Germanic Trias

The Germanic Triassic is composed of the lithostratigraphic units of red sandstone, Muschelkalk and Keuper geological Super group of middle earth's history, the Mesozoic. The succession of its layers was - not least because of their often distinctive coloring - explored relatively early.

Formerly the individual subdivisions of the Germanic Triassic were treated as concepts of time, some even equated with the Lower, Middle and Upper Triassic. However, this is due to recent research untenable, since the beginning or the end of each lithostratigraphic units in some cases regional is quite different and do not coincide with the boundaries of the Triassic series. The lithostratigraphic group of the Germanic Triassic is limited to the Central European area north of the Alps. In the Alps ( and south of ) the triad is formed as Alpine-Mediterranean Triassic.

History

The system of the Triassic was founded in 1834 by Friedrich von Alberti. He was guided by the typical three breakdown of deposits ( Buntsandstein, Muschelkalk and Keuper ) in central and southern Germany. It is the only geological system that has been set up in Germany. The names of sandstone, limestone and Keuper rich partially back in the 18th century. For a long time they were seen as concepts of time. Recent research has revealed, however, that they are depending on the region of different ages. At the border areas, for example, the shell will be nearly completely. Local is formed only small powerful of red sandstone. Very different and the Keuper in Central Europe is developed. In recent times has now passed to define Bunter, Muschelkalk and Keuper as exclusively lithostratigraphic units in the hierarchical lithostratigraphic rank of a group. All three units are combined into a lithostratigraphic supergroup Germanic Triassic.

Definition

The supergroup Germanic Trias is on average about 800 m thick. However, the widths vary regionally very strong. Regional can, for example, the sandstone be mighty alone up to 1400 m in Lower Saxony. It is composed of the three lithostratigraphic groups Bunter, Muschelkalk and Keuper. Only the shell represents a predominantly marine education, Buntsandstein and Keuper are primarily determined festländisch. The lower limit (and thus the limit Zechstein / sandstone ) is defined in the pelvic center with the onset of Calvörde sequence. In the Spessart and Odenwald, the lower limit of the red sandstone is the lower limit of Heigenbrucken - sandstone. In the Black Forest, the limit is applied to the base of the so-called Eck'schen conglomerate. The type area of the Germanic Triassic is Central Europe, where the unit is formed at the most. It is the center of the Germanic Basin, the large areas of Central and Western Europe included in the Triassic to the North and Baltic Seas.

According to recent biostratigraphic studies, the lower limit of the red sandstone group and thus the Germanic Triassic super group to settle in the highest part of the Changhsingium, the highest chronostratigraphic stage of the Permian. The Germanic Triassic is superimposed by the law, but in between a gap layer is formed. According to biostratigraphic data, the upper limit of the Keuper and thus the Germanic Triassic supergroup is the chronostratigraphic Rhaetian stage, but still well ahead of the chronostratigraphic Triassic / Jurassic boundary. Especially in the Keuper are also greater between the formations layer gaps, ie that large sections of the Upper Triassic are not documented by sediments. Under the current correlation of the Germanic Triassic chronostratigraphy and geochronology thus extends from about 252 to about 200.5 million years .. The boundaries of the lithostratigraphic unit Germanic Trias not differ greatly from the chronostratigraphic boundaries of the Triassic, but are against the international chronostratigraphic boundaries slightly shifted back in time.

Subdivision

The well-known tripartite division of the Germanic Triassic, from the name is derived, has already been addressed. Accordingly, the lithostratigraphic unit Germanic Trias supergroup is divided into three lithostratigraphic groups:

• Keuper ( further subdivided into Lower, Middle and Upper Keuper, these units are considered as subgroups )
• Muschelkalk ( further subdivided into Lower, Middle and Upper Muschelkalk: be construed as subgroups in the hierarchy of lithostrafischen units)
• Sandstone ( further subdivided into Lower, Middle and Upper Bunter: be construed as sub-groups in the hierarchy of lithostrafischen units)

The groups of the Germanic Triassic can be very difficult to attach to the international chronostratigraphic stages. This is due to the almost total absence of fossils that can be used for biostratigraphic dating. The Ammonites have gone through their own development, such as limestone. Today we would say they were endemic in the Germanic Basin. The Zechstein / sandstone boundary is located in the central basin parts already in Oberchanghsingium. The sandstone / Muschelkgrenze is currently dated to the Unteranis, the Muschelkalk / Keuper boundary approximately in the middle Ladin. The Keuper from the Middle Ladinian to Rhaetian and represents by far the longest of the three groups of the Germanic Triassic.

The Alpine - Mediterranean Triassic

This Germanic Trias facing the Alpine Triassic or, more generally, the Alpine-Mediterranean Triassic. It is also called " pelagic Triassic " and was deposited in the peripheral areas of the Tethys Ocean. It is usually much more powerful and predominantly marine. There are flachmeerische Riffkomplexe next stratified deposits of clays, limestones and marls that have arisen in deeper water. The names of chronostratigraphic stages of the Triassic were mainly characterized in the Alps, only the names of the stages of the Triassic were set up in other areas: Indus, Olenek, anise, Ladin, Karn, Nor and Advises.