumaroles occur in the summit region, between the two summits.
The Altiplano-Puna Magma Body (APMB), a magma body located within the Altiplano-Puna plateau approximately 10-20 km beneath the Altiplano-Puna Volcanic Complex (APVC) in the Central Andes. High resolution tomography shows that this magma body has a diameter of ~200 km, a depth of 14-20 km, with a total volume of ~500,000 km3, making it the largest known active magma body on Earth. Thickness estimates for the APMB are varied, with some as low as 1 km, others around 10-20 km, and some extending as far down as the Moho. The APMB is primarily composed of 7-10 wt% water andesitic melts and the upper portion may contain more dacitic melts with partial melt percentages ranging from 10-40%. Measurements indicate that the region around the Uturuncu volcano in Bolivia is uplifting at a rate of ~10 mm/year, surrounded by a large region of subsidence. This movement is likely a result of the APMB interacting with the surrounding rock and causing deformation. Recent research demonstrates that this uplift rate may fluctuate over months or years and that it has decreased over the past decade. Various techniques, such as seismic, gravity, and electromagnetic measurements have been used to image the low-velocity zone in the mid to upper crust known as the APMB.
Volcanic and igneous plumbing systems (VIPS) consist of interconnected magma channels and chambers which are responsible for the production, storage and transportation of magma in Earth's crust. Volcanic plumbing systems can be found in all active tectonic settings, such as mid-oceanic ridges, subduction zones, and mantle plumes, when magmas generated in continental lithosphere, oceanic lithosphere, and in the sub-lithospheric mantle are transported. Magma is first generated by partial melting, followed by segregation and extraction from the source rock to separate the melt from the solid. As magma propagates upwards, a self-organised network of magma channels develops, transporting the melt from lower crust to upper regions. Channelled ascent mechanisms include the formation of dykes and ductile fractures that transport the melt in conduits. For bulk transportation, diapirs carry a large volume of melt and ascent through the crust. When magma stops ascending, or when magma supply stops, magma emplacement occurs. Different mechanisms of emplacement result in different structures, including plutons, sills, laccoliths and lopoliths.
Ōkataina Caldera is a massive, recently active volcanic caldera and its associated volcanoes located in Taupō Volcanic Zone of New Zealand's North Island. It is just east of the smaller Rotorua Caldera and southwest of the much smaller Rotomā complex which is usually regarded as part of the same volcano. It is best known for its high rates of explosive rhyolitic volcanism although its last eruption was basaltic. Confusingly the Haroharo Caldera contained within it, has sometimes been described in almost interchangeable terms with the Ōkataina Caldera or volcanic complex or centre and by other authors as a separate complex.
References
- ↑ "CV". ISTerre - Institut des Sciences de la Terre (in French). Retrieved 2022-03-03.
- 1 2 "Catherine Annen - Geofyzikální ústav Akademie věd ČR, v.v.i." Domů. Retrieved 2022-03-03.
- ↑ Annen, Catherine (1999). Modélisation de la croissance des volcans (Thesis). Genève: Université de Genève. Section des sciences de la terre. OCLC 807256862.
- 1 2 3 Bristol, University of. "Directory of Experts". www.bristol.ac.uk. Retrieved 2022-03-03.
- ↑ Annen, C. (2009-07-15). "From plutons to magma chambers: Thermal constraints on the accumulation of eruptible silicic magma in the upper crust". Earth and Planetary Science Letters. 284 (3): 409–416. doi:10.1016/j.epsl.2009.05.006. ISSN 0012-821X.
- ↑ "talks.cam : Magma intrusive rates and the growth of melt reservoirs and magma chambers". talks.cam.ac.uk. Retrieved 2022-03-03.
- ↑ "XV Congreso Geológico Chileno" . Retrieved 2022-03-03.
- ↑ "Catherine Annen". Critmag. 2014-10-11. Retrieved 2022-03-03.
- ↑ "Research Summary". ISTerre - Institut des Sciences de la Terre (in French). Retrieved 2022-03-03.
- 1 2 Bristol, University of. "Ground-breaking work sheds new light on volcanic activity". phys.org. Retrieved 2022-03-03.
- ↑ Caricchi, Luca; Annen, Catherine; Blundy, Jon; Simpson, Guy; Pinel, Virginie (February 2014). "Frequency and magnitude of volcanic eruptions controlled by magma injection and buoyancy". Nature Geoscience. 7 (2): 126–130. doi:10.1038/ngeo2041. ISSN 1752-0908.
- ↑ "Ground-breaking work sheds new light on volcanic activity". ScienceDaily. Retrieved 2022-03-03.
- ↑ "Frontiers in Earth Science (Journal)". University of Bristol. Retrieved 2022-03-03.
- ↑ "Committee Members of the VIPS Commission". VIPS Commission. Retrieved 2022-03-03.
- ↑ "The Geological Society of London - 2022 Award Winners announced". www.geolsoc.org.uk. Retrieved 2022-03-03.
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