The Saxothuringian Zone, Saxo-Thuringian zone or Saxothuringicum is in

geology Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth ...

structural A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

zone in the Hercynian or Variscan orogen (380-270 million years old) of central and western Europe. Because rocks of Hercynian age are in most places covered by younger

strata In geology and related fields, a stratum (: strata) is a layer of Rock (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...

, the zone is not everywhere visible at the surface. Places where it crops out are the northern

Bohemian Massif The Bohemian Massif ( or ''Český masiv'', or ''Böhmisches Massiv'') is a geomorphological province in Central Europe. It is a large massif stretching over most of the Czech Republic, eastern Germany, southern Poland and northern Austria. Th ...

, the

Spessart Spessart () is a ''Mittelgebirge'', a range of low wooded mountains, in the States of Bavaria and Hesse in Germany. It is bordered by the Vogelsberg, Rhön and Odenwald. The highest elevation is the Geiersberg (Spessart), Geiersberg at 586 metre ...

, the

Odenwald The Odenwald () is a low mountain range in the Germany, German states of Hesse, Bavaria and Baden-Württemberg. Location The Odenwald is located between the Upper Rhine Plain with the Bergstraße Route, Bergstraße and the ''Hessisches Ried' ...

, the northern parts of the

Black Forest The Black Forest ( ) is a large forested mountain range in the States of Germany, state of Baden-Württemberg in southwest Germany, bounded by the Rhine Valley to the west and south and close to the borders with France and Switzerland. It is th ...

and

Vosges The Vosges ( , ; ; Franconian and ) is a range of medium mountains in Eastern France, near its border with Germany. Together with the Palatine Forest to the north on the German side of the border, they form a single geomorphological unit and ...

and the southern part of the

Taunus The Taunus () is a mountain range in Hesse and Rhineland-Palatinate, Germany, located north west of Frankfurt and north of Wiesbaden. The tallest peak in the range is '' Großer Feldberg'' at 878 m; other notable peaks are '' Kleiner Feldberg' ...

. West of the Vosges

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its d ...

s on both sides of the

English Channel The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busi ...

are also seen as part of the zone, for example the Lizard complex in

Cornwall Cornwall (; or ) is a Ceremonial counties of England, ceremonial county in South West England. It is also one of the Celtic nations and the homeland of the Cornish people. The county is bordered by the Atlantic Ocean to the north and west, ...

or the Léon Zone of the

Armorican Massif The Armorican Massif (, ) is a geologic massif that covers a large area in the northwest of France, including Brittany, the western part of Normandy and the Pays de la Loire. It is important because it is connected to Dover on the British side o ...

(

Brittany Brittany ( ) is a peninsula, historical country and cultural area in the north-west of modern France, covering the western part of what was known as Armorica in Roman Gaul. It became an Kingdom of Brittany, independent kingdom and then a Duch ...

Location

In central Europe the Saxothuringian Zone is situated between the Rhenohercynian Zone to the northwest and the

Moldanubian Zone The Moldanubian Zone is in the regional geology of Europe a tectonic zone formed during the Variscan or Hercynian Orogeny (400 to 300 million years ago, during the Devonian and Carboniferous periods). The Moldanubian Zone crops out in the Bohemi ...

to the southeast. The Hercynian

metamorphism Metamorphism is the transformation of existing Rock (geology), rock (the protolith) to rock with a different mineral composition or Texture (geology), texture. Metamorphism takes place at temperatures in excess of , and often also at elevated ...

of the former zone is generally lower grade; that of the latter zone higher grade than that of the Saxothuringian Zone. West of the Vosges the zone is displaced to the north by a major

strike-slip fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

, the Bray Fault. The Saxothuringian Zone is in some places transected by Permo-

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

graben In geology, a graben () is a depression (geology), depressed block of the Crust (geology), crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German language, German, meaning 'ditch' or 't ...

s and intramontane basins filled with

Rotliegend The Rotliegend, Rotliegend Group or Rotliegendes () is a lithostratigraphic unit (a sequence of rock strata) of latest Carboniferous to Guadalupian (middle Permian) age that is found in the subsurface of large areas in western and central Europe ...

sediments and older deposits. The Eger Graben in the northwest of the

Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...

and the Saar-Nahe Basin in western

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

are examples of such structures.

