Volcanic system
The term volcanic system comes from geology . Volcanoes often do not occur alone, but form groups that are connected by underground conveying channels. The term volcanic system is often used for this. The terminology is not entirely uniform. Other geologists speak in the context of e.g. B. from volcanic fields . In contrast, the volcano- magma system explains the processes when the magma rises.
Role of the central volcano
Especially with reference to Iceland , the term central volcano is used for the mountain with the largest magma chamber . Geologists also speak of a volcanic center here . From here go passages and conveying channels through which the semi-liquid magma often moves to great distances.
Volcanic systems without a central volcano
However, there are also volcanic systems without a central volcano.
They are characterized by a system of fissures and associated individual volcanoes. In Iceland, examples would be the shield volcanoes on the Reykjanes peninsula (Suðurnes) or the Grímsnes volcanic system .
Volcanic eruption in the system
Where the circumstances favor this, because z. If, for example, movements of the continental plates have damaged the earth's crust or if it is very thin, the magma can then rise by using existing channels or tearing open new ones.
This can be done at great distances from the actual magma reservoir. Bárðarbunga , a central volcano in the Icelandic glacier Vatnajökull , has z. B. a 150 km long volcanic system that extends in the south almost to Landmannalaugar to the craters of Veiðivötn , which are also included in this system. Also Krafla in the north of Iceland has a long volcanic system. It is up to 10 km wide and about 100 km long.
The affiliation of a volcano to a volcanic system can be determined by examining the chemical composition of the magmas or lavas . Every volcanic system has a characteristic magma composition. At the same time, there are local variations from basic (such as basalt ) to intermediate (such as andesite ) to rocky rocks (e.g. rhyolites ). Near the magma chamber one finds i. A. more rocky and intermediate rocks, more basic rocks at craters further away from it. The Felsic and Intermediate Rocks are lighter in weight and are therefore the first to be ejected; H. directly above the magma stove.
Life expectancy of volcanic systems
Volcanic systems have a limited life expectancy, which can range from a few hundred thousand to 1–2 million years. This is explained by the constantly changing crust of the earth. In the case of rift movements, for example, access channels can both close and open.
See also
literature
- Ari Trausti Guðmundsson : Land in the making. An outline of the geology of Iceland. Reykjavík, Vaka-Helgafell, 1996, p. 76 f.
- Ari Trausti Guðmundsson: Living Earth. Facets of the geology of Iceland. Reykjavík, Mál og menning, 2007
- Hans-Ulrich Schmincke: Vulcanism. Darmstadt 2000
- Thor Thordarson, Ármann Hoskuldsson: Iceland. Classic Geology in Europe 3. Harpenden, Terra, 2002
- Þorleifur Einarsson: Geology of Iceland. Rocks and landscape. Reykjavík, Mál og Menning, 2005
Web links
- On the newly discovered volcanic system in Northern Franconia, Univ. Nuremberg (PDF; 2.6 MB)
- On the volcanic system of the powder maar in the Eifel, Univ. Würzburg (PDF; 431 kB)
- Program for the Geography course at the Univ. Marburg, 2009, accessed: February 27, 2010
Individual evidence
- ↑ see orleifur Einarsson, p. 61 ff .; but also in the study program of the 2009 Geography course at Univ. Marburg is the term, s. Web link
- ↑ About Schmincke, p. 90, in relation to the Vulkaneifel.
- ↑ Schmincke, p. 12
- ↑ Þorleifur Einarsson, p. 63
- ↑ z. B. Ari Trausti, Land im Werden, p. 76
- ↑ Þorleifur Einarsson, p. 61 f.
- ^ Thor Thordarson, p. 182.
- ↑ Thor Thodarson, p. 144 f.
- ↑ Þorleifur Einarsson, p. 61
- ↑ Ari Trausti, Land im Werden, p. 81 f.