Germanic Trias
Encyclopedia
The Germanic Trias Supergroup is a lithostratigraphic
unit (a sequence of rock strata) in the subsurface of large parts of western and central Europe
(north of the Alps
) and the North Sea
. Almost all of the Germanic Trias was deposited during the Triassic
period and consists of three clearly different units: Buntsandstein
, Muschelkalk
and Keuper
, that gave the period its name (Triassic means "threefold"). In the past the names of these three units were also used as units in the geologic timescale, but in modern literature they only have a lithostratigraphic meaning.
that covered much of midwestern Europe (including the south of the North Sea and Baltic Sea
) during the Triassic. The Muschelkalk has a predominantly marine
facies whereas the Buntsandstein and Keuper are mostly continental
.
Zechstein Group and below Lower Jurassic units, such as the Lias Group
or Altena Group.
The base is not defined in the same way everywhere. In northern Germany the base is formed by the Calvörde Beds, in the Spessart
and Odenwald
by the base of the Heigenbrücken-Sandstone. Radiometric dating
has shown the age of the Germanic Trias is not totally corresponding with the Triassic period. The base of the Buntsandstein was formed during the Changhsingian
, the uppermost stage of the Permian, about . The top of the Keuper is Rhaetian
in age and at about at least a few million years older than the Triassic-Jurassic boundary. Usually there is a stratigraphic hiatus between the base of the Lias and top of the Germanic Trias.
In German lithostratigraphy, Buntsandstein, Muschelkalk and Keuper are seen as groups
. Dutch
lithostratigraphy divides the Germanic Trias along other boundaries in a Lower Germanic Trias Group and an Upper Germanic Trias Group. The Dutch Keuper and Muschelkalk have the status of formations while the Dutch Buntsandstein is subdivided in a number of formations. The Bunter
of British stratigraphy is similar in age, lithology
and facies to the Buntsandstein.
Lithostratigraphy
Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology...
unit (a sequence of rock strata) in the subsurface of large parts of western and central Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
(north of the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
) and the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
. Almost all of the Germanic Trias was deposited during the Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
period and consists of three clearly different units: Buntsandstein
Buntsandstein
The Buntsandstein or Bunter sandstone is a lithostratigraphic and allostratigraphic unit in the subsurface of large parts of west and central Europe...
, Muschelkalk
Muschelkalk
The Muschelkalk is a sequence of sedimentary rock strata in the geology of central and western Europe. It has a Middle Triassic age and forms the middle part of the Germanic Trias, that further consists of the Buntsandstein and Keuper...
and Keuper
Keuper
The Keuper is a lithostratigraphic unit in the subsurface of large parts of west and central Europe. The Keuper consists of dolostone, shales or claystones and evaporites that were deposited during the Middle and Late Triassic epochs...
, that gave the period its name (Triassic means "threefold"). In the past the names of these three units were also used as units in the geologic timescale, but in modern literature they only have a lithostratigraphic meaning.
Origin
The Germanic Trias formed in the large Germanic Basin, a basinBasin (geology)
A structural basin is a large-scale structural formation of rock strata formed by tectonic warping of previously flat lying strata. Structural basins are geological depressions, and are the inverse of domes. Some elongated structural basins are also known as synclines...
that covered much of midwestern Europe (including the south of the North Sea and Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
) during the Triassic. The Muschelkalk has a predominantly marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
facies whereas the Buntsandstein and Keuper are mostly continental
Continental
Continental is the adjective form of continent.Continental may also refer to:* Continental , an album by UK band Saint Etienne* Continental , a brand of dried and pre-packaged foods used by Unilever in Australia...
.
Stratigraphy
In the central parts of the Germanic Basin, the Germanic Trias has an average thickness of 800 meters, but regional differences are considerable. In the north of Germany the thickness of the Buntsandstein alone can exceed 1400 meters. The Germanic Trias lies on top of the PermianPermian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
Zechstein Group and below Lower Jurassic units, such as the Lias Group
Lias Group
The Lias Group or Lias is a lithostratigraphic unit found in a large area of western Europe, including the British Isles, the North Sea, the low countries and the north of Germany...
or Altena Group.
The base is not defined in the same way everywhere. In northern Germany the base is formed by the Calvörde Beds, in the Spessart
Spessart
The Spessart is a low mountain range in northwestern Bavaria and southern Hesse, Germany. It is bordered on three sides by the Main River. The two most important towns located at the foot of the Spessart are Aschaffenburg and Würzburg....
and Odenwald
Odenwald
The Odenwald is a low mountain range in Hesse, Bavaria and Baden-Württemberg in Germany.- Location :The Odenwald lies between the Upper Rhine Rift Valley with the Bergstraße and the Hessisches Ried in the west, the Main and the Bauland in the east, the Hanau-Seligenstadt Basin – a subbasin of...
by the base of the Heigenbrücken-Sandstone. Radiometric dating
Radiometric dating
Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...
has shown the age of the Germanic Trias is not totally corresponding with the Triassic period. The base of the Buntsandstein was formed during the Changhsingian
Changhsingian
In the geologic timescale, the Changhsingian or Changxingian is the latest age or uppermost stage of the Permian. It is also the upper or latest of two subdivisions of the Lopingian epoch or series. The Changhsingian lasted from 253.8 ± 0.7 to 251.0 ± 0.7 million years ago...
, the uppermost stage of the Permian, about . The top of the Keuper is Rhaetian
Rhaetian
The Rhaetian is in geochronology the latest age of the Triassic period or in chronostratigraphy the uppermost stage of the Triassic system. It lasted from 203.6 ± 1.5 to 199.6 ± 0.6 million years ago...
in age and at about at least a few million years older than the Triassic-Jurassic boundary. Usually there is a stratigraphic hiatus between the base of the Lias and top of the Germanic Trias.
In German lithostratigraphy, Buntsandstein, Muschelkalk and Keuper are seen as groups
Group (stratigraphy)
A group in stratigraphy is a lithostratigraphic unit, a part of the geologic record or rock column that consists of defined rock strata. Groups are divided into formations and are sometimes themselves grouped into "supergroups"....
. Dutch
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
lithostratigraphy divides the Germanic Trias along other boundaries in a Lower Germanic Trias Group and an Upper Germanic Trias Group. The Dutch Keuper and Muschelkalk have the status of formations while the Dutch Buntsandstein is subdivided in a number of formations. The Bunter
Bunter (geology)
Bunter beds are sandstone deposits containing rounded pebbles, such as can notably be found in Warwickshire, Cheshire, Staffordshire, Nottinghamshire, Yorkshire, Devon and Dorset in England...
of British stratigraphy is similar in age, lithology
Lithology
The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples or with low magnification microscopy, such as colour, texture, grain size, or composition. It may be either a detailed description of these characteristics or be a summary of...
and facies to the Buntsandstein.