Geology

The Saxothuringian Zone consists of early

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

marine sediments that were deposited in the ''Saxothuringian Basin''. They were slightly metamorphosed during the Hercynian orogeny. The sedimentary sequence is assumed to be continuous from the

Ediacaran The Ediacaran ( ) is a geological period of the Neoproterozoic geologic era, Era that spans 96 million years from the end of the Cryogenian Period at 635 Million years ago, Mya to the beginning of the Cambrian Period at 538.8 Mya. It is the last ...

to the Visean (330 million years ago). These metasediments form a wide zone north of the city of

Dresden Dresden (; ; Upper Saxon German, Upper Saxon: ''Dräsdn''; , ) is the capital city of the States of Germany, German state of Saxony and its second most populous city after Leipzig. It is the List of cities in Germany by population, 12th most p ...

Saxony Saxony, officially the Free State of Saxony, is a landlocked state of Germany, bordering the states of Brandenburg, Saxony-Anhalt, Thuringia, and Bavaria, as well as the countries of Poland and the Czech Republic. Its capital is Dresden, and ...

. Tectonostratigraphically,

gneiss Gneiss (pronounced ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. This rock is formed under p ...

es (high-grade metamorphic rocks) and

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

s are found under these metasediments. They crop out as the competent

massif A massif () is a principal mountain mass, such as a compact portion of a mountain range, containing one or more summits (e.g. France's Massif Central). In mountaineering literature, ''massif'' is frequently used to denote the main mass of an ...

s of the

Ore Mountains The Ore Mountains (, or ; ) lie along the Czech–German border, separating the historical regions of Bohemia in the Czech Republic and Saxony in Germany. The highest peaks are the Klínovec in the Czech Republic (German: ''Keilberg'') at ab ...

and Saxonian Granulite Massif. They were deformed and recrystallized during the Cadomian orogeny (in the Ediacaran, 650-550 million years ago) and intruded by

felsic In geology, felsic is a grammatical modifier, modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted ...

pluton In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s during the

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

and

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

(540-420 million years ago). In some places klippes of

allochthonous River ecosystems are flowing waters that drain the landscape, and include the biotic (living) interactions amongst plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions of its many parts.Angelier ...

crystalline rock A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosco ...

s are found on top of these two units. These klippes are the Münchberg complex, Wildenfels complex and Frankenberg complex. They consisted originally of a sequence of deep-marine (

flysch Flysch () is a sequence of sedimentary rock layers that progress from deep-water and turbidity flow deposits to shallow-water shales and sandstones. It is deposited when a deep basin forms rapidly on the continental side of a mountain building ep ...

) sediments of Ordovician to

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

age (480-360 million years old) and early Paleozoic mid-oceanic ridge basalts. The latter have been metamorphosed at a high grade (up to eclogite facies). These allochthonous

nappe In geology, a nappe or thrust sheet is a large sheetlike body of rock that has been moved more than or above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the ...

s can probably be correlated with the Teplá terrane in the Moldanubian Zone further south. The Saxothuringian Zone is often also supposed to include the Mid-German Crystalline High, which then forms the northern part of the zone and lies directly next to the Rhenohercynian Northern Phyllite Zone. The Mid-German Crystalline High crops out in the Odenwald, the Spessart and the northern Vosges. It consists of

Proterozoic The Proterozoic ( ) is the third of the four geologic eons of Earth's history, spanning the time interval from 2500 to 538.8 Mya, and is the longest eon of Earth's geologic time scale. It is preceded by the Archean and followed by the Phanerozo ...

orthogneisses and early Paleozoic

volcanic A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...

(

amphibolite Amphibolite () is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose ...

s with MORB-

protolith A protolith () is the original, unmetamorphosed rock from which a given metamorphic rock is formed. For example, the protolith of a slate is a shale or mudstone. Metamorphic rocks can be derived from any other kind of non-metamorphic rock and ...

s and

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock co ...

s) and

sedimentary Sedimentary rocks are types of rock formed by the cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedime ...

