The Kössen Formation is a

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...

(

Rhaetian The Rhaetian is the latest age (geology), age of the Triassic period (geology), Period (in geochronology) or the uppermost stage (stratigraphy), stage of the Triassic system (stratigraphy), System (in chronostratigraphy). It was preceded by the N ...

-age)

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

in the

Northern Calcareous Alps The Northern Limestone Alps (), also called the Northern Calcareous Alps, are the ranges of the Eastern Alps north of the Central Eastern Alps located in Austria and the adjacent Bavarian lands of southeastern Germany. The distinction from the l ...

Austria Austria, formally the Republic of Austria, is a landlocked country in Central Europe, lying in the Eastern Alps. It is a federation of nine Federal states of Austria, states, of which the capital Vienna is the List of largest cities in Aust ...

and

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 ...

, in the Tiroler-Lech Nature Park. During the Late Triassic, the area now occupied by the Northern Calcareous Alps was instead a long, passive coastline at the western tip of the Neotethys Ocean. The environment was initially dominated by a wide and shallow

carbonate platform A carbonate platform is a Sedimentary rock, sedimentary body which possesses topographic relief, and is composed of Autochthon (geology), autochthonic calcareous deposits. Platform growth is mediated by Sessility (zoology), sessile organisms whose ...

within a

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') an ...

between the shore and a string of reefs. This carbonate platform is nowadays preserved as the

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...

Norian The Norian is a division of the Triassic geological period, Period. It has the rank of an age (geology), age (geochronology) or stage (stratigraphy), stage (chronostratigraphy). It lasted from ~227.3 to Mya (unit), million years ago. It was prec ...

-age Hauptdolomit and Dachstein Formation. The Kössen Formation represents a period of increased

siliciclastic Siliciclastic (or ''siliclastic'') rocks are clastic noncarbonate sedimentary rocks that are composed primarily of silicate minerals, such as quartz or clay minerals. Siliciclastic rock types include mudrock, sandstone Sandstone is a Clastic ...

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...

input into the lagoon, covering up the carbonate platform with

marl Marl is an earthy material rich in carbonate minerals, Clay minerals, clays, and silt. When Lithification, hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. M ...

s and marly

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

s instead of pure limestone or dolomite. The Eiberg Member of the Kössen Formation was deposited in the Eiberg basin, a narrow strip of deeper water which developed between the carbonate platform and the shoreline in the later part of the Rhaetian.

References

External links

* * Triassic System of Europe Triassic Austria Triassic Germany Triassic Switzerland Geology of the Alps {{Triassic-stub

See also

References

External links