Magmatism
This article was due to content flaws on the quality assurance side of Geosciences portal entered. This is done to increase the quality of the articles in the geosciences topic. Please help to correct the deficiencies or take part in the discussion . ( + )
Reason: The introductory chapters have now been created; Bibliography is now mentioned; however, the endogenous igneous processes are still missing. - A. Abdel-Rahim ( discussion ) 1:14 am, Apr 1, 2020 (CEST)
Magmatism is a term that summarizes the geological processes that are related to the outcropping and taking place of natural rock melts (so-called magmas ) on or below the earth's surface .
Basic, extrusion, intrusion
Volcanic activity ( volcanism ) occurs when magmas penetrate to the surface of the earth and spread (extrude) there. The resulting extrusive rock is called " volcanite ". In contrast to this, rock melts that do not reach the surface of the earth, but are only pushed below the surface between the rocks of the earth's crust or the lithospheric mantle , form what are known as intrusive rocks. The formed product of the intrusion that has become rock is called “ plutonite ”. The processes associated with sub-surface localization, which relate to the processes in the earth's crust or in the lithospheric mantle, are subsumed under the term plutonism .
Volcanism and plutonism
Plutonic processes act over a long period of time in the part of the earth's strata at moderate depths (crust below the earth's surface plus lithospheric mantle). The earth's lithospheric mantle reaches an average depth of about 120 kilometers at its lower edge facing the earth's interior; at the shallowest places it is about 60 kilometers deep; under the archaic shields it can reach down to a depth of 160 kilometers. The formation of a pluton , a product of crystallization from the moderately deep magma, can take from a few hundred thousand years to several million years; the processes are thereby largely withdrawn from human observation. Findings about this "deep magmatism" can only be gained from the investigation of the formed rock bodies, the plutonites.
On the other hand, the volcanic processes occurring near the surface are easy for humans to observe, measure and evaluate due to their rapid chronological sequence (for geological conditions) - sometimes occurring in just a few days, weeks or months.
Roughly, it can be said that volcanites cool down much faster than plutonites.
Endogenous igneous processes
Research history
The first known representative of scientific research on magmatism, apart from mythology, was the ancient Greek geographer Strabon (* about 63 BC; † after 23 AD), who was the first to describe three states of volcanism: calm, Prepare and break out. His opinion that this was a subterranean fire in cavities deep in the earth was held in science until the 19th century. Terms such as smoke, ash and slag are still used today in connection with volcanic magmatism. The Roman scholar Pliny the Elder , who perished in the eruption of Vesuvius in 79 AD, was also interested in researching volcanic processes.
The German scholars Albertus Magnus (around 1200–1280) and Georgius Agricola (1494–1555) also believed in these underground fires. The Jesuit scholar Athanasius Kircher (1602–1680) illustrated and interpreted their ideas . The geographer Bernhard Varenius (1622–1650 / 51) was the first to use the term volcano for a fire-breathing mountain and in 1650 wrote the first catalog for the volcanoes known to him. The French philosopher and scientist René Descartes (1596–1650) took the view that solar matter was still present in the interior of the earth, which would ignite the outer rock on the earth's surface.
At the end of the 18th century, with increasing knowledge about magmatism, a dispute broke out between the so-called Neptunists and the Plutonists about the formation of the volcanic effluent rock basalt . The mineralogist Abraham Gottlob Werner (1749–1817) believed that volcanic eruptions were caused by the spontaneous combustion of coal seams and that the sudden influx of water triggered an eruption, whereby the basalt in the water was solidified. However, one of his opponents, Nicolas Demarest (1725–1815), recognized the magmatic origin of basalt. In the 19th century, Leopold von Buch (1774–1853) postulated so-called elevation craters , which he described as bulges of magmatic processes, although without being able to define the forces behind them.
Modern magmatism research began with the English geologist George Julius Scrope (1797–1876), who recognized that volcanic mountains are formed by the ejection of material. He was the first to differentiate between volcanic and plutonic processes, with geothermal energy still coming from the time the earth was formed.
Today, research on magmatism takes into account the knowledge of the laws of geophysics , geochemistry , petrology and tectonic processes. In the 20th century volcanology developed into a science of its own.
literature
- Magmatism - remodeling of rocks . In: Roland Brinkmann (ed.): Textbook of general geology . tape 3 . Enke, Stuttgart 1967, OCLC 1011670318 .
- Paul Niggli: Physico-chemical basics . In: The magma and its products with special consideration of the influence of the volatile components . tape 1 . Academic Publishing Company, Leipzig 1937, DNB 366945858 .
- Alfred Rittmann: Volcanoes and their activity . 3rd, completely reworked edition. Enke, Stuttgart 1981, ISBN 3-432-87793-6 ( formally incorrect ) .
Web links
- Magmatism. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on March 25, 2020 .
Individual evidence
- ↑ Volker Jacobshagen, Jörg Arndt, Hans-Jürgen Götze, Dorothee Mertmann, Carin M. Wallfass: Introduction to the geological sciences (= university paperbacks . Volume 2106 ). Verlag Eugen Ulmer & Co., Stuttgart 2000, ISBN 3-8252-2106-7 , p. 271 ff .
- ↑ Rudolf Hohl (ed.): The history of the development of the earth . Reprint of the 5th edition. Dausien-Verlag, Hanau / Main 1985, ISBN 3-7684-6526-8 , Magmatismus, p. 188 ff .