(

pelite A pelite () or metapelite is a metamorphism, metamorphosed fine-grained sedimentary rock, i.e. mudstone or siltstone. The term was earlier used by geologists to describe a clay-rich, fine-grained clastic sediment or sedimentary rock, i.e. mud or ...

s, calcareous

schist Schist ( ) is a medium-grained metamorphic rock generally derived from fine-grained sedimentary rock, like shale. It shows pronounced ''schistosity'' (named for the rock). This means that the rock is composed of mineral grains easily seen with a l ...

s and

marble Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO3) or Dolomite (mineral), dolomite (CaMg(CO3)2) that have recrystallized under the influence of heat and pressure. It has a crystalline texture, and is ty ...

s) rocks that were metamorphosed at high grade during the Hercynian orogeny (up to

amphibolite facies Amphibolite () is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (fl ...

). These rocks were intruded by two generations of plutons:

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

Early Devonian The Early Devonian is the first of three Epoch (geology), epochs comprising the Devonian period, corresponding to the Lower Devonian Series (stratigraphy), series. It lasted from and began with the Lochkovian Stage , which was followed by the Pr ...

(440-400 million years old)

granitoid A granitoid is a broad term referring to a diverse group of coarse-grained igneous rocks that are widely distributed across the globe, covering a significant portion of the Earth's exposed surface and constituting a large part of the continental ...

s and middle

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

(Hercynian, 340-325 million years old) granites.Oncken (1997); Franke (2000)

Notes

Bibliography

*; 1992: ''Phanerozoic structures and events in central Europe'', in: (''eds.''): ''A Continent Revealed - The European Geotraverse'', 297 pp., Cambridge University Press, , pp. 164–179. *; 2000: ''The mid-European segment of the Variscides: tectonostratigraphic units, terrane boundaries and plate tectonic evolution'', in: (''eds.''); ''Orogenic Processes, Quantification and Modelling in the Variscan Belt'', Geological Society of London, Special Publications 179, pp. 35–61. *; 1927: ''Gliederung des varistischen Gebirgsbaues'', Abhandlungen des Sächsischen Geologischen Landesamtes 1, pp. 1–39. *; 2007: ''The Variscan orogeny in the Saxo-Thuringian zone - heterogeneous overprint of Cadomian/Paleozoic Peri-Gondwana crust'', in: (''eds.''): ''The evolution of the Rheic Ocean: from Avalonian-Cadomian active margin to Alleghenian-Variscan collision'',

Geological Society of America The Geological Society of America (GSA) is a nonprofit organization dedicated to the advancement of the geosciences. History The society was founded in Ithaca, New York, in 1888 by Alexander Winchell, John J. Stevenson, Charles H. Hi ...

Special Paper 423 pp. 153–172. *; 1995: ''The Neoproterozoic terranes of Saxony (Germany)'', Precambrian Research 73, pp. 235–250. *; 2001: ''The Variscan collage and orogeny (480±290 Ma) and the tectonic definition of the Armorica microplate: a review'', Terra Nova 13, 122-128. *; 1990: ''Terrane boundaries in the Bohemian Massif: Result of large-scale Variscan shearing'', Tectonophysics 177, pp. 151–170. *; 1997: ''Transformation of a magmatic arc and an orogenic root during oblique collision and its consequences for the evolution of the European Variscides (Mid-German Crystalline Rise)'', Geologische Rundschau 86, pp. 2–20. *; 2003: ''Gondwana-derived microcontinents — the constituents of the Variscan and Alpine collisional orogens'', Tectonophysics 365, pp. 7–22. *; 2010:
Pre-Mesozoic Geology of Saxo-Thuringia
' 488 p. *; 2003: ''Erdgeschichte – Die Entstehung der Kontinente und Ozeane'', 325 pp., Walter de Gruyter, Berlin (5^e druk), . {{Geology of Europe Geology of Germany Hercynian orogeny Geology of Europe

Location

Geology

See also

Notes

Bibliography