Mid-German Crystalline High

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Structural map of central Europe, showing the positions of the Hercynian massifs and the zones in which the basement rocks can be divided. Gliederung der Varisziden in Mitteleuropa.jpg
Structural map of central Europe, showing the positions of the Hercynian massifs and the zones in which the basement rocks can be divided.

The Mid-German Crystalline High (or Mid-German High) is a structural high in the Paleozoic geology of Germany. The high forms a northeast-southwest oriented zone through Germany, but actual rock outcrops are sparse since Paleozoic basement rocks are in most of central Germany overlain by younger sedimentary rocks. The Mid-German Crystalline High crops out in the Odenwald, the Spessart, the northern Vosges and some small other massifs.

A high in structural geology and tectonics an area where tectonic uplift has taken place relative to its surroundings. Highs are often bounded by normal faults and can be regarded as the opposites of basins. A related word is a massif, an area where relative old rocks layers are found at the surface. A small high can be called a horst.

The PaleozoicEra is the earliest of three geologic eras of the Phanerozoic Eon. It is the longest of the Phanerozoic eras, lasting from 541 to 251.902 million years ago, and is subdivided into six geologic periods : the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era.

Germany Federal parliamentary republic in central-western Europe

Germany, officially the Federal Republic of Germany, is a country in Central and Western Europe, lying between the Baltic and North Seas to the north, and the Alps, Lake Constance and the High Rhine to the south. It borders Denmark to the north, Poland and the Czech Republic to the east, Austria and Switzerland to the south, France to the southwest, and Luxembourg, Belgium and the Netherlands to the west.

Contents

Structure

The Mid-German Crystalline High forms the northern part of the Saxothuringian Zone of the Hercynian orogeny. To the northwest it is bounded by the Northern Phyllite Zone (slightly metamorphosed sediments of mid-Paleozoic age), part of the Rhenohercynian Zone. Southeast of the Mid-German High lies a zone where early to mid-Paleozoic sediments of the Saxothuringian Basin crop out, metamorphosed during the Hercynian orogeny. Supposedly, during the mid-Paleozoic (Devonian and early Carboniferous) the Mid-German Crystalline High formed an area were not much deposition took place, perhaps an archipelago, between two marine or oceanic basins (the Rhenohercynian Basin to the north, the Saxothuringian Basin to the south). Some authors assume the northern basin's oceanic crust subducted beneath the Mid-German High. [1]

Saxothuringian Zone A structural or tectonic zone in the Hercynian or Variscan orogen of central and western Europe

The Saxothuringian Zone, Saxo-Thuringian zone or Saxothuringicum is in geology a structural or tectonic zone in the Hercynian or Variscan orogen of central and western Europe. Because rocks of Hercynian age are in most places covered by younger strata, the zone is not everywhere visible at the surface. Places where it crops out are the northern Bohemian Massif, the Spessart, the Odenwald, the northern parts of the Black Forest and Vosges and the southern part of the Taunus. West of the Vosges terranes on both sides of the English Channel are also seen as part of the zone, for example the Lizard complex in Cornwall or the Léon Zone of the Armorican Massif (Brittany).

Metamorphism The change of minerals in pre-existing rocks without melting into liquid magma

Metamorphism is the change of minerals or geologic texture in pre-existing rocks (protoliths), without the protolith melting into liquid magma. The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. The chemical components and crystal structures of the minerals making up the rock may change even though the rock remains a solid. Changes at or just beneath Earth's surface due to weathering or diagenesis are not classified as metamorphism. Metamorphism typically occurs between diagenesis, and melting (~850°C).

Rhenohercynian Zone A fold belt of west and central Europe, formed during the Hercynian orogeny

The Rhenohercynian Zone or Rheno-Hercynian zone in structural geology describes a fold belt of west and central Europe, formed during the Hercynian orogeny. The zone consists of folded and thrusted Devonian and early Carboniferous sedimentary rocks that were deposited in a back-arc basin along the southern margin of the then existing paleocontinent Laurussia.

Lithologies

The zone consists of Proterozoic orthogneisses and early Paleozoic volcanic (amphibolites with MORB-protoliths and tuffs) and sedimentary (pelites, calcareous schists and marbles) rocks that were metamorphosed at high grade during the Hercynian orogeny (up to amphibolite facies). These rocks were intruded by two generations of plutons: Silurian to Early Devonian (440-400 million years old) granitoids and middle Carboniferous (Hercynian, 340-325 million years old) granites. [2]

The Proterozoic is a geological eon spanning the time from the appearance of oxygen in Earth's atmosphere to just before the proliferation of complex life on the Earth. The name Proterozoic combines the two forms of ultimately Greek origin: protero- meaning "former, earlier", and -zoic, a suffix related to zoe "life". The Proterozoic Eon extended from 2500 mya to 541 mya, and is the most recent part of the Precambrian "supereon." The Proterozoic is the longest eon of the Earth's geologic time scale and it is subdivided into three geologic eras : the Paleoproterozoic, Mesoproterozoic, and Neoproterozoic.

Volcanic rock rocks composing or associated with volcanoes, volcanic activity or volcanism

Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "volcaniclastics," and these are technically sedimentary rocks.

Amphibolite A metamorphic rock containing mainly amphibole and plagioclase

Amphibolite is a metamorphic rock that contains amphibole, especially the species hornblende and actinolite, as well as plagioclase.

See also

Notes

  1. For example Ziegler (1990)
  2. Oncken (1997); Franke (2000)

Bibliography

Peter Ziegler Swiss geologist

Peter Alfred Ziegler was a Swiss geologist, who made contributions to the understanding of the geological evolution of Europe and the North Atlantic borderlands, of intraplate tectonics and of plate tectonic controls on the evolution and hydrocarbon potential of sedimentary basins. Ziegler's career consists of 33 years as exploration geologist with the petroleum industry, 30 of which with Shell, and 20 years of university teaching and research.

Royal Dutch Shell Anglo-Dutch oil company

Royal Dutch Shell plc, commonly known as Shell, is a British-Dutch oil and gas company headquartered in the Netherlands and incorporated in the United Kingdom. It is one of the six oil and gas "supermajors" and the fifth-largest company in the world measured by 2018 revenues. Shell was first in the 2013 Fortune Global 500 list of the world's largest companies; in that year its revenues were equivalent to 84% of the Dutch national $556 billion GDP.

International Standard Book Number Unique numeric book identifier

The International Standard Book Number (ISBN) is a numeric commercial book identifier which is intended to be unique. Publishers purchase ISBNs from an affiliate of the International ISBN Agency.

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